Gonads

Indifferent development

Development of the gonads begins at S14 but there is no discernable morphological difference between male and female until S17. At S14, the coelomic epithelium thickens on the ventro-medial aspect of the mesonephric ridge (crista mesonephrica). In this way, the genital ridge arises. It extends in the same way as the mesonephric ridge, from the heart region down to the vicinity of the cloaca. However, only the middle part develops into the gonadal anlage.