Vascular system of human fetal pancreas demonstrated by corrosion casting and scanning electron microscopy

Vascular architecture of the human pancreas was investigated by corrosion casting combined with scanning electron microscopy in fetuses aged 20 and 25 gestational weeks. The general pattern of the microvascular system was similar to that of the postnatal pancreas, with an evident insulo-acinar portal system and with three types of capillary networks: capillaries of exocrine lobules, islet capillaries and periductal capillaries around large ducts located in the interlobular septa. All these capillary networks were supplied by arteriolar branches of the interlobular arteries. As compared with the postnatal pancreas, capillaries of exocrine lobules formed denser meshworks, had a more sinusoidal character and revealed morphological features indicative of angiogenesis (blind capillary sprouts). The number of efferent (portal) capillaries per islet was lower and the predominant pattern of islet vasculature was top to bottom rather than inner to outer, as observed in adults. These results show that in the second trimester the human pancreatic vascular architecture is almost completely developed and requires only minor remodeling to be fully functional in the postnatal period.     

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.     

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. Postoperative bladder specimens obtained from patients with advanced bladder tumors were filled with small amount (80 ml) of saline and perfused via at least four largest arteries with anticoagulant-containing saline followed by paraformaldehyde/glutaraldehyde fixative and Mercox resin. After polymerization of the resin, the vascular casts were macerated with potassium hydroxide, cleaned with formic acid and water and freeze dried. Only regions of the bladder wall distant to the tumor were examined in light and scanning electron microscopes. The almost empty state of the bladder was manifested by extensive folding of the mucosa and tortuosity of almost all vessels other than capillaries. The branches of main arteries and veins formed an adventitial/serosal plexus which directly supplied/drained the capillary network of the muscularis and sent long perpendicular vessels to the mucosal plexus. These vessels had straight or coiled course depending on whether they terminated at the top or at the base of the mucosal folds. The rich mucosal plexus followed the folds parallel to their surface and gave off short, straight, mostly perpendicular twigs communicating with the subepithelial capillary network. Apart from very few vascular interconnections between the mucosal plexus and the muscularis, the submucosa was generally avascular. The subepithelial capillary network showed extreme density and uneven contours of the capillaries, only in less folded areas of trigone and urethral orifice the network was looser and capillaries thinner. The capillary system of the muscularis was poorly developed. Due to its architecture, tortuosity, and coiling/uncoiling capabilities, the microvasculature of the human urinary bladder wall seems to efficiently accommodate changes associated with cyclic contraction and stretching. Disturbances in blood flow induced by overdistension of the bladder reported in several studies may be due to pressure of the urine affecting the patency of the vessels rather than to the spatial insufficiency of the vascular system.     

Morphometric changes in the spinal cord during prenatal life: a stereological study in sheep

This study describes the volumetric changes in the spinal cord during prenatal life in sheep using quantitative stereological methods. Twenty healthy sheep fetuses were included in the present study, divided into four groups representing 9–11, 12–14, 15–17, and 18–20 weeks of gestation. In each group, the spinal cord was dissected out and sampled according to the unbiased systematic random sampling method then used for stereological estimations. The total volume of spinal cord, volume of gray matter (GM), volume of white matter (WM), ratio of GM volume to WM volume, and volume of central canal (CC) were estimated in the whole spinal cord and its various regions using Cavalieri’s principle. The total volume of the spinal cord increased 8 times from week 9 to week 20. The cervical region showed the greatest (9.7 times) and the sacral region the least (6.3 times) volumetric change. The CC volume of the whole spinal cord increased 5.8 times from week 9 to week 20. The cervical region developed faster (8.2 times) and the thoracic region slower (4.4 times) than the total spinal cord. During development, the volume ratio of GM to WM decreased from lower toward upper regions. The greatest volume changes occurred mostly in weeks 9–11 and 12–14. The cervical region showed the greatest volume changes in comparison with other regions of the spinal cord.     

