Overactivation of hedgehog signaling in the developing Müllerian duct interferes with duct regression in males and causes subfertility

The influence of the hedgehog signaling pathway on reproduction was studied in transgenic mice in which a dominant active allele of the hedgehog signal transducer, smoothened (Smo), was conditionally expressed in the developing Müllerian duct and gonads through recombination mediated by anti-Müllerian hormone receptor 2-cre (Amhr2cre ). Previous studies showed that development of the oviduct and uterus are abnormal in female Amhr2cre/+SmoM2 mice. In the current study, focusing on mutant males, litter size was reduced 53% in crosses with wild-type females. An extra band of undifferentiated tissue extended along each epididymis and vas deferens, a position suggesting derivation from Müllerian ducts that failed to regress fully. Hedgehog signaling was elevated in this tissue, based on mRNA levels of target genes. Amhr2 mRNA was dramatically reduced in the uterus of mutant females and in the extra tissue in the tract of mutant males, suggesting that AMHR2 signaling was inadequate for complete Müllerian duct regression. Spermatogenesis and sperm motility were normal, but testis weight was reduced 37% and epididymal sperm number was reduced 36%. The number of sperm recovered from the uteri of wild-type females after mating with mutant males was reduced 78%. This suggested that sperm transport through the male tract was reduced, resulting in fewer sperm in the ejaculate. Consistent with this, mutant males had unusually tortuous vas deferentia with constrictions within the lumen. We concluded that persistence of a relatively undifferentiated remnant of Müllerian tissue is sufficient to cause subtle changes in the male reproductive tract that reduce fertility.

Normal and abnormal epithelial differentiation in the female reproductive tract

In mammals, the female reproductive tract (FRT) develops from a pair of paramesonephric or Müllerian ducts (MDs), which arise from coelomic epithelial cells of mesodermal origin. During development, the MDs undergo a dynamic morphogenetic transformation from simple tubes consisting of homogeneous epithelium and surrounding mesenchyme into several distinct organs namely the oviduct, uterus, cervix and vagina. Following the formation of anatomically distinctive organs, the uniform MD epithelium (MDE) differentiates into diverse epithelial cell types with unique morphology and functions in each organ. Classic tissue recombination studies, in which the epithelium and mesenchyme isolated from the newborn mouse FRT were recombined, have established that the organ specific epithelial cell fate of MDE is dictated by the underlying mesenchyme. The tissue recombination studies have also demonstrated that there is a narrow developmental window for the epithelial cell fate determination in MD-derived organs. Accordingly, the developmental plasticity of epithelial cells is mostly lost in mature FRT. If the signaling that controls epithelial differentiation is disrupted at the critical developmental stage, the cell fate of MD-derived epithelial tissues will be permanently altered and can result in epithelial lesions in adult life. A disruption of signaling that maintains epithelial cell fate can also cause epithelial lesions in the FRT. In this review, the pathogenesis of cervical/vaginal adenoses and uterine squamous metaplasia is discussed as examples of such incidences.

The Müllerian HOXA10 gene promotes growth of ovarian surface epithelial cells by stimulating epithelial-stromal interactions

The ovarian surface epithelium (OSE) origin of ovarian cancers has been controversial because these cancers often exhibit Müllerian-like features. One hypothesis is that ovarian neoplasia involves the gain of growth advantages by OSE cells via activation of Müllerian programs. The homeobox gene HOXA10 controls formation of the uterus from the Müllerian ducts, and is not expressed in normal OSE. We previously found that HOXA10 is expressed in ovarian cancers with endometrial-like features, and induces transformed OSE cells to form glandular tumors in mice. In the current study, we found that induction of HOXA10 in OSE cells promotes homophilic cell adhesion and prevents anoikis. HOXA10 expression stimulated interactions of OSE cells with the extracellular matrix proteins vitronectin and fibronectin, and with mesothelial cells of the omentum which is a common attachment site for ovarian cancer cells. HOXA10 also stimulated interactions of OSE cells with omental fibroblasts, and these interactions promoted OSE cell growth. Our findings indicate that aberrant activation of a Müllerian program in OSE cells confers growth advantages by stimulating cellular interactions with the microenvironment.

Sonic hedgehog promotes stem-cell potential of Müller glia in the mammalian retina

Müller glia have been demonstrated to display stem-cell properties after retinal damage. Here, we report this potential can be regulated by Sonic hedgehog (Shh) signaling. Shh can stimulate proliferation of Müller glia through its receptor and target gene expressed on them, furthermore, Shh-treated Müller glia are induced to dedifferentiate by expressing progenitor-specific markers, and then adopt cell fate of rod photoreceptor. Inhibition of signaling by cyclopamine inhibits proliferation and dedifferentiation. Intraocular injection of Shh promotes Müller glia activation in the photoreceptor-damaged retina, Shh also enhances neurogenic potential by producing more rhodopsin-positive photoreceptors from Müller glia-derived cells. Together, these results provide evidences that Müller glia act as potential stem cells in mammalian retina, Shh may have therapeutic effects on these cells for promoting the regeneration of retinal neurons.

Reserve Cells in Human Uterine Cervical Epithelium Are Derived from Müllerian Epithelium at Midgestational Age

The role of endocervical reserve cells in squamous metaplasia and neoplasia is still debated. Their origin in the cervix is open to speculation and it is unclear how they are targeted during carcinogenesis. To further understand the primary characteristics of reserve cells, we phenotyped them in the developing human cervix. In 13 perinatal autopsies of fetuses between 16 and 40 weeks of gestation, the human fetal cervix was evaluated in serial sections. Immunostaining comprised a panel of antibodies for cytokeratins, p63, and bcl-2; then, the sections were stained with Alcian blue and periodic acid-Schiff before and after diastase treatment. Reserve cells are first identified at approximately 20 weeks of gestation. They are first noted under müllerian-type columnar cells lining the developing uterine cavity. There is considerable overlap in the expression profiles of müllerian cells and reserve cells for p63, bcl-2, and cytokeratins 5, 8, and 18 at this stage of development, with increasing gestational age expression localized to respective cell compartments. Eventually, the phenotype of these cells correspond fully with that described for adult reserve cells and endocervical cells. Müllerian epithelial cells are the stem cell for endocervical reserve cells and endocervical columnar cells. They have the capacity to transform into both endocervical columnar and squamous-type epithelium in the endocervix during early cervical development.

