Cytogenetical Analysis in In-Vitro Produced (IVP) Porcine Blastocysts and Leukocytes of Piglets Derived from In-Vivo and IVP System

Abstract

There is no detailed report about the chromosome constitution in piglets derived from IVP system although high incidences of chromosomal abnormalities have been observed in preimplantation porcine embryos. In the present study, the chromosome constitution in porcine blastocysts and piglets derived from IVP system and piglets derived from in vivo was determined. Porcine oocytes were collected from 3-6-mm ovarian follicles and matured in modified NCSU-37 medium for 44 h. Following in-vitro fertilization with a final concentration of 1x10⁵ sperm/ml for 3 h, presumptive zygotes were cultured in vitro for 6 days. The resultant Day 6 blastocysts (Day 0 = day of IVF) were analyzed chromosomally. Leukocytes of 8 piglets derived from IVP (4 piglets) and in-vivo systems (4 piglets) were cultured in RPMI-1640 medium for 71 h, and then they were prepared as chromosome samples. The whole incidence of chromosomal abnormalities in IVP blastocysts was 45.3%. Incidences of polyploidy and mixoploidy, 23.8% and 16.2%, respectively, were higher than the incidence of haploidy, 4.3%. Between piglets derived from in-vivo and IVP systems, there was no difference in the average frequency of diploid cells, 96.7% and 95.9%, respectively. Some cells of hypodiploidy, hyperdiploidy and polyploidy were observed as chromosome imbalance in all samples. Tetraploidy, among several kinds of polyploidy, was the most frequently founded in both piglets derived from in-vivo and IVP systems. The results indicated that although high incidences of chromosomal abnormalities were observed in preimplantation porcine embryos, the borne IVP piglets were similar in normal chromosome constitution to in-vivo piglets.