Developmental features of porcine haemal nodes: a histological perspective

Abstract

Histological techniques were employed to provide detailed information on the histological features of haemal nodes in piglets and adult pig. Ten pigs were used for this study. The result demonstrated progressive changes in the structure of porcine haemal nodes. The capsule and trabeculae of piglet haemal nodes exhibited dense irregular connective tissues with reticular cells and smooth muscle cells. The cortex was more central while the medulla was peripheral with poorly defined boundaries. However, the sinusoids contained less densely packed erythrocytes. In adult pigs, haemal nodes demonstrated capsules composed of loose irregular connective tissue, fat cells, and mostly reticular cells while the trabeculae showed dense irregular connective tissues with reticular cells and smooth muscle cells. The atypical cortex and medulla of adult pig haemal nodes were distinct. The paracortex of adult pig haemal node showed high endothelial venules and the sinusoids contained densely packed erythrocytes. Afferent lymphatics, efferent lymphatics, blood vessels and veins were observed in the haemal nodes of piglets and adult pigs. Finally, the present study has provided essential information on the structural features of haemal nodes in piglets and adult pigs, revealing its atypical nature, and probable roles of blood storage, erythrophagocytosis and immune functions.

Keywords: Piglets, Adult pigs, Haemal nodes, High endothelial venules, Histological features