The origin of the Mullerian duct in chick and mouse

In vertebrates the female reproductive tracts derive from a pair of tubular structures called Mullerian ducts, which are composed of three elements: a canalised epithelial tube, mesenchymal cells surrounding the tube and, most externally, coelomic epithelial cells. Since the first description by Johannes Peter Muller in 1830, the origin of the cells making up the Mullerian duct has remained controversial. We report the results from lineage-tracing experiments in chicken and mouse embryos aimed to provide information of the dynamics of Mullerian duct formation. We show that all Mullerian duct components derive from the coelomic epithelium in both species. Our data support a model of a Mullerian epithelial tube derived from an epithelial anlage at the mesonephros anterior end, which then segregates from the epithelium and extends caudal of its own accord, via a process involving rapid cell proliferation. This tube is surrounded by mesenchymal cells derived from local delamination of coelomic epithelium. We exclude any significant influx of cells from the Wolffian duct and also the view of a tube forming by coelomic epithelium invagination along the mesonephros. Our data provide clues of the underlying mechanism of tubulogenesis relevant to both normal and abnormal development of the female reproductive tract.

Lineage infidelity of epithelial ovarian cancers is controlled by HOX genes that specify regional identity in the reproductive tract

Although epithelial ovarian cancers (EOCs) have been thought to arise from the simple epithelium lining the ovarian surface or inclusion cysts, the major subtypes of EOCs show morphologic features that resemble those of the müllerian duct-derived epithelia of the reproductive tract. We found that HOX genes, which normally regulate mullerian duct differentiation, are not expressed in normal ovarian surface epithelium (OSE), but are expressed in different EOC subtypes according to the pattern of mullerian-like differentiation of these cancers. Ectopic expression of Hoxa9 in tumorigenic mouse OSE cells gave rise to papillary tumors resembling serous EOCs. In contrast, Hoxa10 and Hoxa11 induced morphogenesis of endometrioid-like and mucinous-like EOCs, respectively. Hoxa7 showed no lineage specificity, but promoted the abilities of Hoxa9, Hoxa10 and Hoxa11 to induce differentiation along their respective pathways. Therefore, inappropriate activation of a molecular program that controls patterning of the reproductive tract could explain the morphologic heterogeneity of EOCs and their assumption of müllerian-like features.

Secretory and basal cells of the epithelium of the tubular glands in the male Mullerian gland of the caecilianUraeotyphlus narayani (Amphibia: Gymnophiona)

Caecilians are exceptional among the vertebrates in that males retain the Mullerian duct as a functional glandular structure. The Mullerian gland on each side is formed from a large number of tubular glands connecting to a central duct, which either connects to the urogenital duct or opens directly into the cloaca. The Mullerian gland is believed to secrete a substance to be added to the sperm during ejaculation. Thus, the Mullerian gland could function as a male accessory reproductive gland. Recently, we described the male Mullerian gland of Uraeotyphlus narayani using light and transmission electron microscopy (TEM) and histochemistry. The present TEM study reports that the secretory cells of both the tubular and basal portions of the tubular glands of the male Mullerian gland of this caecilian produce secretion granules in the same manner as do other glandular epithelial cells. The secretion granules are released in the form of structured granules into the lumen of the tubular glands, and such granules are traceable to the lumen of the central duct of the Mullerian gland. This is comparable to the situation prevailing in the epididymal epithelium of several reptiles. In the secretory cells of the basal portion of the tubular glands, mitochondria are intimately associated with fabrication of the secretion granules. The structural and functional organization of the epithelium of the basal portion of the tubular glands is complicated by the presence of basal cells. This study suggests the origin of the basal cells from peritubular tissue leukocytes. The study also indicates a role for the basal cells in acquiring secretion granules from the neighboring secretory cells and processing them into lipofuscin material in the context of regression of the Mullerian gland during the period of reproductive quiescence. In these respects the basal cells match those in the epithelial lining of the epididymis of amniotes.

Roles of p63 in the diethylstilbestrol-induced cervicovaginal adenosis

Women exposed to diethylstilbestrol (DES) in utero develop abnormalities, including cervicovaginal adenosis that can lead to cancer. We report that transient disruption of developmental signals by DES permanently changes expression of p63, thereby altering the developmental fate of Müllerian duct epithelium. The cell fate of Müllerian epithelium to be columnar (uterine) or squamous (cervicovaginal) is determined by mesenchymal induction during the perinatal period. Cervicovaginal mesenchyme induced p63 in Müllerian duct epithelium and subsequent squamous differentiation. In p63(-/-) mice, cervicovaginal epithelium differentiated into uterine epithelium. Thus, p63 is an identity switch for Müllerian duct epithelium to be cervicovaginal versus uterine. P63 was also essential for uterine squamous metaplasia induced by DES-exposure. DES-exposure from postnatal day 1 to 5 inhibited induction of p63 in cervicovaginal epithelium via epithelial ERalpha. The inhibitory effect of DES was transient, and most cervicovaginal epithelial cells recovered expression of p63 by 2 days after discontinuation of DES-treatment. However, some cervicovaginal epithelial cells failed to express p63, remained columnar and persisted into adulthood as adenosis.

Development of the human Müllerian duct in the sexually undifferentiated stage

An embryological explanation for the development of the Müllerian duct still poses a major challenge. The development of this duct was investigated systematically in human embryos. Seven embryos (Carnegie stages 18-23) were serially sectioned in the frontal, sagittal, and transversal planes at a thickness of 10 microm and stained with hematoxylin and eosin (H&E) for histological analysis. In all observed embryos, the caudal end of the Müllerian duct was found to be intimately connected to the Wolffian duct. The opening of the Müllerian duct to the coelomic cavity was formed as the result of an invagination of the coelomic epithelium at Carnegie stage 18. The duct grew independently from the invagination during stages 19-23. The fused duct (uterovaginal canal) bifurcated at the caudal portion at Carnegie stages 22 and 23. This is the first description of the caudal portion of the fused Müllerian ducts separating again and returning to each of the Wolffian ducts in human embryos.

