Influence of Apoptosis in Bovine Embryo’s Development

Abstract

The correlation between apoptosis and early bovine embryonic loss is still not fully elucidated. In the present study, the relationship between the arrest of bovine embryos at the different stages of development and apoptosis was evaluated. We used embryos 7 days after in vitro maturation and fertilization, and morphologic and biochemical apoptotic analyses were performed by using a phase contrast microscope and by the terminal transferase dUTP nick end-labelling respectively. For the statistic, the apoptotic cell ratio (ACR) was determined as the percentage of apoptotic cells per embryo. To evaluate the relation between ACR and fragmentation pattern, embryos were divided into five groups, groups I-V. To assess the relation between ACR and cytoplasmatic fragmentation, embryos were divided into three groups, according to the fragmentation percentage (<5%; 5-15% and >15%). Of the total 139 embryos included, 65 arrested at 2-8 cells; 14 arrested at 9-16 cells; 18 compacted morula and 42 were non-arrested blastocysts. The average number of embryonic fragmentation at different stages of the development, 2-8 cells, 9-16 cells, compacted morula and blastocyst, was 16.0 +/- 1.5, 28.7 +/- 4.4, 4.4 +/- 2.4 and 1 +/- 0.3 respectively. The embryos at the stage of arrested 9-16 cells and compacted morula had higher ACR than those at the blastocyst stage, excluding the stage of 2-8 cells (the genome is not yet active). The correlation detected between embryonic development and ACR was 0.92 (p < 0.01). It was observed that embryos possessing high fragmentation showed the higher ACR value (r = 0.98, p < 0.05). Comparing the results between fragmentation percentage and ACR, it was observed that the embryos with higher percentage of fragmentation corresponded to higher ACR (r = 0.97, p < 0.01). These results clearly demonstrated that bovine embryonic arrest at different stages of development is correlated with the apoptotic mechanisms.

Experimental research Comparisons of the effects of long-acting and short-acting GnRH agonists on embryo quality, endometrial thickness and pregnancy rate in human in vitro fertilization

“…Several studies have shown that increased embryonic fragmentation in human in vitro fertilization might have a relationship with endotoxin contamination [1], high reactive oxygen species [2] or low total antioxidant levels in culture media [3]. Other factors that might influence embryonic fragmentation include apoptosis [4], serum nitric oxide [5], human follicular fluid levels of high-density lipoprotein cholesterol and apolipoprotein AI levels [6], follicle size [7], absence of a cytoplasmic halo [8], telomere length in human eggs [9], embryos derived from the andrological infertility group [10], polyspermic embryos [11], number of oocytes and embryos and age [12]. …”

A Cathepsin B Inhibitor, E-64, Improves the Preimplantation Development of Bovine Somatic Cell Nuclear Transfer Embryos

“…The TUNEL reaction is the most frequently used method for detection of apoptotic cells, which is accomplished by labeling of extensive oligonucleosomal DNA fragmentation generated by endogenous DNase activity during the apoptotic process [12]. Application of the TUNEL reaction assay for preimplantation embryos has confirmed apoptosis in the bovine embryo development [13]. Moreover, increased incidence of cell death is an important indicator of inadequate or suboptimal embryo culture conditions [14].…”

Inhibition of c-Jun N-terminal kinase (JNK) suppresses porcine oocyte ageing in vitro

“…Greater development competency, when exposed to the effects of a JNK inhibitor, is apparently influenced by the suppression of DNA fragmentation by means of caspase activation. The course of early embryonic development is closely related to apoptosis (Antunes et al, 2010) and the effect of caspase-3 inhibitor on a higher ratio of blastocysts in parthenogenetically activated embryos has been described in porcine (Coutinho et al, 2011).…”