Oocyte Development and Female Reproductive Cycle in the Freshwater Crab Travancoriana schirnerae

Özet

The seasonal changes in the ovary of T. schirnerae were described based on histological and histochemical analyses. The development of oocytes was divided into ten stages: oogonia, chromatin nucleolus (1 to 3), perinuclear, primary vitellogenic, secondary vitellogenic (1 to 3) and tertiary vitellogenic. The seasonal ovarian development was classified into six phases: proliferation, previtellogenic, primary vitellogenic, secondary vitellogenic, tertiary vitellogenic and oosorption. Yolk accumulation started during primary vitellogenesis, when basophilic small yolk globules appeared at the cortical cytoplasmic region. The highly basophilic large yolk globules of secondary vitellogenic stage 1 underwent a series of morphological changes to become mildly basophilic yolk platelets in secondary vitellogenic stage 2. The ooplasm noted with strongly acidophilic large yolk platelets in secondary vitellogenic stage 3. The entire ooplasm formed an acidophilic, homogeneous matrix during tertiary vitellogenic stage. The primary vitellogenic stage oocytes showed a strong positive reaction to PAS and MBB, indicating the glycoproteinaceous nature of the yolk. In the secondary and tertiary vitellogenic oocytes, yolk platelets showed positive reaction for MBB, PAS and Sudan black B, demonstrating the lipoglycoproteinaceous nature of the yolk. In T. schirnerae, vitellogenesis extended from October to March and spawning occurred in April. It is concluded that T. schirnerae is an annual breeder accommodating a single ovarian cycle during the intermoult period