Cortical Granule Loss Research Articles

Loss of cortical granules in mouse ova activated in vivo by electric shock.

AbstractThis report documents for the first time the occurrence of a cortical reaction in parthenogenetic mouse ova activated by electric shock in vivo.

Ultrastructural changes in rabbit eggs aged in vivo.

Utilizing the techniques of light and electron microscopy, rabbit ova, aged for varying periods in vivo, were examined in order to determine the relation, if any, between the morphological changes of the unfertilized egg at various times following ovulation and the developmental defects that are known to occur as a result of delayed mating. Structural alterations of the second meiotic apparatus and the cytoplasm are noted as early as 14 h following the induction to ovulate (FITO) in approximately 20% of the eggs examined. The changes include an increase in cortical granules along the cortex, the structural alteration of microvilli, and the disruption of the meiotic spindle. With further aging, there is a progressive deterioration of the egg’s cytoplasm and meiotic spindle. By 20–30 h FITO, all of the eggs demonstrate alterations in the structure and orientation of the meiotic spindle. Later, the meiotic spindle is completely disrupted and the chromosomes are scattered throughout the cytoplasm. No nucleus is observed in aged eggs that have not fragmented. There is a gradual aggregation of the cytoplasmic organelles in specimens obtained approximately 30 h FITO, and, by 60 h, all of the particulate cytoplasmic components are located in one or several groups. During this period there is also a loss of cortical granules due to an apparent blebbing of the cortex of the egg. Dehiscence of the cortical granules as observed in inseminated eggs is not found.