A Post-Hatch Study of Larynx and Syrinx in Kuttanad Ducks

Firdous A. Dar1,*, Maya S. Krishnan2 and Ashok N.  Pillai3

1 Division of Veterinary Anatomy and Histology, FVSC and AH, SKUAST-Kashmir
2,3 Department of Veterinary Anatomy and Histology, College of Veterinary and Animal Sciences, Mannuthy, 
Thrissur 680651, Kerala India

*Corresponding author: drromey@gmail.com

Abstract: A developmental study of the larynx and syrinx in Kuttanad ducks was carried out using seventy-eight female birds ranging from one day to twenty-four weeks of age. The material was collected from six birds in each group at fortnightly intervals. Caudal to the base of the tongue protruding on the floor of the pharynx was a conspicuous elevation, known as the laryngeal mound. In this study, it is a raised, elongated lozenge-shaped structure occupying the caudal third of the floor of the pharyngeal cavity. The larynx is formed by cricoid, procricoid and paired arytenoid cartilages which become ossified with progression of age. The procricoid was found to be the smallest median cartilage of the laryngeal skeleton placed dorsally. An increase in the laryngeal length and width was observed as the age advanced; both attained their maximum value by the eighteenth week of age. The laryngeal mound is covered by stratified squamous epithelium with numerous pointed caudally directed papillae. These papillae are covered by the keratinized epithelium. The syrinx is a laterally dilated organ, situated ventral to the esophagus above the base of heart at the thoracic inlet, suspended within the clavicular air sac. In Kuttanad ducks, the syrinx is of a tracheobronchial type; viz. formed by the transformed six caudal rings of trachea and four to five rings of extrapulmonary primary bronchi. The skeleton of the syrinx consists of three components, namely the cranial cartilages (tympanum), rings of the dilated part, and the pessulus. The length of the syrinx increased linearly from the first day to the twenty-fourth week of age recording a maximum growth by week twenty-four. The width of the syrinx also increased with age. A slight decrease was observed in twenty-week-old birds followed by an increase in the succeeding groups.

Keywords: larynx, syrinx, Kuttanad duck, post-hatch.

Jordan Journal of Natural History, 6, (2019),  19-29.

Other articles published in the same issue: Jordan Journal of Natural History, vol.6, iss. 6.

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