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Recent research has highlighted the remarkable heterogeneity of the vascular system, composed of both the blood and lymphatic vasculatures. These systems vary significantly across organs, with differences in morphology, function, and developmental origin. In particular, the lymphatic system has emerged as an important organ-specific regulator of tissue homeostasis, extending beyond its traditional role in fluid drainage to active shaping local immune responses through modulation of adaptive immunity. Moreover, lymphatic endothelial cells (LECs) produce paracrine (lymphangiocrine) factors that regulate organ growth and regeneration. The growing recognition of the diverse functions of the lymphatic system in important physiological processes and disease conditions, such as autoimmune disease and atherosclerosis, highlights the need for a better understanding of the underlying mechanisms.