The differentiation of mouse gonads in vitro: a light and electron microscopical study.

Indifferent urogenital complexes were excised from mouse foetuses assessed by developmental criteria as day 10.5 or 11. After 4 or 6-7 days in culture, complexes were fixed and examined by light and electron microscopy. The effect of culturing sexed complexes in mixed sex groups was investigated. The effect of the presence or absence of foetal calf serum in the culture medium was considered. No evidence of inhibition of one sex by the other was found. Ovaries developed further in cultures than testes.