Development Of Male Reproductive Tract Research Articles

Developmental variations of the reproductive organs of ganders from different goose breeds and the underlying mechanisms

A deep understanding of the dynamics and mechanisms of male reproductive tract development is necessary for adoption of either genetic techniques or environmental management practices for improving fertility and hatchability in poultry. However, compared with other poultry such as chickens and ducks, less is known about the age- and breed-related changes in the reproductive tract development of domestic goose ganders exhibiting relatively poor reproductive performance as well as the regulatory mechanisms. In the present study, by taking 2 Chinese domestic goose breeds (Sichuan White goose, SW and Gang goose, GE; Anser cygnoides) and one European goose breed (Landes goose, LD; Anser anser) as the experimental objects, we comprehensive analyzed the morphological, histological, and genome-wide transcriptomic variations in their testicular and external genital development during the period from hatching to sexual maturity. Results from histomorphological analysis demonstrated that the reproductive tract of all goose breeds developed in both age- and breed-dependent manners, and the left and right testis developed asymmetrically throughout posthatch development. The tenth week posthatch was a critical developmental stage for all goose ganders, because both the testicular and external genital histomorphological parameters significantly changed before and after this period. During the first 10 wk posthatch, the weight, organ index, or size of male reproductive organs developed more rapidly in SW than in LD, and so were the testicular parenchymal-to-interstitial ratio and the external genital lymphatic lumen diameter. However, the testicular seminiferous epithelium thickness, seminiferous tubule diameter, and Leydig cell number, as well as the external genital keratinized epithelium thickness were significantly higher in LD than in SW at 10 wk of age. Through comparative transcriptomics analysis and RT-qPCR validation, several pathways related to germ and somatic cell function, organ remodeling, and energy metabolism were thought to be responsible for the developmental variations in the early testicular development between Chinese and European domestic ganders, where 10 hub genes involved in the cell cycle, RNA polymerase II-dependent transcription, and mitotic cell division pathways might play essential roles. These data shed new light on the interbreed differences in the male goose reproductive tract development and the molecular mechanisms regulating male goose testicular functions and fertility.

Expression patterns of sex steroid receptors in developing mesonephros of the male mouse: three-dimensional analysis.

The androgen pathway via androgen receptor (AR) has received the most attention for development of male reproductive tracts. The estrogen pathway through estrogen receptor (ESR1) is also a major contributor to rete testis and efferent duct formation, but the role of progesterone via progesterone receptor (PGR) has largely been overlooked. Expression patterns of these receptors in the mesonephric tubules (MTs) and Wolffian duct (WD), which differentiate into the efferent ductules and epididymis, respectively, remain unclear because of the difficulty in distinguishing each region of the tracts. This study investigated AR, ESR1, and PGR expressions in the murine mesonephros using three-dimensional (3-D) reconstruction. The receptors were localized in serial paraffin sections of the mouse testis and mesonephros by immunohistochemistry on embryonic days (E) 12.5, 15.5, and 18.5. Specific regions of the developing MTs and WD were determined by 3-D reconstruction using Amira software. AR was found first in the specific portion of the MTs near the MT-rete junction at E12.5, and the epithelial expression showed increasing strength from cranial to the caudal regions. Epithelial expression of ESR1 was found in the cranial WD and MTs near the WD first at E15.5. PGR was weakly positive only in the MTs and cranial WD starting on E15.5. This 3-D analysis suggests that gonadal androgen acts first on the MTs near the MT-rete junction but that estrogen is the first to influence MTs near the WD, while potential PGR activity is delayed and limited to the epithelium.

Loss of Adgra3 causes obstructive azoospermia with high penetrance in male mice.

