| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
ARTICLE |
Biocenter Oulu and Department of Biochemistry (M.H., H.P.), Biocenter Oulu and Department of Physiology (J.L., M.I., O.V.), Biocenter Oulu and Department of Biochemistry (S.V.), Faculties of Science and Medicine, University of Oulu, FIN-90014 University of Oulu, Finland
Address all correspondence and requests for reprints to: Prof. Seppo Vainio, Biocenter Oulu and Department of Biochemistry, Faculties of Science and Medicine, P.O. Box 3000, University of Oulu, FIN-90014 University of Oulu, Finland. E-mail: seppo.vainio{at}oulu.fi.
 |
Abstract |
|---|
 Top Abstract IntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
|
Introduction |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
As the cortex maintains water, electrolyte, and carbohydrate balances, its proper functioning is vital. Dozens of steroidal compounds, collectively referred to as corticosteroids, have been isolated from the cortex, but only a few of them have biological activity. The production of these corticosteroids, which can be divided into mineralocorticoids, glucocorticoids, and androgens, is regulated by the renin-angiotensin system and hypothalamic-pituitary-adrenal axis. The main mineralocorticoid, aldosterone, is synthesized in the zona glomerulosa, whereas the zona fasciculata and zona reticularis produce glucocorticoids such as corticosterone and cortisol. The adrenal medulla consists of ganglion and chromaffin cells, the latter producing norepinephrine, epinephrine, chromogranins, and neuropeptides, which are components of the autonomic nervous system (1, 3). Despite the different characteristics of the cortex and medulla, the adrenocortical and chromaffin cells of the medulla are intermingled and interact with each other (3).
The murine adrenal gland starts its development on embryonic day (E) 11, when the anlage of the adrenal cortex is formed (4). At the same time the first medullary cells also appear: two chains of sympathoblasts located on either side of the aorta. The cortex forms by budding from the coelomic epithelium between the mesogastrium and the urogenital fold, and the anlage is further pushed out between the mesonephros and the aorta. On E12 the cortical cells are found close to the adrenal medulla sympathoblasts, and by E14 the medullary cells are located within the adrenal gland. The capsule surrounding the adrenal gland and the cortical capillaries are also formed on E14, and both the cortex and the capsule have completed their development by E15. The murine adrenal gland is fully functional at birth (1). Key factors in adrenal cortex development are steroidogenic factor-1 (Sf1) and Wilm’s tumor-1, a deficiency in which will cause a total lack of the adrenal gland (5, 6, 7). Development of the cortex is also connected with the functioning of the hypothalamus-pituitary-adrenal axis, in that a lack of CRH and its receptors will cause severe alterations in the structure of the adrenal cortex, and steroidogenic acute regulatory protein knockout mice show abnormal cellular architecture and abundant lipoid deposits in the cortex, for example (8, 9).
Wnt signaling is involved in the development of several organs. Wnts are molecules regulating growth and differentiation, and they mediate their signal via at least three pathways; the ß-catenin (10) and the planar cell polarity (11, 12) pathways, which are dependent on frizzled receptor and disheveled, and the disheveled-independent, protein kinase C pathway (13). Wnt-4 is essential for the proper development and functioning of the kidney (14), pituitary gland (15), Mullerian duct, and ovary (16). Wnt-4-deficient mice die within 24 h of birth, probably because of kidney dysfunction, as the kidney tubules fail to form without the Wnt-4 gene (14). The pituitary gland of the Wnt-4 mutant mouse is also poorly developed and is practically devoid of all cell types other than corticotropes, the cells producing proopiomelanocortin-derived hormones, such as ACTH, MSH, ß-endorphin, and ß-lipotropin (15). Both male and female Wnt-4-deficient mice lack any Mullerian duct, and the females show partial sex reversal, with oocyte degeneration (16). Finally, Wnt-4 is involved in progesterone-dependent mammary gland branching (17). We report here on the expression of Wnt-4 in the adrenal gland and show that lack of the gene leads to altered functioning of the gland as well.
