Physiological roles of growth factors in mammalian reproduction.

点击翻译按钮获取中文摘要

Physiological roles of growth factors especially epidermal growth factor (EGF) were studied in the field of mammalian reproduction and major findings are as follows :I. Establishment of pregnancy and fetal growth.Plasma EGF concentrations were elevated during pregnancy in human and there was positive correlation between maternal and fetal EGF levels although fetal levels were significantly lower than maternal ones.Sialoadenectomy (removal of the submandibular glands) of pregnant mice was shown to cause EGF deficiency during pregnancy which resulted in intrauterine growth retardation (IUGR). This makes an animal model to study the mechanism of fetal growth and IUGR.II. Maturation of oocyte and spermatozoa.EGFlike substance (EGF-L) was present in the human follicular fluid obtained from patients in our in vitro fertilization program. The concentration of EGF-L was related with the maturity of oocyte within. EGF-L was also present in human seminal fluid and concerned with sperm morbidity.EGF stimulated the maturation of rat oocyte in culture in terms of both germinal vesicle breakdown (resumption of meiosis) and phosphofructokinase activity (rate-limiting enzyme present in the cytoplasma).III. Development of preimplantation embryo.Presence and number of EGF receptor was determined using binding assay with I-125 EGF. Presence of EGF receptor was demonstrated in mouse oocyte and the number of EGF receptor was increased as embryos developed in preimplantation period. EGF added to the culture medium stimulated the development of 2-cell embryos.