Intragonadal somatic cells (ISCs) in the male oyster Crassostrea gigas: morphology and contribution in germinal epithelium structure

The ultrastructure of somatic cells present in gonadal tubules in male oyster Crassostrea gigas was investigated. These cells, named Intragonadal Somatic Cells (ISCs) have a great role in the organization of the germinal epithelium in the gonad. Immunological detection of α-tubulin tyrosine illustrates their association in columns from the basis to the lumen of the tubule, stabilized by numerous adhesive junctions. This somatic intragonadal organization delimited some different groups of germ cells along the tubule walls. In early stages of gonad development, numerous phagolysosomes were observed in the cytoplasm of ISCs indicating that these cells have in this species an essential role in the removal of waste sperm in the tubules. Variations of lipids droplets content in the cytoplasm of ISCs were also noticed along the spermatogenesis course. ISCs also present some mitochondria with tubullo-lamellar cristae.