J.A. Litwin

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.

Morphological and clinical characteristics of antrochoanal polyps: comparison with chronic inflammation-associated polyps of the maxillary sinus.

OBJECTIVES to compare morphological and clinical features of antrochoanal polyps and chronic inflammation-associated polyps of the maxillary sinus. STUDY DESIGN histological and scanning electron microscopic examination of ten antrochoanal polyps and ten chronic inflammation-associated polyps of the maxillary sinus; comparison of clinical data in both groups of patients. METHODS following surgical removal, the polyps were halved, the halves being processed for routine light microscopy (formalin fixation, paraffin embedding, HE staining) and scanning electron microscopy (formaldehyde/glutaraldehyde fixation, critical point drying, gold coating), respectively. Clinical data were retrospectively reviewed, tabulated and compared. RESULTS the antrochoanal polyps differed from chronic inflammation-associated polyps of the maxillary sinus only in a few minor features; slightly longer duration of the process, lower incidence of maxillary ostial obstruction, higher incidence of frequent headaches, persistent nasal obstruction, presence of cysts in the polyp stroma, thickened basement membrane, lower incidence of squamous cell metaplasia, and higher proportion of migratory cells in nasal smears. In two cases, allergy was diagnosed but it seemed not to influence the polyps, which did not show morphological features typical of allergy-associated (eosinophilic) polyps. CONCLUSIONS In spite of minor differences, antrochoanal polyps can be regarded as chronic inflammation-associated polyps with cystic origin and peculiar localization.

Immunocytochemical investigation of catalase and peroxisomal lipid β-oxidation enzymes in human hepatocellular tumors and liver cirrhosis

A significant reduction of catalase activity, a peroxisomal marker enzyme, occurs in human hepatic neoplasias, but no information is available on other peroxisomal proteins. We have studied by means of immunohistochemistry four specific proteins of peroxisomes (catalase and three enzymes of lipid β-oxidation) in human hepatocellular tumors of various differentiation grades from adenoma to anaplastic carcinoma. In all tumors, except the adenomas, the tumor cells contained fewer peroxisomes than extrafocal hepatocytes and the reduction of antigenic sites in the tumor types generally correlated with the degree of tumor dedifferentiation as assessed by classical histopathological criteria. Two poorly differentiated tumors had no detectable peroxisomes at all. There were no major differences in the intensities of the immunocytochemical staining for all four studied peroxisomal antigens in different tumors, suggesting that the neoplastic transformation affects the biogenesis of the entire organelle and not merely the individual peroxisomal enzyme proteins. Some tumors exhibited a distinct peripheral distribution of peroxisomes. In cases with associated liver cirrhosis, the hepatocytes in the adjacent liver showed marked peroxisome proliferation, forming large perinuclear aggregates, occupying occasionally the entire cytoplasm. Taken together, our observations indicate that peroxisomes are significantly altered in both hepatocellular tumors and liver cirrhosis and, thus, could be responsible for some of the metabolic derangements observed in those disease processes.

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.

Vascular architecture of human urinary bladder carcinoma: a SEM study of corrosion casts

Abstract The vascular architecture of five advanced invasive papillary tumours of the urinary bladder was investigated using corrosion casting and scanning electron microscopy. The superficial vasculature was composed predominantly of capillary systems of two types: dense flat networks with numerous interconnections and tightly packed tortuous loops, forming multiple irregular folds that reflected the papillary morphology of the tumours. The capillaries were supplied and drained by numerous straight nonanastomosing arterioles and venules, which arose by way of multiple branching of larger vessels originating from the mucosal plexus of the bladder. Differences between the tumours in the spatial arrangement of these vessels probably reflect different growth dynamics. The intramural parts of the tumours contained a chaotic network of straight, uniform capillaries with numerous sprouts, which was very different from the superficial capillary system. It is postulated that different angiogenesis-targeted growth factors may be expressed in the phases of exophytic growth and muscularis invasion of the tumour, leading to the formation of different microvascular patterns.

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 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.

Architecture of blood vessels in human fetal gastric corpus: a corrosion casting study

Vascular architecture of the gastric corpus was investigated in 16-24 wk human fetuses using a corrosion casting technique and the scanning electron microscopy. The general distribution of blood vessels seen in adults has already been established in the fetus, with three major vascular plexuses located in the serosa, submucosa and mucosa. The serosal plexus, supplied and drained by large extramural vessels, contained anastomosing, arcade-like arrays of arteries and veins with their branches piercing the muscularis and communicating with the compact submucosal plexus. Vertical arterioles and capillaries were sent by submucosal arteries to supply a very dense capillary plexus which surrounded the gastric pits and consisted of wide, sinusoidal vessels showing morphological manifestations of angiogenesis by intussusceptive growth. The plexus was drained by vertical venules emptying into submucosal veins. In contrast to the richly vascularized upper half of the mucosa, the lower half showed a relative paucity of blood vessels, probably due to the thinness of the fetal mucosa allowing an effective diffusion of oxygen and nutrients from the upper half. Neither arteriovenous anastomoses, nor end-arteries were found in the fetal stomach. Results of this study support one of the two existing models of mucosal vascularization in the human stomach: i.e. the model postulating the presence of short and long arterioles and two distinct, albeit interconnected capillary networks in the upper and lower zones of the mucosa respectively. In human fetuses, the latter network is absent; it probably develops by remodelling of the preexisting vertical capillaries in the last phase of pregnancy, prior to the onset of gastric gland function.

Vascular architecture of the human fetal adrenal gland: A SEM study of corrosion casts

The vascular architecture of adrenal glands was investigated in human fetuses aged from 16 to 24 weeks, using microcorrosion casts and scanning electron microscopy. The fetal adrenals showed an arrangement of blood vessels remarkably similar to that described in adult glands. There was a clear centripetal pattern from superficial arteries and their branches, via irregular capillaries of the subcapsular plexus and definitive cortex, and then via the radial sinusoids and venous sinuses of the fetal cortex, to the central vein. Rare medullary arterioles traversed the cortex to break up into small local capillary networks in the central region of the gland. Some superficial capillaries were drained by occasional subcapsular veins. No portal system was observed in the fetal adrenals.