The distribution and structure of the lymphatic system in dog atrioventricular valves.

Abstract

Summary. A morphological study of the lymphatic system in atrioventricular (AV) valves of adult dogs and puppies was carried out using a series of techniques including India ink injection, a hydrogen peroxide technique, light microscopy, and electron microscopy. Lymphatic capillaries were found in all cusps of the AV valves, and were shown to extend delicate networks in the subendocardium of the atrial side of the valves. The extent of their development varied among cusps, being most prominent in the anterior cusp of the mitral valve. Marked differences were noted in the intravalvar distribution between lymphatic capillaries and blood microvessels. The ultrastructures of the lymphatic capillaries in the AV valves were also demonstrated.

Comparative and Developmental Anatomy of Cardiac Lymphatics

“…It is not known whether the lack of lymphatics in the tricuspid valve may have been caused by technical problems, whether it depends on species specificity, and/or whether it is typical only for human hearts. Lymphatics were not found in the semilunar valves of the aorta and the pulmonary trunk of human, pig and dog hearts [17, 28, 33, 34]. …”

Pathology of myxomatous mitral valve disease in the dog

“…There is marked variability in intravalvular distribution between lymphatic capillaries and small blood vessels. 94 Ultrastructural characteristics of lymphatic capillaries include interstitial spaces lined by irregular, occasionally fenestrated endothelium, absence of basal membrane, and absence of erythrocytes within the lumen. 92 A relatively dense concentration of lymphatics also occur in the region of the papillary muscles.…”

Anatomy of the Mitral Valve Apparatus

“…This tissue is excitable via the atria, isolated from LV excitation, and resembles atrial myocardium (36). The healthy, mature MV has a very rudimentary vascular and lymphatic system (23,47), interstitial cells are mostly dormant, and the ECM turnover is slow. Physiologic or pathologic-induced leaflet stress can induce prominent EMT, interstitial cell activation & proliferation, ECM remodeling and neovascularization (3,42,48,49).…”