Development of blood vessels in the human eyeball

Blood vessels of 167 eyeballs of human embryos and fetuses have been studied, using macro- microscopical, histological and morphometrical methods. Time of appearance and differentiation of blood vessels in the eye anlage has been determined. Topography and architecture of the vitreous body artery are described in detail, as well as the vascular tunic of the lens and the pupil membrane. Regularities and time of reversal development of the vascular formations mentioned are followed during the whole intrauterine development. The data obtained add to extend our knowledge on the role of disturbances of the normal morphogenesis of the eyeball blood bed in pathogenesis of its congenital diseases.     

Adrenergic innervation of human mesenteric blood vessels.

A fluorescent histochemical technique has been applied to study the adrenergic innervation of human superior mesenteric arteries obtained at autopsy. Specific catecholamine fluorescence was demonstrated in the smaller branches of this artery taken from three infants and one child. No specific fluorescence was seen in arteries from three adult subjects.     

Development of the cardiac blood vessels in staged human embryos

Serial paraffin sections (mostly stained with hematoxylin and eosin) of 52 human embryos at stages ranging from 13 to 20 (approximate ovulation age of 5-8 weeks) were examined. The first sign of definitive blood vessels was found to be localized in the apical incisure of the heart of an embryo at stage 14. Blood vessels of this kind closely resembled 'blood islands' in appearance, being composed of primitive erythroblasts surrounded by an outer layer of endothelium. At stage 16, a funnel-like invagination of the endothelium was recognized in the posterior wall of the sinus venosus. This structure was considered to represent one of the cardiac veins (probably the middle cardiac vein). A faint endothelial sprout of the left coronary artery was detected at stage 18, while the right one was observed later, at stage 19. Finally, at stage 20, both of the coronary arteries invariably existed with a covering of mesenchymal cells.     

Superficial anastomoses of blood vessels in the human heart.

We investigated superficial interarterial, intra-arterial, arterio-venous and veno-venous anastomoses in 100 hearts from men and women taken at random who died at 20-85 years of age. By means of careful dissection and injection into the blood vessels of a differently stained 12% solution of vinilit in acetone, we studied the number and localization of the anastomoses and their appearance. Interarterial anastomoses, i.e. anastomoses between the ramification of the left and the right coronary artery, were detected in 33 hearts. Intra-arterial anastomoses, i.e. anastomoses between the ramifications of one and the same artery, were seen in 5 hearts. Arterio-venous anastomoses were found in 39 hearts. Veno-venous anostomoses were found in 49 hearts. The veno-venous anastomoses display a great many variations, being commonly the regular finding in human veins.     

Isolating and defining cells to engineer human blood vessels

A great deal of attention has been recently focused on understanding the role that bone marrow-derived putative endothelial progenitor cells (EPC) may play in the process of neoangiogenesis. However, recent data indicate that many of the putative EPC populations are comprised of various haematopoietic cell subsets with proangiogenic activity, but these marrow-derived putative EPC fail to display vasculogenic activity. Rather, this property is reserved for a rare population of circulating viable endothelial cells with colony-forming cell (ECFC) ability. Indeed, human ECFC possess clonal proliferative potential, display endothelial and not haematopoietic cell surface antigens, and display in vivo vasculogenic activity when suspended in an extracellular matrix and implanted into immunodeficient mice. Furthermore, human vessels derived became integrated into the murine circulatory system and eventually were remodelled into arterial and venous vessels. Identification of this population now permits determination of optimal type I collagen matrix microenvironment into which the cells should be embedded and delivered to accelerate and even pattern number and size of blood vessels formed, in vivo. Indeed, altering physical properties of ECFC-collagen matrix implants changed numerous parameters of human blood vessel formation, in host mice. These recent discoveries may permit a strategy for patterning vascular beds for eventual tissue and organ regeneration.     

Optical measurement of age-related calcification in human blood vessels

Vascular calcification is commonly associated with aging. Quantification of calcium accumulation in vessel walls is important in understanding the mechanisms of vascular calcification. To elucidate age-related change of calcification, site dependence of calcification, and the effect of hemodynamic stress on calcification, we measured calcium contents in various blood vessels with atomic emission spectrometry and simulated blood flow in the vessels by computational fluid dynamics. The content of calcium in the arteries increased progressively with aging while there is no change in the veins. The higher accumulation of calcium occurred in the arteries of the lower limb in comparison to the arteries of the upper limb. In the arterial bifurcation, there was the correlation at hemodynamic stress distribution and calcium content. The results of this study quantitatively support clinical findings of nonuniform calcification, and suggest that hemodynamic stress affects vascular calcification.     

Axial mechanical properties of fresh human cerebral blood vessels

Human cerebral blood vessels are frequently damaged in head impact, whether accidental or deliberate, resulting in intracranial bleeding. Additionally, the vasculature constitutes the support structure for the brain and, hence, plays a key role in the cranial load response. Quantification of its mechanical behavior, including limiting loads, is thus required for a proper understanding and modeling of traumatic brain injury--as well as providing substantial assistance in the development and application of preventive measures. It is believed that axial stretching is the dominant loading mode for the blood vessels, regardless of the nature of the insult. Eighteen arteries and fourteen veins were obtained from the cortical surface of the cerebral temporal lobe of patients undergoing surgery. These vessels were stretched to failure in the longitudinal direction, either quasi-statically or dynamically. The significance of specimen and experiment parameters was determined using multivariate analysis of variance (MANOVA) testing. Results demonstrate that the arteries were considerably stiffer than the veins, carrying approximately twice as much stress at failure but withstanding only half as much stretch. No significant rate dependence was measured over a strain rate range of more than four orders of magnitude (0.01 to 500 s -1).     

Exchange of krypton-85 between the blood vessels of the human uterine adnexa

A miniature Geiger-Müller probe was inserted into one ovary of 8 women undergoing hysterectomy. A control probe was inserted into the other ovary of 2 of the women. Krypton-85 in 0.15 M-NaCl was infused into the adjacent utero-ovarian vein and the radioactivity was registered for 5--14 min after the infusion. An increase of radioactivity was recorded in the ovary in 5 cases. In one of the women with 2 probes, no increase in radioactivity was observed in the control ovary. The results show a local transfer of gas from the ovarian branch of the uterine vein into the adjacent ovary, which may be due to a countercurrent exchange mechanism between the vessels of the human uterine adnexa.     

Significance of source and size in the mechanical response of human cerebral blood vessels

Cerebral blood vessels are frequently damaged in traumatic brain injury. Mechanical properties of fresh human cerebral vessels obtained through surgeries have been reported. Because surgical sources of human specimens are rare and produce a limited amount of material, we sought to compare the properties of more readily available cerebral arteries and veins obtained from cadavers to fresh vessel data. Additionally, because the previous study was limited to small vessels available in surgery, it was unknown how generally applicable the results were to larger cerebral arteries and veins. In the current study, large and small cerebral vessels from autopsy were stretched axially. Data from these and similar tests on fresh vessels were combined to determine the significance of source and size on mechanical properties. Structural comparisons of histological samples were additionally utilized to characterize differences. Results indicate that specimens from autopsy and surgery behave similarly except that vessels from autopsy tend to be less extensible. While tests on large vessels were limited, small arteries obtained from autopsy tended to be slightly stiffer than large arteries. In contrast, bridging veins from cadavers were typically stiffer and stretched less before structural failure than cortical veins from the same source. These effects are, however, secondary to differences identified between arteries and veins in the previous study.