Bursa,bursa canal,and female antrum of Dugesia tigrina (Plathelminthes,Tricladida)

Summary The bursa of Dugesia tigrina is located between pharynx and penis and is suspended in a network of muscle fibers. Two cell types are present in the bursa: small outer cells which likely represent replacement cells and tall inner cells. During copulation seminal material, consisting of secretion products, fibrillar and tubular material, and small clusters of spermatozoa, is injected through the bursa canal into the bursa. During the 48 h post-copulatory period the seminal material is absorbed by the inner cells. Phagocytosis of the seminal material is facilitated by broad apical cytoplasm and modified distal cell membranes. Phagocytosed spermatozoa are enclosed in vaculoes and morphologic breakdown occurs as early as 4 h after copulation. Fibrillar and tubular material is phagocytosed directly into the apical, organelle-free cytoplasm without vacuole formation.The bursa canal is ciliated and the distal cell ends are studded with ultrarhabdites. These are also present in the epithelial cells of the female antrum. Antrum epithelial cells furthermore display apical organelle-free cell areas. Numerous glands penetrate through the antrum wall.