Vol. 10, Issue 5, Part F (2025)

Author(s): J Bhagyalakshmi, K Balasundaram, VG Charitha and P Guru Vishnu

Abstract: A total of 18 mesenteeric lymph node specimens were collected from sheep, irrespective of breed and sex, and categorized into three developmental groups: pre-pubertal (2 months), pubertal (6-8 months), and adult (3 years). Histological analysis revealed distinct age-related structural and cellular changes. In the pre-pubertal group, the lymph node capsule exhibited uneven thickness with numerous smooth muscle fibers, while the trabeculae contained fewer smooth muscle fibers. At this stage, an increased number of lymphatic nodules were observed in the cortex, extending into the medulla. These nodules possessed lightly stained germinal centers and were composed of lymphocytes, reticular cells, macrophages, dendritic cells, and neutrophils. In the pubertal group, the capsule and trabeculae displayed an increased amount of collagen and reticular fibers, along with a reduced number of elastic fibers compared to the younger group. In adult sheep, the lymphatic nodules showed a marked increase in size and cellular density in both the cortex and medulla. The medullary cords exhibited enhanced cellularity, predominantly comprising lymphocytes, reticular cells, and macrophages. These findings highlight the progressive morphological and immunological maturation of lymph nodes with advancing age in sheep.