Adam J. Miodoński

Microvascular architecture of the human urinary bladder wall: a corrosion casting study.

The vascular system of the urinary bladder wall effectively performs its function in spite of considerable spatial changes due to the filling/voiding cycle. However, only a few studies have dealt with the microvascular architecture of the bladder wall and only two, using old‐fashioned techniques, were devoted to the human bladder. This study presents the microvasculature of the human bladder wall visualized by scanning electron microscopy of vascular corrosion casts.

Blood vessels in epiphyseal cartilage of human fetal femoral bone: a scanning electron microscopic study of corrosion casts.

Formation of intrachondral vessels (cartilage canals) in the proximal femoral epiphysis was studied in 13- to 22-week-old human fetuses using a corrosion casting technique and scanning electron microscopy. Several successive morphological stages of angiogenesis occurring inside the hyaline cartilage were distinguished. The process of cartilage vascularization starts with the formation of hairpin loops sent off from the perichondrial vascular network into the adjacent cartilage. A capillary glomerulus is then formed at the leading end, and the entire vascular unit grows in length, assuming a mushroom-like shape. Its further elongation is accompanied by a backward expansion of the capillary network which surrounds a pair of main vessels (arteriole and venule) like a manchette. The subsequent branching of such primary vascular units proceeds according to the same morphological patterns. The resulting tree-like vascular formations become interconnected via their lateral branches. This study clearly supports the invasion theory of cartilage canal formation.

SEM BLOODVESSEL CASTS ANALYSIS

Publisher Summary Histological-histochemical techniques and injection of the blood vessels have been used in morphological studies of the circulatory system, especially in angiological examinations. Histological and histochemical techniques of staining or impregnating the tissue elements of the vessels, showing the presence of biologically active substances within their walls or rendering visible the morphotic blood components lying in the lumen, have made it possible to inspect the network of the vascular bed in sections of the organ or tissue that is examined in the light microscope (LM) or the transmission electron microscope (TEM). When these techniques are used, the preparations should be thin. These fine sections enable the walls of the arteries, veins, and capillaries to be distinguished with accuracy on the basis of the microscopic structure, as well as the relationship between the blood vessels and the surrounding tissues to be evaluated. It is not an easy task to prepare and present the network of blood vessels studied.

Microvasculature of the dorsal mucosa of human fetal tongue: a SEM study of corrosion casts.

The vasculature of the dorsal mucosa of the tongue was investigated in 18-21 week human fetuses by corrosion casting and scanning electron microscopy. Microvascular systems of the fungiform, foliate and circumvallate papillae, albeit less complex, showed similarity to those described in children, while the capillary networks of the filiform papillae were not yet fully developed, having either a knot-like or cone-like form instead of the corolla-like pattern typical of the postnatal period. Morphological features suggesting angiogenesis included both capillary outgrowths characteristic of vascular sprouting and tiny holes in the vascular walls regarded as evidence of intussusceptive capillary growth. The subpapillary vascular network supplying and draining the papillary vessels was composed of the more superficial capillary bed and the deeper plexus of larger arterioles and venules.

The architecture of internal blood vessels in human fetal vertebral bodies

The internal vascular system of vertebral bodies was investigated in 17–24 wk human fetuses by acrylic dye injection and by corrosion casting/scanning electron microscopy. The regions of intervertebral spaces did not contain blood vessels. The radial metaphyseal vessels were at the stage of centripetal ingrowth into the vertebral body cartilage and their terminal, blindly ending segments had a form of cuff‐like capillary plexuses. The anterolateral equatorial arteries communicating with the vessels of the ossification centre were only rarely found. The centre was usually supplied by 2 posterior (nutrient) arteries which branched into an arcade‐like array of arterioles equipped with occasional sphincters and giving origin to a dense network of peripherally located capillaries. Numerous blind capillary buds formed the advancing border of the ossification centre. The veins usually accompanied the arteries. In the ossification centre the venous compartment consisted of sinuses drained by larger posterior veins. In the 17 wk fetus, an axial avascular area was observed in the place of notochord localisation, indicating the formation of a ring‐shaped ossification centre around the notochord remnants at earlier stages of fetal development.

Vascular architecture of human uterine cervix visualized by corrosion casting and scanning electron microscopy

BACKGROUND In contrast to the uterine corpus, the vascular architecture of the human cervix has been the subject of only a few studies, mostly dealing with the ectocervical mucosal vessels. This study presents the vascular system of the cervical wall surrounding the endocervical canal visualized by the best currently available technique, corrosion casting combined with scanning electron microscopy. METHODS Uteri collected at autopsy (n= 20) were perfused via afferent vessels with fixative followed by Mercox resin and corroded after polymerization of the resin. The obtained vascular casts of the cervix visualizing all vessels including capillaries were examined in the scanning electron microscope. RESULTS The vascular system of the cervix was nearly completely replicated in only two (10%) of the samples. In the wall of the cervix, four distinct vascular zones surrounding the endocervical canal were observed: (i) the outer zone containing larger vessels, arteries and veins of 0.3-1 mm diameter; (ii) the zone containing arterioles and venules; (iii) the zone of endocervical mucosal capillaries showing a very high density, parallel arrangement and relatively few interconnections and (iv) the innermost, subepithelial zone containing small veins running along the endocervical canal. CONCLUSIONS Despite the loss of the delicate ectocervical mucosal vessels from the cast during the corrosion step, we have successfully visualized the majority of the cervical vasculature. The vascular pattern of the human cervix, especially that of the endocervical mucosa, may facilitate the adaptation of the cervical vasculature to the extensive remodeling of the cervix during parturition.

