This Article Full Text (PDF) Purchase Article View Shopping Cart Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Copyright Permission Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by MacLaughlin, D. T. Articles by Donahoe, P. K. Search for Related Content PubMed PubMed Citation Articles by MacLaughlin, D. T. Articles by Donahoe, P. K.

Perspective: Reproductive Tract Development—New Discoveries and Future Directions

Pediatric Surgical Research Laboratories Massachusetts General Hospital Boston, Massachusetts 02114

Address all correspondence and requests for reprints to: Patricia K. Donahoe, M.D., Pediatric Surgical Research Laboratories, Warren 10, Massachusetts General Hospital, Boston, Massachusetts 02114. E-mail: pdonahoe{at}partners.org

	Introduction

Top Introduction Reproductive tract development... Fetal development of male... Genetic control of testis... MIS and testosterone: generation... Gonadal position Generation of the female... Future directions References

 
At first glance, sexual reproduction among animals with sex organs seems to be accomplished by a wide variety of species-specific processes. Fertilization can be internal or external requiring no intromission, and animals can be oviparous, viviparous, and even ovoviviparous. The number of viable offspring per mating can vary from one to thousands, and gestation can take anywhere from days to nearly 2 yr to complete, depending upon the species. Ovulation itself can be reflex in nature, induced by the act of copulation, or it can be completely unrelated to the mating process.

Closer examination of the process, however, reveals many unmistakable similarities in this array of phenotypic differences. Mature sperm and oocytes have to be produced by testes and ovaries and brought into close proximity with one another. If fertilization results, there needs to be a suitable place for embryonic and fetal development to take place, and there must be a process whereby the new member of the species is introduced into its environment. Clearly, there are species-dependent solutions to these problems, but the overarching theme is common among all sexually reproducing animals: namely, all species need a mechanism to ensure that males and females are produced in nearly equal numbers in each breeding cycle to ensure future propagation of their kind. Subsequent sex-dependent gene expression functions to develop two distinct male and female phenotypes.

The development of two distinct reproductive systems is, in fact, accomplished by basic molecular mechanisms that share a great deal of homology across species. Studies conducted in one species, therefore, can yield extremely relevant information to others, just as is true for the remarkable conservation of cell cycle control proteins, transcription machinery, and DNA repair enzymes from yeast to humans. These processes are initially completely independent of the sex of the developing animal, and they produce sexually indifferent structures with the capacity to be either the male or female reproductive tracts. That is, both male and female embryos develop Wolffian ducts and Müllerian ducts, but only one of these precursor ductal systems will survive as a functional reproductive tract. At a specific point in embryonic development, the genetic sex of the animal is declared, the organization of testes or ovaries is initiated, and the subsequent differentiation of male and female reproductive tract phenotypes is begun. What follows is an overview of much of what is known about the process of reproductive tract development and a discussion of some interesting challenges for the future.

	Reproductive tract development begins in the embryo and is sex independent

Top Introduction Reproductive tract development... Fetal development of male... Genetic control of testis... MIS and testosterone: generation... Gonadal position Generation of the female... Future directions References

 
The development of the reproductive tract is a process that begins shortly after the creation of a zygote at fertilization and continues throughout incubation in the case of oviparous species and gestation for viviparous animals. The duration of these periods varies among species. For example, in the human, the embryonic period spans weeks 2–8 of gestation, whereas the remaining 32 weeks are the fetal period; but in rodents, the embryonic and fetal periods are of near equal length and comprise a total of 3 weeks. However, the process is not complete until after birth as adolescents mature into adults with the capacity to reproduce sexually. This Perspective will focus on the development of embryonic and fetal reproductive tracts. The development of the adult reproductive tract is the subject of other Perspectives in this issue of Endocrinology.

The reproductive tract is defined as the structures derived from the Müllerian ducts in females, those from the Wolffian ducts in males, the testes and ovaries, and the relevant external genitalia arising from the urogenital tubercle and labioscrotal structures. The ducts and gonads have their embryonic origins in the tissues of the urogenital ridge that arise from the enlarging intermediate mesoderm that forms upon gastrulation, becomes populated with germ cells, and undergoes continued growth and morphogenesis during the embryonic period (Fig. 1A).

View larger version (38K): [in this window] [in a new window]   Figure 1. A, Formation of the urogenital ridge in the embryo. The development of the intermediate mesoderm into the urogenital ridge during the embryonic period sets the stage for later differentiation into the gonads, Wolffian and Müllerian ducts. Under the control of several sex-independent genes, the ridge takes shape awaiting the sex-dependent signals that will evoke gonadal identity and the subsequent reproductive duct growth. B, Gonadogenesis and reproductive duct development. Later in embryonic development at least six gonad-determining genes (SF-1, Lim 1, WT-1, GATA-4, Lhx 9, and Emx2) direct formation of the indifferent gonads from the intermediate mesoderm. Absence of any of these genes blocks gonadal development. Thereafter, in males the genes necessary for normal testes, Sry, SF-1, Sox-9, and Dhh act to produce the gonad. The secretion of testosterone and MIS ensure the development of the normal male phenotype. In females, on the other hand, the lack of male determining genes allows for the development of ovaries. Wnt-4, Fa, and several of the Hoxa genes promote the proper growth and development of the Fallopian tubes, uterus, cervix, and vagina.