|
Materials and Methods |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
Whole mount and section in situ hybridization
Embryos at given developmental stages were obtained by dissection of pregnant mice. The day when the plug was detected was designated d 0.5 of gestation. The tissues collected were fixed in 4% paraformaldehyde overnight, dehydrated in a graded methanol series, and stored in 100% methanol at -20 C for whole mount in situ hybridization. For section in situ hybridization, the fixed samples were dehydrated in an ethanol series, washed with xylene, and embedded in paraffin. Finally, the tissues were sectioned at 5 or 7 µm and placed on glass slides (Menzel-Glaser, Freiburgh, Germany) treated with triethoxysilylpropylamine (Sigma, St. Louis, MO).
The probes were Wnt-4 (14), Cyp21 and Cyp11B2 (Keith Parker, University of Texas Southwestern Medical Center, Dallas, TX), Hsd3b1 (Robin Lovell-Badge, National Institute for Medical Research, London, UK), Sf1 (18) and rat preadipocyte factor 1 (Pref-1; Hiroshi Takemori, Osaka University Medical School, Suita, Japan) cDNAs or parts of them, and the Cyp17-expressed sequence tag clone AA822113 (National Center for Biotechnology Information).
The riboprobes for whole mount in situ hybridization were labeled with digoxigenin (digoxigenin RNA labeling kit, Roche, Indianapolis, IN), and those for in situ sections were labeled with digoxigenin or [35S]UTP (Amersham Pharmacia Biotech, Arlington Heights, IL). The in situ hybridizations were performed according to standard procedures at 54 C for Pref-1 and at 65 C for the other probes (19), and hematoxylin eosin staining was performed as described by Hogan et al. (20). Both whole mount and in situ hybridization analyses were carried out for at least five independent samples in each case, and a representative one is shown here.
Morphometric studies
The adrenal glands were collected from E14.5 embryos and newborn mice and divided into four groups: wt females, wt males, Wnt-4 mutant females, and Wnt-4 mutant males. Two pairs of glands from each group were fixed overnight in 4% paraformaldehyde and dehydrated in an ascending series of ethanol solutions and xylenes, and the tissues were embedded in paraffin. Serial sections of 5 µm were cut, placed on microscope slides, and stained with toluidine blue. The total area of the adrenal gland was measured on each section with a digital image analysis system MCID-M4 (Imaging Research, Brock University, St. Catharines, Canada); the images were acquired with a Sony DXC-930P color video camera (Sony, Tokyo, Japan) attached to a Nikon Optiphot II microscope and a x4 objective (Nikon, Tokyo, Japan). Tissue volume was determined by integrating the section areas over their thicknesses. The volumes of the left and right adrenal glands of each animal were added together, and volume measurements were performed on two animals in each group.
Conventional and quantitative RT-PCR
The adrenal glands of the newborn mice were collected, quickly frozen in liquid nitrogen, and stored at -80 C. Later, 5–8 dissected adrenal glands were pooled by sex and phenotype (wt female, Wnt-4 mutant female, wt male, and Wnt-4 mutant male) for quantitative RT-PCR, and 10–20 pieces of gland for the conventional procedure. Total RNA was isolated with the Quick Prep kit from Amersham Pharmacia Biotech, and the reverse transcriptase reaction was carried out using the First Strand cDNA synthesis kit from MBI Fermentas (Hanover, NH) or Ready-To-Go RT-PCR Beads from Amersham Pharmacia Biotech. Cyp11B2 and Cyp21 mRNA concentrations in the samples were measured by quantitative RT PCR analysis as described (21). Conventional RT-PCR was carried out twice for Cyp17 using independent RNA samples and the expression of glyceraldehyde-3-phosphate dehydrogenase was used to assess the quality of the RNA. The forward and reverse primers and probes used are listed in Table 1
.
|
The evaporated organic phase was reconstituted with 500 µl RIA buffer (DRG Instruments GmbH, Marburg, Germany), and double aliquots of 25–100 µl were subjected to DHEA and androstenedione RIAs. Duplicate 5- to 25-µl aliquots of the plasma samples were submitted to the following RIAs: aldosterone (ICN Pharmaceuticals, Inc., Costa Mesa, CA), corticosterone (DRG Instruments GmbH), cortisol (Orion DG, Espoo, Finland), and ß-endorphin, also depicting the proportion of ACTH (ß-endorphin RIA) (22). The detection limits were 2 pg/ml for ßendorphin, 0.7 fmol/ml for dehydroepiandrosterone, 1 fmol/ml for androstenedione, 0.6 pmol/ml for aldosterone, 0.13 pmol/ml for corticosterone, 10 pg/ml for cortisol, and 1 µg/ml for total protein.
