Oogenesis and ovarian development in the freshwater Crab Sodhiana iranica (Decapoda: Gecarcinuaidae) from the south of Iran.

In this study, the reproductive biology of female freshwater crab Sodhiana iranica, oogenesis and ovarian development were described. An H-shaped ovary consisting of a pair of long ovarian sacs connected by a narrow bridge tube was located in the cephalothorax on the dorsal side of the stomach. Females at different stages of ovarian development were anesthetized and their ovaries were removed, photographed, fixed, and processed for histological examination. Based on the light microscopic observations of cells' sizes, chromatin patterns, and amount of lipid vesicles, the female germ cells could be classified into seven different stages: (1) oogonia (Oog), (2) primary oocytes (pOc), (3) early previtellogenic oocyte (Oc1), (4) late previtellogenic oocyte(Oc2), (5) early vitellogenic oocyte (Oc3), (6) late vitellogenic oocyte (Oc4), and (7) mature oocyte (mOc). Oog are small oval-shaped cells with irregular-shaped nuclei. Oog undergo first meiotic division to become primary oocytes. The primary oocytes are small oval-shaped cells with large nuclei. The secondary oocytes derived from 2nd meiosis and comprise five steps. Four ovarian development stages were found for females based on the number and types of oocytes present in each stage: spent I (Spent), II (Proliferative) and III (Premature) and stage IV (Mature). The ovaries, macroscopically, varied in size and color during each developmental stage and, microscopically, the ovarian stages differed in proportion oogonia, and the secondary oocytes. During ovarian stage I, ovary contains primarily oogonia, primary oocytes and Oc1. In stage II, contains mainly Oc1, Oc2, and Oc3, while in stage III the predominant cells are Oc4. Mature oocytes appear synchronously in stage IV.