Another gene whose expression is critical for normal reproductive tract determination is Wnt-4. This ligand is expressed in the coelomic epithelium that invaginates to form the Müllerian duct and then in the mesenchyme surrounding the duct. Wnt-4 is a member of the Wg/wnt family of secreted proteins that function in intracellular communication via the frizzled family of receptors and are required for early pattern formation, cell fates, and polarity (7, 8). Wnt4 knockout has no consequence for the male reproductive tract because it is not expressed in Wolffian ducts, but females in whom the gene was deleted do not have Müllerian duct-derived internal reproductive structures. Although Wnt-4 is required for Müllerian duct formation in both males and females, and thus, is not sex specific, it is only in females that its functional expression persists. Nephrogenesis (8, 9) depends upon Wnt-4 because both males and females die at birth with renal agenesis. The association of Müllerian and renal agenesis in Rokitansky Hauser syndrome in which the uterus is absent and the kidney on one side is absent, abnormal, and/or ectopically positioned in the pelvis, implicates Wnt-4 or its pathway in this disorder. Bilaterality is lethal, however, and patients who normally have unilateral defects are probably reflective of a hypomorphic mutation.

Wnt-7a, another member of the family, is also required for Müllerian duct differentiation. Viable mice lacking Wnt-7a ligand have limb defects and are infertile; males had persistent Müllerian ducts attributed to the failure of Müllerian Inhibiting Substance (MIS) type II receptor expression and females had poorly differentiated Müllerian duct derived structures (10). Wnt-7a, therefore, normally mediates the expression of the MIS type II receptor (see below) allowing complete regression of the Müllerian duct in males. Poor Müllerian duct development in females implies a role for Wnt-7a in the subsequent differentiation of this tissue. It is interesting to note that diethylstilbestrol, a synthetic estrogen known to cause uterine anomalies in fetal females (11), suppresses Wnt-7a expression (12) and alters the expression of Hoxa 9 and 10 (13). Although the exact mechanism involved with DES is unknown, these findings may, in part, explain the molecular pathophysiology of the defects observed in the so-called DES babies (14). The effects of disrupting Wnt-7a on the female tract are not due to any affect of homozygous deletion of the gene on gonadal function or hormonal regulation since the ovaries undergo normal follicular growth, ovulation, and cycling, but to a defect intrinsic to the Müllerian duct.

At the end of this embryonic phase the anlagen of all major structures are present but organogenesis is incomplete and genetic males and females are virtually indistinguishable. The genes thus far identified are involved in processes intrinsic to tissue patterning and axis formation rather than the sex-specific development, which occurs after gonadal differentiation. The identification of these early genes and the nature of the genes regulated by them open new areas of investigation and link the development of the urinary and genital tracts at this stage of their ontogeny. The Wilms’ tumor factor, WT1 (15), and the steroidogenic factor, SF-1 (16), are other examples of factors that when mutated fail to develop both urinary tracts and gonads with subsequent consequences for reproductive tract development. Both will be important in regulating genes such as MIS that are important in sex differentiation later in development, as well, as is GATA-4, another transcriptional regulator, also expressed in primitive gonads in both male and female embryos (17). In males, GATA-4 expression continues in somatic cells of the testes throughout development but is transient in the ovary suggesting a role in sexually dimorphic development in the gonads (17).

	Fetal development of male and female reproductive tracts is sex specific

Top Introduction Reproductive tract development... Fetal development of male... Genetic control of testis... MIS and testosterone: generation... Gonadal position Generation of the female... Future directions References

 
Reproductive tract development becomes sexually dimorphic, producing two distinct phenotypes emerging under the control in mammals, for example, of two distinct pairs of sex chromosomes, XX for females and XY for males. This process, which is well cataloged anatomically in nearly all species, begins in the embryo and continues well after birth and can take years to complete, as is the case in humans. A number of sex-specific genes have been found to regulate gonadal differentiation and subsequent male and or female reproductive duct development.

It is at the transition from embryonic life, which is completely independent of the sex chromosomes, to fetal life that the genetic sex of embryos is declared as primordial gonads are induced to differentiate into testes or ovaries according to their chromosomal complement to direct further development (Fig. 1B). In males, the newly formed testes produce testosterone, which stimulates the differentiation of the Wolffian ducts into the epididymides, vas deferens, and the seminal vesicles while MIS, also known as anti-Müllerian hormone, is secreted by the fetal Sertoli cells and ablates the Müllerian duct. In females, in the absence of MIS, the Müllerian ducts, which have formed from an invagination of the coelomic epithelium, become the uterus, cervix, upper third of the vagina, and the Fallopian tubes. The coelomic epithelium persists as the lining of the ovaries. Because testosterone is required for the development of the Wolffian ducts, in its absence they atrophy. There does not appear to be a female homolog of MIS for the Wolffian ducts.

