Human antral folliculogenesis: what we have learned from the bovine and equine models

Ano: 2009 | Volume: 6 | Número: 1

Autores: A.R. Baerwald

Palavras-chave: antral, bovine, equine, follicle, human

Resumo Inglês:

The study of ovarian folliculogenesis has been
of great interest to scientists and clinicians in the human
and veterinary health fields for more than 20 centuries.
Initial studies of the ovarian follicle were based on
anatomical descriptions post-mortem, followed by
histologic and endocrinologic evaluation of ovarian
status. The introduction of high resolution
ultrasonography in the 1980s provided a long-awaited
tool to image the reproductive tissues in situ in both
animal and human species. The bovine and equine
species have been established as models for the study of
human ovarian folliculogenesis. Profound similarities in
the dynamics of follicle development exist between the
menstrual cycle in humans and the estrous cycle in
cattle and horses. Disparities between species appear
specific rather than general. Research performed in
women thus far has led to the concepts that: 1) follicle
development occurs in a wave-like manner during the
menstrual cycle, 2) the number of waves per cycle
correlates positively with the length of the cycle, 3) the
emergence of follicle waves in women are preceded by
a rise in circulating FSH, 4) selection of a dominant
follicle may occur in each wave of the cycle, and 5) a
decline in circulating FSH and increase in follicular
estradiol, inhibin A, and IGF-II act collectively to
enable the dominant follicle to continue to grow in an
endocrine environment of decreasing FSH and
increasing LH, while subordinate follicles undergo
regression. The goal of continued research using animal
models for studying human ovarian function is to provide
the hypothetical basis for further studies in women, which
will ultimately lead to the development of safer and more
efficacious infertility and contraceptive therapies.