Cleavage Capability of Water Buffalo Follicular Oocytes Classified by Cumulus Cells and Fertilized In Vitro

Abstract

Water buffalo (Murrah) oocytes were collected from ovaries obtained from the slaughter house. They were classified according to the character of the cumulus cells under a stereomicroscope, and cultured in 25 mM Hepes buffered Tissue Culture Medium-199 (TCM-199) supplemented with 5% estrous water buffalo serum in an atmosphere containing 5% CO₂ in air at 39°C. After 20-24 hr of in vitro maturation, the oocytes were fertilized using capacitated sperm obtained from 4 different bulls. For cleavage the oocytes were cultured at 39°C in TCM-199 supplemented with 1% estrous water buffalo serum and in an atmosphere containing 5% CO₂ in air. The good oocytes, with compact and dense cumulus cells cleaved significantly higher (p<0.01, 67.3%, 33/49), than those of fair, partially naked oocytes with thin cumulus layers (27.5%, 25/91) or small remnants of cumulus cells and poor naked oocytes (3/100). A substantial variation in fertilization and developmental rates (16.0% to 43.8%) was observed among 4 different bulls. Late non-surgically into 14 buffalo recipients on day 6 or 7 of their estrous cycle. One recipient was diagnosed to be pregnant by rectal palpation on day 60 and confirmed to be so on day 90 post-estrus.