B. Singh et al., FACTORS INFLUENCING RESUMPTION OF MEIOTIC MATURATION AND CUMULUS EXPANSION OF PORCINE OOCYTE-CUMULUS CELL COMPLEXES IN-VITRO, Molecular reproduction and development, 36(1), 1993, pp. 113-119
The present study was undertaken to examine effects of various combina
tions of epidermal growth factor (EGF), transforming growth factor-bet
a1 (TGF-beta1), follicle-stimulating hormone (FSH), luteinizing hormon
e (LH), androstenedione (A4), and estradiol-17beta (E2) on meiotic mat
uration and cumulus expansion in the pig using an in vitro model syste
m. Oocyte-cumulus cell complexes (OCC) were cultured in the media cont
aining the above-mentioned agents for 24 hr and were observed for germ
inal vesicle breakdown (GVBD), indicative of initiation of meiotic mat
uration, and for expansion of their cumulus cells. Treatment with EGF
significantly increased (P < 0.05) incidence of GVBD, with maximal sti
mulation occurring at 1 ng/ml (55% vs. 12% in the control). Concentrat
ions of EGF as low as 100 pg/ml significantly stimulated GVBD over con
trol (37% vs. 12%). Addition of EGF (1 ng/ml) and FSH (1.5 mug/ml) tog
ether and LH (2 mug/ml) and FSH (1.5 mug/ml) together resulted in sign
ificantly higher (P < 0.01) GVBD levels than were observed in response
to EGF, FSH, or LH alone. Addition of E2 (1 mug/ml) had no effect by
itself but significantly decreased the incidence of GVBD in the presen
ce of FSH and of LH + FSH. Addition of A4 (1 mug/ml) significantly red
uced the percentage of oocytes undergoing GVBD when added alone or wit
h FSH. Although both EGF and LH stimulated cumulus expansion, FSH was
more effective in stimulating cumulus expansion than EGF or LH. TGF-be
ta1 had no effect on GVBD or cumulus expansion. These studies indicate
that these hormones may have differing roles in oocyte maturation and
that their interactions may be part of an intricate system regulating
the maturation of oocytes during follicular development in vivo. (C)
1993 Wiley-Liss, Inc.