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vol-29HISTOLOGICAL AND HISTOCHEMICAL STUDIES ON OOGENESIS OF
COMMON CARP, CYPRINUS CARPIO (L)
BY
ABD EL HAKIM E. EL GAMAL
National Institute ojOceanography and Fisheries. Alexandria, Egypt.
Key words : Oogenesis, Histochemistry, Gonadosomatic index, Cyprinus carpio
(Teleostei) .
ABSTRACT
Common carp, Cyprinus carpio has short spawning season in April and
May. The gonadosomatic index increase gradually from late August and
reach its maximum value in Febnlary and March. In April and May the
gonadosomatic index decreased due to throw of ripe eggs and some of
atretic oocytes. The water temperature dUring the spawning season ranged
benveen 23 – 25.55
C. The annual cycle ofovary undergoes two successive
developmental phases. The primary growth phase includes the immature
oocyte characterized by a large nucleus, containing one large nucleolus.
Thereafter, the nucleoli increase in number and scatter in the center of
nucleus. At the end ofthis stage, the nucleoli are mostly arranged towards
the periphery ofnuclear m.embrane. The secondary growth phase includes
vacuolization of cytoplasm, yolk depositions and mature ova. The yolk
granules appear around the nucleus, first in the large oocyte, occupy the
cytoplasm, with exception the periphery ofcytoplasm. The fidly mature ova
reach its maximum size 970micron in diameter. By using histochemical
techniques, there are three types of yolk materials in the oocytes of
Cyprinus carpio namely oil droplet, yolk globues and cortical granules. It
seems likely that, the oil droplet first appear followed by cortical granules
and then yolk granules. The yolk granules are mainly composed ofprotein,
carbohydrate and lipid However, the vacuoles in the periphery of
cytoplasm are composed ofcarbohydrate, and protein. On the other hand,
the granulosa cells in the wall of the ripe ova are maineiy composed of
carbohydrates and protein. However, the thecal celis are composed of
lipid and protein.
