Ultrastructural cytochemistry of anchoring filaments of human lymphatic capillaries and their relation to elastic fibers.

In previous studies "anchoring filaments" of human lymphatic capillaries have been shown to consist of microfibrils having histochemical and ultrastructural characteristics similar to elastin-associated microfibrils. When not associated with an elastin component, these microfibrils are referred to as "oxytalan microfibrils." In this study, alpha-glycol-containing carbohydrates and glycoconjugated sulfate groups, originating from sulphydryls and/or disulfide bridges, have been detected in anchoring filament microfibrils of human lymphatic capillaries by Thiery reaction (PA-TCH-SP) and "Hight Iron Diamine" cytochemical method (HID), respectively. Both of these chemical groups belong to the putative glycoprotein of which the microfibrils are constituted. Similar molecular characteristics have been demonstrated in elastic fiber microfibrils and oxytalan microfibrils of connective tissue. These findings suggest a close molecular similarity among these different types of microfibrils. Thus, whatever their individual location or denomination (anchoring filaments, oxytalan fibers, or elastin-associated microfibrils), these microfibrils form an uniform population of fibrous elements. These findings further support a structural (and functional) continuity between the lymphatic capillary wall and the elastic network of adjacent connective tissues previously described and termed "Fibrillar Elastic Apparatus" (FEA). Of interest, endothelial cells also selectively react positively to the PA-TCH-SP and HID methods.