الفهرس 
Embryological studyOnly 14 pages are availabe for public view
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Abstract
The development and histological structure of the kidney and its related structures of the ovoviviparous lizard Chalcides ocellatus were investigated. Also the adult kidney of Chulcides was compared with that of Urorrzustix aegyytuis to correlate the differences in morphology and histology of the kidneys to the size and habitat of the animals. The study was supplied by the representative photographs of the development of pronephroi, mesonephroi and metanephroi; and their related structures such as the blood supply and the urinary bladder. I embryological study of Chalcides ocellatus: The following results were obtained from this study: Development of the pronephros: The pronephros originates from the segmental nephrotomes against the somites 4 to 12 inclusive. The developing nine pronephrotomes separate firstly from the dorsal somites and later on from the somatosplanchenic mesodem of the lateral plate in a cephalocaudal sequence. Each pronephrotome rapidly hollows and extends dorsally from one end to form the pronephric tubule anlage. The pronephric tubule anlagen (especially those of the second, third and fourth pronephrotomes) bend posteriorly, uniting together to form a collecting duct. The remaining five pronephrotomes give five pronephric tubule anlagen which meet the collecting duct and fuse with it. The collecting duct or the pronephric duct anlage on each side of the body continues in the posterior extension, independently, towasd the cloaca. It was noticed that the pronephric tubule anlage of the first pronephrotome which faces the fourth somite has no part in the pronephric duct formation. Two abortive pronephrotomes were appeared against the second and third somites. The proximal ends of the nine pronephric rudiments form the pronephric chambers which constitute nine pronephric corpuscles by invasion of the pronephric glomeruli which consist of vascular masses of cells from the intermediate cell mass. Finally, each pronephros appears as a tubular structure consisting of nine pronephrons. The average diameter of both pronephric chambers and glomeruli are 73 and 56 microns respectively. The pronephrons begin their degeneration as follows: 1-The first vestigial pronephron and the second one degenerate precociously. 2-The pronephric duct separates anteso-posteriorly from the remaining seven pronephrons. 3-The third pi-onephric chamber unit with the fourth one leading to formation of a large glomus. 4-The subsequent three pronephric tubules separate from their nephric corpuscles. 5-The last two pronephric chambers fuse together and their glomerular tissue precociously dissolves leaving a large space. Finally all degenerated units are completely disappeared at 16-19 mm. long embryonic stage.