The adhesion receptor ADGRA3 (GPR125) is a known spermatogonial stem cell marker, but its impact on male reproduction and fertility has not been examined. Using a mouse model lacking Adgra3 (Adgra3-/- ), we show that 55% of the male mice are infertile from puberty despite having normal spermatogenesis and epididymal sperm count. Instead, male mice lacking Adgra3 exhibited decreased estrogen receptor alpha expression and transient dilation of the epididymis. Combined with an increased estradiol production, this indicates a post-pubertal hormonal imbalance and fluid retention. Dye injection revealed a blockage between the ejaculatory duct and the urethra, which is rare in mice suffering from infertility, thereby mimicking the etiologies of obstructive azoospermia found in human male infertility. To summarize, male reproductive tract development is dependent on ADGRA3 function that in concert with estrogen signaling may influence fluid handling during sperm maturation and storage.

OR25-1 Bilateral and Unilateral Malformations of Male Reproductive Tracts in Mice with Androgen Receptor Gene Deletion in the Mesenchyme

Abstract Congenital unilateral defects of male reproductive tracts have been documented in men, suggesting the potential left-right asymmetry in male reproductive tract development. However, classic textbooks of endocrinology have been teaching us that the development of the paired male reproductive tract is governed by the universal action of the androgen receptor (Ar). During sexual differentiation, testis-derived androgens activate the Ar to promote the stabilization of the bilateral Wolffian ducts, the progenitor for the male reproductive tract. The Wolffian ducts then differentiate into the paired male reproductive tract organs, which include the epididymes, vas deferentes, and seminal vesicles. The Ar is expressed both in the epithelium and mesenchyme of the male reproductive tract during fetal development. Landmark tissue recombinant studies and the observation of normal morphology in the epithelium-specific Ar knockout mouse all support the notion that Ar action in the mesenchyme dictates the morphogenesis of the male reproductive tract. However, no genetic study has been performed to investigate the consequence of the loss of mesenchymal Ar on male reproductive tract development. To test the functional significance of the mesenchymal Ar, we designed a mesenchyme-specific Ar knockout mouse model (ARcKO) to ablate Ar specifically in the mesenchyme prior to the initiation of sexual differentiation. We performed immunohistochemistry of AR to confirm that Ar expression was absent in the mesenchyme while epithelial Ar remained intact in this ARcKO model. Based on the widely accepted notion that mesenchymal Ar regulates epithelial morphogenesis of the male reproductive tract, we expected to see abnormal patterning of the male reproductive tract. Indeed, the epididymis lost its characteristic coiling and became cystic. However, 40% of the 23 collected ARcKO males displayed these abnormalities on both horns; 43% and 17% displayed these abnormal phenotype solely on the left and right horn, respectively. This surprising observation might result from asynchronous activities of Cre on the left and right horns. However, when the Cre was crossed with a reporter (tdTomato), we observed comparable reporter expression on both horns at the onset of sexual differentiation of reproductive tracts. These observations suggest that the developmental programs in the morphogenesis of the left and right male reproductive tracts are asymmetrical and there could be a compensation mechanism for the loss of mesenchymal AR. We are currently in the process of comparing the left and the right horns in Ar knockout male mice to determine any biased signaling. Taken together, our study provides a unique model for not only studying congenital defects of male reproductive tracts but also for investigating the potential asymmetry in the masculinization program. Presentation: Monday, June 13, 2022 11:00 a.m. - 11:15 a.m.

RF34 | PMON254 Why Does Androgens Fail to Promote the Survival of the Wolffian Duct in the Absence of Wnt9b?

