Genetic Regulation of Avian Testis Development

As in other vertebrates, avian testes are the site of spermatogenesis and androgen production. The paired testes of birds differentiate during embryogenesis, first marked by the development of pre-Sertoli cells in the gonadal primordium and their condensation into seminiferous cords. Germ cells become enclosed in these cords and enter mitotic arrest, while steroidogenic Leydig cells subsequently differentiate around the cords. This review describes our current understanding of avian testis development at the cell biology and genetic levels. Most of this knowledge has come from studies on the chicken embryo, though other species are increasingly being examined. In chicken, testis development is governed by the Z-chromosome-linked DMRT1 gene, which directly or indirectly activates the male factors, HEMGN, SOX9 and AMH. Recent single cell RNA-seq has defined cell lineage specification during chicken testis development, while comparative studies point to deep conservation of avian testis formation. Lastly, we identify areas of future research on the genetics of avian testis development.

Automated summary

Avian testes, similar to other vertebrates, undergo differentiation during embryogenesis leading to the formation of seminiferous cords where germ cells interact with steroidogenic cells. Current understanding of testis development in birds is mainly derived from studies on chicken embryos, highlighting the regulation by the DMRT1 gene. Recent single cell RNA-seq has identified cell lineage specification during chicken testis development, indicating deep conservation in avian testis formation. Future research is focused on the genetics of avian testis development.