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Compaction and surface polarity in the human embryo in vitro
1Human Embryology Laboratory, Institute of Obstetrics and Gynaecology, Royal Postgraduate Medical School, Hammersmith Hospital, London, United Kingdom.
Biology of Reproduction
|July 1, 1996
Summary
Human embryo development involves surface changes. Scanning electron microscopy shows microvilli on oocytes and early embryos, with compaction and polarity emerging by Day 4 at the morula stage.
Area of Science:
- Reproductive Biology
- Developmental Biology
- Cell Biology
Background:
- Human oocyte and early embryo surface morphology are critical for development.
- Understanding early embryonic changes, such as compaction and polarity, is essential for reproductive science.
Purpose of the Study:
- To investigate the surface morphology of human oocytes and embryos during in vitro fertilization and culture.
- To examine the processes of embryo compaction and surface polarity development up to the morula stage.
Main Methods:
- Scanning electron microscopy (SEM) was used to visualize the surface of unfertilized oocytes and in vitro cultured embryos.
- Embryos were analyzed at various stages, from Day 0 (unfertilized oocytes) to Day 4 postinsemination.
Main Results:
- Unfertilized oocytes exhibited long, dense microvilli.
- Microvilli length and density decreased in fertilized oocytes and early cleavage stage embryos (Days 2-3).
- Compaction and polarized microvilli distribution on blastomeres were observed by Day 4 in morula-stage embryos.
Conclusions:
- Human embryos do not show significant compaction or polarity before Day 4 of in vitro development.
- Marked compaction and surface polarity emerge at the morula stage (Day 4) in human embryos cultured in vitro.
- Ultrastructural changes in surface morphology correlate with key developmental events in early human embryogenesis.