Effect of estrogens on ontogenetic expression of progesterone receptor in the fetal female rat reproductive tract

Ontogenetic expression of progesterone receptor (PR) and effect of estrogens on PR expression in the fetal female rat reproductive tract were investigated. To evaluate ontogenetic PR expression, female reproductive tract from untreated fetuses was examined on gestational days (GD) 15.5, 17.5, 19.5 and 21.5. To evaluate estrogen effects, pregnant rats were injected once per day with oil, 17beta-estradiol (E(2)) or diethylstilbestrol (DES) from GD 15 through 21. Female fetuses were prepared for real-time reverse-transcription polymerase chain reaction (RT-PCR) or immunohistochemistry for PR. Increase in PR mRNA expression was detected in the Müllerian duct on GD 21.5 compared to that on GDs 15.5 and 17.5 in untreated fetuses (P<0.05). Prenatal administration of E(2) or DES increased Müllerian PR mRNA levels by GD 21.5 compared with oil controls (P<0.01). To identify cell and region in which PR was expressed and up-regulated by E(2) and DES, localization was evaluated within three regions along the Müllerian duct axis which differentiate into oviduct, uterus and upper vagina in immunohistochemistry. In untreated fetuses, Müllerian epithelial PR immunoreactivity was weak on GDs 15.5 and 17.5, but then became moderate on GDs 19.5 and 21.5 in all three regions. These fetuses exhibited faint signals in Müllerian mesenchymal PR immunoreactivity during gestational monitoring. Critically, Müllerian mesenchymal PR staining became intense after E(2) exposure in all three regions by GD 21.5, but no change was observed in Müllerian epithelial PR. Similarly, DES dramatically induced Müllerian mesenchymal PR in all regions by GD 21.5, and also enhanced proximal epithelial PR. On the other hand, middle and caudal epithelial PRs were reduced by DES. These affected mesenchymal and epithelial cells by DES were ER alpha immunopositive in the Müllerian duct, except for middle Müllerian epithelium. These findings clearly demonstrate cell-specific PR localization and region-specific effect of DES on PR in the developing rat Müllerian duct, and provide fundamental information critical for investigating the tissue-specific mechanisms underlying the prenatal response to estrogen receptor agonists.

Sympathetic neuronal survival induced by retinal trophic factors

Neuronal survival in the vertebrate peripheral nervous system depends on neurotrophic factors available from target tissues. In an attempt to identify novel survival factors, we have studied the effect of secreted factors from retinal cells on the survival of chick sympathetic ganglion neurons. Embryonic day 10 sympathetic neurons undergo programmed cell death after 48 h without appropriate levels of nerve growth factor (NGF). Retina Conditioned Media (RCM) from explants of embryonic day 11 retinas maintained for 4 days in vitro supported 90% of E10 chick sympathetic neurons after 48 h. Conditioned medium from purified chick retinal Muller glial cells supported nearly 100% of E10 chick sympathetic neurons. Anti-NGF (1 microg/mL) blocked the survival effect of NGF, but did not block the trophic effect of RCM. Neither BDNF nor NT4 (0.1-50 ng/mL) supported E10 sympathetic neuron survival. Incubation of chimeric immunoglobulin-receptors TrkA, TrkB, or TrkC had no effect on RCM-induced sympathetic neuron survival. The survival effects were not blocked by anti-GDNF, anti-TGFbeta, and anti-CNTF and were not mimicked by FGFb (0.1-10 nM). LY294002 at 50 microM, but not PD098059 blocked sympathetic survival induced by RCM. Further, the combination of RCM and NGF did not result in an increase in neuronal survival compared with NGF alone (82% survival after 48 h). The secreted factor in RCM is retained in subfractions with a molecular weight above 100 kDa, binds to heparin, and is unaffected by dialysis, but is heat sensitive. Our results indicate the presence of a high-molecular weight retinal secreted factor that supports sympathetic neurons in culture.

Roles of p63 in differentiation of Müllerian duct epithelial cells

In the mouse female reproductive tract, p63, a homologue of the p53 tumor suppressor gene, is highly expressed in basal cells of the vaginal and cervical epithelium, but not in the uterine epithelium. P63 is undetectable in the undifferentiated epithelium of the embryonic Müllerian duct. The Mullerian vaginal epithelium becomes p63 positive and stratified during the first week of postnatal development. P63 expression in the Müllerian vaginal epithelium is induced by vaginal mesenchyme. When vaginal mesenchyme was combined with uterine epithelium from newborn mouse, the uterine epithelium was induced to undergo vaginal differentiation and to express p63. Conversely, when the vaginal epithelium from the newborn mouse was recombined with uterine mesenchyme, it underwent uterine differentiation and failed to express p63. After the uterine epithelium or vaginal epithelium differentiates, the expression status of p63 in uterine (negative) and vaginal (positive) epithelia is not altered by heterotypic mesenchyme. Studies with p63-null mice demonstrate that p63 is essential for vaginal epithelial differentiation, because p63-null Müllerian vaginal epithelium developed as uterine epithelium. Thus, p63 determines whether Müllerian duct epithelial cells become uterine or vaginal. Misexpression of p63 in uterine and vaginal epithelial lesions induced by neonatal diethylstilbestrol (DES) exposure induces pathological changes. Irregularities in p63 expression (and thus epithelial differentiation) are observed in the uterine and vaginal epithelia of neonatally DES-exposed mice during the first week of postnatal development. Thus, neonatal DES exposure abnormally transforms uterine and vaginal epithelial differentiation by perturbing epithelial expression of p63 during development.