The external genitalia of both sexes arise from the genital tubercle and the urogenital folds that differentiate from the underlying mesenchyme in the embryonic period. In males dihydrotestosterone, a steroid 5- reduced metabolite of testosterone, stimulates growth of the phallus. There are two 5- reductase enzymes, called 1 and 2, that convert testosterone to DHT (18). Mutations in type 2, which is expressed in liver and gonad and genital skin, results in male pseudo-hermaphroditism (19). The female external genitalia develop autonomously in the fetus requiring no hormonal stimuli at this stage.

	Genetic control of testis and ovarian differentiation

Top Introduction Reproductive tract development... Fetal development of male... Genetic control of testis... MIS and testosterone: generation... Gonadal position Generation of the female... Future directions References

 
The testis determining factor gene product, SRY (sex-related gene on the Y chromosome), which is expressed in the intermediate mesoderm at the end of embryonic development, is a nuclear transcription factor that is absolutely required to produce normal testes in mammals, as shown in Sry mutated mice (20), and mutations in the human homolog of this are associated with sex reversal (21). SRY is assumed to be a transcription factor because its homology to the HMG family but a direct target for the transcriptional regulation has yet to be described (22). Structural mutations and transcriptional analyses point to a requirement for DNA binding and bending for functional activation by SRY (22, 23). SRY may, more importantly, provide a nuclear scaffold to allow better access of transcription factors to the promoter regions of genes required for male-specific differentiation. In mice Desert hedgehog, Dhh, is another male specific gonadal gene, which functions after the action of Sry to signify early testicular differentiation. Dhh regulates Sertoli-germ cell interactions; homozygous knockout males have testes but they are azoospermic (24). Although not required for testis formation, estradiol does play a role in normal spermatogenesis. Adult male mice in which the estradiol -receptor has been mutated have greatly reduced sperm counts and are infertile (25).

To date, no such gene has been identified for the generation of ovaries from indifferent gonads. DAX-1 (deleted in adrenal hypoplasia congenita from the X chromosome (26, 27, 28) was originally thought to be related to ovarian determination because a duplication of the dosage-sensitive sex reversal (DSS) locus on the X chromosome, which also contains the DAX-1 site, caused male to female sex reversal (29, 30). However, female mice deficient in DAX-1 have normal phenotypes and are fertile, but males exhibit abnormal testicular development and ultimately infertility (26). Therefore, DAX-1 is necessary for the maintenance of normal seminiferous tubule function in the adult (26). DAX-1, is a member of the nuclear hormone receptor superfamily and a potent transcription repressor. Recent studies show Dax-1 functions to suppress testicular development by blocking the transcriptional activity of SRY (31) indicating that normal gonadal development, particularly in the male relies on a proper balance of Sry and Dax-1 gene activities. DAX-1 also suppresses SF-1 (32) and GATA-4 function by engaging the corepressor NCoR (33). Wnt-4, previously described for its role in Müllerian duct determination in males and females, is also expressed in indifferent gonads. However, Wnt-4 expression ceases in the testes but it is preserved in the ovaries where it maintains oocyte number (8). The fact that Sox 9 (SRY-related homeobox protein 9) is mutated with patients with sex reversal associated with campomelic dysplasia (34), provides further evidence of its important role in male reproductive tract development (Fig. 1B).

	MIS and testosterone: generation of the male phenotype

Top Introduction Reproductive tract development... Fetal development of male... Genetic control of testis... MIS and testosterone: generation... Gonadal position Generation of the female... Future directions References

 
Once the testis begins to differentiate after the action of Sry, the fetal Leydig cells secrete testosterone and Sertoli cells release MIS. These two hormones have widely differing functions and mechanisms of action, but it is their combined activities that produce a normal male internal reproductive tract.

Testosterone binds to its intracellular receptor to function as a transcriptional regulator leading to the proliferation and differentiation of the Wolffian duct into the vas deferens, epididymis, and seminal vesicles. Absent testosterone or its functional receptor these events do not occur. These receptors are present first in the mesenchyme of the developing duct and the action of these cells, perhaps by paracrine mechanisms in response to the androgen, directs the epithelial cell compartment to its proper fate. Cunha and colleagues have shown, in both Wolffian and Müllerian ducts, the pivotal role played by the mesenchyme in the ultimate differentiation of these ducts (for reviews see Refs. 35, 36). Although the downstream genes regulated by testosterone in the Wolffian duct remain to be identified, the dependence of male tract development on this steroid hormone is undisputed. An experiment of nature, testicular feminization, proves this point. In the most extreme cases, genetic males with nonfunctioning testosterone receptors mature as phenotypic females. They have testes, although undescended; they lack Müllerian structures because of the action of MIS (see below), but they also lack any Wolffian duct derivatives.

