Development of the Skin of Some Fresh-Water Fishes

The present study was carried out on 188 African or Nile-cat-fish(Clarias lazera L.) ranging from one to 106 days-old corresponding to5-120m.m. body length and 28 common carp (Cyprinus carpio L.) rangingfrom 61 to 120 days-old which correspond to 30-55m.m. body length.The skin specimens were selected from the different regions of thelips, snout,opercula, head, trunk and tail of the fish, as well, the barbelsandfins were included.The collected specimens were prepared by different standardtenchniques and were examined by the light. binocular dissecting stereoand scanning electron microscopes. Also, the specimens were subjectedto many morphometrical sutdies.This study revealed that, the development of the skin, fins and barbelsof the cat-fish could be divided into four stages:Stage I: Free-embryonicor pre-Iarval stage: (1-11 days-old, 5-12m.m.body length):At one day-old post-hatching, the covering epithelium of the lips”snout and head is composed of 2-3 cell layers thickness. While, theepidermis of the trunk and tail is formed of 1-2 cell layers. The futuredermis of the snout, lateral aspect of head and that of the trunk espciallyat its mid line is considerable dermal space filled with mesenchymal cells.