| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
ARTICLES |
Department of Molecular in Integrative Physiology (L.L.B., O.D.S.) and the College of Medicine (O.D.S.), University of Illinois at Urbana-Champaign, Urbana, Illinois 61801
Address all correspondence and requests for reprints to: Dr. O. D. Sherwood, Department of Molecular in Integrative Physiology, University of Illinois at Urbana-Champaign, 524 Burrill Hall, 407 South Goodwin Avenue, Urbana, Illinois 61801. E-mail: od-sherw{at}uiuc.edu
 |
Abstract |
|---|
 Top Abstract IntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
Primiparous pregnant rats were ovariectomized or sham ovariectomized (group C; n = 8) on day 9 of pregnancy (D9). Ovariectomized rats were then treated with physiological doses of progesterone plus estrogen (n = 7) or progesterone, estrogen, and porcine relaxin (n = 7). Cellular proliferation was determined by continuously administering a low dose of 5-bromo-2'-deoxyuridine (BrdU) via miniature osmotic pump from D9–D22. On D22, cervices and vaginas were collected, fixed in formalin, paraffin embedded, and serially sectioned (4 µm). Adjacent serial sections were either immunostained for BrdU to assess cell proliferation or stained with hematoxylin to determine total cell number. Cell proliferation was evaluated by counting BrdU-positive nuclei and total nuclei in the same area on adjacent sections. Cell counts were determined using computerized digital morphometric analysis at x575.
In control rats, nearly 75% of the epithelial cells and 55% of the stromal cells within the cervix at term had proliferated during the second half of pregnancy. The accumulation of approximately half of the new cells was relaxin dependent. Within the cervical stroma, relaxin increased the accumulation of cells associated with blood vessels and also the number of isolated cells (probably fibroblasts). Relaxin did not appear to affect smooth muscle cell proliferation in the cervix. In contrast to the cervix, a minority of vaginal epithelial cells (45%) and stromal cells (20%) proliferated during the second half of pregnancy. Although relaxin appeared to have a tendency to increase the accumulation of new vaginal epithelial and stromal cells, morphometric analysis did not provide support for such an effect.
In conclusion, this study demonstrates that relaxin promotes a marked increase in the accumulation of new epithelial cells and stromal cells within the cervix. The relaxin-induced increase in new epithelial and stromal cells probably contributes to relaxin’s effects on growth and remodeling of the cervix that are required for rapid and safe delivery.
|
Introduction |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
We recently obtained evidence that relaxin probably promotes cervical and vaginal growth during pregnancy in part by promoting an increase in their cell contents. Using DNA levels as a measure of cell content, we found that the approximately 1.5-fold increase in both cervical (5) and vaginal (5, 6) DNA content from midpregnancy until term is relaxin dependent.
The objective of this study was to identify and quantify cells in the rat cervix and vagina that accumulate in response to relaxin. Relaxin-replete and relaxin-deficient pregnant rats were treated with the S-phase marker 5-bromo-2'-deoxyuridine (BrdU), a thymidine analog, throughout the second half of pregnancy. Proliferating cells that incorporated BrdU within their nuclei were identified by immunohistochemistry, and the new epithelial and stromal cells within the cervix and vagina were determined by quantitative morphometric analysis.
|
Materials and Methods |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
Treatments
Rats were randomly assigned to one of three treatment groups
(n = 7 or 8/group): 1) sham-ovariectomized controls (group C), 2)
ovariectomized (O) and progesterone (P)- and estrogen (E)-treated group
(group OPE), and 3) ovariectomized, progesterone, estrogen, and porcine
relaxin (R)-treated (group OPER). On D9 rats were anesthetized with
ether, and ventral laporotomy was performed to determine the number of
implantation sites. Only rats with 8 or more implantation sites were
included in this study, as serum levels of relaxin were found to be
directly related to the number of conceptuses in rats with small
litters. Serum levels of relaxin in rats with 5 or fewer fetuses were
significantly lower than those in rats with 10 or more fetuses (17). To
monitor cellular proliferation, BrdU was administered continuously to
all 3 treatment groups from D9–D22. Miniature osmotic pumps (model
2ML2, Alza Corp., Palo Alto, CA) were filled with 2 ml BrdU (20 mg/ml;
Sigma, St. Louis, MO) dissolved in sterile saline (0.9% NaCl). At
laporotomy on D9, a miniature osmotic pump was inserted sc over the
spine caudal to the scapula. The BrdU solution was released at a rate
of 5 µl/h (100 µg BrdU/h). This dosage of BrdU has been previously
shown to be safe and effective over extended periods (18, 19).
