THE COLLECTION OF OOCYTES FROM BOVINE OVARIES

Various needle sizes (17- and 20-g) and aspiration pressures (25, 50, 75 and 100 mmHg) were used to aspirate a total of 5,827 ovarian follic les from bovine ovaries from a slaughterhouse source to assess the imp act on the quantity and quality of recovered immature oocytes. The cum ulus oocyte complexes (COC's) were graded according to the presence an d consistency of cumulus cells surrounding the oocyte and the data ana lyzed using general linear models. Overall recovery rates and the reco very of oocytes considered viable for IVM/IVF procedures (Classes A,B and C) were both significantly higher using a 17-g needle than a 20-g needle (P<0.01). As the vacuum pressure increased so did the recovery rate of the total number of oocytes, although the number of viable ooc ytes reached a maximum at a calculated vacuum pressure of 55 mmHg for the 17-g; needle and 77 mmHg for the 20-g needle, with an increased in cidence of denuded oocytes at higher vacuum pressures. In a second exp eriment conducted on 1,473 follicles, no significant difference was fo und between 17-g double (flushing) and 17-g single lumen needles in th e recovery rate of either the total number or number of viable oocytes when using a vacuum pressure of 50 mmHg. (C) 1997 by Elsevier Science Inc.