Analysis of Morphokinetic Parameters of Feline Embryos Using a Time-Lapse System

Abstract

The aim of this study was to analyze the morphokinetic parameters of feline embryos using a time lapse system. Oocytes matured in vitro were fertilized (IVF) and in vitro cultured in a time lapse-system (Primo Vision®, Gothenburg, Sweden). The first cell division of embryos occurred between 17 h post insemination (hpi) and 38 hpi, with the highest proportion of embryos (46%) cleaving between 21 and 24 hpi. The timing of the first cleavage significantly affected further embryo development, with the highest development occurring in embryos that cleaved at 21–22 hpi. Embryos that cleaved very early (17–18 hpi) developed poorly to the blastocyst stage (2%) and none of the embryos that cleaved later than 27 hpi were able to reach the blastocyst stage. Morphological defects were observed in 48% of the embryos. There were no statistically significant differences between the timing intervals of the first cleavage division and the frequency of morphological defects in embryos. Multiple (MUL) morphological defects were detected in more than half (56%) of the abnormal embryos. The most frequent single morphological defects were cytoplasmic fragmentation (FR) (8%) and blastomere asymmetry (AS) (6%). Direct cleavage (DC) from 1–3 or 3–5 blastomeres, reverse cleavage (RC) and vacuoles were rarely observed (2–3%). The timing of blastocyst cavity formation is a very good indicator of embryo quality. In our study, blastocyst cavity formation occurred between 127–167 hpi, with the highest frequency of hatching observed in blastocysts that cavitated between 142–150 hpi. Blastocysts in which cavitation began after 161 h did not hatch. In conclusion, the timing of the first and second cleavage divisions, the timing of blastocyst cavity formation and morphological anomalies can all be used as early and non-invasive indicators of cat embryo development in vitro.

Cat presumptive zygotes assessment in relation to their development

“…The results presented in our study indicate a similar number of blastocysts (P=0.050948) and hatching blastocysts (P= 0.5) developed from regular and irregular shaped presumptive zygotes, despite significant differences in the number of embryos (P= 0.000319) developed from such zygotes. In another study, the average diameters of the oocytes of the domestic cat, Pallas cat, lynx, and serval were all found to be approximately 161±4 μm (Kochan et al, 2021 b). Here, we measured the diameter of the PZ, but assuming no differences between the diameters of oocytes and zygotes, these results should be comparable, and we found an average PZ diameter of 161.37±17.42 μm.…”

Relationships of morphological and phototextural attributes of presumptive ovine zygotes and early embryos to their developmental competence in vitro: a preliminary assessment using time-lapse imaging

“…As previously demonstrated by Jeong et al (2009), oocyte color, as a measure of lipid content, can be predictive of embryo developmental potential. Kochan et al (2021a, b) have shown that oocytes with light cytoplasm were significantly smaller than oocytes with dark cytoplasm in adult and prepubertal cats. Low light permeation of oocytes reflects their high lipid content (Jeong et al, 2009).…”