Relevance. The domestic cat (Felis catus) and the eurasian lynx (Lynx lynx) belong to the same family — feline, predatory order. The cat was domesticated more than 10 thousand years ago. Lynx is the most promising animal for domestication. It is successfully bred in fur farms and, which is no longer uncommon, is kept by private owners as a pet. At the same time, the anatomy of these animals has not been studied to date. This makes it much more difficult to provide medical care and does not allow us to trace changes in organs with intensive anthropogenic impact on the body during domestication. In this regard, the study of the morphology of the eurasian lynx is very relevant and timely. Material for research (11 eurasian lynx corpses) wasobtained in hunting farms of the North-Western region of the Russian Federation. Corpses of a domestic cat (mestizos) were obtained from veterinary clinics of St. Petersburg (15 animals studied).Methods. A complex of modern and traditional methods was used in the study: fine anatomical dissection, angiorentgenography, computed tomography; production of corrosive and enlightened vascular preparations, morphometry and photographing.Results. The domestic cat (Felis catus) and the eurasian lynx (Lynx lynx) have significant differences in the topography and branching of the aortic arch and thoracic aorta, despite the close relationship in taxonomy. The eurasian lynx is characterized by the presence of a brachiocephalic trunk and a trunk of common carotid arteries. Similar vascular structures are absent in a domestic cat. For them, the presence of the brachiocephalic artery and the independent departure of the right and left common carotid arteries, without the formation of a common trunk, was established. At the same time, we state that some main arterial transport vessels and their branches in these animals have common principles of location. This pattern has been determined for the vertebral, internal and external thoracic arteries, including their branches of the first order.

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The secretory cells of the mammary gland are very diverse in their size, shape, and structure. These are highly specialized cells adapted to the synthesis, accumulation, storage, and excretion of milk. The main feature of glandular cells is the presence of secreted substances. Electron microscopy shows that substances of different secretory cells types have various electron densities. Occasionally, two or more types of secretory granules differing in size and composition can be found in one cell. The material for the morphological study was small (2‐4 mm) tissue samples of goat lactating mammary glands. Pieces were taken from deeper areas of the breast parenchyma. Ultrathin sections with a 50‐70 nm thickness were obtained for electron microscopic analysis using Leica UC7 ultramicrotome. Electron microscopy was performed using a JEOL JEM 1011 microscope. Micrographs were obtained using a Morada camera (Digital Imaging Solutions Inc.). The secretion of the mammary gland occurs according to the apocrine type. Picture of the lactocytes' cytoplasm apical part separation into the lumen of the alveoli is often observed on semi‐thin sections. Thus, numerous droplets of material secreted by lactocytes are found in the lumen of the alveoli. The shape of lactocytes in the lactating mammary gland is close to cubic. The height of the epithelial layer, generally, is 10‐12 microns (µm). The milk ducts, like the alveoli, are dilated. Most of them contain a significant amount of osmiophilic material secreted by the cells of the mammary alveoli. The cells of the epithelium of the single‐layered ducts have a flattened or cuboidal shape. The diameter of the ducts varies noticeably depending on location in the gland parenchyma. The intralobular milk ducts are 10‐20 µm in diameter. At the same time, the larger interlobular ducts reach a diameter of 40‐50 microns and are located in groups in the connective tissue stroma of the mammary gland. Notably, an increase in the mammary alveoli mass in the lactating gland is associated with a decrease in connective tissue volume and the almost complete disappearance of fat cells groups from it. The milk ducts of the teat zone in the lactating gland are strongly expanded, round, or slightly oval‐shaped in cross‐section with a diameter of 30‐60 microns. In contrast to the deeper zones of the mammary gland, we were unable to detect secreted substances in the dilated milk ducts near the teat area. The milk ducts we studied are located close to the most terminal sections of the mammary gland excretory system (gland cistern and teat canal). The milk is inevitably washed out from the ducts during chemical fixation and subsequent stages of objects preparation for histological analysis.