Cytological Features of Oogenesis in Donax Trunculus (Bıvalvıa: Donacıdae): A Light Microscopy Study

Abstract

Donax trunculus is a bivalve species with high economic value and potential for international marketing in Turkey. Considering their cultivation, research on the reproductive biology, particularly oogenesis, of bivalves holds significant importance. Investigating the cytological and histological aspects of the ovary and oogenesis provides fundamental information about the reproductive system of an organism. In this context, this study investigates the oogenesis process of Donax trunculus at the light microscope level. Sections taken from the ovarian tissue of samples belonging to the population of Şile (İstanbul) were stained with hematoxylin-eosin and phosphotungstic acid-hematoxylin and examined. Cytological features such as the increase in the number of oogonia through mitosis, formation of nucleolar rings, thickening of the nuclear membrane and the structure of the amphinucleolus in vitellogenic oocytes have been photographed for the first time. Oocyte follicle cells association has been observed at every stage of oocyte development. It has been determined that oocyte degeneration primarily occurs in middle and late vitellogenic oocytes and mature oocytes. Studies should be conducted in Donax trunculus to determine both the type of vitellogenesis and to elucidate the detailed role of follicle cells in oogenesis, using labeling techniques and histochemical methods targeting enzyme activity.