The following methods of the studies have been used in the scientific work: corrosion, histological and electron microscopic, morphometric and statistical methods. The obtained results of the study provide a deeper insight into pathomorphology of the submandibular gland under the influence of opioids, create the basis for further studies of pathogenesis of the opioids effect on the systems and organs aiming at elaboration of correctional methods and prevention of complications in the clinical application of this group of preparations in cases of both short- and long-term use. Macroscopically, it was found that the submandibular gland of a white rat is a round, light pink gland covered with a capsule. It belongs to the complex branched alveolar and tubular glands. The blood supply to the submandibular gland of a white rat is provided by the facial artery. Venous blood from the submandibular gland flows into the sublingual vein. Microscopically, it was found that the parenchyma of the gland is represented by protein and mixed acinuses and a system of branched excretory ducts. The stroma is formed by the connective tissue that envelops the gland and forms a capsule from which the partitions that divide the gland into lobes branch off. Protein and mixed acinuses occur in the lobes of the submandibular gland. Based on the morphometric study, the diameter of arterioles was determined to be (19.64 ± 0.90) μm, capillaries - (5.66 ± 0.35) μm, venules - (25.25 ± 0.62) μm, arteriolar venular ratio - 0.78, packing density of metabolic vessels - (20.89 ± 0.91) and trophic activity of tissue - (56.05 ± 0.53) μm. The first structural changes of the submandibular gland components were noticeable after 2 weeks of the experiment, in particular, stasis was observed in the vessels of the hemomicrocirculatory channel.The development of vacuolar serocyte dystrophy was observed in some acinuses. After 3 weeks of opioid exposure, vacual dystrophy and necrotic changes of the striated epithelium were noted as well. After 4 weeks of experimental opioid exposure, pronounced dystrophic and necrotic changes in the acinus epithelium, as well as in the intraparticle excretory ducts, hyperemia, mainly of the venous bed vessels, blood stasis in them. After 5 weeks of the experiment, vacuolar dystrophy of the granular duct epithelium and pronounced hyperemia of the interparticle venules and arterioles were observed. After 6 weeks of experimental opioid exposure, we found that microstructural changes in the vascular system of the submandibular gland were significantly pronounced and characterized by the expansion of all parts of the hemomicrocirculatory channel, their overflow with erythrocytes.The development of vacuolar dystrophy and necrosis was also noted in serocytes. At the ultrastructural level, after 2 weeks of experimental opioid exposure, we detected the appearance of destructive changes in the organelles of protein acinuses exocrinocytes, as well as dyscirculatory processes in the vessels of the hemomicrocirculatory channel. After 3 weeks, under the opioid analgesic effect, a significant expansion of the spherocytes cisterns in the granular endoplasmic reticulum and the development of perivascular edema were detected. After 4 weeks of experimental opioid exposure, organelle destruction was found in protein acinuses serocytes, a decrease in the volume of the nucleus and the development of necrotic changes were noted. After 5 weeks, under the influence of an opioid analgesic, an increase in dyscirculatory processes was detected. Destructive changes in parenchymal elements were registered, in particular, vacuoles containing electron-light masses accumulated in the cytoplasm of serocytes of secretory protein divisions. After 6 weeks of experimental opioid exposure, damage to all components of the vascular wall of the hemomicrocirculatory tract was observed, which led to the increase in the phenomena of circulatory disorders and perivascular edema. Degenerative and necrotic changes with subsequent destructuring of their organelles were noted in serocytes of protein acinuses. Thus, with the help of modern complementary research methods, new information was obtained on the morphological features of the submandibular gland structure in the normal state and the dynamics of their changes at different stages of the experimental opioid effect. The method of statistical analysis used in the work allowed to systematize the obtained results, to draw parallels between the processes occurring in the structure of the submandibular gland in the normal state and in the dynamics of the experimental opioid effect. Key words: salivary gland, submandibular gland, serocyte, experimental opioid effect, white rat. Branch-Medicine.
