Intracytoplasmic sperm injection of in vitro matured oocytes of domestic cats with frozen-thawed epididymal spermatozoa

The ability to mature and fertilize oocytes of endangered species may allow us to sustain genetic and global biodiversity. The first objective of this study was to compare the effect of two different culture media and two dif ferent incubation times on in vitro maturation (IM of domestic cat oocytes. The second objective was to determine the developmental competence of in v itro matured cat oocytes after intracytoplasmic sperm injection (ICSI) with cat spermatozoa. Oocytes recovered from ovaries of ovariectornized cats we re cultured either in TCM 199 medium or in synthetic oviductal fluid (SOF), both of which were supplemented with cysteamine, BSA, FSH, LH. Nuclear mat uration was assessed after 24 h and 40 h of incubation. Results of IVM show ed that the percentage of oocytes reaching MlI after 24 h and 40 h of incub ation were significantly higher (P<0.001) after culture with SOF (88/110, 8 0% and 159/192, 82.8%) than TCM 199 (86/129, 66.7% and 58/90, 64.4%). Oocyt es (n = 231) matured in vitro in SOF for 24 h were fertilized by ICSI with frozen-thawed epididymal cat spermatozoa. After ICSI, one group of oocytes (n = 129) was activated with ethanol, and a second group (n = 102) was not activated. The developmental competence of all ICSI oocytes was examined af ter 7 days of in vitro culture. After 28 h of culture, the cleavage frequen cy of ICSI-activated oocytes was significantly higher (P<0.001) than that o f ICSI nonactivated (106/129, 82.2% vs. 42/102, 41.2%). After 7 d in vitro culture, the frequency of in vitro development of cleaved embryos to morula . stage was higher (P<0.001) in the ICSI activated group (37/106, 34.9%) th at the ICSI nonactivated (2/102, 4.8%), while the development to blastocyst was not different (0 vs 7/106, 6.6%; P=0.088). We conclude that a higher p ercentage of oocytes will undergo meiotic maturation in SOF than in TCM 199 . We also conclude that embryos can be produced with ICSI of in vitro matur ed oocytes using frozen-thawed epididymal cat semen. (C) 2001 by Elsevier S cience Inc.