COMPARATIVE HISTOLOGICAL STUDY ON THE SPLEEN OF HUMAN, GOAT, DOG, RABBIT AND PIG

Background: The spleen is the largest secondary lymphoid organ and contributes to immune defence, blood filtration, clearance of senescent erythrocytes, iron recycling, and haematological regulation. Its microarchitecture varies among species in keeping with these functional demands, yet comprehensive comparative studies of human and animal spleens employing uniform histological criteria remain scarce, particularly in the Indian context. Objective: To compare the histological architecture of the spleen in humans, goats, dogs, rabbits, and pigs, and to identify the structural variations associated with functional adaptation. Methods: A cross-sectional comparative study was conducted at Shyam Shah Medical College, Rewa, over 18 months. Results: In total, 150 spleen specimens were examined, comprising 30 from each of the five species. Tissues were fixed in 10% neutral buffered formalin, processed by routine paraffin embedding, sectioned at 4-5 µm, and stained with haematoxylin and eosin (H&E) and Masson’s trichrome. Capsule thickness, trabecular architecture, white-pulp proportion, lymphoid follicles, red pulp, vascular pattern, and macrophage density were assessed. Porcine spleens had the thickest capsule (170 ± 20 µm), prominent trabeculae, a predominance of red pulp (85-90%), and a high macrophage density. Rabbit spleens showed the thinnest capsule (85 ± 10 µm), the highest white-pulp proportion (30-35%), prominent lymphoid follicles, and well-developed periarteriolar lymphoid sheaths. Goat spleens displayed intermediate features, whereas human and canine spleens showed a balanced organisation of red and white pulp. The spleen demonstrates substantial species-specific histological variation, reflecting functional adaptation between immune surveillance and haematological storage. Conclusion: These observations are relevant to anatomical teaching, veterinary pathology, immunological research, and the rational selection of animal models for translational studies.