Gross and Histological Studies on the Proventriculus and Gizzard of Budgerigar (Melopsittacus undulatus)

Abstract

Aims: The present study was conducted to examine the morphological and histological organisation of the proventriculus and gizzard of the budgerigar (Melopsittacus undulatus). Study Design: The investigation was conducted on 6 adult budgerigar birds, comprising 3 birds of each sex, procured from the Teaching Veterinary Clinical Complex of West Bengal University of Animal and Fishery Sciences, Kolkata-37, West Bengal. Place and Duration of Study: The study was conducted in the Department of Veterinary Anatomy and Histology, Faculty of Veterinary and Animal Sciences, West Bengal University of Animal and Fishery Sciences, Kolkata-700037, India, between January 2020 and June 2020. Methodology: A total of 6 adult budgerigar birds, comprising 3 birds of each sex, that had died due to predator attack were opened, and the proventriculus and gizzard were observed for gross morphological studies. Portions of the two organs were fixed in normal buffered formalin and later processed and prepared for histological studies. Results: The proventriculus of the budgerigar was a small, spindle-shaped, thick-walled tube positioned between the oesophagus and gizzard. The proventricular mucosa was composed of numerous folds of different heights. The folds, termed plicae, were separated by depressions called sulci. Lamina epithelialis was lined by mucus-secreting simple columnar epithelial cells. Lamina propria consisted of typical loose connective tissue that invaded the central part of the mucosal folds. In the muscularis mucosae, longitudinal smooth muscle fibres were seen. The gizzard of the budgerigar was a small spheroid rather than a biconvex disc-like organ. It was more muscular than the proventriculus and consisted of two pairs of opposing thick and thin muscles. The ventriculus, or gizzard, was made up of four tunics: mucosa, submucosa, muscularis and serosa. Lamina epithelialis was lined by a single layer of columnar cells covered by a very thick layer of keratinoid or cuticle called Koilin. Conclusion: The study provides baseline descriptive information on the gross morphology and histological organisation of the proventriculus and gizzard of budgerigar birds. The observations from the present study may provide useful baseline reference data for further studies on the developmental anatomy, comparative morphology, physiology and pathological alterations of the proventriculus and gizzard in other pet or domesticated birds.