الفهرس 
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Abstract
The present study was carried out on 82 samples of claries gariepinus, 72 Mature female and 10 immature females. About 6 fishes of mature female catfish nearly 600- 700 gm in weight and 40-45 cm in length were collected monthly throughout the year from the Nile River, crossing Sohag city in Egypt, during the year 2011-2012 to elucidate the gross anatomical, morphometerical and light microscopical features of the ovary in different seasons of the year. About 10 immature female catfish were collected once during the year of the experiment nearly 100 gm in weight and 15 cm in length and used to observe basic information of the ovarian morphology in the immature period. The gonads of fihes were processed for histological study. In addition, some morphometric parameters of ovaries were accountted Puberty is evidenced by the appearance of mature follicles in the ovary.
The ovaries of the immature C. gariepinus were paired, very small organs situated dorsally in the caudal half of the body cavity. Right ovary measured about 3.175 mm in length, Left ovary measured 3.425 mm and 0.925 g in weight.
Ovaries of mature C. gariepinus were paired elongated organs located in the coelmic cavity ventral to the swim bladder and attached to the dorsal body wall by mesovarium. The left ovary was significantly longer than the right one in all seasons. from November to Febrruary the ovaries were small and occupied less than one third of the body cavity. They were white –yellow in color and the ova coudnt be seen. from March to October the ovaries were very long, wide and occupied almost entire of abdominal cavity.They were yellwish in color, vascularized and the ova were be easly visible.
The mean ovarian weight of the C. gariepinus females recorded 45.5 ± 9.48 g. The minimal mean values 4.46 ± 1.2 was seen in December. The maximum mean value 90.71 ± 6.84 g were recorded in July
The mean ovarian length the C. gariepinus females recorded 8.92 ± 0.86 cm for left ovary and 8.34 ± 0.8 cm for the right one. The minimum mean values (4.4 ± 0.49 cm for left ovary in november and 4.26 ± 0.46 cm for the right one in december ) while the maximum mean values ( 13.58± 0.37 cm for left ovary and 12.45 ± 0.39 cm for right ovary) were seen in July.
Ovary of claries gariepinus was covered by a thick capsule during the non breeding season, but became thin and vascular during the breeding period.
The present study showed no histological variation found between anterior, middle and posterior portions of the ovary.
It was observed that the ovary of immature C.gariepinus had mainly oogonia which appeared small rounded cells collected in clusters and may contain oocyte in early stage of development.
But the ovary of mature claries had all stages of development and there is six stages of oogenesis process have been established on the basis of changes in size, nucleus, ooplasm and egg membrane; oogenia (stage 1), chromatin nucleolus stage ( stage 2), perinucleolar stage (stage 3), yolk vesicle stage (stage 4), yolk globule stage (stage 5), and mature stage (stage 6). Yolk nucleus appeared in perinucleolar stage while yolk vesicles appeared peripherally in yolk vesicle oocytes.
The chromatin nucleolus stage ( stage 2)and perinucleolar stage (stage 3) represented the stage before yolk formation which charecterized by basophilic cytoplasm but the yolk vesicle stage (stage 4)and yolk globule stage (stage 5) represented the stage of yolk formation which charecterized by appearence of yolk vesicles and yolk globules. The stage after yolk formation included the mature oocyte which characterized by thier large diameter, The ooplasm collected to form athin coat at the periphery surrounding the yolk . the rest of the oocyte was occupied by large globules of different sizes. The nucleus was irrigular, appeared acidophilic after Hx & E stain and it gradually disappeared and begin to migrate to the animal pole (germinal vesicle migration stage) which usually occured at the end of vitellogenesis. At the end of this stage , zona radiata reached to its maximum thickness surrounded by high layer of follicular cells and thin theca cells. Strong PAS positive reaction was observed in the cytoplasm of mature follicles between yolk globules.
Its maximum number was 14 ± 0.5 /unite area in may and 13.5 ± 0.5 in July while its minimum number was 0/unite area in February.
Oocyte was large in diameter , its diameter reached the maximum 910.7 ± 0.7 µm in may and 895.85 ± 0.15 µm in july while reached to minimum diameter 0 in February.
The GSI was 14.1% in May and 14.08% in July which indicate 2 reproductive cycle in catfish