Time of the first cleavage has been used as an indicator to determine developmental rate and quality of embryos in many species. The aim of this study was to examine effect of time of the first cleavage on cat embryo development and blastocyst quality. After in vitro fertilization, embryos were observed twice at 27 and 42 hours. Embryos cleaved at 27 hours post-fertilization (pf) were classified as early cleaved embryos and were separated from the remainder which were determined as delayed cleaved embryos (cleaved between 27 and 42 hours). These two groups were separately cultured in the same condition for 7 days to observe embryo developmental and blastocyst formation rates. To evaluate the embryo quality, cells of the blastocyst were classified into inner cell mass (ICM) and trophectoderm cell (TE). The results showed that the percentages of the 8-cell and morula of the early cleaved embryos and the delayed cleaved embryos were not different (100.0 vs. 96.0% and 97.1 vs. 92.0%, respectively; p>0.05), whereas the blastocyst rates of the early cleaved embryos were greater than the delayed cleaved embryos (68.4 vs 20.0%; p<0.05). The total and ICM cell numbers of the blastocysts derived from the early cleaved embryos were higher than those of the delayed cleaved embryos (85.9 vs 71.6 cells, p<0.05). Moreover, the early cleaved embryos had a higher percentage of ICM cells than the delayed cleaved embryos (38.0 vs 31.9%, p<0.05). In conclusion, the cat embryos cleaved at early stage likely have the potential to develop to the blastocyst stage with high number of inner cell mass. The time of the first cleavage can be used as an indicator to select good quality of the cat blastocysts.
Faculty of Veterinary Science, Chulalongkorn University
Klincumhom, Nuttha; Thongphakdee, Ampika; Techakumphu, Mongkol; and Chatdarong, Kaywalee
"Time of the First Embryonic Cleavage Indicates Cat Blastocyst Quality,"
The Thai Journal of Veterinary Medicine: Vol. 42:
1, Article 16.
Available at: https://digital.car.chula.ac.th/tjvm/vol42/iss1/16