The ovarian follicle is the fundamental unit of
the ovary. It contains the oocyte that may eventually
ovulate, undergo fertilization and form an embryo. It
also provides the steroid and protein hormones required
for maintenance of the ovarian cycle, the secondary sex
characteristics and preparation of the uterus for
implantation. Follicle formation and folliculogenesis
have been well documented for many mammalian
species. However, the control of follicular reserves and
entry of follicles into the growth path towards atresia or
ovulation are not well understood. We have investigated
several aspects of follicle formation and folliculogenesis
by (a) using unbiased assumption-free stereological
methods to accurately count follicles, particularly
primordial follicles in the follicular reserve, (b) testing
the effects of members of the transforming growth
factor-β family on folliculogenesis and follicle function,
and (c) examining the role of estrogen in
folliculogenesis using the aromatase knock-out mouse
model. These studies are summarized and reviewed.