Vascular system of intramural leiomyomata revealed by corrosion casting and scanning electron microscopy

BACKGROUND: The vascular system of leiomyomata, the most common benign tumours in women, is an important factor controlling development and growth of the tumour. It has not been, however, investigated morphologically using the best currently available technique, corrosion casting combined with scanning electron microscopy. METHODS: Myomatous uteri collected upon autopsy were perfused via afferent vessels with fixative followed by Mercox resin and corroded after polymerization of the resin. The obtained vascular casts visualizing all vessels including capillaries were examined using scanning electron microscopy. RESULTS: The smallest (1-3 mm) fibroids were avascular, in larger ones (<1 cm) a few small vessels invaded the lesion from the periphery. The largest tumours (>1 cm) contained irregular networks of blood vessels with density similar to or lower than that of normal myometrium. Such tumours were surrounded by an extremely dense vascular layer ('vascular capsule') which was the source of larger vessels supplying and draining the tumour. CONCLUSIONS: During development of leiomyoma, the pre-existing blood vessels undergo regression and new vessels invade the tumour from the periphery, where intense angiogenesis, probably promoted by growth factors secreted by the tumour, leads to the formation of a 'vascular capsule' responsible for supply of blood to the growing tumour.     

Neurotensin receptors in the human spinal cord: a quantitative autoradiographic study

The anatomical localization of neurotensin receptors in the human spinal cord was examined in 12 cases aged 4-68 years using quantitative autoradiographic methods following the incubation of fresh, unfixed cryostat sections with 4 nM [3H]neurotensin. Characterization of the pharmacological specificity of the [3H]neurotensin binding sites in the human spinal cord from displacement studies with neurotensin and various neurotensin fragments indicated that, whereas 1.0 microM neurotensin and the carboxy-terminal fragment neurotensin almost completely displaced [3H]neurotensin binding (4 nM), the amino-terminal fragments neurotensin and neurotensin1-11 were weak inhibitors. This requirement for the carboxy-terminal fragment neurotensin is consistent with [3H]neurotensin binding to specific neurotensin receptors in the human spinal cord. In all cases the autoradiograms demonstrated that neurotensin receptors were distributed in a similar fashion in the gray matter of the cervical, thoracic, lumbar, sacral and coccygeal regions of the human spinal cord. At all 21 spinal levels examined, the highest density of neurotensin receptors was localized in lamina II of the dorsal horn. Within lamina II the receptors were especially concentrated in the deeper inner segment (IIi) where they formed a dense band lying immediately dorsal to lamina III. The density of receptors in this inner region of lamina II (23.5 fmol/mg) was almost double that in the outer segment of lamina II (12.2 fmol/mg), which showed the next highest density of receptors, and more than three times that in the adjacent lamina I (6.9 fmol/mg) and lamina III (7.1 fmol/mg). A moderate density of receptors was present in the intermediomedial (8.0 fmol/mg) and intermediolateral (8.0 fmol/mg) nuclei of lamina VII, and in lamina IX (4.4 fmol/mg). The density of labelling in the remaining laminae of the spinal cord was very low. These results indicate that neurotensin receptors are mainly localized in somatic and visceral sensory and motor regions of the human spinal cord and suggest that neurotensin may play a role in modulating sensory-motor functions in the human spinal cord.     

Vascular malformation of the spinal cord

A case of the arteriovenous aneurysm is described. This congenital anomaly occurs rarely in all parts of the central nervous system including the spinal cord. The aneurysm damages the spinal cord due to haemodynamic and haemorrhagic complications, inflammation and compression resulting in the neuron death and the disturbance of the spinal cord functions.     

Benzodiazepine receptors in the human spinal cord: a detailed anatomical and pharmacological study

The anatomical distribution and pharmacological characteristics of benzodiazepine receptors in the human spinal cord were examined in four cases aged 20-41 years using in vitro autoradiography and biochemical assays of [3H]flunitrazepam binding. In all cases, the autoradiograms demonstrated that benzodiazepine receptors were distributed in a consistently similar fashion in the gray matter of the cervical, thoracic, lumbar and sacral regions of the human spinal cord. At all levels, the highest densities of benzodiazepine receptors were found to be localized within lamina II of the dorsal horn as defined on cytoarchitectonic, myeloarchitectonic and substance P immunocytochemical criteria. Within this lamina the receptors were concentrated mainly in its deeper, inner portion which lies immediately adjacent to lamina III, with some overlap dorsally into the outer segment of lamina II and ventrally into the adjacent region of lamina III. The lowest density of receptors was found in regions of laminae I, IV, VII and X; in particular, in lamina VII the lowest concentration of receptors was found in the dorsal nucleus of Clarke and the sacral parasympathetic nucleus. The remaining laminae of the spinal gray (laminae, V, VI, VIII and IX) showed a moderate density of receptors. Biochemical assays of membranes prepared from the lumbosacral cord indicated that these [3H]flunitrazepam binding sites have high affinity and have the pharmacological characteristics of the "central" Type II benzodiazepine receptor. These results show a high concentration of Type II benzodiazepine receptors in the substantia gelatinosa of the human spinal cord and suggest a possible role for these receptors in spinal sensory functions.     