The other well understood fetal testicular product of relevance to the reproductive tract is MIS. This protein is highly conserved among mammalian species and it is tightly regulated in a developmental and tissue-specific manner in fetal, neonatal, prepubertal, and adult Sertoli cells, and prepubertal and adult granulosa cells. This glycoprotein homodimer hormone, whose existence was predicted by the experiments of Professor Alfred Jost, is a member of the TGFß family of growth factors. Alfred Jost’s (37) in vivo embryonic experiments demonstrated the existence of what he called the Müllerian "l’hormone inhibitrice" or the "Müllerian inhibitor." After implanting embryonic testicular fragments in female rabbit embryos before sexual differentiation had begun, Jost found that the animals were masculinized externally. Internally they showed stimulation of Wolffian ducts and regression of the Müllerian ducts. Testosterone replacement alone masculinized the female embryos but did not cause regression of the Müllerian ducts leading him to conclude that there must be a testicular hormone in addition to testosterone that was responsible for Müllerian duct regression.

The MIS ligand interacts with the MIS type II serine threonine kinase receptor (38, 39, 40, 41, 42) and Type I receptors (42A, 43) that are expressed on the mesenchymal cell surfaces of the fetal Müllerian duct and by Sertoli cells and granulosa cells of both embryonic and adult gonads. Mice with mutated MIS type II receptor have retained Müllerian ducts, as do patients with persistent Müllerian duct syndrome often. Of the mutations in MIS type II receptor gene found in patients with this syndrome, a 27-bp deletion in exon 10 was the most common (44, 45). Because the homozygous female MIS type II receptor knockout mice have normal fecundity (42), it would appear that MIS is not required for either blastocyst implantation or fetal and embryonic development. Experiments to identify the signal transducing type I receptor suggest that ALK-2 (42A, 43, 46), or BMPR-IB (ALK 6) (47) might be functioning in this role, with the more conclusive evidence for function in the Müllerian duct mesenchyme falling to Alk-2 (42A, 43) because male mice homozygously deleted for Alk6 (48) do not have retained Müllerian ducts (43).

The up-regulation of MIS expression that occurs in the fetal male is driven by a complex combination of transcription factors (49) in which SF-1 and WT1 (50) combine with GATA-4 (33) and Sox 9 (51). In addition, disruption of the Sox9 gene, but not one of two SF-1 binding sites, in the MIS promoter significantly reduced MIS expression in vivo and caused sex reversal (52) indicating that a second SF-1 site is required for MIS expression (49). In fetal females and perhaps after puberty in males, the repressor Dax-1 suppresses the SF-1 (50) and GATA-4 driven activation of the MIS gene (33).

	Gonadal position

Top Introduction Reproductive tract development... Fetal development of male... Genetic control of testis... MIS and testosterone: generation... Gonadal position Generation of the female... Future directions References

 
A relatively late fetal event in reproductive tract development completes another sexually dimorphic phenotypic characteristic, namely the final positioning of the gonads. The ovaries remain in the pelvis held in place by the cranial suspensory ligament (CSL) adjacent to the kidneys, while the testes descend into the scrotum as the gubernaculum grows. For proper localization of the ovaries, therefore, the gubernaculum regresses in the absence of testosterone and the CSL remains. In males, the CSL is regressed by the action of testosterone, which also stimulates the gubernaculum to complete the abdominal descent into the scrotum.

It is now understood that at least two different molecules, both of these Leydig cell products, are required for testis descent and regression of the CSL in males, namely testosterone and Insl3. Insl3 is an insulin-like growth factor molecule (53), which may interact with a relaxin-like factor receptor (54). These two molecules stimulate gubernaculum growth, a process considered necessary for testicular descent (55). Hoxa10 (56, 57) and Hoxa11 (57) may also be involved in this process because knockouts of these genes leads to cryptorchid testes and abnormal gubernaculi. In male Insl3 knockout mice, the gubernaculum fails to develop and, therefore, the testes remain freely mobile in the abdomen (58). If the androgen receptor is also deleted in the Insl3-/- mice, the CSL does not regress under the action of testosterone and the testes occupy a position near the kidneys a location normally filled by the ovaries (58). Down-regulation of the Insl3 gene due to prenatal exposure to estrogens can lead to cryptorchidism (59), suggesting that a proper balance of androgen and estrogen exposure in utero must be achieved for normal male phenotypic development.

