Abstract

The application of biotechnology is an attempt to improve animal reproduction efficiency, specifically to produce cattle of high quality and quantity. One method that is seen to be successful and efficient in the field of reproduction is embryo transfer. The capacity of donor females to produce embryos limits the amount of embryos that can be produced in vivo. An alternate source of embryos in this instance is in vitro embryo production. It has been demonstrated that two mitogenic chemicals, estrogen and insulin-like growth factor-I (IGF-I), can be employed to promote and speed up cell proliferation. The polypeptide growth factor IGF-I, also known as somatomedin, is released by the liver and other tissues in reaction to growth hormone stimulation. The molecular weight of the 70 amino acids that make up IGF-I is 7649 Dalton, or 7.65 kDa. Specifically produced by developing follicles in the ovary, corpora lutea, and placenta, estrogen is a steroid hormone with a molecular weight of 300–400 Dalton (272.3 Dalton). IGF-I and estrogen promote mitogenic activity in proliferating cells in paracrine, autocrine, and endocrine ways. IGF-I and estrogen can be produced by the liver and ovaries. Both the ovary and the liver are the primary producers of the sex steroid estrogen and IGF-I, respectively, and both may be produced using monolayer cell culture by supplementing them with either bovine serum albumine (BSA) or foetal calf serum (FCS) as precursor substances. According to the descriptions, IGF-I and the steroid sex hormones progesterone and estrogen in liver and cumulus cell monolayer culture may be used as a culture medium for embryo development.

Key words: Bovine IVF; Embryo development; IGF-1; Sex steroids; Cumulus cells.