Statistical analyses
P values for the hormone and RT-PCR samples were calculated by t test with a two-tailed distribution and two-sample unequal variance.
|
Results |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
), similar to the case of Sf1 expression (Fig. 1b), an early marker of the developing adrenal gland (23). By E12.5 the developing adrenal cortex was a distinct organ, and expression of Wnt-4 and Sf1 could clearly be seen in it (Fig. 1 1 , c and d). Section in situ hybridization of samples from E14.5 and E18.5 mice showed that the expression of Wnt-4 was located in the cortical region of the adrenal gland, whereas no expression could be detected in the medulla (Fig. 1, e and f). Wnt-4 expression in the developing adrenal gland was similar in both sexes (data not shown).
|
, a and b). Volume measurements, i.e. morphometric studies, performed on a few adrenal glands also suggested that the adrenal glands of the wt and Wnt-4 mutant mice were similar in size (data not shown), and hematoxylin-eosin staining did not reveal any obvious histologically anomalous structures in the Wnt-4 mutant adrenal glands (Fig. 2, c and d).
|
, a and b), with no detectable quantitative difference (Table 2). In contrast, both in situ hybridization (Fig. 3, c and d) and the real-time PCR results (Table 2) showed the expression of Cyp11B2 to be reduced in the adrenal cortex of Wnt-4 mutant mice. As in Cyp11B2, the number of cells expressing Pref-1, which is a specific marker of the zona glomerulosa in the cortex (24), was markedly lower in the cortex of Wnt-4-deficient mice (Fig. 3, e and f). Pref-1 is also expressed in medullae (24), as seen here in the glands of both wt and Wnt-4 mutant mice. The male and female mice demonstrated similar expression patterns for these genes (data not shown).
|
|
, a–d), and was most intensive in the cortex of the wt females (Fig. 4c). Thereafter it continued in the adrenal glands of the wt female animals until birth (Fig. 4g), but was lost between E16.5 and E18.5 in the glands of the wt and Wnt-4-deficient males and Wnt-4-deficient females (Fig. 4, e, f, and h). Thus, the expression of Cyp17 in the adrenal cortex of female Wnt-4 mutant mice followed that in wt male mice. RT-PCR confirmed the results of the whole mount in situ hybridization, showing Cyp17 expression to exist in the glands of newborn female wt mice, but not in those of Wnt-4-deficient mice, and to be more abundant on E14.5 than at birth (Fig. 4, i, j, and k). The expression was not seen in samples from adult wt mice (Fig. 4i).
|
), whereas that of ß-endorphin (Fig. 5b), also reflecting ACTH production, was enhanced in these animals. In addition, a statistical difference in the production of corticosterone was seen between the wt and Wnt-4 mutant mice, both male and female (Fig. 5c). There was a high variation in corticosterone concentrations, which may be due to the effects of the circadian rhythm on corticosterone secretion. This rhythm could not be taken into account when collecting samples, because Wnt-4-deficient mice die soon after birth (14 16). The concentration of DHEA was constant in all the groups measured, and cortisol, androstenedione, and testosterone were below the detection level (data not shown), suggesting that Wnt-4 deficiency does not alter the main routes of steroidogenesis in the adrenal cortex, at least after birth.
|
, a–f). Expression took place in a clear, circular area in the developing adrenal glands from wt mice (Fig. 6, a, c, and e), whereas in the Wnt-4 mutant mice, cells expressing Cyp21 were also dispersed outside the future adrenal cortex (Fig. 6, b, d, and f). Some Cyp21-positive cells were seen in the gonadal area (Fig. 6f), which does not normally express the gene (Fig. 6e), suggesting that the cells may be at least partially of adrenal origin. Expression patterns were similar in female and male mice (data not shown).