	Generation of the female phenotype

Top Introduction Reproductive tract development... Fetal development of male... Genetic control of testis... MIS and testosterone: generation... Gonadal position Generation of the female... Future directions References

 
In the absence of testes and therefore testosterone and MIS, the Müllerian ducts develop into the Fallopian tubes, uterus cervix, and the upper third of the vagina. The coelomic epithelium, which invaginates to form the Müllerian duct, also covers the ovary. Despite the expression of both types of estradiol receptor in the mesenchyme and subsequently the epithelium of the Müllerian duct, estrogens are not required for Müllerian duct development in utero (for a review see Ref. 60). ERKO animals (estrogen receptor knockouts) for both the and ß forms of the estradiol receptor show little impact on the development of any tissue whether in a male or female fetus. Female tract development appears normal although after birth the uterus, Fallopian tubes, cervix, and vagina lack normal responsiveness to estradiol and are hypoplastic. Additional proof that neither fetal estradiol nor another ovarian product is required for Müllerian duct development is found in the SF-1 knockout animals. The females lack adrenals and ovaries but have normal reproductive tracts (16). In addition, the males also lack gonads and adrenals but are sex reversed. The absence of testosterone leads, therefore, to disappearance of the Wolffian duct and Müllerian duct development progresses, thus reinforcing the concept of the female phenotype as an autonomous pathway of differentiation and development. Among the genes known to be required for normal Müllerian duct development, none are sex dependent. Wnt-7a, for example, induces the transcription of the type II receptor for MIS and males lacking functional Wnt-7a have retained Müllerian ducts, whereas females are infertile because they have later poorly differentiated Fallopian tubes and uteri.

	Future directions

Top Introduction Reproductive tract development... Fetal development of male... Genetic control of testis... MIS and testosterone: generation... Gonadal position Generation of the female... Future directions References

 
The quantity and quality of significant discoveries related to developmental biology and to the organogenesis and differentiated function of tissues over the last decade are staggering and will be enhanced as the sequences of the human and other genomes become increasingly available. The ability of a reasonably well equipped laboratory to conduct sophisticated genetic analyses, clone genes, express proteins, and either alone or by collaboration with specialized research centers, to create genetically altered animals, has revolutionized research and quickened the pace of discovery and the promise of greater relevance to human health and disease. It is really no longer necessary to discover a new gene but to discover how genes operate in a particular biological system. In this new era as scientists we enjoy an embarrassment of riches.

We have outlined many, but certainly not all, of the embryonic and fetal genes and factors involved in normal sexually dimorphic reproductive tract development. Most of the developmental genes encode either transcription factors or secreted ligands, but we must now determine which genes the transcription factors regulate and unravel the combinatorial molecular consequences of signaling activities of the ligands.

With that knowledge it will be possible to address a number of questions of a more systems-related nature. For example, how does testosterone alone direct the Wolffian development for males? What directs early growth and differentiation of the female reproductive tract that apparently requires no sex steroids? Are estrogens required at all for reproductive tract development before birth despite the presence of receptors in Müllerian ducts? Can there be a sex-specific role for estradiol in the embryo because both male and female fetuses are bathed in estrogen from the amniotic fluid and receptors are present in the mesenchyme of the reproductive ducts? Our next challenge is to determine the secondary signals from the mesenchyme to the epithelium to enhance or suppress growth and differentiation. Expression screens and microarray technology to identify differential gene expression and techniques to analyze small quantities of secreted proteins will permit these questions to be addressed. In vivo detection strategies that permit real time observations and analyses will further advance our understanding, and combinatorial bioinformatics will be essential to formulating new hypotheses. With these new tools at hand it is not difficult to imagine finally discovering the answers to the most intriguing questions that have plagued reproductive biologists for decades. These solutions, in turn, will open our eyes to other questions we had not considered asking.

Received March 13, 2001.

	References

Top Introduction Reproductive tract development... Fetal development of male... Genetic control of testis... MIS and testosterone: generation... Gonadal position Generation of the female... Future directions References

 

