Effects of epidermal growth factor in the final stages of nuclear and cytoplasmic oocyte maturation in humans

Abstract

Evidence has accumulated in mammals suggesting a positive role for epidermal growth factor (EGF) as an inducer of oocyte maturation. The potential use of EGF as inducer of cytoplasmic and nuclear maturation was tested in women with > 10 oocytes retrieved in in-vitro fertilization (IVF), since we have previously observed that such oocytes are immature. Oocytes from 17 high responders were randomly allocated to one of the three treatment groups upon retrieval: control receiving no EGF (n = 93), 1.0 ng/ml EGF (n = 92) and 10.0 ng/ml EGF (n = 77) for 6 h before insemination. The rates of fertilization were respectively 54.6, 59.0, and 46.1%, suggesting that EGF is not effective at this maturational stage after this length of exposure. Embryo development was further analysed by the appearance of the embryos under the dissecting microscope and the number of blastomeres developed 48 h after insemination. No difference between groups was observed considering the number of blastomeres developed. However, embryos derived from oocytes treated with 10 ng/ml EGF displayed a worse appearance under the microscope. It is concluded that a 6 h incubation with EGF does not seem to affect cytoplasmic maturation in oocytes obtained after gonadotrophin treatment, as ascertained by the rate of fertilization following oocyte insemination.

The molecular mechanisms of oocyte maturation and early embryonic development are unveiling new insights into reproductive medicine

“…Whether these factors promote the nuclear maturation via their direct effects on the oocyte, or via the coronal cells, also expressing EGF, EGF receptors and IGF receptors (Maruo et al, 1993) is not known. However, fertilization or resulting embryo quality was not enhanced when human oocytes were fertilized in the presence of EGF (Gómez et al, 1993b).…”

Amphiregulin is much more abundantly expressed than transforming growth factor-alpha and epidermal growth factor in human follicular fluid obtained from patients undergoing in vitro fertilization–embryo transfer

“…Thus, EGF may not play a major role in hCG signal transduction, at least in human beings. G omez et al (32) reported that EGF, when added to culture media before insemination, had no positive effects on either the FR or blastomere development of human oocyte. This is consistent with our finding of scant EGF in FF.…”

Human choriogonadotropin prior to controlled ovarian stimulation and in vitro fertilization improves implantation, and pregnancy rates

“…Luteinizing hormone, and thus presumably hCG, can stimulate granulosa cells of antral follicles to produce EGF-like factors [7], and theca cells to produce insulin-like growth factors [37]. These factors are known to influence oocyte cytoplasmic maturation [38,39] which may translate into effects on subsequent embryonic developmental competence. Based on DNA microarray analyses of ovarian genes during the preovulatory period, Kawamura and colleagues [40] have found major increases in BDNF (brain-derived neurotrophic factor) expression after LH or hCG stimulation.…”