At laporotomy on D9, rats in groups OPE and OPER were ovariectomized to remove the source of circulating relaxin. These two groups received hormone replacement therapy with progesterone, estrogen, and porcine relaxin (group OPER only) continuously from D9–D22 in doses that were previously demonstrated to maintain normal pregnancy parameters, parturition parameters, cervical weights, and vaginal weights (5). Construction and preparation of steroid implants were described in detail previously (5). In brief, progesterone and estrogen were administered from silicone tubing. At ovariectomy on D9, four progesterone implants, each containing 60 mg crystalline progesterone (Sigma), were inserted sc in pairs over the flanks. On the evening of D21, the progesterone implants were removed to mimic the decline in progesterone levels that occurs at luteolysis (5, 16, 20). Two doses of estrogen were employed. At ovariectomy on D9, a 16-mm implant containing a total of 2 µg 17ß-estradiol (Sigma) dissolved in sesame oil (Sigma) was inserted sc through a small incision at the nape of the neck. To mimic the increase in estrogen levels that occurs during late pregnancy (5, 20, 21), the 16-mm estrogen implant was replaced on the morning of D18 with a 26-mm capsule containing a total of 12 µg 17ß-estradiol. Sham-ovariectomized controls (group C) were treated with empty implants (progesterone controls) or implants containing sesame seed oil (17ß-estradiol controls).
Relaxin was administered to group OPER from D9–D22 via the same miniature osmotic pump used to administer BrdU. Miniature osmotic pumps were filled with a solution containing 20 mg/ml BrdU and 0.2 mg/ml highly purified porcine relaxin (22) dissolved in sterile saline. Relaxin was released at a rate of 1 µg/h. The animal experimentation described in this report was approved by the University of Illinois laboratory animal care advisory committee.
Tissue collection and processing
On the morning of D22, approximately 16 h before delivery,
rats were killed, and cervixes and vaginas were collected, rinsed with
PBS (0.14 M NaCl and 0.01 M NaPO4,
pH 7.0), weighed, and placed in 10% neutral buffered formalin (23).
The number and weight of live fetuses in utero were also
determined.
Cervexes and vaginas were prefixed whole in neutral buffered formalin for 2 h. Each cervix was then bisected in the middle to obtain a uterine and a vaginal portion. The vagina was cut into thirds, which were designated cephalic, mid, and caudal. Fixation was continued in fresh neutral buffered formalin for a total of 24 h. After fixation, cervexes and vaginas were dehydrated in an ascending series of ethanol, cleared in xylene, and embedded in paraffin. The uterine cervix, vaginal cervix, and midvagina were serially sectioned (4 µm) and mounted on positively charged slides (Superfrost Plus, Fisher Scientific, Pittsburgh, PA). Each slide contained four serial sections. To avoid the possibility of evaluating the same cells on consecutive slides, there was a distance of at least 20 µm between sections on adjacent slides. The four sections per slide were stained in one of three ways. Two sections per slide were stained immunohistochemically for BrdU to determine the extent of cellular proliferation. One section per slide was stained with hematoxylin to determine the total cell number. Lastly, one section per slide was stained both immunohistochemically for BrdU and with hematoxylin to investigate the proliferation of the cells associated with blood vessels and to take photographs.
BrdU immunohistochemistry
BrdU incorporation into proliferating cells was determined
immunohistochemically using a mouse monoclonal antibody (clone
NCL-BrdU, Vector Laboratories, Burlingame, CA) and a Vectastain Elite
ABC kit (Vector Laboratories). The immunohistochemical protocol was
developed following the recommendations of Vector Laboratories and the
methods of Schutte et al. (24). Briefly, slides were cleared
and rehydrated in a descending series of ethanol. Monoclonal antibody
NCL-BrdU recognizes BrdU incorporated into single stranded DNA.