Epithelial-stromal tissue interaction in paramesonephric (Müllerian) epithelial differentiation

During organogenesis, the middle to caudal portion of Müllerian epithelium differentiates into uterine and vaginal epithelia in females. Functional differentiation of uterine and vaginal epithelia occurs in adulthood, and is regulated by 17beta-estradiol (E(2)) and progesterone. In this report, the roles of mesenchyme/stroma in differentiation of uterine and vaginal epithelia were studied in tissue recombination experiments. At birth, Müllerian epithelium was negative for uterine and vaginal epithelial markers. Tissue recombinant experiments showed that uterine and vaginal gene expression patterns were induced in neonatal Müllerian epithelium by the respective mesenchymes. Differentiated adult uterine and vaginal epithelia did not change their original gene expression in response to heterotypic mesenchymal induction. In the adult vagina, E(2) induced expression of involucrin, a CCAAT/enhancer-binding protein beta and cytokeratin 1 via estrogen receptor alpha (ERalpha). Tissue recombination experiments with wild-type and ERalpha knockout mice demonstrated that epithelial gene expression is regulated by E(2) via epithelial-stromal tissue interactions. Uterine/vaginal heterotypic tissue recombinations demonstrated that functional differentiation of uterine and vaginal epithelia required organ-specific stromal factors. In contrast, stromal signals regulating epithelial proliferation appeared to be nonspecific in the uterus and vagina.

Onset of sex differentiation: dialog between genes and cells

During the late 1940s, Alfred Jost demonstrated that mammalian sex differentiation begins in fetal testis, producing two factors necessary for the establishment of phenotypic males. Castrated embryos prior to testis differentiation led to phenotypic female differentiation. Jost proposed the existence of a testis-determining factor (TDF), elucidated in 1990 and named SRY for humans and Sry for mice. Thereafter, an increasing list of genes expressed in the genital ridges of mouse embryos at the onset of gonad differentiation has appeared. To date, it is clear that complete understanding of the mechanisms underlying gonadal sex differentiation in mammals requires identification of key cell lineages in which gonadal-specific genes are expressed. Here, a correlation between known gene expression and gonadal morphologic changes is attempted.

Differential activation of MAPK during Müllerian duct growth and apoptosis: JNK and p38 stimulation by DES blocks tissue death

To investigate the involvement of the mitogen-activated protein kinases (MAPKs) in c-Jun-mediated Müllerian duct (MD) differentiation, Western immunoblot with antibodies against c-Jun N-terminal kinase (JNK), extracellular signal-regulated kinases (ERK1 and 2), p38, phosphorylated JNK (p-JNK), and p-ERK were used to investigate these kinases in the left and right MDs (LMD and RMD, respectively) of female chicks. The content of these kinases in the LMD and RMD of various stages of embryos was detected by measuring their density in autoradiograms by a Spot-denso-program with Alpha Ease software. In the LMD, the growing embryonic sex tract, the amount of JNK increased from the 8th to 10th embryonic day and reached its highest at the 12th to 18th day. The content of ERK1, ERK2, and p38 remained at the same level throughout development. In the RMD, the apoptotic embryonic sex tract, the level of these four MAPKs showed a linear increase from the 8th to 10th day and then declined at the 12th day. Before the RMD entered the apoptotic stages (10th day of incubation), MAPKs were overexpressed. The findings following the application of p-MAPK antibodies, e.g., p-JNK and p-ERK, mirrored the result showing that differential activation of MAPKs existed in the LMD and RMD. When the RMD entered the apoptotic stages (13th to 18th day of incubation), the reduction in JNK activity was higher than that of the other three kinases. The apoptotic death of RMD was prevented by in vivo diethylstilbestrol treatment, which restored the level of JNK, p-JNK, and p38. No stimulatory effect was found for ERK and p-ERK.

Effect of diethylstilbestrol on cell proliferation and expression of epidermal growth factor in the developing female rat reproductive tract

To evaluate mechanisms of cell proliferation in the fetal female rat reproductive tract, diethylstilbestrol (DES) effects on cell division and estrogen receptor (ER), epidermal growth factor (EGF) and EGF receptor (EGF-R) expressions were determined from gestational day (GD) 15.5 to 21.5. Reproductive tracts were evaluated within three regions along the Müllerian duct axis; these were proximal, middle and caudal, which differentiate into oviduct, uterus and upper vagina respectively. In fetuses from non-treated dams, epithelial and mesenchymal proliferation, as evaluated by 5-bromo-2'-deoxyuridine incorporation, was decreased with development in all regions of the Müllerian duct. EGF levels were determined by immunohistochemistry. Müllerian epithelial EGF immunoreactivity was intense in the proximal and middle regions on GDs 15.5 and 17.5. EGF staining remained intense only in the proximal epithelia by GD 19.5 and was weak in the caudal epithelium, but substantially reduced throughout epithelia in all regions by GD 21.5. Thus, decreased cell proliferation correlated with decreased EGF expression in the developing Müllerian duct. DES (100 microg/kg body weight) was injected from GD 15 to 19 and female fetuses were collected on GD 19.5. DES increased Müllerian duct cell proliferation in the proximal epithelium and mesenchyme but decreased it in the caudal epithelium compared with oil-treated controls. No proliferative DES effect was observed in any cell type in the middle region. Müllerian duct EGF immunoreactivity was suppressed by DES compared with oil. Competitive RT-PCR indicated DES also decreased mRNAs for EGF, ERbeta1 and ERbeta2, but not ERalpha and EGF-R. These results indicate EGF may be an important regulatory factor of Müllerian duct cell proliferation, and that DES may alter cell proliferation by disrupting normal EGF, ERbeta1 and ERbeta2 expression in the developing female rat reproductive tract.

