Vascular Corrosion Cast Technique Research Articles

Unique morphological aspects of the rat ventral prostate gland revealed by vascular corrosion casting

BACKGROUND There is growing interest as to the potential role of the prostatic vascular system in mediating the effects of androgenic steroids on growth control of the prostate. Here we describe the use of a vascular corrosion casting technique that enables the visual characterization of the vascular system of the rat ventral prostate and the description of some unique morphological features of the mature rat prostate gland that were never previously observed. METHODS Anesthetized adult male Sprague-Dawley rats were vascularly perfused with a fixative solution and then with a catalyzed methacrylate-based casting solution that was allowed to polymerize in situ. Ventral prostate glands were dissected from these rats and the tissues were subsequently dissolved in a corrosive solution, leaving residual vascular casts. The casts were then examined by scanning electron microscopy for pertinent morphological features. RESULTS Vascular corrosion casts of individual lobes of the mature rat ventral prostate revealed a complex vascular structure that entered into the prostate near the base of the bladder. The morphological correspondence of the prostatic vasculature to the previously described ductal organization of the prostate was readily apparent. Examination of the entire vascular complex (under low-power scanning electron microscopy) revealed three differing surface features of the tissue and suggested that the glandular elements of the ventral prostate were directionally oriented towards a single surface (the anterior-lateral surface). An opposing face (posterior-medial) of the tissue demonstrated some unique spiral vessels, suggesting the need for a potential stretch-compensation mechanism at the prostate surface immediately adjacent to the bladder. CONCLUSIONS Vascular casts of the rat ventral prostate gland reveal the obvious ductal organization of the prostatic parenchyma and demonstrate that these ducts are directionally oriented so that the glands of the prostate (at the distal tips of the ducts) uniformly lie near the anterior-lateral surface of the tissue. Unusual spiral arterioles found proximal to the bladder surface suggest that the rat ventral prostate gland has acquired the means to adapt to an anatomical position adjacent to a tissue (bladder) that acutely varies in size during the micturition cycle. Prostate 39:240–245, 1999. © 1999 Wiley-Liss, Inc.

Unique morphological aspects of the rat ventral prostate gland revealed by vascular corrosion casting.

There is growing interest as to the potential role of the prostatic vascular system in mediating the effects of androgenic steroids on growth control of the prostate. Here we describe the use of a vascular corrosion casting technique that enables the visual characterization of the vascular system of the rat ventral prostate and the description of some unique morphological features of the mature rat prostate gland that were never previously observed. Anesthetized adult male Sprague-Dawley rats were vascularly perfused with a fixative solution and then with a catalyzed methacrylate-based casting solution that was allowed to polymerize in situ. Ventral prostate glands were dissected from these rats and the tissues were subsequently dissolved in a corrosive solution, leaving residual vascular casts. The casts were then examined by scanning electron microscopy for pertinent morphological features. Vascular corrosion casts of individual lobes of the mature rat ventral prostate revealed a complex vascular structure that entered into the prostate near the base of the bladder. The morphological correspondence of the prostatic vasculature to the previously described ductal organization of the prostate was readily apparent. Examination of the entire vascular complex (under low-power scanning electron microscopy) revealed three differing surface features of the tissue and suggested that the glandular elements of the ventral prostate were directionally oriented towards a single surface (the anterior-lateral surface). An opposing face (posterior-medial) of the tissue demonstrated some unique spiral vessels, suggesting the need for a potential stretch-compensation mechanism at the prostate surface immediately adjacent to the bladder. Vascular casts of the rat ventral prostate gland reveal the obvious ductal organization of the prostatic parenchyma and demonstrate that these ducts are directionally oriented so that the glands of the prostate (at the distal tips of the ducts) uniformly lie near the anterior-lateral surface of the tissue. Unusual spiral arterioles found proximal to the bladder surface suggest that the rat ventral prostate gland has acquired the means to adapt to an anatomical position adjacent to a tissue (bladder) that acutely varies in size during the micturition cycle.

Angioarchitecture of the coeliac sympathetic ganglion complex in the common tree shrew (Tupaia glis).

