Morphological observations on cleavage of the egg of the medaka,Oryzias latipes, following injection with flagellar microtubules of sea urchin spermatozoa
✍ Scribed by Ohta, Tadayuki ;Iwamatsu, Takashi
- Publisher
- John Wiley and Sons
- Year
- 1981
- Tongue
- English
- Weight
- 880 KB
- Volume
- 218
- Category
- Article
- ISSN
- 0022-104X
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✦ Synopsis
Abstract
Mature unfertilized eggs of the medaka, Oryzias latipes, were injected with sperm flagellar microtubules of the sea urchin, Hemicentrotus pulcherrimus, and were observed with reference to the process of early development. Groups of injected eggs, most of which initiated cleavage and developed to morulae, were fixed with Feulgen fixative at 10, 30, 45, 60, 80, and 90 minutes and at 5 hours after injection. Light microscopic observation revealed that by 45 to 60 minutes, the eggs had radially organized astral fibers originating from the periphery of the droplet of injected microtubule suspension. First cleavage then occurred at 80 to 90 minutes. At the morula stage (5 hours), each blastomere always contained an aster‐like structure composed mainly of endoplasmic reticula. These observations confirmed that the injected flagellar microtubules induced aster formation and first cleavage in unfertilized eggs of the fish.