Inhibition of autophagy of fetal rabbit gonoducts by puromycin, tunicamycin and chloroquin in organ culture

At the end of ambisexual stage, mullerian or wolffian ducts are programmed to die. Cell degeneration is initialized by an appearance of lysosomes, subsequently involved in invading autophagic vacuoles. In an organ culture assay, performed for 6 days, treatments by puromycin, tunicamycin and chloroquine, known to act on synthesis, transport and activation of lysosomal enzymes, were applied to inhibit the duct regression. Four situations were studied: female genital tract of 17 day post coitum (d.p.c.) cultured with differentiated testis of 19 d.p.c.; male genital ducts of 17 d.p.c. cultured without testis; female and male genital tracts of 17 d.p.c. cultured alone as controls. The stabilization of the mullerian duct cultured with testis and of the wolffian duct cultured without testis was obtained. Ultrastructuraly, the lysosomes were scarce or absent and no autophagic vacuoles were observed. In preventing the formation of lysosomes, it was possible to avoid the duct cell autophagy and to comfirm the existence of a wolffian lysosomal system spontaneously active when testosterone is absent, while a mullerian one spontaneously inactive when AMH is absent.

Apocrine metaplasia: a new type of müllerian metaplasia

Apocrine differentiation was an incidental finding in an ovarian cyst. This is considered to be a further example of Müllerian metaplasia that has not been described before and which, theoretically, could occur in any organ of Müllerian derivation (ovary, uterus, cervix or fallopian tube). It is suggested that sites of such metaplasia could in turn be the origin of primary apocrine carcinoma in any of the above locations.

Effect of human recombinant mullerian inhibiting substance on isolated epithelial and mesenchymal cells during mullerian duct regression in the rat

The effect of human recombinant Mullerian Inhibiting Substance (MIS) on the regression of the Mullerian duct (MD) of female rat fetuses was examined in vitro to determine whether MIS acts on MD epithelium and/or mesenchyme at the critical periods of sexual differentiation. Urogenital ridges (URs) of female rat fetuses at 14.5- to 18.5-days of gestation (plug day = 0) were cultured for 3 days with or without recombinant human MIS in CMRL 1066 medium with 10% female fetal calf serum. In URs from 14.5- and 15.5-day-old fetuses, the cranial portion of the MD regressed almost completely during the 3-day culture period in the presence of MIS, whereas the caudal half to third of the MD remained intact but tapered to a fine point cranially. MDs survived in URs from 16.5-day-old fetuses cultured in the presence of MIS except that the cranial portion of the MDs was deformed. MIS did not elicit regression of MDs in URs obtained from 17.5- and 18.5-day-old fetuses, but instead caused the MD epithelium to form bulges projecting into the mesenchyme. MD epithelium at 15.5-days of gestation was separated from the surrounding UR mesenchyme, and both components (MD epithelium and mesenchyme) were cultured separately for 3 days in the presence or absence of MIS. Both epithelial and mesenchymal cells survived in the presence or absence of MIS. MD epithelium formed typical epithelial colonies, whereas UR mesenchyme spread as fibroblastic cells. Analysis of labeling index after incorporation of [3H] thymidine demonstrated that MD epithelial DNA synthesis was not influenced by MIS. In contrast, mesenchymal labeling index was reduced significantly by MIS. This effect of MIS on UR mesenchyme in conjunction with earlier histological observations of mesenchymal condensation during MD regression and an absence of direct effects of MIS on the epithelium suggests that MIS elicits its effect on the MD epithelium via the surrounding mesenchyme.

The response of female urogenital tract epithelia to mesenchymal inductors is restricted by the germ layer origin of the epithelium: prostatic inductions

The epithelium of the mammalian vagina arises from two distinct germ layers, endoderm from the urogenital sinus and mesoderm from the Müllerian ducts. While neonatal vaginal epithelium can be induced to form prostate which is normally an endodermal derivative, it has not been determined whether this ability to form prostate is shared by both mesoderm- and endoderm-derived vaginal epithelia. To test the competence of vaginal epithelia we have isolated sinus-derived and Müllerian-derived vaginal epithelia from newborn mice, combined them with rat urogenital sinus mesenchyme, and grown the tissue recombinants for 4 weeks in male athymic nude mice. Endoderm-derived sinus vaginal epithelium was induced to form prostatic tissue which expressed prostate-specific secretory proteins in 21 of 23 tissue recombinants. Müllerian-derived vaginal epithelium formed small ducts and cysts lined by a simple epithelium. These latter tissue recombinants lacked any evidence of prostatic secretory proteins. Similarly, endoderm-derived urethral epithelium was induced to form prostate (17 of 17 cases), while mesoderm-derived uterine epithelium was not (0 of 13 cases). Therefore, the ability to form prostatic epithelium was limited to endodermal derivatives of the urogenital tract.

Role of cell-matrix contacts in cell migration and epithelial-mesenchymal transformation

Epithelial cells make contact with extracellular matrix via receptors on the basal surface that interact with the basal actin cortex. In 3D matrix, the mesenchymal cell makes contact with matrix all around its circumference via similar receptors. When moving, the fibroblasts is constantly constructing a new front end. We postulate in a 'fixed cortex' theory of cell motility that the circumferential actin cortex is firmly attached to matrix and that the myosin-rich endoplasm slides past it into the continually forming new front end. During epithelial-mesenchymal transformation, the presumptive mesenchymal cell seems to turn on the new front end mechanism as a way of emigrating from the epithelium into the underlying matrix with which it makes 'fixed' contacts. Master genes may exist that regulate the expression of epithelial genes on the one hand, and mesenchymal genes on the other.

Biosynthesis and secretion of fibronectin in the cultured mesenchymal cells of the developing chick müllerian duct

We have developed a method to separate and isolate the mesenchymal cells from the epithelial cells in the left Müllerian duct of the developing chick. We then cultured the mesenchymal cells in a serum-free medium. Through an enzyme-linked immunosorbent assay, we detected fibronectin synthesis and release into the medium at stages of Müllerian duct development. Our results demonstrate that the amount of fibronectin secreted by cultured cells gradually decreased in accordance with Müllerian duct differentiation. Similar observations found in the developing embryonic intestine indicate that the highest fibronectin synthesis occurs during early stages of development, when morphogenetic movement and mesenchymal-epithelial interaction are prominent features of embryonic organ differentiation and growth.