Abstract The male reproductive tract development has been predominantly dependent upon androgen action, which is mainly mediated by the androgen receptor (AR). Under the influence of androgen actions, the primitive male reproductive tract, also known as the Wolffian duct, is first stabilized then differentiates into the epididymis, vas deference and seminal vesicle. Impairment of androgen signaling during fetal programming causes a spectrum of male reproductive disorders that manifest in adulthood. Despite the dominant roles of androgen action in the male reproductive tract development, it has been noticed that androgen's capability in promoting Wolffian duct survival and development is completely lost in the absence of Wnt9b. Wnt9b belongs to the WNT family of secreted proteins. It is specifically expressed in the Wolffian duct epithelium to regulate the surrounding mesenchyme. This project aims to investigate why the androgen action fails to maintain the male reproductive tract in the absence of Wnt9b. We first examined the expression pattern of Wnt9b during the window of sexual differentiation, which was not investigated in the previous publication. We found that during sexual differentiation, Wnt9b is still specifically expressed in the Wolffian duct epithelium in both XX and XY embryos. Androgen action exists in XY but not in the XX embryos during sexual differentiation. These observations indicate that Wnt9b does not lie downstream of the androgen signaling. We are in process of collecting Wnt9b+/+ and Wnt9b-/- male embryos to examine whether expression of AR and AR downstream genes is altered in the absence of Wnt9b. In addition, WNT9B can activate two intracellular pathways under the context of target cells: β-catenin dependent and independent pathways. Since Wolffian duct mesenchyme is the major target of epithelium-derived WNT9B, we next determined which pathways WNT9B acts through in the mesenchyme by specific deletion of β-catenin in the Wolffian duct mesenchyme. Interestingly, the loss of β-catenin in the mesenchyme led to the partial degeneration of Wolffian ducts at the caudal region and cystic formations at the cranial region, the similar phenotypes observed in mesenchymal AR knockout male embryos. Taken together, our study demonstrates that the local WNT9B/β-catenin pathway provides the permissive signaling for androgen actions in Wolffian duct development. Presentation: Monday, June 13, 2022 12:30 p.m. - 2:30 p.m., Monday, June 13, 2022 1:12 p.m. - 1:17 p.m.

The Fate of Leydig Cells in Men with Spermatogenic Failure.

The steroidogenic cells in the testicle, Leydig cells, located in the interstitial compartment, play a vital role in male reproductive tract development, maintenance of proper spermatogenesis, and overall male reproductive function. Therefore, their dysfunction can lead to all sorts of testicular pathologies. Spermatogenesis failure, manifested as azoospermia, is often associated with defective Leydig cell activity. Spermatogenic failure is the most severe form of male infertility, caused by disorders of the testicular parenchyma or testicular hormone imbalance. This review covers current progress in knowledge on Leydig cells origin, structure, and function, and focuses on recent advances in understanding how Leydig cells contribute to the impairment of spermatogenesis.

Male fertility in mice requires classical and nonclassical androgen signaling.

Molecular mechanisms by which androgens signal through the androgen receptor (AR) to maintain male fertility are poorly understood. Transgenic mice were produced expressing mutant ARs that can only (1) alter gene transcription through the classical response pathway (AR-C) or (2) activate kinase signaling cascades via the nonclassical pathway (AR-NC). AR-C is sufficient to produce sperm and fertility. Haploid germ cell production, the blood-testis barrier, and spermatid migration are supported by AR-NC. Gene expression essential for chromosome synapsis during meiosis requires AR-C. We identify targets of androgen signaling required for male fertility and provide a mechanistic explanation for meiotic germ cell arrest in the absence of androgen signaling. Prostate differentiation occurs with AR-C alone, but full development requires synergistic nonclassical signaling. Both AR signaling pathways are necessary for normal male reproductive tract development and function, validating our mouse models for studies of AR functions in other target tissues.

Neurotoxicity of Ortho-Phthalates: Recommendations for Critical Policy Reforms to Protect Brain Development in Children.

Robust data from longitudinal birth cohort studies and experimental studies of perinatally exposed animals indicate that exposure to ortho-phthalates can impair brain development and increase risks for learning, attention, and behavioral disorders in childhood. This growing body of evidence, along with known adverse effects on male reproductive tract development, calls for immediate action.Exposures are ubiquitous; the majority of people are exposed to multiple ortho-phthalates simultaneously. We thus recommend that a class approach be used in assessing health impacts as has been done with other chemical classes. We propose critically needed policy reforms to eliminate ortho-phthalates from products that lead to exposure of pregnant women, women of reproductive age, infants, and children. Specific attention should be focused on reducing exposures among socially vulnerable populations such as communities of color, who frequently experience higher exposures.Ortho-phthalates are used in a vast array of products and elimination will thus necessitate a multipronged regulatory approach at federal and state levels. The fact that manufacturers and retailers have already voluntarily removed ortho-phthalates from a wide range of products indicates that this goal is feasible.

