The myocytes of the lymphatic vessels]

Histo- and ultrastructure of myocytes of the lymphatic vessels has been studied in some farm animals. Architectonics, amount and interconnection of myocytes in the lymphangion wall have been investigated. Communicational and gap myo-myocytic contacts revealed give a possibility to suppose that there exists a direct connection between myocytes. This is important for conducting electrical stimulation from one cell to another. For the myocytes abundance of myofilaments, and in some--an essential accumulation of mitochondria are specific; they are morphological manifestation of contractile function of myocytes.     

Determinants of valve gating in collecting lymphatic vessels from rat mesentery

Secondary lymphatic valves are essential for minimizing backflow of lymph and are presumed to gate passively according to the instantaneous trans-valve pressure gradient. We hypothesized that valve gating is also modulated by vessel distention, which could alter leaflet stiffness and coaptation. To test this hypothesis, we devised protocols to measure the small pressure gradients required to open or close lymphatic valves and determine if the gradients varied as a function of vessel diameter. Lymphatic vessels were isolated from rat mesentery, cannulated, and pressurized using a servo-control system. Detection of valve leaflet position simultaneously with diameter and intraluminal pressure changes in two-valve segments revealed the detailed temporal relationships between these parameters during the lymphatic contraction cycle. The timing of valve movements was similar to that of cardiac valves, but only when lymphatic vessel afterload was elevated. The pressure gradients required to open or close a valve were determined in one-valve segments during slow, ramp-wise pressure elevation, either from the input or output side of the valve. Tests were conducted over a wide range of baseline pressures (and thus diameters) in passive vessels as well as in vessels with two levels of imposed tone. Surprisingly, the pressure gradient required for valve closure varied >20-fold (0.1-2.2 cmH(2)O) as a passive vessel progressively distended. Similarly, the pressure gradient required for valve opening varied sixfold with vessel distention. Finally, our functional evidence supports the concept that lymphatic muscle tone exerts an indirect effect on valve gating.     

The relationship between the lymphatic vessels of the nerves of the human lower extremity and the perineural spaces]

The lymphatic vessels and perineural spaces of superficial and profound nerves of the extremity were studied on the material of 50 lower extremities of corpses of humans by the method of intratissue and direct injection. Initial lymphatic capillaries and extraorganic lymphatic vessels and their paravasal plexuses were found. It is concluded that closed lymphatic capillaries having no immediate connection with the perineural space are the roots of the lymphatic bed in the nerve.     

Anatomical variants of the lymphatic vessels connecting the inguinal lymph nodes]

The study of anatomical variants of lymphatic vessels connecting inguinal lymph nodes was carried out on 56 corpses of adult persons of both sex whose deaths were not connected with lesions in the lymphatic system of the pelvis and lower extremities. The inguinal lymph nodes and their afferent and efferent lymphatic vessels were detected by the method of intradermal injection and by the method of direct injection into the lymphatic vessels. It was stated that groups of the inguinal lymph nodes, as well as the nodes in every group determined, can serve as nodes of different stages for afferent lymphatic vessels running from different parts of the body and organs.     

Early changes in dissected small vessels: experimental study on rat arteries and veins

This study was undertaken to investigate the cause of the early endothelial damage that is seen at sites of microvascular anastomosis and in particular to study the possibility of a connection between damage to the vasa vasorum and subsequent endothelial denudation. Rat femoral vessels were subjected to a variety of experimental injuries, including simple dissection, clamping, and ligation. The vessels were examined in longitudinal section by light microscopy at intervals ranging from 5 minutes to 1 day. The endothelial cells were counted and the numbers were analyzed statistically. In addition, the anatomy of the vasa vasorum was studied using india ink perfusion. Simple dissection of the femoral vessels and excision of the vasa vasorum without interruption of blood flow were followed by ischemic lesions of the tunica media with subendothelial edema and ballooning and exfoliation of endothelial cells. Endothelial denudation reached a maximum level in 30 minutes. Adherence of leukocytes was found on damaged endothelial cells. Mural thrombi were seen in 13.6 percent of arteries and in 40 percent of veins following simple dissection.