Accordingly, DNA was denatured in tissue sections by incubation in
aqueous 2 N HCl for 30 min at 37 C. After this and all
other incubations, unless otherwise noted, slides were rinsed in three
changes of PBS (pH 7.5; 5 min/rinse; 25 C). Antibody penetration was
improved by an incubation in 0.01% trypsin (Sigma) in PBS for 15 min
at 37 C. Sections were then rinsed in three changes of cold PBS (5
min/rinse, 4 C) to stop the reaction. Endogenous peroxidases were
neutralized by incubating sections in 3% aqueous peroxide for 15 min.
Blocking buffer (3% normal horse serum in PBS; Vector Laboratories)
was applied for 30 min. Blocking serum was blotted off, and anti-BrdU
antibody (1:300 dilution in blocking buffer) was applied. Slides were
incubated overnight (
16 h) in humidified chambers. Biotinylated
horse antimouse IgG and avidin-biotin-peroxidase complex were prepared
as directed (Vectastain Elite ABC kit, Vector Laboratories).
Biotinlyated horse antimouse IgG (1:65 dilution in blocking buffer) was
applied for 30 min. The avidin-biotin-peroxidase complex was applied
for 30 min. Antibody binding sites were visualized using a
3,3'-diaminobenzidine peroxidase substrate kit (Vector Laboratories).
The 3,3'-diaminobenzidine was prepared as directed and applied to
sections for 2–3 min. Slides were rinsed with tap water for 10 min.
Two sections per slide were then stained with hematoxylin (Hematoxylin
2, Richard Allen Medical, Richland, MI): one of the three sections
immunostained for BrdU and the nonimmunostained section. After
staining, slides were dehydrated in ethanol, cleared, and coverslipped
with Permount (Fisher Scientific). All incubations, unless otherwise
noted, were performed at 25 C. For negative control slides, either
anti-BrdU antibody was omitted (blocking buffer only) or nonspecific
mouse IgGs were substituted (1:300 in blocking buffer; Sigma).
Evaluation of epithelial and stromal cell proliferation
Cellular proliferation was evaluated using digital morphometric
analysis at x575. Fields of analysis were captured with an Olympus
CUE-2 Video Image Analysis System (Olympus Corp., Melville, NY). Fields
of analysis were analyzed on a Macintosh computer using the public
domain NIH Image program developed at the U.S. NIH and available on the
internet at http://rsb.info.nih.gov/nih-image/. For both cervix and
vagina, epithelial cell proliferation and stromal cell proliferation
were analyzed independently. Cellular proliferation was evaluated by
counting BrdU-positive nuclei on immunostained sections and total
nuclei in the same area on an adjacent serial section stained with
hematoxylin. Five paired fields of analysis (one BrdU immunostained,
one hematoxylin stained; field size = 0.084 mm2) were
randomly collected in both the epithelium and stroma (
0.50 mm from
the epithelial basement membrane). Therefore, there were a total of 10
paired fields of analysis/slide. Three slides were evaluated per tissue
(uterine cervix, vaginal cervix, and midvagina) for a total of 30
paired fields of analysis/tissue/rat or 210–240 paired fields of
analysis/tissue/group. Luminal circumference and stromal
cross-sectional area were also determined.
Epithelial cell proliferation was determined by counting the number of cells per field and normalizing the cell count to millimeters length of epithelial basement membrane. The percentage of proliferating epithelial cells was determined by dividing the number of BrdU-positive cells per mm basement membrane length by the total number of cells per mm basement membrane length x 100. Epithelial cell proliferation was normalized to luminal circumference by multiplying the number of cells per mm basement membrane length and the number of BrdU-positive cells per mm basement membrane length by the luminal circumference. This was to account for the increase in size of the cervical (3, 25) and vaginal (6) lumen that occurs in response to relaxin.
Stromal cell proliferation was examined in both epithelial fields and stromal fields. The number of cells proliferating in the stroma proximal to the epithelium, which will be designated subepithelial stroma, was determined by counting the number of stromal cells per epithelial field. To account for differences in the amount of stroma from epithelial field to epithelial field, cell counts were normalized to cells per mm2. Stromal cell proliferation in the stromal fields was determined similarly. The percentage of proliferating stromal cells was determined by dividing the number of BrdU-positive cells per mm2 by the total cells per mm2 x 100. Stromal cell proliferation was normalized to stromal cross-sectional area by taking the mean of the number of total and BrdU-positive cells per mm2 in the subepithelial and stromal areas and then multiplying by stromal cross-sectional area.