Vascular system of the human spinal cord in the prenatal period: a dye injection and corrosion casting study.

The vascularization of the spinal cord was investigated in 50 human fetuses aged from 10 to 28 gestational weeks using dye injection methods and corrosion casting accompanied by scanning electron microscopy. In the investigated period of fetal development, the general vascular architecture of the spinal cord, corresponding to that described postnatally, seemed to be already established. The observed changes included: (1) remodeling of the supplying (extrinsic) arterial branches, (2) transformation of the posterior anastomotic chain into two distinct posterior spinal arteries, and (3) development of the capillary networks in the gray and white matter. The remodeling of the radicular arteries supplying the spinal cord was accompanied by a decrease in their number and transition from regular to irregular distribution (appearance of intersegmental differences in their frequency). The anterior spinal artery and regular array of the central arteries were already present in the youngest fetuses examined, but the final remodeling of the posterior anastomotic chain into two posterior spinal arteries occurred between 15th and 20th week of fetal life indicating that the vascularization of the anterior region of the spinal cord in the investigated period of fetal life was more advanced as compared with that of the posterior region. The capillary network of the gray matter in the youngest fetuses had the form of discrete glomerular plexuses supplied by groups of central arteries and mainly vascularizing the anterior horns. Successively, the plexuses fused to form a continuous system along the anterior columns and the system expanded to fully vascularize the posterior horns. The white matter in the earlier fetal period seemed to be partially avascular, later the density of capillaries vascularizing those areas was still much lower than in the gray matter. The veins showed considerably greater variability than the arteries, as far as their topography and distribution was concerned. High tortuosity characterized the superficial veins, especially in the younger fetuses, although the degree of tortuosity differed even between individual fetuses. Only anterior spinal and central arteries were usually accompanied by their venous counterparts, the other veins seemed to have no regular topographical relations with the arteries.

Model of skin vascularization in Rana esculenta L.: scanning electron microscopy of microcorrosion casts.

SummaryMicrocorrosion casts of blood vessels in the skin of Rana esculenta L. were examined by means of scanning electron microscopy with particular reference to the subepidermal network of respiratory capillaries. Due to the fact that arteries and veins lie in the deeper layers of the stratum spongiosum of the corium, the respiratory vessels form a morphologically homogeneous network. Functionally, however, this network is subdivided into small areas with a centripetal direction of blood flow. The deep capillary net, situated at the base of the stratum compactum of the corium, is not so dense as the respiratory network and does not directly communicate with it. Alveolar glands of the skin have no effect on the distribution of capillaries in the two networks.

Angiomorphology of the pigmented bomirski melanoma growing in hamster eye

An melanotic line of Bomirski Hamster Melanoma (BHM Ma) was implanted into the anterior chamber of the hamster eye and the ensuring vascular system was studied using scanning electron microscopy (SEM) of vascular corrosion casts. The tumor vasculature, induced mainly from the host iris vessels, showed generally disorganized and irregular patterns. Tortuous tumor capillaries of uneven contour with local dilatations and constrictions were drained by markedly dilated, thin-walled, venous vessels connected with the eye veins. Vascular sprouting and, less frequently, intussusceptive formation of new vessels were observed at the periphery and also within the tumor mass. The presence of numerous nodular outgrowths, varying in size, on the surface of dilated venules and venous vessels represent morphological evidence for continuous remodeling of the tumor vasculature. The observed features of the vascular system seem to provide a pathway for further tumor expansion. Our study showed that BHM Ma line, originating from an aggressive skin melanotic melanoma, implanted to the eye anterior chamber gave rise to rapidly growing tumors with the capability of inducing abundant vasculature which allows metastasis to the lungs, kidneys and regional lymph-nodes.

The superficial vascular hyaloid system in the eye of the frogs, Rana temporaria and Rana esculenta

SummaryThe angioarchitecture of the superficial vascular hyaloid system (membrana vasculosa retinae) of the frog eye was studied by means of scanning electron microscopy of vascular corrosion casts. The terminal vessels form a single-layered sheath intimately adjacent to the vitreal side of the avascular retina. The hyaloid system is subdivided by the ventral venous trunk into three central areas: the dorsal, the temporo-ventral, and the naso-ventral area. Toward the ora serrata, the hyaloid system is bordered by an arterial ring, and by nasal and temporal venous branches forming more or less complete hemicircles. A vascular zone composed of several tongue-like sectors establishes an inter-connection between the peripheral vascular rings and the central areas of the fundus. The arterial blood is supplied from the arterial ring. The drainage of the hyaloid system is provided via two routes: (1) the Y-shaped ventral trunk collects blood from the central areas, (2) the two peripheral venous branches drain the tongue-like sectors. The vessels within the dorsal area follow preferentially a dorso-ventral meridional direction. This densely capillarized territory corresponds in localization to the area centralis retinae. The ultrastructure of microvessels of the hyaloid system is characterized by features typical for capillaries of the central nervous system.