Development of a putative adverse outcome pathway network for male rat reproductive tract abnormalities with specific considerations for the androgen sensitive window of development

Structured approaches like the adverse outcome pathway (AOP) framework offer great potential for depicting complex toxicological processes in a manner that can facilitate informed integration of mechanistic information in regulatory decisions. While this concept provides a structure for organizing evidence and facilitates consistency in evidence integration; the process, inputs, and manner in which AOPs and AOP networks are developed is still evolving. Following the OECD guiding principles of AOP development, we propose three AOPs for male reproductive tract abnormalities and derive a putative AOP network. The AOPs were developed using a fundamental understanding of the developmental biology of the organs of interest, paying close attention to the gestational timing of key events (KEs) to very specifically inform the domain of life stage applicability for the key event relationships (KERs). Chemical stressor data primarily from studies on low molecular weight phthalates (LMWPs) served to ‘bound’ the pathways of focus in this dynamic period of development and were integrated with the developmental biology data through an iterative process to define KEs and conclude on the extent of evidence in support of the KERs. The AOPs developed describe the linkage between 1) a decrease in Insl3 gene expression and cryptorchidism, 2) the sustained expression of Coup-tfII and hypospadias and 3) the sustained expression of Coup-tfII and altered Wolffian duct development/ epididymal agenesis. A putative AOP network linking AOP2 and AOP3 through decreased steroidogenic biosynthetic protein expression and converging of all AOPS at the population level impaired fertility adverse outcome is proposed. The network depiction specifies and displays the KEs aligned with their occurrence in gestational time. The pathways and network described herein are intended to catalyze collaborative initiatives for expansion into a larger network to enable effective data collection and inform alternative approaches for identifying stressors impacting this sensitive period of male reproductive tract development.

Systematic comparison of the male reproductive tract in fetal and adult Wistar rats exposed to DBP and DINP in utero during the masculinisation programming window

This study investigates possible effects of in utero exposure of rats to a low dose (125 mg/kg bw/day) and a high dose (750 mg/kg bw/day) of Diisononyl phthalate (DINP) during the masculinisation programming window (MPW) which is embryonic days 15.5–18.5 (e15.5 - e18.5). Dibutyl phthalate (DBP) was used at a high dose level (750 mg/kg bw/day) as an established positive control substance for anti-androgenic effects on the developing male reproductive tract.We focussed on the MPW and measured a multitude of biological endpoints at various life stages and applied state of the art histopathology staining techniques to refine the characterization of potential changes to the testis, beyond what is currently available with DINP. If DINP can mediate testicular dysgenesis (TDS) disorders, this exposure window would be sufficient to induce androgen impacts and alter male reproductive tract development as shown earlier in this validated experimental model with DBP.Overall, the results of this systematic comparison provide convincing evidence on the differences between the effects occurring with DBP and DINP. In contrast to what was seen with DBP, DINP did not cause cryptorchidism or hypospadias, had no effect on anogenital distance/anogenital index (AGD/AGi) and Leydig cell aggregates on e17.5 and e21.5 did not increase. With DINP no reduction of intratesticular testosterone, no effects on sperm motility and sperm count and no effect on adult testosterone or luteinizing hormone (LH) levels were seen. Our results demonstrate that DINP does not cause the adverse reproductive effects known to occur with DBP, a well-established endocrine disruptor.