Evaluation of cervical blood vessel proliferation
Cervical blood vessel proliferation was examined at x400 in
sections stained immunohistochemically for BrdU and hematoxylin. The
percentage of cells proliferating per blood vessel was determined by
dividing the number of BrdU-positive cells by the total number of cells
per vessel x 100. The proliferation of cervical arterioles and
blood vessels was analyzed separately. Cervical arterioles were
determined by the presence of vascular smooth muscle. All other blood
vessels, presumably capillaries and venules (designated capillaries
plus venules), were identified by the lack of vascular smooth muscle.
Only capillaries plus venules with 3 or more endothelial cells were
analyzed. Five arterioles and 5 capillaries plus venules were randomly
chosen per slide. Three slides were examined per portion of the cervix
(uterine cervix and vaginal cervix) for a total of 105–120 capillaries
plus venules and arterioles/portion of the cervix/group.
Statistics
Results were analyzed by ANOVA. Differences between treatments
were determined by Tukey’s test.
|
Results |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
. In the relaxin-deficient group
OPE, the number of implantation sites on D9, the number of live fetuses
on D22, the percent fetal survival, and fetal weight did not differ
from those in relaxin-replete intact controls (group C). Consistent
with earlier findings, cervical (4, 5, 6, 7, 11) and vaginal (5, 6) wet
weights on D22 were significantly lower in group OPE than in group C.
When hormone replacement therapy consisted of ovarian steroids plus
relaxin (group OPER), both cervical and vaginal wet weights did not
differ from those in intact controls. The number of live fetuses on D22
in group OPER was lower than that in intact controls. This may be
attributable at least in part to the fact that the number of
implantation sites on D9 in group OPER tended to be lower than that in
intact controls. The observation that fetal weights were smaller or
tended to be smaller in relaxin-replete rats than in relaxin-deficient
animals has been previously reported (6, 11).
|
and 2 contain representative micrographs of
the cervix. Figure 1 demonstrates that cervical epithelial cells
proliferated during the second half of pregnancy in all three treatment
groups. Regardless of treatment, most of the basal epithelial cells are
BrdU positive. Figure 2 demonstrates that cervical stroma cells also
proliferated during the second half of pregnancy in all three treatment
groups. Stromal cell proliferation was not limited to a single cell
type. BrdU staining was readily observed in blood vessel cells and
isolated cells throughout the extracellular matrix (Fig. 2). As
fibroblasts are numerous in the extracellular matrix, presumably a
portion of the BrdU-positive isolated cells are fibroblasts.
BrdU-positive smooth muscle cells were seldom found (Fig. 2). Whereas
it is not possible to reach definitive conclusions concerning
differences among treatments on the basis of visual examination of the
micrographs, there appeared to be more BrdU-positive cells associated
with blood vessels in relaxin-replete groups C and OPER than in
relaxin-deficient group OPE (Fig. 2).
|
|
. There were no significant differences
between the uterine and vaginal portions of the cervix. Accordingly,
the data from the two portions of the cervix were pooled. Whereas there
was no difference among groups in the total number of cells per mm
basement membrane length (Fig. 3A), both the luminal circumference
(Fig. 3B) and the total number of cells per luminal circumference (Fig. 3C) were lower in relaxin-deficient group OPE rats than in groups C and
OPER. Additionally, the percentage of BrdU-positive cells in
relaxin-deficient group OPE (Fig. 3D) was lower than that in group C.
As a consequence of these differences among groups (Fig. 3, B–D), the
total number of BrdU-positive cells per luminal circumference of the
cervix was lower in relaxin-deficient group OPE than in groups C and
OPER (Fig. 3E).
|
and 5.
