The ultrastructure of human cumulus-corona cells at the time of fertilization and early embryogenesis. A scanning and transmission electron microscopic study in an in vitro fertilization program.

摘要: We observed the ultrastructure of cumuluscorona cells (CC cells) surrounding: 1) human preovulatory oocytes unfertilized after in vitro insemination and 2) vitro-fertilized polypronuclear ova (PO) at pronuclear stage (3 pronuclei) during early cleavage, 3-8 cell (cleaving PO). All samples were obtained from women who underwent pharmacological hormonal stimulation vitro-fertilization procedures. Both groups composed irregularly rounded CC cells, showing an oval nucleus with one or more reticular nucleoli. Spermatozoa close contact also seen. Linear annular gap junctions between neighbouring present, particularly Group 1. Lipid droplets present both groups, appearing slightly numerous electron-dense 2. In 1, mitochondria numerous, polymorphic, provided cristae varying lamellar to tubular. 2, showed polymorphism, bacilliform organelles tubular being predominant. cisternae associated vacuoles vesicles belonging Golgi complex scattered cytoplasm cells. Similarly, vesicular profiles smooth endoplasmic reticulum abundant uniformly distributed throughout groups. contrast, rough 1 was formed by parallel stacks flattened cisternae, whereas it less plentiful not arranged The CC-cell surface appeared covered membrane expansions mainly blebs various sizes a few short microvilli, 2 microvilli surface.These observations demonstrate that gradual establishment maintainance steroidosynthetic capability (luteinization) takes place shortly fertilization, as occurs contemporaneously granulosa postovulatory follicle. Our results may be considered ultrastructural confirmation produce small amounts steroids (estrogens progesterone). These hormones, alone together other substances (proteins, nutrients, growth factors?), might—around fertilization time—act positively upon embryo itself, well on microenvironment which develops, vivo conditions.