Recombinant human müllerian inhibiting substance inhibits epidermal growth factor receptor tyrosine kinase

Autophosphorylation of the epidermal growth factor (EGF) receptor in A-431 cells and plasma membrane fractions was inhibited by partially purified recombinant human Müllerian Inhibiting Substance (MIS). Immunoprecipitation of the EFG receptor using anti-EGF receptor or anti-phosphotyrosine antibodies, and phosphoamino acid analysis of this receptor, demonstrated that MIS specifically inhibited EGF-induced tyrosine phosphorylation. Inhibition of EGF receptor autophosphorylation by MIS in membrane preparations was not affected by increasing concentrations of EGF, manganese or [gamma-(32)P] ATP. Thus, it is unlikely that MIS competes for EGF binding sites or sequesters substrate. Immunoabsorption of MIS with anti-human MIS antibody blocked the MIS inhibition of EGF receptor autophosphorylation, indicating that the inhibition was due to MIS. Our data suggest that MIS regulates the activity of the EGF receptor tyrosine kinase in A-431 cells.

Differentiation and development of the reproductive system in the iguanid lizard, Sceloporus undulatus

Embryos of the lizard Sceloporus undulatus were sampled throughout incubation, and the differentiation and development of the reproductive system was documented histologically. The undifferentiated gonads possess both a cortex and medulla, both of which contain germ cells until embryonic stage 34. Beginning at stage 34, the cortex of the presumptive ovary thickens, and cortical germ cells are more abundant. By the time of hatching, the ovarian cortex is 6 to 10 cells thick and filled with oogonia and oocytes; primordial follicles, however, are not yet present. In males at embryonic stage 34, seminiferous tubules appear in the medulla of the testis, and Sertoli cells begin to differentiate. Seminiferous tubule formation is complete by hatching, and both Sertoli and Leydig cells are apparent. The mullerian ducts develop in both sexes but begin regressing in the male at embryonic stage 37. The wolffian ducts also develop in both sexes and are present in males and females at hatching.

Purification of chicken testicular müllerian inhibiting substance by ion exchange and high-performance liquid chromatography

A highly purified protein molecule was obtained from the secretory proteins of 8-week-old chicken testes using ion-exchange column chromatographic procedures, including DEAE Bio-Gel A, CM Bio-Gel A, wheat germ lectin columns, and high-performance liquid chromatographic (hplc) separation techniques. This protein molecule has a molecular weight of 74,000 Da (74K protein). The isolated 74K protein induces regression of chicken Müllerian ducts grown in vitro. The 74K protein does not cause regression of cultured embryonic intestine or Wolffian duct. When the total testicular secretory proteins are resolved in a two-dimensional gel electrophoresis, approximately 120 polypeptides are obtained. The purified 74K protein has a pI of 6.1. Analysis of amino acid composition indicates that the 74K protein is relatively acidic in nature with a ratio of acidic to basic amino acids of 1.93.

Different antigen expression on Wolffian and Müllerian cells in rat embryos as detected by monoclonal antibodies

The Wolffian duct and the developing Müllerian duct of 14 and 15 day old rat embryos were examined with the monoclonal antibodies GZ1 and GZ2. These antibodies react with antigens situated in the cell membrane of Wolffian cells; they do not react with Müllerian cells. This different antigen expression confirms the current opinion that these cells are of different types. A cellular contribution from the Wolffian duct to the developing Müllerian duct was not found.

Müllerian duct maintenance in heterotypic organ culture after in vivo exposure to diethylstilbestrol

Prenatal exposure to diethylstilbestrol (DES) results in the persistence of Müllerian ducts in male offspring. The influence of DES on Müllerian duct regression was studied using an organ culture system in which DES-treated or control indifferent ducts (embryonic reproductive tracts) were cocultured along with treated or control embryonic testes. Prenatal DES exposure was by sc injection of the mother (100 micrograms/kg BW) on days 9 through 12 of gestation. Embryonic tissues were removed on day 13 of gestation and cultured for 72 h. In organ culture, Müllerian duct regression, comparable to that seen in vivo, occurred when control reproductive tracts were associated with control testes. However, maintenance of the Müllerian duct was observed in 100% of the tissues when DES-treated testes and DES-treated reproductive tracts were cultured together. When recombinations were formed by the association of control reproductive tracts and DES-treated testes, there was regression of the Müllerian duct (87%). However, in the combinations of DES-treated reproductive tracts and control testes, 41% of the cultured tissue demonstrated partial regression of the Müllerian duct, and 59% showed no regression. These data support previous in vivo results that prenatal exposure to DES has an inhibitory effect on Müllerian duct regression and further suggest that this inhibitory effect is mainly due to a decrease in responsiveness of the treated embryonic Müllerian duct.

The fate of the grafted quail Mullerian duct in the chick embryonic coelom

Recent morphological analyses of Mullerian duct regression suggested that some ductal cells might survive, in contrast to the previous view that regression was an example of "programmed cell death." The present study was designed to demonstrate survival of Mullerian duct cells after regression, and to map migration into local or distant tissues. Seven or eight-day-old chick embryos received intraabdominal grafts of Mullerian ducts from seven- or eight-day-old quails, creating chick-quail chimeras. Three or four days later the abdomen was serially sectioned and examined histologically using a modified Feulgen stain. Sixty-six of the 230 grafted embryos survived (29%). After sectioning, grafts were found in 34 of the 58 embryos in the body wall, peritoneum or mesenephros, with several adherent to the hosts' Mullerian ducts. Twenty female embryos contained grafts, all of which were developing normally. Fourteen male embryos contained grafts in various stages of regression. Regression was more advanced in mesonephric or body wall grafts while free intraperitoneal grafts showed the least regression. Migration of quail cells was striking when seen in grafts placed in the mesonephros or adherent to the host Mullerian duct. In these, regressing quail cells migrated into and became incorporated in adjacent chick mesenephros. Migration patterns were seen also in non-regressing cells in female hosts, where quail cells "homed" to the host chick Mullerian duct structures.

