[Recent findings concerning follicular growth]

Area of Science:

• Reproductive Endocrinology
• Molecular Genetics
• Cell Biology

Background:

• Follicular maturation is a complex process regulated by hormonal, autocrine, and paracrine factors.
• Recent molecular genetics advances enable in vitro studies of these regulatory mechanisms.
• This facilitates a reevaluation of the roles of key hormones in folliculogenesis.

Purpose of the Study:

• To reevaluate the precise roles of gonadotropins (FSH and LH) and other factors in human follicular maturation.
• To understand the molecular mechanisms underlying granulosa cell proliferation, differentiation, and hormone synthesis during folliculogenesis.
• To identify potential targets for optimizing fertility treatments.

Main Methods:

• In vitro studies using human recombinant gonadotropins (FSH and LH).
• Investigation of autocrine and paracrine ovarian regulation factors.
• Analysis of hormonal actions on granulosa cells and their products.

Main Results:

• Follicle-stimulating hormone (FSH) promotes granulosa cell mitosis and differentiation, alongside synthesis of somatomedin, inhibin, activin, and LH receptors, especially with low luteinizing hormone (LH) levels.
• High LH levels inhibit granulosa cell proliferation and, with insulin-like growth factor 1, enhance estrogen synthesis from androgens.
• Both FSH and LH contribute to the production of growth factors and preovulatory progesterone.

Conclusions:

• Aberrant endocrine, paracrine, or autocrine regulation of follicular maturation can lead to atresia.
• Rational use of human FSH and LH can optimize ovulation induction and in vitro fertilization outcomes for infertile women.