The angioarchitecture of the coeliac sympathetic ganglion complex (CGC) of the common tree shrew (Tupaia glis) was studied by the vascular corrosion cast technique in conjunction with scanning electron microscopy. The CGC of the tree shrew was found to be a highly vascularised organ. It normally received arterial blood supply from branches of the inferior phrenic, superior suprarenal and inferior suprarenal arteries and of the abdominal aorta. In some animals, its blood supply was also derived from branches of the middle suprarenal arteries, coeliac artery, superior mesenteric artery and lumbar arteries. These arteries penetrated the ganglion at variable points and in slightly different patterns. They gave off peripheral branches to form a subcapsular capillary plexus while their main trunks traversed deeply into the inner part before branching into the densely packed intraganglionic capillary networks. The capillaries merged to form venules before draining into collecting veins at the peripheral region of the ganglion complex. Finally, the veins coursed to the dorsal aspect of the ganglion to drain into the renal and inferior phrenic veins and the inferior vena cava. The capillaries on the coeliac ganglion complex do not possess fenestrations.

Liver metabolic zonation and hepatic microcirculation in carbon tetrachloride-induced experimental cirrhosis.

The exact cause of the hepatic failure in liver cirrhosis is currently unclear, and two main theories have been proposed: the first is based on the altered hepatocyte function (sick hepatocyte hypothesis); the second on the abnormal hepatic architecture (intact hepatocyte hypothesis). Moreover, the microcirculation, a fundamental component in liver structure, shows dramatic changes in cirrhosis that would heavily influence the development of the disease. In order to determine the importance of the microvascular alterations on liver morphofunctional features in experimentally induced cirrhosis, their relationships with structural, ultrastructural, and histoenzymological hepatocyte modifications were investigated. Experimental cirrhosis was induced with controlled intragastric CCl4 administration. Scanning electron microscopy of the vascular corrosion cast technique, associated with light microscopy, transmission electron microscopy, and histoenzymology techniques were employed. The results demonstrated a characteristic micronodular cirrhosis in all the livers studied; the microcirculation displayed the presence of newly formed perinodular plexus. Inside the nodule, areas with two or more hepatocyte-thick laminae were present. Moreover, a rearrangement of the hepatocyte quantitative ultrastructure without real pathological changes and a loss of normal metabolic lobular zonation were noted in the liver parenchyma. These findings support the concept that the progressive modifications of the microcirculation during experimental CC14 cirrhosis modify not only the normal blood flow direction, but also the normal hepatic metabolic gradient with a loss of the normal hepatocytic zonation.

Hepatic microcirculation and peribiliary plexus in experimental biliary cirrhosis: A morphological study

BACKGROUND & AIMS: The peribiliary plexus plays a fundamental role in supporting the secretory and absorptive functions of biliary epithelium. Little information is available on the rearrangement of the peribiliary plexus during conditions associated with ductular proliferation. This study investigated the chronological modulation of bile duct and peribiliary plexus proliferation after common bile duct ligation in the rat. METHODS: Light microscopy and scanning electron microscopy vascular corrosion cast technique was used to study the architecture of the peribiliary plexus in rats with 1, 2, and 4 weeks of common bile duct ligation or in sham-operated controls. RESULTS: After 1 week of common bile duct ligation, no evident change of hepatic microvasculature was observed despite significant proliferation of bile ducts. After 2 and 4 weeks, significant microvasculature proliferation was observed extending from the peribiliary plexus of bile tracts. Vascular proliferation coincides with the extension of portal tract connective tissue. No evidence of vascular proliferation or other morphological modifications was present at the level of sinusoids around the portal tracts. CONCLUSIONS: After common bile duct ligation, the peribillary plexus undergoes marked proliferation, thus supporting the increased nutritional and functional demands from the proliferated bile ductal system. However, the proliferation of the peribillary plexus only occurs after that of the bile ductal system. (Gastroenterology 1996 Oct;111(4):1118-24)

Vascularization of the pineal gland in the crow.

