Comparative Morphological and Histological Characterisation of the Thymus in Haringhata Black and Commercial Broiler Chickens (Gallus gallus domesticus)
Nowel Chaudhury
Department of Veterinary Anatomy, College of Veterinary Sciences & A.H, R.K. Nagar, Tripura, India.
Sanjay Ray
Department of Veterinary Anatomy, Faculty of Veterinary and Animal Sciences, WBUAFS, Kolkata-37, India.
Arun Kumar Mondal
Department of Veterinary Anatomy, Faculty of Veterinary and Animal Sciences, WBUAFS, Kolkata-37, India.
Sudip Das
Department of Veterinary Parasitology, College of Veterinary Sciences & A.H, R. K. Nagar, Tripura, India.
Rupam Malakar
Department of Animal Resources Development, College of Veterinary Sciences & A.H, R.K. Nagar, Tripura, Affiliated to Tripura University, India.
Partha Das
Department of Veterinary Anatomy, Faculty of Veterinary and Animal Sciences, WBUAFS, Kolkata-37, India.
Nirmal Kumar Tudu
Department of Veterinary Anatomy, Faculty of Veterinary and Animal Sciences, WBUAFS, Kolkata-37, India.
Sukanta Das *
Department of Veterinary Anatomy, College of Veterinary Sciences & A.H, R.K. Nagar, Tripura, India.
*Author to whom correspondence should be addressed.
Abstract
Background: The thymus is a primary lymphoid organ involved in avian T-lymphocyte development. Comparative information on thymic development in Haringhata Black and commercial broiler chickens is limited.
Aim: The study aims to compare the gross morphology, morphometry, histology, and histochemical features of the thymus in Haringhata Black and commercial broiler chickens (Gallus gallus domesticus) during post-hatch development.
Study Design: An experimental study involving Haringhata Black and commercial broiler chickens at 0, 15, 30, 45, and 60 days post-hatch.
Methodology: A total of 30 apparently healthy Haringhata Black and commercial broiler chickens were examined at 0, 15, 30, 45, and 60 days of age. Gross anatomical observations and morphometric measurements (weight, length, width, and thickness of the thymus) were recorded, and the organs were photographed. Microscopic tissue architecture was evaluated using routine histological and histochemical staining techniques. Periodic acid-Schiff (PAS) and Alcian Blue staining were performed.
Results: In both groups, the thymus consisted of paired chains of cervical lobes extending from the third cervical vertebra to the thoracic inlet. Thymic weight and dimensions generally increased with age. Commercial broilers showed larger absolute thymic dimensions at several ages, whereas Haringhata Black chickens showed a thicker cortex and a higher cortico-medullary index. Histologically, the thymus was enclosed by a connective tissue capsule with trabeculae that incompletely divided the gland into lobules containing a darkly stained cortex and a lightly stained medulla. PAS and Alcian Blue reactivity generally increased during early development, with age-related variation at 60 days. Cortical and medullary thicknesses, lobule width, and Hassall's corpuscle diameter increased across the sampled ages. At 60 days, Haringhata Black chickens had a thicker cortex, whereas commercial broilers had a thicker medulla and wider lobules.
Conclusion: The study provides baseline gross, morphometric, microscopic, and histochemical data on thymic development in Haringhata Black and commercial broiler chickens. Breed-associated differences were identified; however, the morphological findings alone do not establish functional differences in immune competence or disease resistance. These data may support future comparative anatomical, immunological, and poultry-breeding investigations.
Keywords: Thymus, Haringhata Black, commercial broiler, Gallus gallus domesticus, gross morphology, morphometry, histology, histomorphometry, histochemistry, post-hatch development.