Final answer:
The SRY gene on the Y chromosome initiates testis development and represses female structures, leading to male characteristics. It produces testis-determining proteins and is crucial for male sex differentiation.
Step-by-step explanation:
The gene on the mammalian Y chromosome that is essential for the development of male characteristics is called the SRY gene. This gene is responsible for initiating the development of the testes and repressing the formation of female reproductive structures. During embryonic development, the testis-determining SRY protein, encoded by the SRY gene, sets off a cascade of events leading to the differentiation of the sexually undifferentiated gonadal tissue into testes.
The testes then produce testosterone, which stimulates the development of male genitalia and secondary sex characteristics. If an XY embryo does not express the SRY gene, as seen in Swyer syndrome, the absence of this trigger results in the development of female sex characteristics despite the presence of a Y chromosome. In other words, the SRY gene's activity determines male sex differentiation and is crucial for male development.
The gene on the mammalian Y chromosome that is essential for the development of male characteristics is called SRY gene. During human embryonic development, this gene starts a chain of events that lead to the development of male sex characteristics. A deletion or mutation of the SRY gene can result in the individual not developing into a male, even if they have an XY genotype, a condition known as Swyer syndrome.