The peritoneal lymphatic system plays a crucial role in the maintenance of fluid homeostasis and immune surveillance within the abdominal cavity. Despite its physiological significance, detailed morphological characterization of peritoneal lymphatic capillary endothelium and its spatial relationship with the mesothelium remains inadequately described. This study aims to elucidate the structural features of the endothelial lining of peritoneal lymphatic capillaries and to define their morphological association with the adjacent mesothelial layer under normal physiological conditions. Samples of peritoneal tissue were obtained from adult Wistar rats (n = X) and processed for light and transmission electron microscopy. Endothelial cell morphology, intercellular junctions, basement membrane continuity, and the ultrastructural interface between lymphatic endothelium and mesothelium were examined. Quantitative morphometric analyses were conducted to assess endothelial thickness, pore density, and relational topography. Lymphatic capillary endothelium exhibited a thin, attenuated architecture with sparse basal lamina and numerous discontinuities facilitating fluid uptake. Endothelial cells displayed characteristic overlapping flaps and anchoring filaments. The mesothelial surface was continuous, with well-developed microvilli and tight intercellular junctions. Spatial analysis revealed specialized contact zones where mesothelial basal lamina closely approached lymphatic endothelial discontinuities, suggesting potential structural pathways for interstitial fluid transfer. Morphometric data demonstrated statistically significant associations between endothelial pore density and mesothelial proximity (p < 0.05). The peritoneal lymphatic capillary endothelium is structurally adapted for efficient fluid absorption, exhibiting a unique morphology with specialized endothelial–mesothelial interfacing. These findings provide fundamental insights into peritoneal fluid dynamics and may have implications for understanding pathophysiological conditions such as ascites and peritoneal inflammation.

peritoneal lymphatics, endothelial morphology, mesothelium, ultrastructure, fluid homeostasis.

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