The blood vascularization in the pineal gland of the crow was investigated in detail using a vascular corrosion cast technique and by scanning electron microscopy. The pineal gland received two afferent arteries on either side, each artery arising from the A. cerebralis caudalis (CC) which supplied its branches to the hemisphere. The pineal gland of the crow was so highly vascularized as to be suggestive of its high metabolic and endocrine activities. The efferent veins drained into the Sinus occipitalis and the Sinus sagittalis dorsalis. There was a direct vascular connection between capillaries of the stalk of the gland and those of the Plexus choroideus.

Some quantitative applications of vascular corrosion casting

Preparation of replicas of the complex arrangement of blood vessels in various organs and tissues has been accomplished by infusing low viscosity resins into the vasculature. Subsequent removal of the surrounding tissue by maceration leaves a model of the intricate three-dimensional anatomy of the blood vessels of the tissue not obtainable by any other procedure. When applied with care, the vascular corrosion casting technique can reveal fine details of the microvasculature including endothelial nuclear orientation and distribution (Fig. 1), locations of arteriolar sphincters (Fig. 2), venous valve anatomy (Fig. 3), and vessel size, density, and branching patterns. Because casts faithfully replicate tissue vasculature, they can be used for quantitative measurements of that vasculature. The purpose of this report is to summarize and highlight some quantitative applications of vascular corrosion casting. In each example, casts were prepared by infusing Mercox, a methyl-methacrylate resin, and macerating the tissue with 20% KOH. Casts were either mounted for conventional scanning electron microscopy, or sliced for viewing with a confocal laser microscope.

Microvascularization of the rat superior cervical ganglion. A three-dimensional observation.

The three-dimensional image of the microvascularization of the rat superior cervical ganglion (SCG) was examined using the vascular corrosion cast technique in conjunction with scanning electron microscopy. It was found that the rat SCG was a highly vascularized organ. Arteries supplying the ganglion gave rise to a subcapsular capillary plexus before branching off to become intraganglionic capillaries. Two types of intraganglionic capillaries, large and small, were observed throughout the organ. Numerous anastomoses among these capillaries were found before they converged into venules and collecting veins. However, a pattern of blood vessels resembling portal-like intraganglionic microcirculation could not be demonstrated.

Cellular and microvascular changes of the ovarian follicle during folliculogenesis: a scanning electron microscopic study.

In order to study the three-dimensional topographic arrangement of the oocyte and zona pellucida, follicular cells and follicle microvasculature, this study applied alkali maceration methods for tissue exposure, the ruthenium red-detergent method for the extracellular matrix visualization, and the vascular corrosion cast technique to rabbits, guinea-pigs and mice ovaries at different stages of follicular development. Macerated samples showed a gradual differentiation of the oocyte surface. This, in primordial follicles, appeared rather smooth, but, with the follicular development, displayed a gradual increase of blebs and microvilli. The latter widely covered the surface of oocytes contained in large or mature follicles. The outer surface of the zona pellucida showed numerous fenestrations, whereas the inner one was smooth. The ruthenium red-detergent method permitted a well detailed view of the filamentous texture of the zona pellucida. The three-dimensional distribution of the contacts between oocyte and neighbouring follicular cells was clearly evaluated in macerated samples. Follicular cells of primary follicles were characterized by their short cytoplasmic processes reaching the oocyte surface. In secondary follicles, these processes issued secondary processes. In larger follicles, the secondary processes of the corona cells were much longer and thinner, and took a tortuous course to reach the oocyte surface, which ran among the numerous oocyte microvilli. This microvillous arrangement greatly increases contact between the oocyte and corona cells, and suggests a coordinated reciprocal control of the activities of both cell types. These data also showed that the spongy and filamentous nature of the zona pellucida is closely dependent upon the temporal differentiation and enormous increase in number of follicular cell projections and their ramifications. Maceration revealed the theca cells surface. In smaller follicles these appeared as fusiform cells which resembled fibroblasts. In larger or mature follicles, many theca cells differentiated to possess morphological features of steroidogenic cells. In addition, these cells delimited a series of intercellular communicating lacunae, continuous with wide pericapillary spaces. The gradual differentiation of the follicle towards a structure having an endocrinal role was further emphasized in vascular corrosion casts. A simple microvascular net made of thin capillaries supplying primary follicles was seen to transform into an elaborate sinusoidal network made of thick permeable capillaries, supplying mature follicles.