Prenatal exposure to betamethasone causes intergenerational impairment of epididymal development in the rat

Studies on epididymal toxicology are scarce. Betamethasone (BM) is a glucocorticoid used in clinical practice for antenatal therapy. We previously reported changes to testicular morphology, altered sperm quality, and fertility in adult rats following intrauterine administration of BM. Given that high levels of corticosteroids during gestation lead to fetal androgen depletion, and the essential role of testosterone during epididymal development, here we investigated epididymal morphology and physiology in the F1 and F2 male offspring of female rats treated with BM during gestation. Pregnant rats were randomly divided into two experimental groups: control (saline vehicle, n=11) and BM-treated group (0.1mg/kg betamethasone 21-phosphate disodium, n=13). Rats received an intramuscular injection of vehicle or BM on gestational days 12, 13, 18, and 19. This encompasses the beginning of the critical window of male rat reproductive tract development. A subset of three males from each litter (n=5 litters/group) was used: One rat per litter was euthanized at puberty, one was euthanized at adulthood, while the others were mated with a non-treated female to obtain the F2 generation. The same protocol described for the F1 was applied for F2, except for the mating protocol. In both F1 and F2 generations, prenatal BM exposure resulted in delayed differentiation of the cauda epididymal epithelium, characterized by increased cribriform appearance on PND 45, and displayed weaker or non-detectable Cx43 immunostaining. Furthermore, in the F1 generation only, immunostaining of TP63, a transcription factor expressed in basal cells, appeared more intense with a greater number of TP63-positive cells observed in the cauda epididymis. In adults, the epithelial area was reduced in the F1 BM rats. The contractile activity of isolated epididymal ducts was comparable between groups. Prenatal BM exposure leads to intergenerational impairment in the development and structure of the rat epididymis.

Expression of Hippo signaling pathway components in Hu sheep male reproductive tract and spermatozoa

Hippo signaling pathway is essential for tissue development and homeostasis, while its specific role in male reproductive tract development is still unclear. The objective of this study is to elucidate the localization and expressions of key Hippo pathway components (MST1/2, LATS1/2 and YAP1) in male reproductive tract (testis, epididymis, and ductus deferens) of prepubertal (3-month-old) and postpubertal (9-month-old) Hu sheep, as well as in the cauda epididymal and ejaculated spermatozoa. Results showed that the Hippo pathway proteins were diversely localized in male reproductive tract portions, and most of their expression levels increased during sheep testicular maturation. In addition, these Hippo components were mainly localized and highly expressed in ejaculated spermatozoa compared with cauda epididymal spermatozoa. In ejaculated spermatozoa, LATS1 was localized in the acrosomal head region, and LATS2 and YAP1 were expressed in the midpiece part. Taken together, the presence of Hippo signaling cascade in the pubertal development of male reproductive tract and spermatogenesis of Hu sheep, provides new insights on the function of these components in the process of male sexual maturation, capacitation and fertilization.

In utero exposure to bisphenol A disrupts fetal testis development in rats

Bisphenol A (BPA) is widely used in consumer products and is a potential endocrine disruptor linked with abnormal development of male reproductive tract. However, its action and its effects on the pathways in the development of male gonad are still unclear. Here we report that effects of BPA exposure during gestation on male gonad development. Sprague-Dawley rats were gavaged daily with BPA (0, 4, 40, and 400 mg/kg body weight) from gestational day 12 to day 21. BPA dose-dependently decreased serum testosterone levels (0.45 ± 0.08 ng/ml and 0.32 ± 0.08 ng/ml for 40 and 400 mg/kg BPA, respectively) versus the control level (1.11 ± 0.22 ng/ml, Mean ± SE). BPA lowered Leydig cell Insl3 and Hsd17b3 mRNA and their protein levels at doses of 40 and 400 mg/kg. BPA also lowered Leydig cell (Lhcgr, Cyp11a1, and Cyp17a1) and Sertoli cell (Amh) mRNA and their protein levels at 400 mg/kg. BPA decreased fetal Leydig cell number via inhibiting their proliferation, but it did not affect fetal Sertoli cell number. In conclusion, the current study shows that in utero exposure to BPA inhibits fetal Leydig and Sertoli cell differentiation, possibly disrupting the development of male reproductive tract.

