Chronological Reorganization of Microtubules, Actin Microfilaments, and Chromatin during the First Cell Cycle in Swamp Buffalo (Bubalus bubalis) Embryos

Abstract

This paper aimed to study the dynamics of early embryonic development, in terms of redistribution of cytoskeleton (microtubules, actin microfilaments) and chromatin configurations during the first cell cycle in swamp buffalo embryos. Oocytes were matured and fertilized in vitro, and they were fixed at various time points after IVF. At 6 h after IVF, 44.4% matured oocytes were penetrated by spermatozoa. Partial ZP digestion, however, did not improve fertilization rate compared to control (P > .05). At 12 h after IVF, the fertilized oocytes progressed to the second meiotic division and formed the female pronucleus simultaneously with the paternal chromatin continued to decondense. A sperm aster was observed radiating from the base of the decondensing sperm head. At 18 h after IVF, most presumptive zygotes had reached the pronuclear stage. The sperm aster was concurrently enlarged to assist the migration and apposition of pronuclei. Cell cleavage was facilitated by microfilaments and firstly observed by 30 h after IVF. In conclusion, the cytoskeleton actively involves with the process of fertilization and cleavage in swamp buffalo oocytes. The centrosomal material is paternally inherited. Fertilization failure is predominantly caused by poor sperm penetration. However, partial digestion of ZP did not improve fertilization rate.

Effects of Porcine Immature Oocyte Vitrification on Actin Microfilament Distribution and Chromatin Integrity During Early Embryo Development in vitro

“…Actin is an essential component of the cytoskeleton that achieves functions such as cell migration and division, and the regulation of gene expression, which are basic processes for ED. Besides, microfilaments rearrange the organelles involved in fertilization ( Sun and Schatten, 2006 ), such as extrusion of the second polar body and reorganization of the smooth endoplasmic reticulum for the generation of intracellular Ca 2+ during oocyte activation ( Chankitisakul et al, 2010 ; Bunnell et al, 2011 ; Gualtieri et al, 2011 ; Egerszegi et al, 2013 ; Martin et al, 2017 ). In mammals, the cortical distribution of actin microfilaments in mature oocytes is polarized, which is evidenced by swelling near the metaphase axis and less in the opposite cortical domain.…”

Vitrificación de ovocitos porcinos y su efecto a nivel estructural en embriones y en el ADN de las células del cúmulo

“…Actin is an essential component of the cytoskeleton that achieves functions such as cell migration and division, and the regulation of gene expression, which are basic processes for ED. Besides, microfilaments rearrange the organelles involved in fertilization (Sun and Schatten, 2006), such as extrusion of the second polar body and reorganization of the smooth endoplasmic reticulum for the generation of intracellular Ca 2+ during oocyte activation (Chankitisakul et al, 2010;Bunnell et al, 2011;. In mammals, the cortical distribution of actin microfilaments in mature oocytes is polarized, which is evidenced by swelling near the metaphase axis and less in the opposite cortical domain.…”