|
, a–d), and the expression was intensive in the gonads of wt (Fig. 7a) and Wnt-4-deficient (Fig. 7b) males and was detectable in the gonads of female Wnt-4-deficient mice (Fig. 7d), but not in female wt embryos (Fig. 7c). Ectopic expression of Hsd3b1 in the gonads of Wnt-4-deficient females was also distinct at birth (Fig. 7e) (16). Detailed examination showed that the 3ß-HSDI-positive cells were always located at the anterior end of the ovary, close to the adrenal, in the Wnt-4 mutant animals (Fig. 7d), as was also the case with Cyp21 (Fig. 6f
). Similarly, Cyp17 was not expressed in the developing ovaries of normal mice, but extensive expression was seen in the anterior area of the Wnt-4 mutant ovary (Fig. 4, d and h).
|
|
Discussion |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
Although the adrenal glands of wt and Wnt-4 mutant mice were similar in shape and size, it is possible that the elevated ß-endorphin concentration in the plasma of the Wnt-4-deficient animals, also reflecting the ACTH concentration, may lead to hyperplasia and/or hypertrophy, as is the case in Cushing-like syndrome (27), overexpression of CRH (28), and glucocorticoid receptor-deficient mice (29), even though the increase in corticosterone is more conspicuous in the later cases. As Wnt-4 mutant mice die soon after birth, it is unfortunately not possible to see how the production of corticosterone and ACTH and their effects are balanced out or whether the phenotype later shows adrenal hyperplasia or hypertrophy.
Hsd3b1, Cyp21, and Cyp11B2, which are needed for mineralocorticoid biosynthesis are expressed in the adrenal cortex of Wnt-4 mutants, although that of Cyp11B2 is significantly reduced, resulting in decreased production of aldosterone, the most important mineralocorticoid, which is exclusively synthesized in the zona glomerulosa (30). The principal functions of aldosterone are to stimulate sodium reabsorption in the distal tubule of the kidneys, to increase the total body sodium level, and to control the plasma potassium level. Lack of aldosterone causes reduced fluid volume, leading to hypovolemic shock and death. Hence Wnt-4 affects control of the electrolyte balance on at least two levels, being necessary for tubule formation in the kidney (14) and for maintaining a proper concentration of aldosterone.
The present section in situ hybridization results demonstrated that expression of Cyp11B2, the gene encoding P450c11aldo, and Pref-1, another marker of zona glomerulosa, is limited to a small number of cells, suggesting that the zona glomerulosa has not developed normally in the adrenal glands of Wnt-4 mutants. P450c11aldo is needed for the 11ß-hydroxylation of deoxycorticosterone to corticosterone and for the 18-hydroxylation and 18-hydroxydehydrogenation of corticosterone to aldosterone. The corticosterone concentrations in the mutant Wnt-4 mice suggest that the reduced amount of P450c11aldo does not significantly limit corticosterone biosynthesis, but instead affects the subsequent reactions on the path toward aldosterone, resulting in an accumulation or maintenance of corticosterone and a reduction in aldosterone. The situation is parallel, even though not equal, to that prevailing in human congenital hypoaldosteronism, in which corticosterone levels are increased and aldosterone levels decreased due to specific mutations in P450c11aldo affecting its 18-hydroxylation or 18-hydroxydehydrogenation activities (31, 32).
