We, the developing rete testis, efferent ducts, and Wolffian duct, all hereby agree that we need to connect

Abstract

Background:The mechanisms by which the rete testis joins the efferent ducts, which joins the Wolffian duct during development, are not known. Mouse and chick models have been helpful in identifying genes that are important for the development of each part, but genes have not been identified as to those that play a role in the joining of each part. Clinical implications of the failure of the male reproductive tract to form a fully functional conduit for spermatozoa are not trivial. Epididymal disjunction, the failure of the efferent ducts to join the testis, is one of several epididymal anomalies that have been observed in some boys who were cryptorchid at birth. Objective: A systematic review of studies focusing on the morphogenesis of the mesonephric duct and mesonephric tubules in different species, and identification of clinical issues should there be failure of these tissues to develop. Design: PubMed and GUDMAP databases, and review of books on kidney development were searched for studies reporting on the mechanisms of morphogenesis of the kidney and epididymis. Main outcomes measure(s): Gaps in our knowledge were identified, and hypotheses coupled with suggestions for future experiments were presented. Results: A total of 64 papers were identified as relevant, of which 53 were original research articles and 11 were book chapters and reviews covering morphogenesis and clinical issues. Investigators utilized multiple species including, human, mouse, chick, Xenopus, bovine, and sheep. Conclusion: Fundamental understanding of the morphogenesis of the male reproductive tract is limited, especially the morphogenesis of the rete testis and efferent ducts. Therefore, it is not surprising that we do not understand how each part unites to form a whole. Only one mechanism of joining of one part of the tract to another was identified: the joining of the Wolffian duct to the cloaca via controlled apoptosis.

Prostate and testicular growth analysis in human fetuses during the second gestational trimester

“…The testis and the prostate have important correlations in their development. The prostate develops from the urogenital sinus in response to testosterone stimulation by the fetal testis production, which starts at 8 weeks of gestation 4,8,9 . Testicular production of steroid hormones during fetal life is essential to the masculinization of the internal tract and male genitalia 17,18 .…”

“…The prostate develops from the urogenital sinus through several different and complex stages during organogenesis, controlled by the male hormones androgens 20 . The growth of the prostate accelerates during the second gestational trimester, which exactly coincides with the onset of urinary production from the kidneys 4,8,9 . During the 12th gestational week, the mesenchyme around the prostatic urethra is stimulated by androgens, inducing the proliferation of the epithelium.…”

“…The development of the prostate is associated with the production of testosterone and dihydrotestosterone (DHT) 5–7 . The prostatic buds appear in the 10th gestational week 1 and between the 11th and 12th gestational weeks, the mesenchyme around the prostatic urethra is stimulated by androgens, inducing the proliferation of the epithelium and initially, the prostatic ducts are solid, but after the 30th week, they acquire a lumen 8 …”

Connection between seminiferous tubules and epididymal duct is originally induced before sex differentiation in a sex‐independent manner

“…Actually, many previous studies demonstrated critical genes that caused malformation of the male reproductive tract; however, almost all genes are responsible for the formation itself of the WD or MT. So, the mechanisms underlying the connection between the testis and epididymis are still unclear …”

What Does AMH Tell Us in Pediatric Disorders of Sex Development?

“…Initially, the internal reproductive tract is identical in XX and XY embryos. Mesonephric (Wolffian) ducts form in the intermediate mesoderm during the 4th week and elongate caudally in direction of the urogenital sinus (1). During the 5th week, coelomic cells specified to become Müllerian cells form a cleft between the gonadal and mesonephric ridges, laterally to the Wolffian ducts.…”