Oogenesis in a tropical loach Lepidocephalus thermalis (Cuv. & Val.)

Abstract

The development of oocytes has been traced in detail in the loach Lepidocephalus thermalis. The various stages of oocytes are described under distinctive stages namely 1. chromatin nucleolus stage; 2. perinucleolus stage; 3. yolk vesicle stage; 4. primary yolk stage; 5. secondary yolk stage; 6. tertiary yolk stage; 7. migratory nucleus stage; 8. pre-ripening stage; 9. ripe egg stage. The yolk deposition is initiated as minute globules in the extravesicular ooplasm. A yolk nuclous is entirely wanting in any stage of oocyte maturation. The origin of new crops of oocytes and the formation of the micropyle are described. Nature of degeneration of unextruded ripe oocytes has been followed.