Post Natal Developmental Studies on the Respiratory System of Uttara Fowl

Abstract

The present work was carried out on respiratory system of 24 apparently healthy Uttara fowl at newlinedifferent age groups viz. 0, 7, 28 and 112 days. Respiratory system of fowl consisted of nares as newlineoperculum, nasal cavity (cavitas nasalis), larynx, trachea, syrinx and lungs. On gross observations the newlineexternally nasal cavity opened as elliptical-shaped nostrils located at the base of the upper beak on newlineeither side. Black pigmentation was present on operculum in all age group of Uttara fowl except 0 day. newlineEach half of the nasal cavity exhibited three types of creamy white cartilaginous (hyaline) conchae i.e. newlinerostral, middle and caudal out of these middle conchae was the largest in all the age groups. Larynx was newlineformed by single cricoids, procricoid cartilage and paired arytenoid cartilage. The cricoid was the newlinelargest laryngeal cartilage. The catilagenous tracheal rings were flattened dorsoventrally and their newlinenumber varied between 101 to 128. Uttara had tracheobronchial type syrinx. The lungs appeared as newlinebright pink color, pyramidal- shaped shape. Histologically cranially vestibule was (external nares) lined newlineby heavily keratinized stratified squamous epithelium. The degree of keratinization decreased gradually newlinetowards the caudal aspect and lining epithelium modified into slightly keratinized stratified squamous newlineepithelium towards the rostral concha. Middle concha was lined by ciliated pseudostratified columnar newlineepithelium with neumerous tubuloalveolar intraepithelial glands. Larynx revealed outer epithelial layer newline(dorsal surface) lined by keratinized stratified squamous epithelium containing keratinized pointed newlinepapillae. The inner most layer (lining epithelium towards the laryngeal lumen) was made up of ciliated newlinepseudostratified columnar epithelium with numerous intraepithelial mucous glands. Trachea and syrinx newlinewas lined with ciliated pseudostratified columnar epithelium and numerous intraepithelial mucous newlinegland. Trachea bifurcated into Primary or mesobronchi which divided into secondary bronchi which newlinecontinued into tertiary or parabronchi. The parabronchi further continue into infundibula, atria and air newlinecapillaries. The mucous membrane of the primary bronchi and secondary was lined by ciliated newlinepseudostratified columnar epithelium with ciliated, goblet cells. Tertiary bronchi, atria and air capillary newlinewere lined by simple squamous to simple cuboidal epithelium cells. Histochemically, the lining newlineepithelium, intraepithelial mucous glands, muscles, perichondrium and chondrocyte cells of cartilage in newlinerespiratory system show PAS positive reaction. Intraepithelial mucous glands of entire respiratory newlinesystem showed intense reaction for Acid and neural mucin. Acidic sulphated mucins were more than newlineneutral mucins in intraepithelial mucous glands. The intense acid phosphatase, alkaline phosphatase and newlineATPase positive reaction was observed in capsule, surface epithelial layer of tertiary bronchi, blood newlinevessels, and interlobular connective tissue and air capillaries. Under SEM observation each half of newlinelaryngeal mound had two transverse rows of papillae. Some cranial papillae had bifurcated apices. The newlinemedial most papillae of cranial transverse rows were broader compare to lateral papillae and at their newlinebase of thorn like small papillae were present. Various sized opening of intraepithelial glands were newlinepresent near the rim of glottis. The lung parenchyma was arranged around the secondary bronchi in newlinehoney comb like appearance. In between parabronchi interparabronchial septae were clearly visible. newlineThe parabronchi opened into atria which lead to the air capillaries surrounded by blood capillaries. newline