Analysis of the influence of relaxin on cell proliferation in the
cervical stroma was complicated by the fact that the density of cells
differed both among treatment groups and between subepithelial and deep
regions of the stroma (Fig. 4A). Relaxin influenced the proliferation
of the cells in both the subepithelial and deep stroma. In both
regions, the percentage of cells that were BrdU positive was greater in
relaxin-replete groups C and OPER rats than in relaxin-deficient group
OPE (Fig. 4B). To obtain a quantitative estimation of the influence of
relaxin on stromal cell proliferation throughout the entire
cross-section of the cervix, the means for the subepithelial and deep
stroma were used for the analysis shown in Fig. 5. The density of
cervical stroma cells was greater (Fig. 5A), the cross-sectional area
of the stroma was smaller (Fig. 5B), and the total number of stromal
cells per cross-section (Fig. 5C) did not differ in group OPE rats from
those in groups C and OPER. The percentage of cells that were BrdU
positive (Fig. 5D) and the total number of BrdU-positive stromal cells
per cross-section (Fig. 5E) of the cervix were less in
relaxin-deficient group OPE than in groups C and OPER.
|
|
. There was no difference between the
uterine and vaginal portions of the cervix. Accordingly, the data from
the two portions were pooled. The percentage of BrdU-positive cells per
cervical capillary plus venule (Fig. 6A) and arteriole (Fig. 6B) was
dramatically lower in relaxin-deficient group OPE than in
relaxin-replete groups C and OPER.
|
contains representative
micrographs of the vagina. Regardless of treatment, BrdU-positive cells
in the vagina were predominantly basal epithelial cells (Fig. 7, left panels). In contrast to the cervix, few vaginal stroma
cells appeared BrdU positive (Fig. 7, right panels).
|
and 9, respectively. Similar results were
found with both components of the vagina. Relaxin had a tendency to
increase both the total number of cells and the total number of
BrdU-positive cells in the vaginal epithelium (Fig. 8, C and E) and
stroma (Fig. 9, C and E), but there was no significant difference among
groups.
|
|
|
Discussion |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
75%) and stromal cells (55%) within the rat cervix at
term proliferate during the second half of pregnancy, and that the
accumulation of approximately half of the new cells is relaxin
dependent. Additionally, this study demonstrates that a minority of the
epithelial cells (45%) and stromal cells (20%) within the rat
vagina proliferates during the second half of pregnancy. Whereas
relaxin has a tendency to increase the number of new vaginal epithelial
cells and stromal cells, morphometric analysis of the data obtained in
the present study did not provide statistical support for such an
effect. The present study does not definitively elucidate the mechanism(s) by which relaxin brings about an increase in the number of cells within the cervical epithelium and stroma during the second half of pregnancy. The findings can be interpreted to infer that it does so both by promoting the proliferation of cells and retarding the rate at which cells undergo programed cell death. The greater number of BrdU-positive cells in both the epithelium and stroma as well as the dramatic increase in the percentage of BrdU-positive stromal cells in relaxin-replete rats than in relaxin-deficient rats are consistent with the hypothesis that relaxin promotes cervical growth by promoting cell proliferation. However, the observation that the percentage of cervical epithelial cells that are BrdU-positive cells is not markedly different among treatments even though the total number of epithelial cells per cross-section increases in relaxin-replete rats is consistent with the hypothesis that relaxin may increase the accumulation of cervical epithelial cells by retarding the rate of programed cell death.
Our finding that relaxin induces an approximately 50% increase in the total number of cells that proliferate during the second half of pregnancy in both the cervical epithelium and stroma extends our earlier findings of a relaxin-dependent 1.5-fold increase in cervical DNA content from midpregnancy to term in the rat (5). Relaxin has been previously reported to increase the area of cervical epithelial involutions (26) and the circumference of the cervical lumen in term pregnant rats (3, 25). This study augments those findings by demonstrating that relaxin promotes a dramatic increase in both the number of new cervical epithelial cells and the total number of epithelial cells per luminal circumference during the second half of pregnancy. The relaxin-driven increase in the total number of cervical epithelial cells contributes to the increase in the circumference of the lumen. The relaxin-dependent increase in the luminal circumference probably aids in the rapid and safe delivery of the fetuses at term. Whereas the mechanism(s) by which relaxin increases cervical epithelial cells remains to be established, there is reason to suggest that relaxin may do so through direct action on these cells. The cervical epithelium contains high affinity relaxin-binding sites in both rats and pigs (27, 28).
