Collection and in vitro maturation of the equine oocyte: The first attempt in Iran

Nowadays, assisted reproduction has become an essential part of the management of horse reproduction in different parts of the world. In vitro production of equine embryos requires established techniques including oocyte collection, in vitro oocyte maturation and intracytoplasmic sperm injection. No report is available on in vitro oocyte maturation of horse oocytes in Iran. Ovaries were immediately collected from newly dead mares of different ages, and transported to the laboratory. The visible follicles were opened using a scalpel blade and the granulosa layers of the follicle wall were scraped from the follicle. Then, the ovaries were cut in ۵ mm sections to collect more oocytes from follicles within the ovarian stroma. The oocytes were cultured in TCM-۱۹۹ medium, supplemented with ۱۰% fetal calf serum and hormones, in a CO۲ incubator at ۳۸.۵ ۰C for ۳۰ h. In addition, using a home assembly devised ovum pick-up (OPU) system, five attempts were made to collect oocytes from preovulatory follicles in four mares. After ۳۰ h in culture, the denuded oocytes were fixed and stained with aceto-orcein to determine the nuclear maturation of the oocytes. Out of ۲۹ cultured oocytes from dead mares, ۱۵ (۵۱.۷%) oocytes reached the metaphase II. Further, of five OPU operations on live mares, one compact COC suitable for culture and one degenerate COC were collected. The results of this report describe the feasibility of ovum pick-up and oocyte collection from either live mares or immediately after death of the animal and further successful in vitro maturation of the equine oocytes.

Keywords:

oocytes , Horse , in vitro maturation , follicles , ovum pick-up