The dissertation paper is devoted to the study of morpho-functional features of the endocrine glands of rabbits under the regulatory influence of different types of the autonomous nervous system tonus. To solve the scientific problem, a set of the following effective methods was used: the method of variation pulsometry by Baevskij; histological methods; histochemical methods; ultrastructural method using transmission electron microscopy; morphometric method. The research results were processed statistically and the correlation between separate indicators was studied.
Using the variation pulsometry method by Baevskij, the following groups of rabbits were formed: sympathicotonic rabbits (ST) – animals with a predominance of sympathetic tonus (70% of animals); parasympathicotonic rabbits (PS) – animals with a predominance of parasympathetic tonus (11% of animals); normotonic rabbits (NT) – animals with a balanced tonus of the sympathetic and parasympathetic centers (19% of animals).
Combining histological and morphometric methods, the relationship between the dominant tonus of autonomic regulation and the morpho-functional conditions of the parenchyma and stroma of the endocrine glands was discovered. The relationship manifested itself in the structure of the pituitary gland, where the dominant positions are occupied by the indicators of ST rabbits.
The results of morphometric studies of pinealocytes of the pineal gland show that the cell area in PS and NT rabbits differs slightly, while the maximum difference between the areas of the pinealocytes’ nuclei in these groups of 1.1 μm2. Instead, the similar indicators of NT rabbits are much lower compared to ST rabbits.
The adrenal glands of ST rabbits are distinguished by the greatest thickness of zona fasiculata due to the physiological hypertrophy of its corticocytes. A significant difference between the groups of animals is observed in the adrenal medulla, which in ST rabbits is 6.4 mm2 larger than in NT rabbits and 6.02 mm2 larger than in PS rabbits.
NT rabbits differ by the largest area of corticosteroids and catecholamines in the adrenal gland. Parasympathicotonic animals are characterized by a thick glomerular zone, which is 154 μm and 122 μm thicker than that of ST and NT animals respectively. A certain dominance of this group of animals is also observed when it comes to the area of the nucleus.
In the reticular zone, larger cell area values also correspond to PS animals. The indicators of ST and NT rabbits are smaller by 22.7 μm2 and 46.1 μm2 respectively.
Electron microscopy research revealed an increased number of peroxisomes and mitochondria in epinephrocytes of the adrenal medulla in ST rabbits. This indicates a greater activity of synthetic and energy processes in these animals. Normotonic and parasympathicotonic rabbits are somewhat behind. The same conclusions apply to the corticocytes of zona fasiculata, where the greatest synthetic activity is also observed in ST rabbits, which is manifested by an expanded granular endoplasmic reticulum and an increased number of mitochondria.
The most dilated follicles with a significant amount of colloid were found in the thyroid gland of ST rabbits. In this case, the thyrocytes in ST rabbits are the smallest, characterized by the lowest activity and remain at the stage of thyroglobulin synthesis. However, an overwhelming majority of these follicles is not active. With the smallest area of follicles, PS rabbits have the highest epithelial cells as well as the largest area of thyrocytes, which is 0.07 μm2 (P <0.05) and 1.23 μm2 larger in NT and ST animals respectively. The obtained indicators compared to the literature sources indicate a high physiological activity of thyrocytes in the group of PS rabbits.
The morpho-functional relationship between the typological features of autonomous regulation and growth indicators of animals was also revealed. Based on body weight indicators, it was found that animals with parasympathetic type of autonomic tonus have the best economic potential. The results of the study are introduced into the initial and research work of morphological departments of higher educational establishments in Ukraine. Based on the research results, rabbit farms are recommended to carry out selection process taking into account the typological features of autonomous tonus and form breeding stock of NT and PS animals.
Key words: rabbits, normotonic rabbits, parasympathicotonic rabbits, sympathicotonic rabbits, pituitary gland, pineal gland, adrenal gland, thyroid gland.
