الفهرس 
Introduction and aim of work
Gross morphologyOnly 14 pages are availabe for public view
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Abstract
Developing chick embryos exhibit epidermal appendages of peculiar characteristic and complicated anatomical and histological structures although they have the similar epidermal origin. This diversity of structures adapted to perform special functions. The present studies aimed to illustrate the molecular, biochemical, histological and ultrastructural variations of epidermal appendages especially feathers, foot scales and beak regions of developing chick embryos. Developing chick embryos at ( 12 ،11،10،9 (16،14،13)،days old were examined and the following parameters are illustrated: 1.Gross morphology: Examining the morphological criteria revealed that feathers are arranged in spinal tracts over the body at 9 and 10 days old chick embryo 2. Keratin and amino acids content: markedly increased in foot scales of 9 days old embryo more than that of feathery skin and beak region. At 12 and 14 days old embryo, the keratin content attained highest increase in beak region. 3 .SEM observation ,Light microscopic observations & TEM observations: Feathers & Foot scales their first appearance as epidermal placaode of populations cells.but with advancement they varing in degree of reconstruction according to thier function. 4.Beak region: Light microscopic observation of beak region of 9 days old embryo reveals that the beak is covered by epidermis with several cell layers thick With the advancement of development at 12and 14 days old, cornification of the beak is more advanced and formed of several cell layers thick.