Scanning electron microscopy of the egg surface of the common toad, Bufo bufo, following fertilization and during first cleavage.
Scanning electron microscopy was applied for surface analysis of unfertilized and fertilized eggs of the common toad, Bufo bufo. In unfertilized eggs two types of surface protrusions were found: microvilli and microfolds. 5 min post fertilization (pf), at the place of sperm entrance, a fertilization body appears, surrounded by a group of small depressions, which gradually spread over the whole egg surface. This phenomenon is considered to reflect structural changes of the egg membrane, occurring in response to cortical granule breakdown. Another process which follows fertilization is the disappearance of microfolds and the formation of microvilli. Shortly before the first cleavage, the egg surface smooths out and a zone of spherical microvilli becomes visible at the presumptive furrow region. While the cleavage furrow penetrates into the egg, microvilli appear at the surface of the newly forming blastomeres.
Semik
D
D
Department of Cytology and Histology, Institute of Zoology, Jagiellonian University, Kraków, Poland.
Kilarski
W
W
D000818:Animals; D001757:Blastomeres / Q000648:ultrastructure; D002023:Bufo bufo; D002462:Cell Membrane / Q000648:ultrastructure; D005306:Fertilization; D008297:Male; D008855:Microscopy, Electron, Scanning; D008871:Microvilli / Q000648:ultrastructure; D008938:Mitosis / Q000502:physiology*; D009865:Oocytes / Q000648:ultrastructure; D015053:Zygote / Q000648:ultrastructure*