P450c17 catalyzes the 17
-hydroxylase and 17,20-lyase reactions and is thus necessary for the biosynthesis of cortisol and androgens. Adult mice and rats do not express Cyp17, and therefore their main glucocorticoid is corticosterone and not cortisol as in humans (33, 34, 35). Cyp17 expression does take place in the adrenal gland of the wt fetal mouse, however, reaching its peak on E14.5, and showing sex dependency. A pattern of Cyp17 expression similar to that demonstrated here in the male fetal adrenal gland has also been reported by Keeney et al. (36), but their material was not analyzed by sex, and expression in female fetuses at birth was not reported separately. Interestingly, we saw continued expression only in the adrenal cortex of wt females, whereas the pattern in Wnt-4-deficient females followed that in wt males. The results suggest that Wnt-4 is also involved in the regulation of steroidogenesis, with Wnt-4-deficient female embryos phenocopying the male pathway. Activation of the genes for the androgen biosynthesis pathway in the ovaries, masculinization of the gonads, and partial female to male sex reversal are also typical of mutant Wnt-4 female mice (16). The role of strong Cyp17 expression in the female adrenal gland remains open, as it was not found to affect cortisol or androgen production in the gland, at least at birth.
Expression of Cyp21 in the urogenital area is more dispersed in Wnt-4 mutant mice than in wt mice during embryological development. Some cells expressing Cyp21 are also seen in the gonadal area in Wnt-4-deficient male and female mice, an area not normally expressing the gene, and ectopic expression of the steroidogenic enzymes 3ß-HSDI and P450c17 also occurs in the gonads of female Wnt-4-deficient mice, leading to activation of the androgen biosynthesis pathway (16). Closer investigation of Wnt-4 mutant ovaries demonstrated that this ectopic expression always takes place at the anterior end of the gonad. The results suggest that the cells showing such expression are also of adrenal origin, and that Wnt-4 plays a role in cell sorting. The adrenal cortex and the gonadal cells have the same origin (37), and the gonad and future adrenal gland are located immediately adjacent to each other early in their development, on E11, without any clear border. A lack of Wnt-4 at that stage may thus allow some adrenal cells to migrate into the gonadal region, where they are able to maintain their original identity, still expressing Cyp17 and Hsd3b1.
The results show that Wnt signaling plays a role in the development of the adrenal cortex. The zona glomerulosa does not develop properly in Wnt-4-deficient mice, which leads to a decrease in the production of aldosterone. In addition, Wnt-4 may be involved in the regulation of steroidogenesis or at least in the expression of Cyp17, and finally, Wnt-4 may shape cell sorting between the adrenal cortex and the gonads.
|
Acknowledgments |
|---|
|
Footnotes |
|---|
1 M.H. and H.P. have made equal contributions to this work. 
Abbreviations: DHEA, Dehydroepiandrosterone; E, embryonic day; 3ß-HSDI, ß-hydroxysteroid dehydrogenase type I; Pref-1, preadipocyte factor 1; Sf1, steroidogenic factor-1; wt, wild-type.
Received March 6, 2002.
Accepted for publication July 19, 2002.
|
References |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
-hydroxylase/17,20-lyase) in cultured human granulosa cells. J Clin Endocrinol Metab 63:202–207[Abstract]
, and iron sulfur protein reductase in Leydig cells and adrenals of inbred strains of mice. Endocrinology 123:2675–2682[Abstract]
-hydroxylase cytochrome P450 in the mouse embryo. Endocrinology 136:4872–4879[Abstract]
This article has been cited by other articles:
 |
|
 |
|
  A. C. Kim, A. L. Reuter, M. Zubair, T. Else, K. Serecky, N. C. Bingham, G. G. Lavery, K. L. Parker, and G. D. Hammer Targeted disruption of {beta}-catenin in Sf1-expressing cells impairs development and maintenance of the adrenal cortex Development, August 1, 2008; 135(15): 2593 - 2602. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 C. H Brennan, A. Chittka, S. Barker, and G. P Vinson Eph receptors and zonation in the rat adrenal cortex J. Endocrinol., July 1, 2008; 198(1): 185 - 191. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