Changing patterns of fibronectin, laminin, type IV collagen, and a basement membrane proteoglycan during rat Mullerian duct regression

Antibodies to type IV collagen, laminin, heparan sulfate proteoglycan, and fibronectin were used to study the regression of the rat Mullerian duct. All four of these matrix constituents are located at the perimeter of the Mullerian duct within the ductal basement membrane. As the Mullerian duct regresses, the staining of all of these basement membrane constituents becomes irregular and discontinuous. Fibronectin, which is also present in the interstitium, becomes undetectable in the mesenchyme which condenses around the regressing Mullerian duct. These data indicate that degradation of the extracellular matrix around the male Mullerian duct is a central event in the regression of this structure.

Contacts between Wolffian and Müllerian cells at the tip of the outgrowing Müllerian duct in rat embryos

The developing Müllerian duct was studied at the light microscopic as well as the electron microscopic level in rat embryos, especially in the section of the terminal bud and its tip, where Wolffian and Müllerian duct are enclosed by a common basal membrane. In this zone desmosomes can be found among Wolffian cells and also among Müllerian cells. In addition, we found cell contacts between Müllerian and Wolffian cells, namely short electron-dense segments on adjacent surfaces or disc-shaped thickenings within opposite plasma membranes, as well as fusions of the plasmalemmata over short distances. Until now, these cell contacts have not been described in rat embryos.

The role of nucleotide pyrophosphatase in Mullerian duct regression

Mullerian inhibiting substance (MIS), a glycoprotein from the fetal testis causing regression of the embryonic Mullerian duct, can be inhibited in vitro in the presence of Mn2+ by a wide range of nucleotides including GTP, NAD, ATP, AMP, and several nonhydrolyzable synthetic ATP analogs. Extracellular nucleotide pyrophosphatase (NPPase), an enzyme able to hydrolyze the wide variety of the nucleotides and analogs found to inhibit Mullerian duct regression, was studied by histochemical staining (H. Sierakowska and D. Shugar (1963). Biochem. Biophys. Res. Commun. 11, 70-74) to determine if NPPase localized in or around the Mullerian duct during regression. Frozen sections of urogenital ridges from 14 1/2- to 17 1/2-day rat fetuses (n = 77) were incubated with a-naphthyl thymidine-5'-phosphate (naphthyl TMP) and Fast Red TR. Nucleotide pyrophosphatase hydrolyzes naphthyl TMP, releasing naphthol, which then reacts with Fast Red to produce color at the enzyme site. Nucleotide hydrolysis was detected around regressing male (n = 16) Mullerian duct cells at 16 1/2 days of gestation, but no hydrolysis was detected around female (n = 17) Mullerian duct cells at any stage. Controls (n = 24) incubated without substrate did not stain. Addition of exogenous ATP (n = 20) to the histochemical incubation medium inhibited nucleotide hydrolysis on male Mullerian ducts, suggesting that this staining is specific for pyrophosphatase activity. Results in vivo were confirmed in vitro by incubating 14 1/2 day female rat urogenital ridges with MIS for 72 hr prior to histochemical staining. The addition of testosterone to MIS was obligatory to detect staining in vitro (n = 10). The localized NPPase activity around the regressing Mullerian duct suggests that NPPase may appear as a consequence of duct regression and may act to control the degree of membrane phosphorylation by degrading excess trinucleotides.

Heritable aspects of uterine anomalies. I. Three familial aggregates with Müllerian fusion anomalies

Familial aggregates of incomplete Müllerian fusion have been reported, but the role of genetic factors has not been elucidated. In the last several years, we have fortuitously encountered three families in which several members were affected with Müllerian fusion anomalies. In two families, several members had incomplete Müllerian fusion as traditionally described. In the third family, several members had the hand-foot-genital syndrome, a rare autosomal dominant disorder characterized not only by Müllerian fusion defects but also by skeletal (hand and foot) malformations. The etiologic heterogeneity of Müllerian fusion defects is considered.

A comparative study of the differentiation and involution of the Mullerian duct and Wolffian duct in the male and female fetal mouse

The present investigation has examined the ultrastructural differentiation of the genital ducts of both sexes of fetal mice. The emphasis of observations was placed on the phenomenon of morphogenetic cytolysis, particularly during the critical periods of Wolffian duct stabilization and Mullerian duct involution. Both developing and regressing genital ducts evidence extensive cytolysis. Autophagy appears to be the mechanism of morphogenetic changes in the developing male Wolffian duct. Autophagy, heterophagy, and degeneration in situ are all prominent cytolytic activities in female Wollfian duct involution. The developing female Mullerian duct undergoes extensive morphogenetic remodeling by the mechanisms of autophagy, heterophagy, and degeneration in situ. In the male Mullerian duct, autophagy, heterophagy, and degeneration in situ are also prominent. In addition, whole degenerated epithelial cells are extruded from the duct early in regression which may be realted to the transformation of periductal mesenchymal cells into an "epithelioid cell cuff" which does not form around the regressing Wolffian duct. The formation of this mesenchymal condensation surrounding the duct is also accompanied by the protrusion of Mullerian epithelial cell cytoplasm into the mesenchymal cells. These observations may evidence a complex epithelial-mesenchymal interaction occurring during male Mullerian duct involution.

Involution of the female Mullerian duct of the fetal rat in the organ-culture assay for the detection of Mullerian Inhibiting Substance

The study of Mullerian Inhibiting Substance (MIS) has been made possible because of the organ-culture bioassay devised by Picon ('69) for detecting MIS in vitro. We have studied the degeneration of the female Mullerian duct of the rat fetus, the target tissue of the assay, with electron microscopy. We have observed that the involution of the female Mullerian duct in the organ-culture assay follows a pattern of degeneration similar to the normal involution of the male Mullerian duct under the influence of MIS from the fetal testis (Price et al., '77). This involution involves alterations in the duct epithelium subsequent to a response of the mesenchyme surrounding the duct. The degeneration of a specific organ system under the direct influence of a specific factor, Mullerian Inhibiting Substance, represents an example of "programmed cell death."

