The article investigates the structure of the suprarenal (adrenal) glands of male rabbits (Oryctolagus cuniculus), in which, on the basis of electrocardiographic and variational-pulsometric studies, different types of autonomic tone were observed. This allowed the animals to be divided into three groups: 1) sympathicotonic rabbits; 2) normotonic rabbits; 3) parasympathicotonic rabbits. The animals of the first two groups were characterized by almost the same body weight, while weight of the rabbits of the third group was slightly higher. After euthanasia, the suprarenal glands were extracted for histological and histochemical analyses. Morphometric study of histopreparations revealed that in the normotonic rabbits the thickness of the zona glomerulosa and zona fasciculata of the suprarenal glands were of average sizes, and the area of the medulla was the smallest. The parasympathicotonic rabbits had the thickest zona glomerulosa and greatest area of the medulla, but the thinnest zona fasciculata. The sympathicotonic rabbits were observed to have the greatest thickness of the zona fasciculata of the suprarenal glands, the area of the medulla was of average values, and the thickness of the zona glumerulosa was of minimum value. The type of autonomic tone also manifests in the saturation of each of the zones with cells. The normotonic rabbits were observed to have the highest number of cells per area of 1,000 µm² in the zona fasciculata and the medulla, sympathicotonic rabbits – in the zona glomerulosa and zona reticularis, and in parasympathicotonic rabbits this parameter had average or lowest values in all the zones. The sizes of cells and their structural parts were characterized on the basis of nuclear-cytoplasmic ratio. In the zona fasciculata and medulla this parameter was highest among parasympathicotonic rabbits, and lowest in sympathicotonic rabbits. In the zona glomerulosa, almost equal values were observed in the normotonic and parasympathicotonic rabbits, while being reliably lower in sympathicotonic rabbits. By the value of nuclear-cytoplasmic ratio in the zona reticularis, the normotonic rabbits dominated, followed by the sympathicotonic animals, and the parasympathicotonic rabbits had the lowest parameters.

For the purposes of the adrenal gland’s study, 27 four months old male rabbits (Oryctolagus cuniculus) of Termond White breed were selected. Based on electrocardiography and variation pulsometry results, three types of autonomous tonus were determined in animals: sympathicotonia (ST), normotonia (NT) and parasympathicotonia (PS), which formed the basis for the division of animals into three groups. All rabbits were subjected to euthanasia and histological preparations were made from their adrenal glands. Apart from the main adrenal gland, accessory adrenal gland was detected in five purposes animals, including three ST rabbits, one NT rabbit and one PS rabbit. Also, four accessory adrenal glands were revealed in one ST rabbit simultaneously. In fact, these accessory adrenal glands became the main object of the further morphological research. The obtained historical indicators accessory adrenal glands were compared to the ones from various animal groups (CT with NT and CT with PS), as well as to the indicators of the main adrenal gland in each group. Statistical analysis of the received data was performed only in the group of ST animals. Accessory adrenal gland of ST rabbits is represented by two zones: zona glomerulosa and zona fasciculata, the area of which is 52% and 48% respectively. In PS and NT rabbits, the glands are formed by zona glomerulosa only. Investigating the accessory adrenal gland’s cellular component, it was found that NT rabbits have the largest cell area in zona glomerulosa, while PS rabbits have the smallest one. At the same time, the area of nucleus has the largest values in ST animals and the smallest ones in PS animals likewise. Сomparing zona glomerulosa and zona fasciculata in ST rabbits, it was found that cell size differs significantly, while the area of nucleus is almost identical. The nuclear-cytoplasmic ratio in zona glomerulosa cells is the largest for PS rabbits. The smallest ratio values were detected among the NT rabbits. Obviously, ST rabbits occupy an intermediate position. Unlike the main adrenal gland, the cells of accessory adrenal gland are of a smaller size and а denser location of cells in all groups of animals. The conducted studies allow concluding that the typological features of the autonomous tonus affect the morphology of accessory adrenal gland.

The tonus of autonomous centers reflected in the morpho-functional features of the organs in mammals. The study aimed to establish the influence of the autonomous regulation and its’ typological peculiarities on the structural features of the rabbits’ Harderian gland. Clinically healthy male rabbits, four months old, weighing 3.6-3.9 kg, were selected for the research. Based on the study of heart rate variability, three types of autonomous regulation were outlined, according to which three groups of rabbits were formed: ST rabbits (sympathetic dominant regulation), PS rabbits (parasympathetic dominant regulation), and NT rabbits (combined sympathetic and parasympathetic regulation). After euthanasia, the Harderian gland was dissected in all animals. Histological specimens were prepared and a morphometric examination was performed. ST rabbits corresponded to the minimal indicators in the tubular alveoli in both parts of the gland, as well as the maximum indicators of capsule thickness. NT rabbits corresponded to the maximum values of the acini area in the pink lobe, and in the white lobe - the maximal values of the cross-sectional area of the tubular alveoli, its wall area, and the epithelium height. The maximum acini area corresponded to PS rabbits in the white lobe, and in the pink lobe - the maximum indicators of the tubular alveoli cross-sectional area, and epithelial height. The pink and white lobes’ structure of the rabbit’s Harderian gland was affected by the combined tonus of the sympathetic and parasympathetic centers. The findings elucidate the regulatory and trophic effects on the Harderian gland in rabbits.

