Formation of the rete testis during mouse embryonic development

Abstract

Background: The rete testis connects seminiferous tubules of the testis with efferent ducts having a mesonephric origin. The development of the rete testis is insufficiently studied, but there is evidence suggesting that it originates from gonadal cells. Here, the formation of the rete testis was investigated from E11.5 to E16.5 using immunofluorescent staining and 3D-modeling. Results: The rete testis became visible by SOX9 and PAX8 staining starting from E12.5. It was located in the mesonephros but connected with testis cords formed by Sertoli cells expressing SOX9, AMH, DMRT1. Between E13.5 and E14.5, AMH+ network of testis cords at the mesonephric side began to disintegrate in a gradient-dependent manner along the anterior-posterior axis of the gonad and connections between testis cords gradually lost AMH becoming a part of the rete. Cells combining features of Sertoli and rete cells (PAX8+ AMH+ and DMRT1+ AMH− cells) were detected starting from E14.5, suggesting that some rete cells originated from Sertoli cells. The rete ovarii, a female counterpart of the rete testis, developed in a similar way as the rete testis until E13.5. Conclusions: A part of the rete testis originates from connections between testis cords. Evidence that Sertoli cells contribute to rete cells is provided.

Origin, specification and differentiation of a rare supporting-like lineage in the developing mouse gonad

“…The technique allowed us to examine the anatomical distribution of the targeted cells in the intact gonad, by preserving the three-dimensional information. The evaluation was carried out at E13.5 when the rete structure develops, at E16.5, and at birth (P0) when testis and ovary development is well underway and rete formation is completed ( 19, 37 ). To this end, we labelled Pax8 -expressing cells and all their derivatives as well as Nr5a1 -expressing cells using a transgenic line Pax8:Cre;Rosa26:tdTomato;Nr5a1:GFP ( 7, 38, 39 ).…”

“…In particular, it remains unclear whether CE-derived progenitor cells contribute to other uncharacterized populations of the developing testis and ovary. Recent investigations leveraging transcriptomics, immunofluorescence and 3D reconstruction revealed that rete testis 3 precursors possess a dual molecular signature reflecting both a Sertoli (Sox9, Gata4, Wt1, Nr5a1) and a rete precursor (Pax8, Krt8 and Cdh1) identity, suggesting a common origin with the CE-derived supporting lineage (19)(20)(21)(22). The rete testis forms an essential bridging system connecting the seminiferous tubules with efferent ducts.…”

Integration of mouse ovary morphogenesis with developmental dynamics of the oviduct, ovarian ligaments, and rete ovarii

“…The rete ovarii (RO) is an epithelial appendage of the ovary thought to arise from the mesonephric tubules (Satoh, 1985). The RO was first described in 1870 by W. Waldeyer (as cited by Byskov and Lintern-Moore, 1973), and was believed to be a functionless female homologue of the male rete testis (Kulibin and Malolina, 2020; Wenzel and Odend’hal, 1985). It was once thought to degenerate in most individuals, however research shows that this structure persists into adulthood in large mammals (Archbald et al, 1971; Hadek, 1958; Mossman and Duke, 1975).…”

Concerted morphogenesis of genital ridges and nephric ducts in the mouse captured through whole-embryo imaging

“…These results demonstrate the feasibility and value of whole embryo immunofluorescence to investigate tissue interactions and morphogenic relationships during development. Holistic data enables exploration of systems interactions which have not been captured in prior studies based on 3D reconstruction from serial sections of gonads (Brambell, 1927a;Kulibin and Malolina, 2020;Satoh, 1991;Wartenberg et al, 1991) and mesonephroi (Brambell, 1927b;Upadhyay et al, 1979;Vasquez et al, 1998aVasquez et al, , 1998b. Through contextualizing genital ridge development, we identified changes in the position of the early gonad within the embryo.…”