Corrigendum to: 131 CHROMOSOMAL ABNORMALITIES IN IN VITRO-PRODUCED 4-DAY-OLD CATTLE EMBRYOS: INFLUENCE OF THE OOCYTE MATURATION MEDIA

Abstract

Chromosomal abnormalities were related to embryo developmental failures in cattle, being highly increased in IVF-produced compared with multiple-ovulation embryo transfer-produced embryos. The origin of this difference remains unclear, but they were related to the suboptimal environmental culture laboratory conditions. We studied the influence of 3 different maturation media in the appearance of chromosomal abnormalities in early in vitro-produced embryos. A total of 562 oocytes classified as Class A were collected by follicular aspiration in slaughterhouse ovaries and matured by 20 h in 3 different culture media supplemented with 10% FCS and antibiotics as follows: TCM-199 (T, 193 oocytes); DME (D, 178 oocytes); and RPMI-1640 (R, 191 oocytes). Matured oocytes were fertilized by 16 h with 1 × 10⁶ spz mL^–1 in IVF-TALP media and cultured by 72 h in SOF media. Later, 48 h after fertilization, 562 presumptive embryos were evaluated showing a normal cleavage rate of 64.7, 55.2, and 54.9% in T, D, and R groups, respectively. After culture, only 181 early embryos (90 hpi) showing normal development were correctly karyotyped following our standard laboratory techniques. Individual blastomeres were stained with Giemsa and assessed by direct observation at ×1250 magnification in a brightfield microscope. The percentage of normal diploid embryos (D) and abnormal haploid (H), polyploid (P), or aneuploid (A) embryos were determined. Only embryos showing almost 2 different blastomeres correctly karyotyped were included in this study. Cleavage rates were statistically higher (P < 0.05) in the oocytes matured in T media in comparison with the oocytes matured in D or R media. The percentage of diploid embryos were almost equals in the 3 groups evaluated (Table 1). There was some variation when each kind of chromosomal abnormality was assessed individually, but no statistical differences were observed. These results are in consonance with our previous studies in which we demonstrated the maturation time and morphological quality are the 2 main oocyte-derived factors influencing the ploidy of early embryos. It was also demonstrated that chromosomal complements were affected, in a much lesser extent, by the maturation media supplementation. However, in the present study, the maturation media did not statistically affected embryo ploidy. However, the higher percentage of cleaved embryos using TCM-199 observed agree with fact that this maturation media is one of the most widely used in IVF procedures in cattle. Based on our data, we suggest that oocyte maturation, a well established technique in cattle, could be performed using different maturation media without expecting major differences in the embryo ploidy, and therefore, the differences observed in cleavage rate must be originated in other physiological factors.

Table 1.  Results