Scanning Electron Microscopy Of Microcorrosion Research Articles

Pododermal angioarchitecture of the bovine claw in relation to form and function of the papillary body: a scanning electron microscopic study.

The region-specific angioarchitecture of the bovine pododerma was examined using systematic scanning electron microscopy of micro-corrosion casts of juvenile and adult bovine claws. Particular emphasis was laid on the demonstration of specialised vascular structures such as arteriovenous anastomoses. Comparing the results of main and dew claws, respectively, of juvenile and adult claws, a relation between burdening of the claw and density and differentiation of the pododermal papillary and lamellar blood vessels was detected. The results suggest a possible influence of body weight (or age) and weight-bearing on the formation and vascularisation of the pododermal papillary body. The lamellar and papillary microvascularisation and microcirculation are discussed.

Postnatal development of the vascular pattern in the rat telencephalic pia-arachnoid. A SEM study.

The postnatal changes in arrangement of the vascular system of the pia-arachnoid of rats are described based on scanning electron microscopy of microcorrosion casts and transmission electron microscopy. At birth, the distal arteries and veins are embedded in a dense plexiform network of immature capillaries. Arteries and veins are interconnected by many small capillary anastomoses. The trunks are located above the pial plexus. The underlying plexiform vessels provide the matrix for the formation of additional collateral and precortical segments during further development. During the first postnatal week, the distal pial arteries and veins become visible as separate channels and emerge from the subjacent capillary plexus. The pattern of anastomosing arterial rings is now clearly visible. The pial arterial tree can be subdivided into conductive, collateral, and precortical distributive segments, according to Jokelainen et al. (1982). Subsequently, passive expansion of the vascular system takes place during the period of rapid brain growth. In young adults the majority of the formerly closed arterial rings are interrupted, possibly by regression of single collateral arterial segments (Fig. 6). The dense venous capillary plexus of the pia is maintained during the first eight days in spite of marked brain growth. The process of reduction of this capillary plexus starts at the arterial side and proceeds from proximal to distal segments of the veins during the second and third week. The capillary segments, which provide anastomosis between arterial and venous vessels, disappear at the same time as the regression of the dense venous capillary network.(ABSTRACT TRUNCATED AT 250 WORDS)

Circulatory pathways in the sinusal spleen of the dog, studied by scanning electron microscopy of microcorrosion casts.

Scanning electron microscopy of microcorrosion casts was used to visualize circulatory pathways in the sinusal spleen of dog. The examination of contracted versus dilated organs and variations of the volume of material injected gave an indication of flow dynamics. Minimal injections of material into contracted spleens produced filling of mainly the fastest routes for flow, whereas injections into dilated spleens primarily filled slower routes. This procedure yielded a more complete, three-dimensional picture of the arterial, intermediate, and venous pathways as a whole, and of the relative amounts of flow through different arterial routes. Evidence of flow from capillary lumina out into ellipsoid sheaths was plentiful in casts from dilated spleens, but rare in casts from contracted organs. The pattern of flow within and out of the marginal sinus has been elucidated: A circumferential filling occurs first, followed by a flow that radiates outward into the marginal zone and red pulp. Venous sinuses filled via two routes in addition to the generally accepted path from the reticular meshwork via fenestrations in sinus walls. First, many venous sinuses extending out from the marginal sinus and surrounding marginal zone originated as open-ended tubes continuous with the reticular spaces of the marginal sinus or marginal zone. Second, direct connections of arterial capillaries with venous sinuses in the red pulp were found. Evidence indicating that some mechanism is controlling the flow via these routes is discussed. The strikingly different arrangement of venous sinuses in the subcapsular region is demonstrated.

Blood vessels in the tongue of the kitten: Scanning electron microscopy of microcorrosion casts

The subepithelial blood vessels of the dorsal surface of the tongue in young kittens has been studied by scanning electron microscopy of micro-corrosion casts. These vessels entwine the vallate papillae distributed in the pharyngeal part of the tongue, form hairpin loops in association with the small conical papillae along the sides and at the tip of the tongue and establish regularly distributed subpapillary conglomerations over almost its entire oral part. These conglomerations lie directly on veins. Small arterioles reach the vessels surrounding the individual subpapillary conglomerations. By contrast with the arrangement of the superficial vascular bed in the tongue of the dog and some other mammals, no anastomoses between arteries and veins were observed in the kitten between the vessels which supply and drain the subepidermal capillaries.