Apoptosis in the germ line.

Apoptosis is a critical process for regulating both the size and the quality of the male and female germ lines. In this review, we examine the importance of this process during embryonic development in establishing the pool of spermatogonial stem cells and primordial follicles that will ultimately define male and female fertility. We also consider the importance of apoptosis in controlling the number and quality of germ cells that eventually determine reproductive success.

Estrogen regulates development of the somatic cell phenotype in the eutherian ovary.

Steroids play a critical role in gonadal differentiation in birds, reptiles, and amphibia whereas gonadal differentiation in mammals is thought to be determined by genetic mechanisms. The gonads of female mice incapable of synthesizing estrogens due to disruption of the aromatase gene (ArKO) provide a unique model to test the role of estrogen in regulating the gonadal phenotype. We have shown that in the absence of estrogen, genetically female mice develop testicular tissue within their ovaries.

Ovarian steroid receptors and their role in ovarian function.

The steroidogenic pathway within the ovary gives rise to progestins, androgens and oestrogens, all of which act via specific nuclear receptors to regulate reproductive function and maintain fertility. The precise role of oestrogen in the ovary remains to be elucidated, hence the data presented here which arises from studies designed to resolve this issue. Oestrogens signal via two receptor subtypes ERalpha and ERbeta, both of which are present in the ovary.