1. Tsang TE, Shawlot W, Kinder SJ, Kobayashi A, Kwan KM, Schughart K, Kania A, Jessell TM, Behringer RR, Tam PP 2000 Lim1 activity is required for intermediate mesoderm differentiation in the mouse embryo. Dev Biol 223:77–90[CrossRef][Medline]
2. Birk OS, Casiano DE, Wassif CA, Cogliati T, Zhao L, Zhao Y, Grinberg A, Huang S, Kreidberg JA, Parker KL, Porter FD, Westphal H 2000 The LIM homeobox gene Lhx9 is essential for mouse gonad formation. Nature 403:909–913[CrossRef][Medline]
3. Miyamoto N, Yoshida M, Kuratani S, Matsuo I, Aizawa S 1997 Defects of urogenital development in mice lacking Emx2. Development 124:1653–1664[Abstract]
4. Kuschert S, Rowitch DH, Haenig B, McMahon AP, Kispert A 2001 Characterization of Pax-2 regulatory sequences that direct transgene expression in the Wolffian duct and its derivatives. Dev Biol 229:128–140[CrossRef][Medline]
5. Shawlot W, Behringer RR 1995 Requirement for Lim1 in head-organizer function. Nature 374:425–430[CrossRef][Medline]
6. Taylor HS, Vanden Heuvel GB, Igarashi P 1997 A conserved Hox axis in the mouse and human female reproductive system: late establishment and persistent adult expression of the Hoxa cluster genes. Biol Reprod 57:1338–1345[Abstract]
7. Cadigan KM, Nusse R 1997 Wnt signaling: a common theme in animal development. Genes Dev 11:3286–3305[Free Full Text]
8. Vainio S, Heikkila M, Kispert A, Chin N, McMahon AP 1999 Female development in mammals is regulated by Wnt-4 signalling. Nature 397:405–409[CrossRef][Medline]
9. Stark K, Vainio S, Vassileva G, McMahon AP 1994 Epithelial transformation of metanephric mesenchyme in the developing kidney regulated by Wnt-4. Nature 372:679–683[CrossRef][Medline]
10. Parr BA, McMahon AP 1998 Sexually dimorphic development of the mammalian reproductive tract requires Wnt-7a. Nature 395:707–710[CrossRef][Medline]
11. Visser JA, McLuskey A, Verhoef-Post M, Kramer P, Grootegoed JA, Themmen AP 1998 Effect of prenatal exposure to diethylstilbestrol on Mullerian duct development in fetal male mice. Endocrinology 139:4244–4251[Abstract/Free Full Text]
12. Miller C, Degenhardt K, Sassoon DA 1998 Fetal exposure to DES results in de-regulation of Wnt7a during uterine morphogenesis. Nat Genet 20:228–230[CrossRef][Medline]
13. Block K, Kardana A, Igarashi P, Taylor HS 2000 In utero diethylstilbestrol (DES) exposure alters Hox gene expression in the developing mullerian system. Faseb J 14:1101–1108[Abstract/Free Full Text]
14. Ulfelder H, Poskanzer D, Herbst AL 1971 Stilbestrol-adenosis-carcinoma syndrome: geographic distribution. N Engl J Med 285:691
15. van Lingen BL, Reindollar RH, Davis AJ, Gray MR 1998 Further evidence that the WT1 gene does not have a role in the development of the derivatives of the Mullerian duct. Am J Obstet Gynecol 179:597–603[CrossRef][Medline]
16. Luo X, Ikeda Y, Lala DS, Baity LA, Meade JC, Parker KL 1995 A cell-specific nuclear receptor plays essential roles in adrenal and gonadal development. Endocr Res 21:517–524[Medline]
17. Viger RS, Mertineit C, Trasler JM, Nemer M 1998 Transcription factor GATA-4 is expressed in a sexually dimorphic pattern during mouse gonadal development and is a potent activator of the Mullerian inhibiting substance promoter. Development 125:2665–2675[Abstract]
18. Russell DW, Wilson JD 1994 Steroid 5 -reductase: two genes/two enzymes. Annu Rev Biochem 63:25–61[Medline]
19. Andersson S, Berman DM, Jenkins EP, Russell DW 1991 Deletion of steroid 5 alpha-reductase 2 gene in male pseudohermaphroditism. Nature 354:159–61[CrossRef][Medline]
20. Goodfellow PN, Lovell-Badge R 1993 SRY and sex determination in mammals. Annu Rev Genet 27:71–92[CrossRef][Medline]
21. McElreavy K, Vilain E, Abbas N, Costa JM, Souleyreau N, Kucheria K, Boucekkine C, Thibaud E, Brauner R, Flamant F, Fellous M 1992 XY sex reversal associated with a deletion 5' to the SRY "HMG box" in the testis-determining region. Proc Natl Acad Sci USA 89:11016–11020[Abstract/Free Full Text]
22. Haqq CM, King CY, Ukiyama E, Falsafi S, Haqq TN, Donahoe PK, Weiss MA 1994 Molecular basis of mammalian sexual determination: activation of Mullerian inhibiting substance gene expression by SRY. Science 266:1494–1500[Abstract/Free Full Text]
23. Ukiyama E, Jancso-Radek A, Li B, Milos L, Zhang W, Phillips NB, Morikawa N, King CY, Chan G, Haqq CM, Radek JT, Poulat F, Donahoe PK, Weiss MA 2001 SRY and architectural gene regulation: the kinetic stability of a bent protein-DNA complex can regulate its transcriptional potency. Mol Endocrinol 15:363–377[Abstract/Free Full Text]