Within the cervical stroma, cells associated with blood vessels, isolated cells within the extracellular matrix (presumably fibroblasts), and to a lesser extent smooth muscle cells all appear to proliferate during the second half of pregnancy regardless of whether animals are treated with estrogen or estrogen plus relaxin. Nevertheless, relaxin increased the number of new cells within the cervical stroma. The observation that relaxin increased the number of new cells while the total cells per cross-section did not differ among groups may indicate that relaxin preferentially increases the numbers of a specific cell type(s) at the expense of another. Indeed, we found that the percentage of cells that proliferated per cervical blood vessel was dramatically larger in relaxin-replete rats than in relaxin-deficient rats.
There is evidence to support a role for relaxin in the proliferation of cervical blood vessel cells. First, cervical blood vessel cells contain relaxin-binding sites in both the rat and the pig (27, 28). Second, relaxin has been reported to increase arterial cross-sectional area or vascularization of the cervix (26, 29), mammary gland (30), mammary nipple (31), and uterus (32). Third, Unemori and co-workers (33) reported that relaxin stimulated the production of vascular endothelial growth factor in cultured human endometrial stromal cells, suggesting that relaxin acts to induce angiogenesis indirectly through the local production of vascular endothelial growth factor.
The significance of the finding that the extent of proliferation of cervical stroma cells was greater near the epithelium than in deeper layers is not known with certainty. It seems likely it is attributable to the difference in the types of cells that populate the two regions. Near the cervical epithelium, the stroma is predominantly fibroblasts and blood vessels, with progressively more smooth muscle cells occurring toward the periphery of the cervix (1). Cervical smooth muscle cells appear to be less proliferative than fibroblasts and blood vessel cells during the second half of pregnancy. This observation appears to be consistent with the findings of Leppert and Yu (34), who reported an increase in cervical smooth muscle cell apoptosis during the second half of pregnancy in the rat. Therefore, the greater extent of proliferation in the subepithelial stroma than in the deep stroma may reflect at least in part a larger population of cells other than muscle cells.
Our finding that relaxin did not induce a significant increase in the number of new or total vaginal cells does not appear to corroborate our earlier finding that the vaginal DNA content is greater on D22 in relaxin-replete rats than in relaxin-deficient rats (5, 6). There are two likely explanations for this apparent lack of total agreement between the two studies. First, this study and others (5, 6) demonstrated that the effects of relaxin on the rat vagina are not as dramatic as those on the cervix. Second, considerable variation occurred within treatment groups. Accordingly, it may require more animals per group and/or more sections analyzed per animal to detect significant differences among treatments. Two other less likely factors could also influence our findings. In this study the effects of relaxin on vaginal cell proliferation were analyzed per cross-section. Zhao et al. (6) reported that relaxin increases the length of the vagina at term. Therefore, it is possible that relaxin may fail to significantly increase vaginal proliferation per cross-section, but has a significant effect on the total cells per vagina. Also, we investigated the effects of relaxin on cell proliferation in the middle of the vagina. It is possible that vaginal cell proliferation varies from one end of the vagina to the other. If this is the case, an understanding of vaginal cell proliferation would require the analysis of sections from multiple portions of the vagina.
In conclusion, the present study demonstrates that relaxin induces the accumulation of both cervical epithelial and stromal cells during the second half of rat pregnancy. Findings provide evidence that relaxin’s effects on both epithelial and stromal cells are probably attributable to induction of proliferation, and relaxin’s effects on epithelial cells may also be attributable to a retardation in the rate of programed cell death. The relaxin-induced increase in epithelial and stromal cells probably contributes to relaxin’s effects on growth and remodeling of the cervix that are required for rapid and safe delivery.
|
Acknowledgments |
|---|
|
Footnotes |
|---|
Received March 9, 1998.
