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

Abstract

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 the lateral 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.