In the absence of a Y-chromosome, what does the germinal ridge differentiate into?

In the absence of a Y-chromosome, the germinal ridge differentiates into ovaries. This process is a key aspect of sexual differentiation during embryonic development. The presence of the Y-chromosome carries genes, particularly the SRY (Sex-determining Region Y) gene, which triggers the development of testes. When the Y-chromosome is absent, there is no SRY gene to promote the formation of male reproductive structures, and consequently, the germinal ridge defaults to developing into ovarian tissue.

The differentiation into ovaries is also supported by the activity of other genes and hormones, including those associated with the development of female reproductive organs. Thus, the absence of the Y-chromosome not only determines the sexual phenotype but also influences subsequent reproductive hormone production and developmental pathways, solidifying the identity of the organism as female.