Mesonephric contribution to testis differentiation in the fetal mouse

Area of Science:

• Developmental Biology
• Reproductive Biology
• Cell Biology

Background:

• Testis cord formation is essential for male reproductive development.
• The cellular and molecular mechanisms regulating testis cord differentiation are not fully understood.
• The role of surrounding tissues in testis development requires further investigation.

Purpose of the Study:

• To investigate the necessity of the mesonephros for the development of testis cords in mouse embryos.
• To determine if cells from the mesonephros can migrate into the developing testis and contribute to its structure.
• To elucidate the role of mesonephric-derived cells in establishing normal testis cord morphology.

Main Methods:

• Organ culture of embryonic mouse testes (11.5 days post coitum) with and without attached mesonephroi.
• Co-culture of testes with mesonephroi, separated by permeable filters, or grafted to limb/heart tissues.
• Utilized transgenic marker to trace cell migration from mesonephros to testis.
• Histological analysis of testis cord development and cell populations.

Main Results:

• Isolated testes showed poor differentiation of testis cords.
• Testes cultured with attached mesonephroi exhibited normal cord development.
• Testes separated from mesonephroi by filters or grafted to other tissues failed to develop normal cords.
• Transgenic cells from the mesonephros were found in testis interstitial and peritubular myoid cells, but not Sertoli or germ cells.

Conclusions:

• Post-11.5 days post coitum, mesonephric cells migrate into the embryonic testis.
• These migrating cells contribute to the interstitial cell population and are necessary for normal testis cord formation.
• Germ cells remain as prospermatogonia, with no evidence of meiosis under the tested conditions.