24. Bitgood MJ, Shen L, McMahon AP 1996 Sertoli cell signaling by Desert hedgehog regulates the male germline. Curr Biol 6:298–304[CrossRef][Medline]
25. Hess RA, Bunick D, Lee KH, Bahr J, Taylor JA, Korach KS, Lubahn DB 1997 A role for oestrogens in the male reproductive system. Nature 390:509–512[CrossRef][Medline]
26. Yu RN, Ito M, Saunders TL, Camper SA, Jameson JL 1998 Role of Ahch in gonadal development and gametogenesis. Nat Genet 20:353–357[CrossRef][Medline]
27. Zanaria E, Muscatelli F, Bardoni B, Strom TM, Guioli S, Guo W, Lalli E, Moser C, Walker AP, McCabe ER, Meitinger T, Monaco AP, Sassone-Corsi P, Camerino G 1994 An unusual member of the nuclear hormone receptor superfamily responsible for X-linked adrenal hypoplasia congenita. Nature 372:635–641[CrossRef][Medline]
28. Muscatelli F, Strom TM, Walker AP, Zanaria E, Recan D, Meindl A, Bardoni B, Guioli S, Zehetner G, Rabl W, et al 1994 Mutations in the DAX-1 gene give rise to both X-linked adrenal hypoplasia congenita and hypogonadotropic hypogonadism. Nature 372:672–676[CrossRef][Medline]
29. Bardoni B, Zanaria E, Guioli S, Floridia G, Worley KC, Tonini G, Ferrante E, Chiumello G, McCabe ER, Fraccaro M, Zuffardi O, Camerino G 1994 A dosage sensitive locus at chromosome Xp21 is involved in male to female sex reversal. Nat Genet 7:497–501[CrossRef][Medline]
30. Goodfellow PN, Camerino G 1999 DAX-1, an ‘antitestis’ gene. Cell Mol Life Sci 55:857–863[Medline]
31. Swain A, Narvaez V, Burgoyne P, Camerino G, Lovell-Badge R 1998 Dax1 antagonizes Sry action in mammalian sex determination. Nature 391:761–767[CrossRef][Medline]
32. Roberts LM, Shen J, Ingraham HA 1999 New solutions to an ancient riddle: defining the differences between Adam and Eve. Am J Hum Genet 65:933–942[CrossRef][Medline]
33. Tremblay JJ, Viger RS 2001 GATA factors differentially activate multiple gonadal promoters through conserved GATA regulatory elements. Endocrinology 142:977–986[Abstract/Free Full Text]
34. Giordano J, Prior HM, Bamforth JS, Walter MA 2001 Genetic study of SOX9 in a case of campomelic dysplasia. Am J Med Genet 98:176–181[CrossRef][Medline]
35. Cooke PS, Buchanan DL, Lubahn DB, Cunha GR 1998 Mechanism of estrogen action: lessons from the estrogen receptor- knockout mouse. Biol Reprod 59:470–475[Free Full Text]
36. Cunha GR, Alarid ET, Turner T, Donjacour AA, Boutin EL, Foster BA 1992 Normal and abnormal development of the male urogenital tract. Role of androgens, mesenchymal-epithelial interactions, and growth factors. J Androl 13:465–475[Abstract/Free Full Text]
37. Jost A 1947 Recherches sur la différenciation sexuelle de l’embryon de lapin. Arch Anat Micro Morph Exp 36:271–315
38. Baarends WM, van Helmond MJ, Post M, van der Schoot PJ, Hoogerbrugge JW, de Winter JP, Uilenbroek JT, Karels B, Wilming LG, Meijers JH, Themmen AP, Grootegoed JA 1994 A novel member of the transmembrane serine/threonine kinase receptor family is specifically expressed in the gonads and in mesenchymal cells adjacent to the Mullerian duct. Development 120:189–197[Abstract]
39. di Clemente N, Wilson C, Faure E, Boussin L, Carmillo P, Tizard R, Picard JY, Vigier B, Josso N, Cate R 1994 Cloning, expression, and alternative splicing of the receptor for anti-Mullerian hormone. Mol Endocrinol 8:1006–1020[Abstract]
40. Imbeaud S, Faure E, Lamarre I, Mattei MG, di Clemente N, Tizard R, Carre-Eusebe D, Belville C, Tragethon L, Tonkin C, Nelson J, McAuliffe M, Bidart J-M, Lababidi A, Josso N, Cate RL, Picard J-Y 1995 Insensitivity to anti-mullerian hormone due to a mutation in the human anti-Mullerian hormone receptor. Nat Genet 11:382–388[CrossRef][Medline]
41. Teixeira J, He WW, Shah PC, Morikawa N, Lee MM, Catlin EA, Hudson PL, Wing J, Maclaughlin DT, Donahoe PK 1996 Developmental expression of a candidate mullerian inhibiting substance type II receptor. Endocrinology 137:160–165[Abstract]
42. Mishina Y, Rey R, Finegold MJ, Matzuk MM, Josso N, Cate RL, Behringer RR 1996 Genetic analysis of the Mullerian-inhibiting substance signal transduction pathway in mammalian sexual differentiation. Genes Dev 10:2577–2587[Abstract/Free Full Text]
42. Visser JA, Olaso R, Verhoef-Post M, Kramer P, Themmen AP, Ingraham HASerine/threonine transmembrane receptor ALK2 mediates Müllerian inhibiting substance signaling. Mol Endocrinol, in press
43. Clarke TR, Hoshiya Y, Yi SE, Liu X, Lyons KM, Donahoe PK Mullerian inhibiting substance signaling uses a BMP-like pathway mediated by ALK2 and induces Smad6 expression. Mol Endocrinol, in press
