Open AccessOocyte growth in vitro: potential model for studies of oocyte–granulosa cell interactions
Author(s) -
Hirao Yuji
Publication year - 2012
Publication title -
reproductive medicine and biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.005
H-Index - 22
eISSN - 1447-0578
pISSN - 1445-5781
DOI - 10.1007/s12522-011-0096-3
Subject(s) - oocyte , microbiology and biotechnology , granulosa cell , paracrine signalling , follicular phase , biology , growth differentiation factor 9 , chemistry , ovarian follicle , folliculogenesis , endocrinology , embryogenesis , genetics , receptor , embryo
Various factors such as gonadotrophins, growth factors, and steroid hormones play important roles in the regulation of oocyte/follicular growth in mammalian ovaries. In addition to these factors, there is a bidirectional interaction between oocytes and granulosa cells that is essential for achieving optimal oocyte developmental competence. Oocytes play a key role in this interaction by secreting paracrine factors that alter the activities of neighboring cumulus cells, such as the expression of a specific amino acid transporter, cholesterol biosynthesis, and levels of glycolysis in the cumulus cells. Among the known oocyte‐derived factors, growth differentiation factor 9 (GDF9) is the dominant factor mediating the regulation by oocytes leading to cumulus expansion and granulosa cell proliferation. GDF9 frequently interacts with other oocyte‐derived factors in a synergistic manner. It seems reasonable to speculate that oocytes growing in vitro require interactions similar to those in vivo. Some of the oocyte‐mediated regulations have been confirmed in vitro, providing evidence of the usefulness of culture systems as a strong tool for such studies. This review discusses in vitro culture of growing oocytes in terms of oocyte–granulosa cell interactions.