In human genetics, the SRY gene that initiates testis development is located on the Y chromosome.
SRY stands for “sex-determining region of Y.” It encodes a transcription factor that activates other genes involved in the development of testes from the embryonic gonads. The gene is found on the short arm of the human Y chromosome.
The presence of SRY usually directs embryonic development toward testes, which then produce hormones that influence further sexual development. However, biological sex development involves many genes, hormones, and pathways, so SRY is a major trigger rather than the only factor.
A common mix-up is confusing SRY with the X or Y chromosome itself. SRY is a gene located on the Y chromosome, and variations in its sequence or activity can affect typical sex development. The gene was identified as the mammalian testis-determining factor in research published in the early 1990s.