44. Imbeaud S, Belville C, Messika-Zeitoun L, Rey R, di Clemente N, Josso N, Picard JY 1996 A 27 base-pair deletion of the anti-mullerian type II receptor gene is the most common cause of the persistent mullerian duct syndrome. Hum Mol Genet 5:1269–1277[Abstract/Free Full Text]
45. Belville C, Josso N, Picard JY 1999 Persistence of Mullerian derivatives in males. Am J Med Genet 89:218–223[CrossRef][Medline]
46. He WW, Gustafson ML, Hirobe S, Donahoe PK 1993 Developmental expression of four novel serine/threonine kinase receptors homologous to the activin/transforming growth factor-ß type II receptor family. Dev Dyn 196:133–142[Medline]
47. Gouedard L, Chen YG, Thevenet L, Racine C, Borie S, Lamarre I, Josso N, Massague J, di Clemente N 2000 Engagement of bone morphogenetic protein type IB receptor and Smad1 signaling by anti-Mullerian hormone and its type II receptor. J Biol Chem 275:27973–27978[Abstract/Free Full Text]
48. Yi SE, Daluiski A, Pederson R, Rosen V, Lyons KM 2000 The type I BMP receptor BMPRIB is required for chondrogenesis in the mouse limb. Development 127:621–30[Abstract]
49. Watanabe K, Clarke TR, Lane AH, Wang X, Donahoe PK 2000 Endogenous expression of Mullerian inhibiting substance in early postnatal rat sertoli cells requires multiple steroidogenic factor-1 and GATA-4-binding sites. Proc Natl Acad Sci USA 97:1624–1629[Abstract/Free Full Text]
50. Nachtigal MW, Hirokawa Y, Enyeart-VanHouten DL, Flanagan JN, Hammer GD, Ingraham HA 1998 Wilms’ tumor 1 and Dax-1 modulate the orphan nuclear receptor SF-1 in sex-specific gene expression. Cell 93:445–454[CrossRef][Medline]
51. De Santa Barbara P, Bonneaud N, Boizet B, Desclozeaux M, Moniot B, Sudbeck P, Scherer G, Poulat F, Berta P 1998 Direct interaction of SRY-related protein SOX9 and steroidogenic factor 1 regulates transcription of the human anti-Mullerian hormone gene. Mol Cell Biol 18:6653–6665[Abstract/Free Full Text]
52. Arango NA, Lovell-Badge R, Behringer RR 1999 Targeted mutagenesis of the endogenous mouse Mis gene promoter: in vivo definition of genetic pathways of vertebrate sexual development. Cell 99:409–419[CrossRef][Medline]
53. Adham IM, Emmen JM, Engel W 2000 The role of the testicular factor INSL3 in establishing the gonadal position. Mol Cell Endocrinol 160:11–16[CrossRef][Medline]
54. Bullesbach EE, Schwabe C 1999 Specific, high affinity relaxin-like factor receptors. J Biol Chem 274:22354–22358[Abstract/Free Full Text]
55. Emmen JM, McLuskey A, Adham IM, Engel W, Grootegoed JA, Brinkmann AO 2000 Hormonal control of gubernaculum development during testis descent: gubernaculum outgrowth in vitro requires both insulin-like factor and androgen. Endocrinology 141:4720–4727[Abstract/Free Full Text]
56. Satokata I, Benson G, Maas R 1995 Sexually dimorphic sterility phenotypes in Hoxa10-deficient mice. Nature 374:460–463[CrossRef][Medline]
57. Branford WW, Benson GV, Ma L, Maas RL, Potter SS 2000 Characterization of Hoxa-10/Hoxa-11 transheterozygotes reveals functional redundancy and regulatory interactions. Dev Biol 224:373–387[CrossRef][Medline]
58. Zimmermann S, Steding G, Emmen JM, Brinkmann AO, Nayernia K, Holstein AF, Engel W, Adham IM 1999 Targeted disruption of the Insl3 gene causes bilateral cryptorchidism. Mol Endocrinol 13:681–91[Abstract/Free Full Text]
59. Nef S, Shipman T, Parada LF 2000 A molecular basis for estrogen-induced cryptorchidism. Dev Biol 224:354–361[CrossRef][Medline]
60. Couse JF, Korach KS 1999 Estrogen receptor null mice: what have we learned and where will they lead us? Endocr Rev 20:358–417[Abstract/Free Full Text]

This article has been cited by other articles:

				D. T. MacLaughlin and P. K. Donahoe Sex Determination and Differentiation N. Engl. J. Med., January 22, 2004; 350(4): 367 - 378. [Full Text] [PDF]

				D. C. Connolly, R. Bao, A. Y. Nikitin, K. C. Stephens, T. W. Poole, X. Hua, S. S. Harris, B. C. Vanderhyden, and T. C. Hamilton Female Mice Chimeric for Expression of the Simian Virus 40 TAg under Control of the MISIIR Promoter Develop Epithelial Ovarian Cancer Cancer Res., March 15, 2003; 63(6): 1389 - 1397. [Abstract] [Full Text] [PDF]

This Article Full Text (PDF) Purchase Article View Shopping Cart Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Copyright Permission Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by MacLaughlin, D. T. Articles by Donahoe, P. K. Search for Related Content PubMed PubMed Citation Articles by MacLaughlin, D. T. Articles by Donahoe, P. K.