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Ultrastructure of the cortex in the human egg
I N Hinduja1, A Kumar, T C Anand Kumar
1Institute for Research in Reproduction, Bombay, India.
Human Reproduction (Oxford, England)
|January 1, 1990
Summary
Human oocytes contain two types of cortical granules: G1 and G2. G1 granules, present before ovulation, may have roles beyond polyspermy blockade, while G2 granules are secreted throughout egg development.
Area of Science:
- Cell Biology
- Reproductive Biology
- Human Embryology
Background:
- Cortical granules play a crucial role in egg activation and fertilization.
- Understanding the heterogeneity and function of cortical granules is essential for reproductive science.
Purpose of the Study:
- To differentiate and characterize distinct types of cortical granules in human oocytes.
- To investigate the synthesis, secretion, and potential roles of these granules during oocyte development and fertilization.
Main Methods:
- Transmission electron microscopy was used to examine human oocytes at various developmental stages.
- Morphometric analysis was performed to determine the size and ultrastructure of different granule types.
Main Results:
- Two distinct cortical granule populations, G1 and G2, were identified based on size and content.
- G1 granules (350 nm) are electron-dense, appear pre-synthesized, and were not observed to be secreted.
- G2 granules (450 nm) possess granular content, are synthesized and secreted throughout oocyte development, and endocytosis was observed.
Conclusions:
- The presence and non-secretory nature of G1 granules prior to ovulation suggest functions beyond polyspermy block.
- G2 granule secretion and endocytosis indicate active participation in fertilization and post-fertilization events.
- Distinct G1 and G2 granule populations highlight the complexity of human oocyte cortical granule biology.