Polarity of responsiveness to sperm and artificial stimuli in medaka eggs

✍ Scribed by Iwamatsu, T. ;Onitake, K. ;Nakashima, S.

• Publisher: John Wiley and Sons
• Year: 1992
• Tongue: English
• Weight: 855 KB
• Volume: 264
• Category: Article
• ISSN: 0022-104X
• DOI: 10.1002/jez.1402640313

✦ Synopsis

Abstract

Experiments were performed to ascertain the polarity of responsiveness to sperm and to artificial stimuli in the egg of teleost, the medaka Oryzias latipes. When the eggs were stimulated by sperm or by microinjection of inositol‐trisphosphate or calcium ions, exocytosis of cortical alveoli began earlier at the animal pole than at the equatorial or vegetal pole regions. The propagation velocity of the exocytosis wave through the cortex was constant to the antipode of the egg. When denuded (dechorionated) eggs were inseminated, the number of spermatozoa that penetrated into the cortical cytoplasm was greater in the animal hemisphere than in the vegetal hemisphere. Most of the swollen sperm heads were found around the animal pole area. This distribution pattern of the sperm heads was also observed in both cytochalasin B‐ and colchicine‐treated eggs. These results suggest that there is polarity in the medaka egg regulating the affinity of the plasma membrane for sperm and the responsiveness of the cortex to sperm or artificial stimuli. © 1992 Wiley‐Liss, Inc.