Relationship between timing of development, morula morphology, and cell allocation to inner cell mass and trophectoderm in in vitro-produced bovine embryos

Abstract

Noninvasive measurements of bovine embryo quality, such as timing of cleavage, morula morphology, blastocyst formation, and hatching ability, were linked with the number of inner cell mass (ICM) cells and trophectoderm (TE) cells of the resulting embryos. First, it was confirmed that fast‐cleaving embryos proved to have significantly higher chances to reach advanced developmental stages vs. intermediate and slow cleavers (P = 0.01). They also showed significantly less fragmentation at the morula stage, implying the presence of more excellent morulae among fast‐cleaving embryos (P < 0.05). Second, the quality of hatched blastocysts, resulting from morulae of different morphological grades, was examined by differential staining. The total cell and ICM cell numbers were significantly lower for hatched blastocysts developed from poor morulae compared to hatched blastocysts developed from excellent, good, or fair morulae. However, hatched blastocysts with <10 ICM cells were seen in embryos belonging to all four morphological scores. Finally, it was found that timing of first cleavage was not significantly correlated with timing of blastocyst formation or with cell number of blastocysts. Timing of blastocyst formation, however, was significantly correlated with cell number: day 8 blastocysts had significantly lower total cell and ICM cell numbers than day 6 and day 7 blastocysts (P < 0.001). These results suggest that the quality of in vitro‐produced bovine embryos is very variable and cannot be linked with a single criterion such as embryo morphology and/or hatching ability. Timing of blastocyst formation was the most valuable criterion with regard to embryonic differentiation. Mol. Reprod. Dev. 47:47–56, 1997. © 1997 Wiley‐Liss, Inc.

Effects of green tea polyphenols, insulin-like growth factor I and glucose on developmental competence of bovine oocytes

“…Thus, the current result suggested that supplementing GTP, IGF-I and glucose to maturation media synchronously can improve the quality of bovine blastocysts. In agreement with our observation, it has been suggested that the proportion of ICM cells in blastocysts is crucial for later post-implantation development (Iwasaki et al, 1990) and an increase in total cell number in blastocysts correlates with improved embryo viability (van Soom et al, 1997).…”

Effect of Post‐IVF Developmental Kinetics on In Vitro Survival of Vitrified‐warmed Domestic Cat Blastocysts

“…In the present study, we were able to demonstrate that embryos which reached the blastocyst stage slower were constituted from smaller number of cells than the faster developing blastocysts, as previously reported in bovine (Van Soom et al. 1997; Enright et al 2000) and ovine (Leoni et al.…”

“…In the present study, we were able to demonstrate that embryos which reached the blastocyst stage slower were constituted from smaller number of cells than the faster developing blastocysts, as previously reported in bovine (Van Soom et al 1997;Enright et al 2000) and ovine (Leoni et al 2006) species. A relatively large variation in cell number of IVF-derived day 8 cat blastocysts (104.4 ± 28.7 cells; differential cell staining) has been reported, with an ICM ratio of 27.8% (Comizzoli et al 2004).…”

Transition of Cell Numbers in Bovine Preimplantation Embryos: In Vivo Collected and In Vitro Produced Embryos

“…We also observed a developmental arrest in the 5th CD (17-32 cells) at 3-4 d after IVF, which was not confirmed in the developmental process for the VIVO embryos. This type of rapid cleavage at the 3-4th CD and development arrest at the 5th CD had been reported previously [8,23,24,29]. It remains unclear why this occurred, but we infer that it is a developmental mode that is characteristic of embryos co-cultured with support cells.…”