Sry, also known as the sex-determining region Y, is the Y-linked testis-determining gene in mammals. It serves as a master regulator of male sex determination, triggering the differentiation of the bipotential genital ridge into testes [2,3,4,5,6]. Sry initiates a gene network cascade, mainly through directly regulating Sox9 expression, which then promotes multiple processes like supporting cell differentiation, Leydig cell specification, vasculature formation, and testis cord development [2]. The accurate regulation of Sry is crucial for male development in XY animals, as its insufficient or delayed expression can lead to XY gonadal sex reversal, and in humans, its dysregulation may cause disorders of sex development [1]. Mouse Sry has been a valuable genetic model for studying sex determination [1].

In mouse models, Sry expression is transiently activated in a center-to-pole wave along the anteroposterior axis of developing XY gonads [6]. Shortly after, Sox9 is also activated in a similar pattern. This sequential activation is associated with several male-specific cellular events in XY gonads, such as glycogenesis, coelomic epithelium proliferation, mesonephric migration, and vasculogenesis [6]. These observations from mouse models clearly demonstrate Sry's role in initiating the molecular and cellular processes leading to testis differentiation.

In conclusion, Sry is essential for mammalian male sex determination, playing a pivotal role in triggering the complex cascade of events that lead to testis development. Insights from mouse models have been instrumental in understanding how Sry functions in normal male development and how its dysregulation can potentially lead to disorders of sex development in humans.

References:

1. Okashita, Naoki, Tachibana, Makoto. 2021. Transcriptional Regulation of the Y-Linked Mammalian Testis-Determining Gene SRY. In Sexual development : genetics, molecular biology, evolution, endocrinology, embryology, and pathology of sex determination and differentiation, 15, 351-359. doi:10.1159/000519217. https://pubmed.ncbi.nlm.nih.gov/34583357/

2. She, Zhen-Yu, Yang, Wan-Xi. 2016. Sry and SoxE genes: How they participate in mammalian sex determination and gonadal development? In Seminars in cell & developmental biology, 63, 13-22. doi:10.1016/j.semcdb.2016.07.032. https://pubmed.ncbi.nlm.nih.gov/27481580/

3. Koopman, P. . Sry and Sox9: mammalian testis-determining genes. In Cellular and molecular life sciences : CMLS, 55, 839-56. doi:. https://pubmed.ncbi.nlm.nih.gov/10412367/

4. Koopman, P. . Sry, Sox9 and mammalian sex determination. In EXS, , 25-56. doi:. https://pubmed.ncbi.nlm.nih.gov/11301599/

5. Sekido, Ryohei. 2009. SRY: A transcriptional activator of mammalian testis determination. In The international journal of biochemistry & cell biology, 42, 417-20. doi:10.1016/j.biocel.2009.12.005. https://pubmed.ncbi.nlm.nih.gov/20005972/

6. Kanai, Yoshiakira, Hiramatsu, Ryuji, Matoba, Shogo, Kidokoro, Tomohide. . From SRY to SOX9: mammalian testis differentiation. In Journal of biochemistry, 138, 13-9. doi:. https://pubmed.ncbi.nlm.nih.gov/16046443/