[Three-dimensional study of the microvascular network in the excretory end portion and the excretory ducts system of dog parotid gland]

Abstract

The purpose of this study was to undertake a three-dimensional analysis of the microvascular network of the glandular body and the excretory ducts system of the dog parotid gland using microcorrosive resin casting technique and examined under scanning electron microscope. Results were as follows: 1. Contributed to the direct injection of the resin through the papilla of parotid, not only the excretory ducts but also the striated ducts, intercalated ducts and the end portion were completely filled with resin, thus enabling the fabrication of the intact casts. 2. One of the advantages of the present method was the ability to distinguish the each portion of the excretory ducts system based on the resin casts surface appearance of the different structure of the wall of the lumen. 3. Within the glandular body arteries, veins and excretory ducts vessels were found running their course through the connective tissue, finally emerging through the hilus of lobules into the lobules. However, several arterioles and venules, besides of running through the hilus, directly terminated at the capillary network in lobules. 4. No arteriovenous anastomoses (AVAs) were found in the lobules. However, AVAs were observed between the arterioles and venules distributed in the connective tissue around the lobules. 5. A large number of venous valves were observed in the veins immediately emerging from the hilus of lobules and also in the veins within the connective tissue of the gland. 6. Observing the vascular network of excretory ducts system, there was no proper vascular network belong to the intercalated ducts, however, on the striated ducts, one layer of the vascular network composed of dense capillaries was identified. Confluencing with each other, the diameter of excretory duct increased and its vascular network consist of two layers of vascular network of which inner layer was a dense capillary network similar to the striated ducts, the outer layer was a loose network composed of arterioles and venules. In the main excretory duct, these two layers of the vascular network were composed completely. 7. Some AVAs were observed in the arteriole and venule network around the main excretory duct.