development of the respiratory tract in red sokoto goat ( capra hircus ): histological perspective

The foetal development of the respiratory tract in the red sokoto goat was investigated in this study using morphological techniques. sections of the respiratory tract were obtained from the foetuses of 40 apparently healthy red sokoto goats that were grouped into the first term, early 2nd term, late 2nd term, and 3rd term (n = 10/group). laryngeal glands formed in the early 2nd term and also secreted neutral mucin within the same period, while apical budding and proliferation of the naïve epithelium led to the formation of stratified squamous epithelium just at the beginning of the 3rd term. the trachea consisted of a bi-stratified epithelium at foetal days (fd) 53 and later became ciliated pseudostratified columnar epithelium during the early 3rd term. at fd 102, the glandular epithelia contained bluish-stained areas, while the glandular lumina contained acidic mucins. the lungs of red sokoto goats were at the pseudo-glandular stage at fd 54, canaliculi stage between fds 71-76, terminal sac stage between fds 76 – 104, and alveolar stage from fd 129. the structural changes in the respiratory tract of this breed are essential changes needed for neo-natal and post-natal functions. the lungs were structurally mature in the 3rd term and could support the animal even in preterm kids.