Novel function of LHFPL2 in female and male distal reproductive tract development.

Congenital reproductive tract anomalies could impair fertility. Female and male reproductive tracts are developed from Müllerian ducts and Wolffian ducts, respectively, involving initiation, elongation and differentiation. Genetic basis solely for distal reproductive tract development is largely unknown. Lhfpl2 (lipoma HMGIC fusion partner-like 2) encodes a tetra-transmembrane protein with unknown functions. It is expressed in follicle cells of ovary and epithelial cells of reproductive tracts. A spontaneous point mutation of Lhfpl2 (LHFPL2G102E) leads to infertility in 100% female mice, which have normal ovarian development, ovulation, uterine development, and uterine response to exogenous estrogen stimulation, but abnormal upper longitudinal vaginal septum and lower vaginal agenesis. Infertility is also observed in ~70% mutant males, which have normal mating behavior and sperm counts, but abnormal distal vas deferens convolution resulting in complete and incomplete blockage of reproductive tract in infertile and fertile males, respectively. On embryonic day 15.5, mutant Müllerian ducts and Wolffian ducts have elongated but their duct tips are enlarged and fail to merge with the urogenital sinus. These findings provide a novel function of LHFPL2 and a novel genetic basis for distal reproductive tract development; they also emphasize the importance of an additional merging phase for proper reproductive tract development.

Prenatal Stress as a Modifier of Associations between Phthalate Exposure and Reproductive Development: results from a Multicentre Pregnancy Cohort Study.

Prenatal phthalate exposure is associated with altered male reproductive tract development, and in particular, shorter anogenital distance (AGD). AGD, a sexually dimorphic index of prenatal androgen exposure, may also be altered by prenatal stress. How these exposures interact to impact AGD is unknown. Here, we examine the extent to which associations between prenatal phthalate exposure and infant AGD are modified by prenatal exposure to stressful life events (SLEs). Phthalate metabolites [including those of diethylhexyl phthalate (DEHP) and their molar sum (ΣDEHP)] were measured in first trimester urine from 738 pregnant women participating in The Infant Development and the Environment Study (TIDES). Women completed questionnaires on SLEs, and permitted infant AGD measurements at birth. Subjects were classified as 'lower' and 'higher' stress (0 first trimester SLEs vs. 1+).We estimated relationships between phthalate concentrations and AGD (by infant sex and stress group) using adjusted multiple regression interaction models. In the lower stress group, first trimester ΣDEHP was inversely associated with two measures of male AGD: anoscrotal distance (AGD-AS; β = -1.78; 95% CI -2.97, -0.59) and anopenile distance (AGD-AP; β = -1.61; 95% CI -3.01, -0.22). By contrast, associations in the higher stress group were mostly positive and non-significant in male infants. No associations were observed in girls. Associations between prenatal phthalate exposure and altered genital development were only apparent in sons of mothers who reported no SLEs during pregnancy. Prenatal stress and phthalates may interact to shape fetal development in ways that have not been previously explored.

AB159. Endocrine disrupting chemicals: toxicological risk assessment in vivo and in vitro models

