STRUCTURE OF THE FINGER-LIKE GLAND OF VAGINULA BORELLIANA (COLOSI) (GASTROPODA PULMONATA)

SUMMARY The finger-like gland of Vaginula borelliana (Colosi) (Gastropoda Pulmonata) was studied in serial sections obtained from both secretory tubules and draining pathways. There are two types of secretory tubules which differ chiefly in the staining properties of both the secretory cells and the secretion within the tubular lumina. Both tubules have in their walls two additional layers besides the secretory layer: one of smooth muscle cells and one of periluminal epithelial cells. The muscle layer, located upon the secretory cells, occupies an unusual position and probably aids in the rapid discharge of the secretion accumulated in the tubular lumen. The role of the periluminal epithelium, whose structure varies in different zones of the gland, may change according to its localization. A comparison between the histology of the finger-like gland of Vaginula and that of the multifid glands of Helix reported in the literature, reveals clear differences between these sex organs which are regarded as analo...