Structure of cutaneous lymphatics propelling lymph

Area of Science:

• Vascular Biology
• Lymphatic System Physiology
• Microcirculation Research

Background:

• The lymphatic system is crucial for fluid balance and immune function.
• Understanding lymph propulsion mechanisms is vital, particularly in conditions like edema.
• Previous knowledge on lymph transport in postcapillary lymphatic segments is limited.

Purpose of the Study:

• To investigate the structural and functional characteristics of lymphatic vessels in oedematous rat skin.
• To identify specialized structures involved in active lymph propulsion.
• To elucidate the role of these structures in lymph transport during dextran-induced edema.

Main Methods:

• Histological examination of serial sections from oedematous rat hind limb skin.
• Induction of dextran-edema to increase lymph formation and transport.
• Ultrastructural analysis using electron microscopy to identify myofilaments.

Main Results:

• Identification of postcapillary sack-like sinuses between lymph capillaries and lymph vessels proper.
• Observation of valve-like structures regulating lymph flow into these sinuses.
• Detection of actin- and myosin-type myofilaments within the muscle cell sheaths of lymphatic vessels.
• Demonstration of varying lumen diameters in artery-type lymph vessels, suggesting contractile activity.

Conclusions:

• The identified postcapillary sinuses and contractile lymphatic vessels function as
• lymph hearts
• in oedematous skin.
• These structures actively accumulate and transport lymph towards the center.
• The findings provide new insights into lymphatic system mechanics during edematous states.