In several studies, scientists asserted that many of endocrine disruptors (EDs), which have been involved in developmental, reproductive, neural, immunological, and other problems in wildlife and laboratory animals. Some environmental EDs, such as di-(2-ethylhexyl) phthalate (DEHP), flutamide (Flu), parabens, are used in many products in life and environment. However, the adverse effects caused by EDs can be temporary or permanent and the mechanism(s) through which these chemicals elicit their effects on biological systems of human and animal health is not clearly understood. The specific aim of this study is to evaluate endocrine disrupting chemicals-induced impact on the male or female reproductive system. An attempt is also made to elucidate the impact of these EDs in an in vitro model, i.e., GH3 rat pituitary cell line. A great deal of work has been carried out on the toxicity of phthalate, Flu, parabens in vivo and in vitro models. In brief, studies have been indicated that long-term and short-term exposure to various endocrine disrupting compounds (i.e., DEHP, Flu, parabens) during development stage (i.e., gestation, neonatal, immature, peripubertal) were done to find alternative dysfunctions later in animal life. The development and function of male or female reproductive tract showed many abnormalities, e.g., menstrual cycle irregularities; impaired fertility, endometriosis, and polycystic ovarian syndrome in female or morphological and functional gonadal dysfunction, e.g., infertility and decreased libido, congenital malformations (altered embryonic and fetal intrauterine development) and testicular dysgenesis syndrome in male. In addition, the differential gene expression patterns by microarray analysis following EDs exposure were found, particularly in steroid hormone synthesis, androgen and/or estrogen synthesis, and sex determination-related gene. On the other hand, studies revealed that parabens, a weak estrogenic chemical, exerted their actions on the stimulation of CaBP-9k gene, an estrogenic biomarker, via binding to estrogen receptor and/or progesterone receptor in immature female rat and GH3 cell line. An increasing number of chemical compounds in the environment have been identified as endocrine disruptor in vivo and in vitro bioassay. A future challenge is required to confirm a theoretical toxicology and risk assessment of EDs for human and animal health.

Region-specific regulation of cell proliferation by FGF receptor signaling during the Wolffian duct development

The Wolffian duct (WD) is a primordium of the male reproductive tract and kidney collecting duct system. Fibroblast growth factor receptors (FGFRs), members of the receptor tyrosine kinase (RTK) family, are essential for kidney development. Although the functions of FGFR signaling in kidney morphogenesis have been analyzed, their function in WD development has not been comprehensively investigated. Here, we demonstrate that Fgfr2 is the major Fgfr gene expressed throughout the WD epithelia and that it is essential for the maintenance of the WD, specifically in the caudal part of the WD. Hoxb7-Cre mediated inactivation of Fgfr2 in the mouse WD epithelia resulted in the regression of the caudal part of the WD and abnormal male reproductive tract development. Cell proliferation and expression of the downstream target genes of RTK signaling (Etv4 and Etv5) were decreased in the caudal part of the WD epithelia in the mutant embryos. Cranial (rostral) WD formation and ureteric budding were not affected. Ret, Etv4, and Etv5 expression were sustained in the ureteric bud of the mutant embryos. Taken together, these data suggest region-specific requirements for FGFR2 signaling in the developing caudal WD epithelia.

Understanding normal and abnormal development of the Wolffian/epididymal duct by using transgenic mice

The development of the Wolffian/epididymal duct is crucial for proper function and, therefore, male fertility. The development of the epididymis is complex; the initial stages form as a transient embryonic kidney; then the mesonephros is formed, which in turn undergoes extensive morphogenesis under the influence of androgens and growth factors. Thus, understanding of its full development requires a wide and multidisciplinary view. This review focuses on mouse models that display abnormalities of the Wolffian duct and mesonephric development, the importance of these mouse models toward understanding male reproductive tract development, and how these models contribute to our understanding of clinical abnormalities in humans such as congenital anomalies of the kidney and urinary tract (CAKUT).

Unzipping androgen action through ZIP9: a novel membrane androgen receptor.

