Fig. 8

Topo IIα is expressed in the germ cell only prior to follicle formation in the mouse and human ovary. a, b Topo IIα was localised within the germ cells during pre-natal mouse ovary development (Ai,ii), and during the equivalent time in vitro, for the first 5 days of culture (Bi,ii). After follicles formed, Topo IIα expression was no longer found within germ cells, instead localised to surrounding somatic cells, both in vivo (Aiii) and in vitro (Biii). c Topo IIα expression was localised to germ cells not yet enclosed in follicles, in ovaries from week 19 human embryos (Ci, Cii). Cii: red arrow denotes example of Topo IIα expression in germ cell prior to follicle formation, while yellow arrowhead denotes example of absence of Topo IIα expression in germ cell enclosed within ovarian follicle. Scale bars: all 50 μm, except Ci where 200 μm