Morphometry of the digestive glands of terrestrial mollusk Cornu aspersum (Gastropoda, Helicidae)

Abstract

Histological and histochemical techniques were used to study specifics of parenchyma and stroma in digestive gland of Cornu aspersum. The parenchyma had 28.8 digestive ducts/mm2 on average (CV = 11.2 %) round-to-oval, with average cross-section of 27700.9 µm2 (CV = 28.1 %). The duct area (79.8 % of parenchyma) and the area of inter-duct connective tissue (20.2 % of parenchyma) were in ratio 4 : 1. The gland completely lacked elastic fibers. The muscle elements between the ducts were of different shape and arrangement, on average 59.7 µm long (CV = 42.3 %) and 1.41 µm wide (CV = 63.2 %). The gland’s capsule was formed by three layers: epithelial, muscular, and the layer of collagen fibers. More than 60 % of the capsule’s thickness belonged to the muscular layer. The proportion of calcium cells in the digestive duct wall was 15.5 % (CV = 23.5 %). Cells of digestive ducts contained a lot of vacuoles with brown granules (336.8 per 1 mm2, CV = 36.1 %). The vacuole area was 2.2 % of all area of digestive gland (CV = 15.8 %). The uneven location of muscle elements and brown granules in the glandular parenchyma indicated the functional features of the individual parts of the digestive gland.