Histogical structure of the thyroid gland in rabbits with different types of autonomous tonus

Abstract

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.

Histological and immunohistochemical study of thyroid gland in Caucasian squirrel (Sciurus anamalus) (Gmelin, 1778) by using marker (Anti-Thyroglobulin, Code IR5090)

“…On the other hand, the results of this study regarding the capsule for both animals did not agree with the findings of the study of the thyroid gland in the African giant rat [27] and white hybrid pigs [25], where it was found that the capsule is consist of a single layer of connective tissue. Furthermore, it did not agree with the study on black Bengal goat thyroid gland [28] and rabbits [29], as the capsule was found to be composed of three layers: inner layers and outer layer consisting of connective tissue and middle layer consisting of fatty and nervous tissue. The reason for the difference in the results of this study with the previous studies mentioned above may be due to the need for energy to accomplish the function and to the different nature of the environment as well as the variation in the sizes of animals.…”

Morphological Description and Histological Study of Thyroid Gland in Felis catus (Linnaeus,1758)

“…Several previous studies indicate that there are some differences in the capsule structure that surrounds the thyroid gland, as the study of the thyroid gland goat [18], the local Iraqi sheep [16], and the African giant mouse [19] indicates that the capsule consists of a thin layer of connective tissue. While the studies of the thyroid gland in Indian buffalo [20], the black Bengal goat [21] and rabbit [22] observed that the thyroid gland consists of three layers: outer, middle, and inner layers, whereas this study showed that the capsule consists of two layers, an outer and inner layer, and a layer of fatty tissue interferes with the outer layer. This is consistent with the findings of the guinea pig [14], Hussin and Al-Taay's [23] study on Iraqi buffalo, domestic rabbits [24], and other studies.…”