Studies on sex-organ development. Prenatal effect of oestrogenic hormone on tubular-gland cell morphogenesis and ovalbumin-gene expression in the chick Müllerian duct

The effects of diethylstilboestrol on morphogenesis and cyto-differentiation of the chick-embryo left Müllerian duct were examined. Embryos were treated at different stages of development with maximal-responsive doses of diethylstilboestrol over a 5-day interval. The shell gland and magnum regions of the Müllerian duct were then assayed for growth and histological morphogenesis. The results were correlated with diethylstilboestrol-induced ovalbumin-gene expression as measured by ovalbumin-mRNA (mRNAov) accumulation and the relative rate of ovalbumin synthesis. Treatment of the embryo from day 10 to day 15 of incubation induces morphogenesis of tubular-gland cells in the Müllerian-duct magnum. Although these cells constitute 10% of the total cell population and contain an average of 8000 molecules of mRNAov per cell, ovalbumin synthesis is only 0.85% of total magnum protein synthesis. The Müllerian-duct magnum of embryos treated from day 13 to day 18 of incubation contains about 30% tubular-gland cells, which have accumulated an average of 7000 molecules of mRNAov per cell, but ovalbumin synthesis is only 3.25% of total magnum protein synthesis. The Müllerian-duct magnum of embryos treated from day 16 to day 21 of incubation contains about 50% tubular-gland cells, which have accumulated an average of 6500 mRNAov molecules per cell, and ovalbumin synthesis is 10% of total magnum protein synthesis. Oestrogen responsiveness develops simultaneously in the Müllerian-duct magnum and shell-gland regions. Compared with the rate of diethylstilboestrol-induced oviduct growth, the relative rate of diethylstilboestrol-induced Müllerian-duct growth increases with embryonic age, from 20-fold lower in the 10-day embryo to only 3-fold lower in the 16-day embryo. All results are discussed in comparison with the responses to oestrogen of the immature chick oviduct, and in terms of the ontogeny of hormone-competent epithelial and stromal components of the Müllerian duct. It is concluded that the development of oestrogenic competence in the embryonic Müllerian duct is a multiphasic phenomenon. A dramatic increase in hormone responsiveness in the Müllerian duct occurs between days 10 and 16 of development, and a less dramatic final maturation of oestrogen responsiveness occurs between day 16 of development and 1 week after hatching.

Studies on sex-organ development. Oestrogenic effect on ornithine decarboxylase activity in the differentiating Müllerian ducts and other organs of the chick embryo

The activity of ornithine decarboxylase in the differentiating left and right Müllerian ducts was assayed and compared with that in other embryonic organs, i.e. the liver and the brain throughout the stages of development. In general the enzyme activity was high in the early stages and decreased extensively in the late stages of development. Specifically, in the left and righ Müllerian ducts, the enzyme activity was high from day 8 to day 9 of incubation. In the right duct the enzyme activity started to decline on day 9 and then continuously decreased to an almost undetectable value on day 18 of incubation. In the left duct the enzyme activity also decreased slightly from day 9 to day 12; however, it increased from day 13 to day 15 and finally decreased to a constant value from day 18 until hatching. The alteration in enzyme activity in the Müllerian duct as assayed in vitro during development is not due to the effect of the size of the endogenous ornithine pool. When the enzyme activity was subjected to oestrogen stimulation, an increase of 5--10-fold for the left duct and of 5--3-fold for the right duct was observed during the course of development. No such stimulation was observed with the treatment of progesterone. Testosterone consistently caused a 25--30% inhibition of the enzyme activity in the Müllerian duct. Oestrogen slightly stimulated the enzyme activity in the developing liver but inhibited that of the brain. The concentration of the three polyamines measured in the Müllerian duct corresponds to the activity of the enzyme determined.

Stromal induction and specification of morphogenesis and cytodifferentiation of the epithelia of the Mullerian ducts and urogenital sinus during development of the uterus and vagina in mice

Homotypic and heterotypic recombinations were preapred with trypsin-separated epithelium and stroma from uterus of 1- to 9-day-old and vagina of 2- to 150-day-old mice. Growth of homotypic recombinants in adult female hosts resulted in normal uterine and vaginal morphogenesis. Heterotypic recombinants composed of uterine stroma and vaginal epithelium (VE) usually formed uterus, while recombinants composed of vaginal stroma and uterine epithelium (UE) usually underwent vaginal morphogenesis. The developmental responses of these heterotypic recombinants was age-dependent. Epithelia (UE and VE) from mice two to five-days old were responsive to stromal induction. However, from days 5 to 9 postpartum a progressive loss in competence was observed in both epithelia, and vaginal epithelium nine or more days old was unresponsive to heterotypic inductors. Inductive activities of uterine stroma were demonstrated in 2- to 7-day-old neonates and of vaginal stroma in 2- to 150-day-old mice. These results indicate that establishment of the regional specification of Mullerian and sinus epithelium during uterine and vaginal morphogenesis is due to inductive activities of the stroma.

The dual origin of vaginal epithelium

The absence of the cranial three-fifths of the vaginae of male mice carrying the gene, Testicular Feminization, provides strong support for the view that vaginal epithelium is of dual origin, the cranial three-fifths being of Mullerian in origin and the caudal two-fifths being derived from the urogenital sinus.

Studies on differentiation of Mûllerian ducts in the quail, Coturnix coturnix japonica. II. Effects of sex hormones on nucleic acid synthesis in isolated female ducts

The present investigations were carried out in an effort to determine the mechanisms underlying differentiation in the avian Müllerian duct, especially the asymmetrical differentiation of the female ducts. Using the isolated female ducts of Japanese quail, the incorporations of 3H-uridine and 14C-thymidine were determined in vitro at several embryonic stages. Incorporation of 3H-uridine was altered with some synchronous fluctuation during the embryonic period in both the left and right ducts, while 14C-thymidine incorporation first decreased rapidly and subsequently, only slightly, during the same period. By administering sex hormones in vitro nucleotide incorporation was affected to an appreciable extent characteristic of the duct at each stage. This hormonal susceptibility was also periodically altered during duct differentiation. The growing left duct continued to receive an apparent stimulation under the hormonal conditions, while the involuting right duct was sometimes inhibited under the same conditions. Such hormonal susceptibilities may explain the asymmetrical differentiation of the female left and right ducts during this embryonic period.