The research was aimed at investigating the influence of the aggregated tonus of sympathetic and parasympathetic centers on the rabbit’s thyroid gland morphology. For this purpose, the rabbit males (Oryctolagus cuniculus (Linnaeus, 1758)) of Blanc de Termond breed at the age of four months, passed an electrocardiographic and variation pulsometry study. According to the results, the animals were divided into three groups: rabbits with sympathicotonia (18 animals), rabbits with normotonia (5 animals) and rabbits with parasympathicotonia (3 animals). After euthanasia, the fragments of the thyroid gland were taken out, fixed in Bouin’s solution and embedded in paraffin blocks. Histological sections were prepared from the paraffin blocks and later stained with hematoxylin and eosin, as well as Gabu-Diban’s aldehyde fuchsin and Heidenhain’s azan. Morphometric study of follicles and cells of the gland was performed using these histopreparations. Based on the obtained data, the indices of gland activity were calculated, i.e. Brown index and the follicle-colloid index. At the same time, it was established that morphofunctional parameters of the thyroid gland depend on the typological features of the autonomous tonus. This is reflected in the thickness of the capsule, the amount of adipose tissue, the size and density of the follicles’ placement, the height of the thyrocytes and the ratio between the areas of their nuclei and the cytoplasm. Rabbits with parasympathicotonia account for the higher values of half (7 from 14) of the studied parameters, while their combination suggests the functional activity of the thyroid gland of the animals in this group is higher compared to the other groups of rabbits. Also, rabbits with parasympathicotonia have a larger body weight. For normotonic and sympatheticontic rabbits, the functional activity of the thyroid gland as well as the body weight is lower and approximately of the same intensity. The existence of correlation between the separate indicators was investigated, the character of which is also related to the type of the autonomous tonus.

For dog’s mammary tumors diagnostics scientists need researches, which can adopt and use methods developed for humans. The aim of this research paper is to set the inter relation between the parameters of nuclear morphometry (nuclear area, diameter, perimeter) and histopathological type of mammary tumors of dogs. Animals aged from 6 to 12 (medium meaning 9.2 ± 1.6 years). According to histopathological research 3 tumors were benign and 25 were malignant, 18 of them – malignant epithelial neoplasms (3 tubular carcinomas, 13 tubulopapillary carcinomas, 1 cystic-papillary carcinoma, 3 colid carcinomas, 1 micropapillary carcinoma), 3 malignant epithelial neoplasms of special type (mucinous, lipid-rich, spindle cell carcinomas) and 4 malignant mesenchymal neoplasms (chondrosarcoma). Nuclear morphometry parameters (nuclear area, perimeter and diameter) of benign tumours (20.48 ± 1.22, 19.13–21.50 µm2; 19.27 ± 0.10, 19.17–19.36 µm and 5.09 ± 0.16, 4.92–5.22 µm) were probably smaller than in malignant tumours, for example in simple carcinoma (38.61 ± 5.61, 29.26–46.16 µm2; 26.42 ± 2.32, 22.10–29.60 µm and 6.96 ± 0.52, 6.03–7.62 µm), tubular (37.89 ± 7.30, 29.94–46.16 µm2, 26.34 ± 2.83, 22,98–29,60 µm and 6.90 ± 0.70, 6.16–7.62 µm), tubulopapillary (40.22 ± 3.48, 34.38–44.75 µm2, 27.02 ± 1.49, 24.41–28.97 µm and 7.12 ± 0.31, 6.58–7.52 µm), colid (43.57 ± 5.54, 37.71–48.73 µm2, 28.05 ± 1.88, 26.54–30.15 µm and 7.41 ± 0.47, 6.91–7.85 µm), other malignant epithelial neoplasms (39.99 ± 5.15, 29.94–48.73 µm2; 26.85 ± 2.03, 22.98–30.15 µm and 7.09 ± 0.50, 6.16–7.85 µm) and malignant epithelial neoplasms of special types (45.89 ± 4.12, 43.41–50.65 µm2; 29.92 ± 0.21, 29.68–30.06 µm and 7.60 ± 0.34, 7.41–8.00 µm). However, there was not statistically significant difference in comparison between benign tumours and sarcomas (25.95 ± 5.21, 21.64–33.00 µm2; 21.85 ± 1.79, 20.21–24.05 µm and 5.68 ± 0.56, 5.21–6.42 µm). Among the different groups of malignant neoplasms lower rates were in sarcoma, the other groups had no difference. Taking into consideration the indicators of nuclear morphometry (nuclear area, diameter and perimeter) different types of neoplasms can be differentiated: benign from malignant tumours and sarcomas from malignant epithelial neoplasms (tubular, tubulopapillary, cystic-papillary, colid, micropapillary, mucinous, lipid-rich and spindle cell carcinomas).