Ultrastructure of marginal zone during prenatal development of human spinal cord

Summary Electron microscopic studies were conducted in the marginal zone (lamina I) in human fetuses ranging from 8–25 weeks of gestational age. At 8 weeks the neurons have indented nuclei and sparse organelles in the cytoplasm. The neuropil shows contacts between the axons and dendritic profiles. Some of them are well defined synapses with post synaptic thickening and agranular spherical vesicles in the presynaptic terminal. At 18 weeks compactly packed organelles with long cisternae of rough endoplasmic reticulum could be visualized in the neuronal cytoplasm. At 25 weeks the neurons have heterochromatin patches in the nuclei. Axosomatic, dendrodendritic, axoaxonic, symmetrical, asymmetrical and multisynaptic contacts with agranular and dense core vesicles are seen at different sequential age periods.     

Vascular abnormalities of the spinal cord ]

Vascular anomalies of the spinal cord were studied in 49 patients. Thirty-three cases were morphologically studied (30 cases presented with operative findings and 3 cases with autopsy material). The anomalies presented as defects of vascular genesis without signs of blastomatous growth (venous and capillary-venous malformations, arteriovenous anastomose and fistulas, varicosis of the spinal cord, etc. located in the spinal cord, its roots, coats, adjacent fat, and vertebra which affect the spinal cord, roots or vessels participating in their blood supply and venous outflow. In 41% of the cases, the above anomalies were associated with congenital anomalies of other systems and organs. The anomalies are clinically characterized. Specific signs are given to differentiate them from their intracranial analogues. Recommendations are given on pathological examination of the content of the vertebral canal in vascular anomalies.     

Vascular configurations of anastomotic basket of conus medullaris in human spinal cord

The arterial basket of the conus medullaris is one of several anastomoses between the anterior and posterior spinal arteries. The anatomy of this structure has attracted little attention. This work sought to investigate its configuration in human spinal cords. Spinal cords from male and female cadavers (n = 32) were injected with colored latex through the intercostal, lumbar, medial sacral and the posterior trunks of the hypogastric arteries. After injection, specimens preserving the dural sac were obtained and fixed in formaldehyde solution. Finally, the spinal arteries were microdissected. In 18.75% of the specimens, the anterior spinal artery divided symmetrically and formed anastomoses with the posterior spinal arteries. In 81.25%, the branching pattern observed was asymmetrical. In 21.87% there were differences in the diameter of the anastomotic arteries, and 40.63% originated at different levels along the craniocaudal axis. Interestingly, 12.5% of the specimens presented an intraparenchymatous anastomosis that has not been described previously. True unilateral anastomosis was only observed in 6.25% of the spinal cords. The most frequent configuration of the anastomotic basket of the conus medullaris is a bilateral asymmetric anastomosis. The asymmetry of the branches could be caused by differences in their diameters or in their origins along the craniocaudal axis. Symmetrical patterns are less frequent, and unilateral anastomoses are rare. In reality, some cases of apparently unilateral anastomosis present an intramedullary course of the anastomotic artery. Clin. Anat. 31:441–448, 2018. © 2017 Wiley Periodicals, Inc.     

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

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.     

A study of the arterial supply of the human acetabulum using a corrosion casting method

This anatomical study concerns the arterial supply of the human acetabulum. The purpose is to contribute to prevention of postoperative necrosis of the acetabular bone fragment after rotational acetabular osteotomy (RAO). The arterial supply of the acetabulum was determined using a corrosion casting method. The acetabular branch of the obturator artery supplies the acetabulum through the acetabular notch. The pubic branches supply the pelvic surface of the acetabulum. Deep branches of the superior gluteal artery supply the superior region and the inferior gluteal artery supplies the postero-inferior region. From these results, we recognized that the important artery for achieving successful RAO is the acetabular branch of the obturator artery that supplies the acetabulum through the acetabular notch. Clin. Anat. 10:77–81, 1997 © 1997 Wiley-Liss, Inc.     

