Electron microscopic observations on sperm entry into eggs of the bitterling during cross-fertilization

✍ Scribed by Ohta, Tadayuki

• Publisher: John Wiley and Sons
• Year: 1985
• Tongue: English
• Weight: 968 KB
• Volume: 233
• Category: Article
• ISSN: 0022-104X
• DOI: 10.1002/jez.1402330218

✦ Synopsis

In the cross-fertilization of the two bitterlings Acheilognathus lanceolata (spermatozoa) and Rhodeus ocellatus ocellatus (eggs), the morphology of the gametes and the process of sperm entry were observed using transmission and scanning electron microscopy (TEM and SEM). The spermatozoon (total length, about 30 pm) had a round head (about 1.8 pm), two centrioles, a single large mitochondrion, and a flagellum. The micropyle of the egg did not permit simultaneous passage of two spermatozoa. The chorion was mainly composed of an outer and an inner layer and progressively decreased in thickness away from the vicinity of the micropyle where it was thickest. Filamentous structures were observed in microplicae and microvilli on the egg cortex. After a fertilizing spermatozoon attached to the specialized sperm entry site, it appeared to be incorporated into the egg by membrane fusion. At this time