H. Chang, F. Gao, F. Guillou, M. M. Taketo, V. Huff, and R. R. Behringer Wt1 negatively regulates {beta}-catenin signaling during testis development Development, May 15, 2008; 135(10): 1875 - 1885. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 K. Tomizuka, K. Horikoshi, R. Kitada, Y. Sugawara, Y. Iba, A. Kojima, A. Yoshitome, K. Yamawaki, M. Amagai, A. Inoue, et al. R-spondin1 plays an essential role in ovarian development through positively regulating Wnt-4 signaling Hum. Mol. Genet., May 1, 2008; 17(9): 1278 - 1291. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 L. Hu, A. Monteiro, H. Johnston, P. King, and P. J O'Shaughnessy Expression of Cyp21a1 and Cyp11b1 in the fetal mouse testis Reproduction, October 1, 2007; 134(4): 585 - 591. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 Q. Yang, R. Kurotani, A. Yamada, S. Kimura, and F. J. Gonzalez Peroxisome Proliferator-Activated Receptor {alpha} Activation during Pregnancy Severely Impairs Mammary Lobuloalveolar Development in Mice Endocrinology, October 1, 2006; 147(10): 4772 - 4780. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
L. Chi, P. Itaranta, S. Zhang, and S. Vainio Sprouty2 Is Involved in Male Sex Organogenesis by Controlling Fibroblast Growth Factor 9-Induced Mesonephric Cell Migration to the Developing Testis Endocrinology, August 1, 2006; 147(8): 3777 - 3788. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 H. H.-C. Yao, J. Aardema, and K. Holthusen Sexually Dimorphic Regulation of Inhibin Beta B in Establishing Gonadal Vasculature in Mice Biol Reprod, May 1, 2006; 74(5): 978 - 983. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 M. Bielinska, S. Kiiveri, H. Parviainen, S. Mannisto, M. Heikinheimo, and D. B. Wilson Gonadectomy-induced Adrenocortical Neoplasia in the Domestic Ferret (Mustela putorius furo) and Laboratory Mouse. Vet. Pathol., February 1, 2006; 43(2): 97 - 117. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. Heikkila, R. Prunskaite, F. Naillat, P. Itaranta, J. Vuoristo, J. Leppaluoto, H. Peltoketo, and S. Vainio The Partial Female to Male Sex Reversal in Wnt-4-Deficient Females Involves Induced Expression of Testosterone Biosynthetic Genes and Testosterone Production, and Depends on Androgen Action Endocrinology, September 1, 2005; 146(9): 4016 - 4023. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
S. Y. Park and J. L. Jameson Minireview: Transcriptional Regulation of Gonadal Development and Differentiation Endocrinology, March 1, 2005; 146(3): 1035 - 1042. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
G. D. Hammer, K. L. Parker, and B. P. Schimmer Minireview: Transcriptional Regulation of Adrenocortical Development Endocrinology, March 1, 2005; 146(3): 1018 - 1024. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 P. J. Hornsby Aging of the Human Adrenal Cortex Sci. Aging Knowl. Environ., September 1, 2004; 2004(35): re6 - re6. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
S. Cui, A. Ross, N. Stallings, K. L. Parker, B. Capel, and S. E. Quaggin Disrupted gonadogenesis and male-to-female sex reversal in Pod1 knockout mice Development, August 15, 2004; 131(16): 4095 - 4105. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 B. K. Jordan, J. H.-C. Shen, R. Olaso, H. A. Ingraham, and E. Vilain Wnt4 overexpression disrupts normal testicular vasculature and inhibits testosterone synthesis by repressing steroidogenic factor 1/{beta}-catenin synergy PNAS, September 16, 2003; 100(19): 10866 - 10871. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
K. Jeays-Ward, C. Hoyle, J. Brennan, M. Dandonneau, G. Alldus, B. Capel, and A. Swain Endothelial and steroidogenic cell migration are regulated by WNT4 in the developing mammalian gonad Development, August 15, 2003; 130(16): 3663 - 3670. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 B. M. Gummow, J. N. Winnay, and G. D. Hammer Convergence of Wnt Signaling and Steroidogenic Factor-1 (SF-1) on Transcription of the Rat Inhibin {alpha} Gene J. Biol. Chem., July 11, 2003; 278(29): 26572 - 26579. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 J. Brennan, C. Tilmann, and B. Capel Pdgfr-alpha mediates testis cord organization and fetal Leydig cell development in the XY gonad Genes & Dev., March 15, 2003; 17(6): 800 - 810. [Abstract] [Full Text] [PDF]
|
|
| |||||||||||||