Hypophyseal angioarchitecture of common tree shrew (Tupaia glis) revealed by scanning electron microscopy study of vascular corrosion casts

The vascular corrosion cast technique in conjunction with scanning electron microscopy (SEM) was used for the study of pituitary microvascularization in the common tree shrew (Tupaia glis). The pituitary vascular casts were obtained by infusion of low viscosity methyl methacrylate plastic (Batson's no.17) mixture. It was found that the blood supplies to the pituitary complex were from branches of the circle of Willis and could be divided into two groups. The first group consisted of two to four superior hypophyseal arteries (SHAs) branching off from the internal carotid artery supplying each half of the median eminence (ME), infundibular stalk (IS), and pars distalis (PD). The SHAs supplying the ME branched into internal and external capillary plexi. The internal plexus had a larger capillary size (approximately 15 microns in diameter), was deeper in position, and had denser and more complex capillary loops than those in the external plexus. The capillaries of the external plexus were approximately 10 microns in diameter. The two plexi drained into 15-20 hypophyseal portal veins (HPVs) which were located mainly along the ventral and ventrolateral surfaces of the IS before breaking up into large capillaries (approximately 18 microns in diameter) with an anteroposterior arrangement within the PD. The second group consisted of one inferior hypophyseal artery (IHA) on each side branching off from the internal carotid artery. These arteries gave off branches to pierce the dorsolateral and ventrolateral aspects of infundibular process (IP) before branching off to form a capillary network. They also gave rise to radiating capillaries to supply the pars intermedia (PI) surrounding the cortical area of the IP. The hypophyseal cleft separating the PI from the PD was clearly seen with very few blood vessels. The capillaries in both PD and IP joined to form confluent hypophyseal veins draining the blood into the cavernous sinus.

Scanning electron microscopic study on pineal vascularization of the common tree shrew (Tupaia glis)

The detailed blood supply including microvascularization of pineal gland in the common tree shrew (Tupaia glis) was investigated using a vascular corrosion cast technique in conjunction with scanning electron microscopy. Adult common tree shrews of both sexes, divided into 3 groups, were injected with red latex, blue vinyl resin, and Batson's No. 17 plastic mixture for the studies of arterial supply, venous drainage, and microvasculature of the pineal gland, respectively. It was found that the pineal gland is a highly vascularized organ. It receives two to four branches from the medial posterior choroidal arteries. Two types of capillary arrangements, fan-like and network, are observed. As in the human, usually one and occasionally two pineal veins, draining directly into the great cerebral vein of Galen, are observed. A pineal portal system is not demonstrated.

Morphological changes of the villous microvascular architecture and intestinal growth in rats with streptozotocin-induced diabetes.

Using intact tissues and vascular corrosion casts, morphological changes in the small intestine of streptozotocin-induced diabetic rats present 1 month after onset were investigated using scanning and transmission electron microscopy. Although there were increases in the height of the villi in the jejunum and not in the ileum, characteristic changes in surface morphology in the diabetic rats were observed only in the ileum. Use of a vascular corrosion cast technique clearly demonstrated the prominent thick marginal vessels of the intestinal villi of the control rats. In the diabetic rats, the central arterioles in the villi were dilated both in the jejunum and the ileum. Marginal vessels were small in the ileum but prominent in the jejunum. Using transmission electron microscopy, decreases in diameter and the number of endothelial fenestra were also evident in the marginal vessels of the ileal villi in the diabetic rats. Thus in rats made diabetic, fine structural alterations of the marginal vessels are induced in the villi of the distal ileum, in addition to quantitative changes in the jejunal villi, presumably related to hyperphagia. The marginal vessels seem to be involved in the regulation of microcirculation of the intestinal villi in the rat.