Nearly 5 decades ago, the existence of an androgen receptor (AR) molecule was originally identified by Shutsung Liao at the University of Chicago with concordant findings published by Nicholas Bruchovsky and Jean Wilson (1–3). These seminal studies used rat prostate tissue and specifically described a protein with high affinity for 5 -dihydrotestosterone (DHT) that accumulated in the nucleus upon binding, initiating RNA synthesis and explaining the mode of action for androgens within target cells.Subsequentstudiesbymultiple laboratoriesdetermined that AR regulates the transcription of androgen-responsive genes and plays a pivotal role in male reproductive tract development, sexually dimorphic brain activities, and multiple other target tissues. Importantly, AR has an essential role in prostate carcinogenesis and progression, with blockade of its activity used as a primary therapeutic target. Classical nuclear AR signaling (also known as genomic actions) in target cells involves the diffusion of testosterone through the cell membrane and into the cytoplasm, where it or its metabolite DHT binds to the AR, triggering conformational changes, dissociation from heat shock protein 90, dimerization, and translocation to the cell nucleus. There, the AR complex binds to DNA at androgen-response elements, recruits coregulators, and activates transcription of genes that are then translated into proteins. This classic or genomic mechanism of androgen action is relatively slow, requiring approximately 1–6 hours for alterations in gene transcriptional activity. It is noteworthy that as early as 1975, Liao also described rapid androgen actions occurring within 10 minutes of DHT administration that were independent of RNA synthesis, speculating that “androgens may affect known protein factors or others that are yet to be identified” (4). While research attention remain focused on nuclear steroid receptor signaling pathways, culminating in the cloning of steroid receptor genes in the 1980s, including that for AR (5, 6), evidence began to emerge in the 1990s that androgens are also capable of exerting rapid effects by interacting with AR in the cytoplasm or at the plasma membrane. Membrane-associated ARs were initially described in cell types such as T lymphocytes, monocytes, and osteoblasts to effect influx of calcium (7–9). Subsequent studies found that similar to membrane estrogen receptors, membrane ARs can also interactwithsignalingmolecules torapidlyactivatesignaling pathways, including the MAPK/ERK (10) and focal adhesion kinase 1 (FAK) /phosphoinositide 3-kinase (PI3K)/protein kinase B (Akt) pathways (11, 12). ARs along the cell surface have also been shown more recently to regulate actin cytoskeletal reorganization and prostate-specific antigen secretion in prostate cancer cells (13). The genomic AR signaling pathway has long been the standard therapeutic target for prostate cancer, and initially blockade of nuclear AR activity is very effective in slowing prostate tumor growth and progression. However, tumors eventually become resistant to nuclear AR antagonists and resume growth and rapid metastatic progression. Nongenomic androgen signaling represents an alternative focus for the development of potential treatment strategies that could enhance tumor response to antiandrogen treatment, particularly in delaying the development of castrate-resistant prostate cancer (14). Progress on studies of nongenomic androgen signaling in prostate cancer cells has been hampered by the challenges associated with identification of novel membrane ARs in these

Lhx1 is required in Müllerian duct epithelium for uterine development

The female reproductive tract organs of mammals, including the oviducts, uterus, cervix and upper vagina, are derived from the Müllerian ducts, a pair of epithelial tubes that form within the mesonephroi. The Müllerian ducts form in a rostral to caudal manner, guided by and dependent on the Wolffian ducts that have already formed. Experimental embryological studies indicate that caudal elongation of the Müllerian duct towards the urogenital sinus occurs in part by proliferation at the ductal tip. The molecular mechanisms that regulate the elongation of the Müllerian duct are currently unclear. Lhx1 encodes a LIM-homeodomain transcription factor that is essential for male and female reproductive tract development. Lhx1 is expressed in both the Wolffian and Müllerian ducts. Wolffian duct-specific knockout of Lhx1 results in degeneration of the Wolffian duct and consequently the non-cell-autonomous loss of the Müllerian duct. To determine the role of Lhx1 specifically in the Müllerian duct epithelium, we performed a Müllerian duct-specific knockout study using Wnt7a-Cre mice. Loss of Lhx1 in the Müllerian duct epithelium led to a block in Müllerian duct elongation and uterine hypoplasia characterized by loss of the entire endometrium (luminal and glandular epithelium and stroma) and inner circular but not the outer longitudinal muscle layer. Time-lapse imaging and molecular analyses indicate that Lhx1 acts cell autonomously to maintain ductal progenitor cells for Müllerian duct elongation. These studies identify LHX1 as the first transcription factor that is essential in the Müllerian duct epithelial progenitor cells for female reproductive tract development. Furthermore, these genetic studies demonstrate the requirement of epithelial–mesenchymal interactions for uterine tissue compartment differentiation.