Mammalian cortical granules: contents, fate, and function

Area of Science:

• Reproductive Biology
• Cell Biology
• Developmental Biology

Background:

• Mammalian cortical granules (CG) contain various components crucial for post-fertilization events.
• Previous studies identified carbohydrates and proteinases within CG, but their precise functions remain largely unknown.

Purpose of the Study:

• To elucidate the composition and functional roles of mammalian cortical granules (CG) in post-fertilization events.
• To investigate the localization and potential functions of CG-derived materials, including glycosylated compounds and proteinases.

Main Methods:

• Cytochemical staining and lectin-binding studies to identify carbohydrate residues in CG.
• Immunocytochemistry to localize specific proteins like p75 within CG and oocytes.
• Observation of material release from oocytes following fertilization and artificial activation.

Main Results:

• Carbohydrates (e.g., mannose, galactose derivatives) and proteinases are present in mammalian CG and released upon activation.
• Released glycosylated materials localize to the oolemma and perivitelline space (PVS), potentially involved in polyspermy block or embryonic development.
• Proteinases modify the zona pellucida (ZP), contributing to ZP hardening and sperm non-receptivity.

Conclusions:

• Mammalian CG release diverse components, including glycosylated materials and proteinases, post-fertilization.
• These released substances likely play roles in preventing polyspermy and supporting early embryonic development.
• Further research is needed to fully define the identity and functions of specific CG components, such as p75 and heparin-binding placental protein.