In livestock animals, the in vitro growth and development of preantral follicles has been successful up
until the embryonic stage (pig: Wu and Tian 2007; buffalo: Gupta et al. 2008; sheep: Arunakumari et al. 2010; caprine:
Saraiva et al. 2010b). However, in all cases, the preantral follicles used are at least 200 μm in diameter.