Artificial fertilization and developmental stages of Solea solea (L.) in Egypt
Zaki, M.I.; Hamza, A.K.
Folia Morphologica 36(3): 229-234
1988
ISSN/ISBN: 0015-5640 PMID: 3198020 Document Number: 320162
Ripe sole (Solea solea) eggs are planktonic; they are small, buoyant and transparent, with a narrow perivitelline space. The membrane, which is 6.6 .mu. thick, consists of a zona radiata without a chorion. The first cleavage occurs after 30 minutes and the subsequent development stages follow at a slower rate. The incubation period varies from three to four days, according to the temperature of the water, which in this case usually ranged from 11 to 14.degree. C. The yolk sac is completely absorbed by the 11th day. As regards the development of the circulatory system, the blood vessels do not reach the body surface, the erythrocytes do not appear for a long time and only plasma is driven along the blood vessels by the heart-beats to avoid predation. The gills are not completely formed until the 10th day, but the small larvae are able to absorb oxygen over the whole of their body surface. As far as pigmentation is concerned, yellow pigment develops early (by 48 h) and its intensity increases at 5 1/2 days. Red pigment makes its first appearance at 10 days. Metamorphosis begins at 16 days and is completed at 30 days.