In humans, clear gender differentiation occurs not at fertilisation, but after the second month of gestation. Which of the following statements describes the first event of this differentiation?
A) Formation of testosterone in male embryos.
B) Formation of oestrogens in female embryos.
C) Activation of SRY in male embryos and masculinisation of the gonads.
D) Activation of SRY in females and feminisation of the gonads.

Question

Quizplus · Accepted Answer

The differentiation of gender in humans occurs after the second month of gestation. The first event in this process is the activation of the sex-determining region Y (SRY) gene on the Y chromosome of male embryos, which leads to the development of the testes and subsequent production of testosterone. This hormone then triggers the differentiation of male genitalia and other masculine features. Therefore, choice C is the correct answer. Choices A and B are incorrect as they do not describe the first event in gender differentiation. Choice D is also incorrect as females do not have the SRY gene on their X chromosomes, and it is not activated in female embryos.

In Humans, Clear Gender Differentiation Occurs Not at Fertilisation, but After