The central canal of the human spinal cord: a computerised 3-D study

Knowledge of the structure and function of the central canal of the human spinal cord is important in understanding the pathogenesis of syringomyelia. Analysis of the morphology of the central canal is difficult using isolated histological sections. A 3-dimensional reconstruction technique using digitised histological sections was therefore developed to visualise the morphology of the central canal. The technique was used to study the canal in the conus medullaris and filum terminale of 1 sheep and 4 human spinal cords. A variety of morphological features were demonstrated including canal duplication, a terminal ventricle and openings from the canal lumen into the subarachnoid space. The findings suggest the possibility of a functionally important fluid communication in the caudal spinal cord which may have a sink function.     

Differentiation and migration of neuroblasts in the developing human spinal cord during the first half of prenatal ontogeny

Processes of differentiation and migration of neuroblasts in the developing human spinal cord were studied in the first half of its prenatal ontogeny by Golgi's method. The dynamics of development of the neuroblast from the neuroepithelial matrix cell to the fully developed neuron was studied. It is postulated that a special process of the neuroblast may play the role of channel of oriented migration of its nucleus toward the site of the final topologic position of the future neuron.Laboratory of Development of the Human Nervous System, Institute of Human Morphology, Academy of Medical Sciences of the USSR, Moscow. (Presented by Academician of the Academy of Medical Sciences of the USSR A. P. Avtsyn.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 87, No. 4, pp. 352–354, April, 1979.     

Vascular response in experimental spinal cord gliomas of the rat

Reported is the immunoreactivity of tumoral and peritumoral vessels of 7 spinal cord gliomas induced in rats by means of ethylnitrosourea. Immunostaining for Factor VIII/RAg has been more strongly pronounced in endothelial cells of newly formed vessels at the tumor periphery, in comparison with tumoral vessels, and this is likely to suggest a differentiation process during extensive neovascularization of the tumor periphery. Endothelial distribution of vimentin in the peripheral vessels is more intensive than within the tumors, suggesting its relation to rapid new blood vessel formation. Immunostaining for GFAP and vimentin overlaps in astrocytes trapped within neoplasms, in astrocytes at the tumor periphery, and in the peritumoral zone.     

PHI-like immunoreactivity co-locates with the VIP-containing system in human lumbosacral spinal cord

We report here that, in comparison to aggregates from retinal cells alone, addition of pigmented epithelial cells to retinal cells in rotary culture results in a pronounced increase of spatial order. A particularly high level of organization is found in about 15-20% of the aggregates. In these 'retinoids' the main layers characteristic of developing in vivo retinae can be distinguished in correct sequential arrangement on the basis of morphological criteria and by using acetylcholinesterase histochemistry [5, 6, 15], peanut agglutinin-lectin binding [11] and Lucifer Yellow staining [7-9].     

Analyzing the human liver vascular architecture by combining vascular corrosion casting and micro‐CT scanning: a feasibility study

Although a full understanding of the hepatic circulation is one of the keys to successfully perform liver surgery and to elucidate liver pathology, relatively little is known about the functional organization of the liver vasculature. Therefore, we materialized and visualized the human hepatic vasculature at different scales, and performed a morphological analysis by combining vascular corrosion casting with novel micro‐computer tomography (CT) and image analysis techniques. A human liver vascular corrosion cast was obtained by simultaneous resin injection in the hepatic artery (HA) and portal vein (PV). A high resolution (110 μm) micro‐CT scan of the total cast allowed gathering detailed macrovascular data. Subsequently, a mesocirculation sample (starting at generation 5; 88 × 68 × 80 mm³) and a microcirculation sample (terminal vessels including sinusoids; 2.0 × 1.5 × 1.7 mm³) were dissected and imaged at a 71‐μm and 2.6‐μm resolution, respectively. Segmentations and 3D reconstructions allowed quantifying the macro‐ and mesoscale branching topology, and geometrical features of HA, PV and hepatic venous trees up to 13 generations (radii ranging from 13.2 mm to 80 μm; lengths from 74.4 mm to 0.74 mm), as well as microvascular characteristics (mean sinusoidal radius of 6.63 μm). Combining corrosion casting and micro‐CT imaging allows quantifying the branching topology and geometrical features of hepatic trees using a multiscale approach from the macro‐ down to the microcirculation. This may lead to novel insights into liver circulation, such as internal blood flow distributions and anatomical consequences of pathologies (e.g. cirrhosis).