HISTOLOGICAL AND HISTOCHEMICAL-STUDY OF EPITHELIAL LINING OF THE RESPIRATORY-TRACT IN ADULT GOATS

Seventeen clinically normal Cashmere goats were used in the present st udy. Tissue samples taken from the nasal vestibule, the alar and basal folds, the nasal conchae, nasopharynx, larynx, trachea, bronchi and l ung parenchyma were routinely prepared for histology, and stained with alcian blue/periodic acid schiff (AB/PAS). The nasal vestibule, rostr al portion of the alar and basal folds, nasopharynx, epiglottis, vocal folds, and the rostral portions of the infraglottic cavity were lined by stratified squamous epithelium. An intermediate epithelium compose d of stratified cuboidal cells was observed in the transitional zone b etween the stratified squamous and the pseudostratified columnar cilia ted epithelia. The rest of the tract was lined by typical respiratory epithelium (pseudostratified ciliated columnar epithelium) except from the terminal bronchiole distally, where the type of epithelium ranged between simple columnar and simple cuboidal. Respiratory bronchioles, lined by a simple cuboidal epithelium and interrupted by the presence of alveoli, were prominent and well developed. The alveolar membrane was lined by a simple squamous epithelium. There were no mucosubstance s produced in the rostral portion of the nasal cavity and serous eland s were prominent in this region. The nasal conchae produced both acidi c and mixed mucosubstances, whereas in the nasopharynx and larynx, aci dic mucosubstances predominated. Within the bronchial tree, both acidi c and mixed mucosubstances were present in equal proportions. No mucus -producing cells were observed from the bronchiolar level distally.