|
References |
|---|
|
TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
|---|
This article has been cited by other articles:
 |
|
 |
|
  L. Yao, A. I. Agoulnik, P. S. Cooke, D. D. Meling, and O. D. Sherwood Relaxin Acts on Stromal Cells to Promote Epithelial and Stromal Proliferation and Inhibit Apoptosis in the Mouse Cervix and Vagina Endocrinology, May 1, 2008; 149(5): 2072 - 2079. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 C. P Read, R A. Word, M. A Ruscheinsky, B. C Timmons, and M. S Mahendroo Cervical remodeling during pregnancy and parturition: molecular characterization of the softening phase in mice Reproduction, August 1, 2007; 134(2): 327 - 340. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
V L Bosquiazzo, J G Ramos, J Varayoud, M Munoz-de-Toro, and E H Luque Mast cell degranulation in rat uterine cervix during pregnancy correlates with expression of vascular endothelial growth factor mRNA and angiogenesis Reproduction, May 1, 2007; 133(5): 1045 - 1055. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
B. C. Timmons, S. M. Mitchell, C. Gilpin, and M. S. Mahendroo Dynamic Changes in the Cervical Epithelial Tight Junction Complex and Differentiation Occur during Cervical Ripening and Parturition Endocrinology, March 1, 2007; 148(3): 1278 - 1287. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 P. G. Drewes, H. Yanagisawa, B. Starcher, I. Hornstra, K. Csiszar, S. I. Marinis, P. Keller, and R. A. Word Pelvic Organ Prolapse in Fibulin-5 Knockout Mice: Pregnancy-Induced Changes in Elastic Fiber Homeostasis in Mouse Vagina Am. J. Pathol., February 1, 2007; 170(2): 578 - 589. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 D. J. Scott, S. Layfield, Y. Yan, S. Sudo, A. J. W. Hsueh, G. W. Tregear, and R. A. D. Bathgate Characterization of Novel Splice Variants of LGR7 and LGR8 Reveals That Receptor Signaling Is Mediated by Their Unique Low Density Lipoprotein Class A Modules J. Biol. Chem., November 17, 2006; 281(46): 34942 - 34954. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
H.-Y. Lee, S. Zhao, P. A. Fields, and O. D. Sherwood The Extent to which Relaxin Promotes Proliferation and Inhibits Apoptosis of Cervical Epithelial and Stromal Cells Is Greatest during Late Pregnancy in Rats Endocrinology, January 1, 2005; 146(1): 511 - 518. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 O. D. Sherwood Relaxin's Physiological Roles and Other Diverse Actions Endocr. Rev., April 1, 2004; 25(2): 205 - 234. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 T.A. Wyatt, J.H. Sisson, M.A. Forget, R.G. Bennett, F.G. Hamel, and J.R. Spurzem Relaxin Stimulates Bronchial Epithelial Cell PKA Activation, Migration, and Ciliary Beating Experimental Biology and Medicine, December 1, 2002; 227(11): 1047 - 1053. [Abstract] [Full Text]
|
|
|
|
 |
|
 J. G. Ramos, J. Varayoud, V. L. Bosquiazzo, E. H. Luque, and M. Munoz-de-Toro Cellular Turnover in the Rat Uterine Cervix and Its Relationship to Estrogen and Progesterone Receptor Dynamics Biol Reprod, September 1, 2002; 67(3): 735 - 742. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
S. Zhao, P. A. Fields, and O. D. Sherwood Evidence That Relaxin Inhibits Apoptosis in the Cervix and the Vagina during the Second Half of Pregnancy in the Rat Endocrinology, June 1, 2001; 142(6): 2221 - 2229. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
O. D. Sherwood, L. M. Olson, S. Zhao, and H. R. Little Inhibition of Nitric Oxide Synthase Activity Diminishes the Acute Effects of Relaxin on Growth, But Not Softening, of the Cervix in the Rat Endocrinology, July 1, 2000; 141(7): 2458 - 2464. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
L. Zhao, C. S. Samuel, G. W. Tregear, F. Beck, and E. M. Wintour Collagen Studies in Late Pregnant Relaxin Null Mice Biol Reprod, March 1, 2000; 63(3): 697 - 703. [Abstract] [Full Text]
|
|
|
|
|
|
J. A. Lenhart, P. L. Ryan, K. M. Ohleth, and C. A. Bagnell Expression of Connexin-26, -32, and -43 Gap Junction Proteins in the Porcine Cervix and Uterus During Pregnancy and Relaxin-Induced Growth Biol Reprod, December 1, 1999; 61(6): 1452 - 1459. [Abstract] [Full Text]
|
|
|
|
|
|
S. Zhao and O. D. Sherwood Monoclonal Antibodies Specific for Rat Relaxin. X. Endogenous Relaxin Induces Changes in the Histological Characteristics of the Rat Vagina During the Second Half of Pregnancy Endocrinology, November 1, 1998; 139(11): 4726 - 4734. [Abstract] [Full Text] [PDF]
|
|
| ||||||||||||||||||||||||||||||||||||
