Gross and morphometric anatomical changes of the thyroid gland in the West African Dwarf Goat (Capra hircus) during the foetal and post-natal periods of development

The thyroid gland morphology of West African Dwarf goat was investigated in the foetal, pre-pubertal and pubertal age of development in an attempt to evaluate the changes that take place during these periods. It was studied by gross dissection and morphometric determination of size. The results showed that the location of the thyroid gland on the larynx and trachea varied between the cricoid cartilage of larynx and 12th tracheal cartilage as the age progressed. The right lobe was more cranially located on the larynx and trachea than the left lobe in all age groups. Thyroid isthmus was absent in few foetal thyroid but was consistent in the postnatal thyroids. It became a mere thin fibrous tissue in the older pubertal goats. Accessory thyroid was not observed in all age groups. There were significant differences (p<0.05) in the mean weight, length, width and thickness of thyroids of the studied age groups. All measured gross parameters increased with advancing foetal and postnatal age. The study demonstrated the variability of location, size and presence of isthmus during development of thyroid in WAD goats.Keywords: Thyroid gland, anatomy, morphometry, development, Goat

Morphological observations on the development of the vomeronasal organ in the prenatal red sokoto goats (Capra hircus)

The morphological developments of the vomeronasal organ (VNO) in Red Sokoto Goat at prenatal ages of 50 days, 70 days, 90 days, and 130 days, were studied grossly by dissection and light microscopy. The specimens used were obtained from the abattoir and ages were estimated by crown to-rump length. In fetuses aged about 50 days, the vomeronasal epithelium was of stratified cuboidal type with 3-4 layers of undifferentiated cells. Surrounding the epithelium was dense mesenchymal connective tissue that contained venous sinuses and developing crescentic vomeronasal cartilage (VNC), the core of which at this stage contained eosinophilic cells. Mitotic figures were apparent in both the epithelium and cartilage. In fetuses aged about 70 days, local differences in the epithelium were observed on the lateral wall. The epithelium reduced to 3 layers, while that of the medial wall was up to 5 layers in places. Precursors of glands invaginated into the underlying maturing connective tissue on the lateral wall. These glands were interposed amongst profiles of venous sinuses. The VNC matured further as the perichondrium developed. The underlying connective tissue on the medial wall showed section of nerve bundles. In fetuses aged about 90 days, the medial and lateral wall maintained the difference in thickness of their epithelium. However at the dorsal and ventral borders, the epithelium was reduced to 2 layers. Glandular ducts were seen to open into the epithelium on this boundary. Profiles of glands and venous were retained in the connective tissue on thelateral wall. The VNC further showed maturation of the perichondrium with clearly differentiated outer fibrous and inner layers. Mitotic figures were not common. In fetuses aged about 130 days, the epithelium on the medial wall matured into sensory pseudostratified columnar type comprising: bipolar sensory neurons, supporting cells and basal cells, supported by an indistinct basal lamina. The lateral wall became folded and 2-3 layers of pseudostratified columnar cells lined it. Other components of the organ seen in earlier fetuses were present