Fractal analysis of STM images of photochemical polymer of coniferyl alcohol.

Fractal analysis was applied to images of photochemical lignin polymer obtained using scanning tunneling microscope. We studied the polymer obtained in vitro by ionic mechanism through UV radiation--induced polymerization. The analysis showed the regularity of the lignin-like polymer at different levels of organization. At the 95% confidence level, there was no significant difference in the fractal dimension between images representing different organizational levels of photochemical lignin. That means that lignin produced in in vitro conditions by photochemical mechanism of synthesis, has a fractal structural organization. The obtained values of the fractal dimension are in good agreement with the theoretically predicted value for the polyaddition and polycondensation mechanism of polymerization, known as the bulk model.

Fractal analysis of STM images of lignin polymer obtained by in vitro synthesis.

Lignin, the structural polymer of the plant cell walls, is produced by free radical polymerization of phenolic alcohols, catalyzed by different peroxidases. The mechanism and the structural organization of lignin in the cell have not been completely understood. In this study we applied fractal analysis to images of lignin polymer obtained using scanning tunneling microscope. The analysis showed the regularity of the polymer at different levels of organization. According to the results obtained, at the 95% confidence level, there is no significant difference in the fractal dimension between images representing different organizational levels of lignin. In other words, lignin produced in in vitro conditions has fractal structural organization and, consequently the polymer can be expected to be regular in in vivo conditions. The value of the fractal dimension 1.929 +/- 0.021 is in good agreement with the theoretically predicted value for polyaddition and polycondensation mechanism of polymerization. The mechanism of in vivo lignin synthesis is discussed in terms of various experimental and theoretical evidences. In this paper, we could show that fractal analysis of the lignin polymer is a useful complementary approach to the experimental data collection in structural and phenomenological studies.

[Vascular characteristics of the human subfornical organ]. / Vaskularne karakteristike humanog subfornikalnog organa.

The aim of the study regarding adult brains is to determine the sources of vascularization, vascular area, the size and density of the capillary network of the human subfornical organ. The examined brain blood vessels under filled with a mixture of Indian ink and gelatin. The serial paraffin sections of 50 and 200 microns were cleared after Spalteholz. In the vascularization of this neuroendocrine structure of the diencephalon, two arterial stems take part with their branches: a. cerebri anterior and a. choroidea posterior. In order to quantify the density of the capillary network, the authors used the standard stereologic parameters volume density, surface density and mean radius of blood vessels. By the comparative test of obtained mean values of males and females no statistically significant differences pertaining to sex and in respect to the size and density of capillary network in subfornical organ were confirmed. While the precise functions of the human subfornical organ have yet to be fully elucidated, the similarity in organization of this region to the vascular organ of the lamina terminalis, has led several authors to suggest that the subfornical organ is a site of receptors which are stimulated by circulating angiotensin II to induce water drinking and vasopressin secretion.

[Morphologic characteristics of the superior temporal gyrus vascular network]. / Morfoloske karakteristike krvne mreze gornje slepoocne vijuge.

The investigation of the morphological features of vascular network of superior temporal gyrus was carried out on eight hemispheres of brains of adults from 36 to 48 years old died in accidents without visible signs of central nervous system diseases. Vascular network of auditory areas is characterised by very dense capillary network of the third vascular layer which is the densest one in these areas. The vascular network of the anterior part of the superior temporal gyrus is distinguished by equal density of the third and fourth vascular layer. Fountain-like arteries are mostly of type A3 and A4 and have been found in all parts of the superior temporal gyrus. Vertical functional units of the cortex are supplied by a number of precapillary arterioles being arranged in the shape of a ring. In the center of each unit there is postcapillary venule through which it is drained.

[The morphologic characteristics of the vascular network of the middle and inferior temporal gyri and middle temporal visual area]. / Morfoloske karakteristike krvne mreze srednje i donje slepoocne vijuge i srednjeg slepoocnog vidnog polja.

The vascular network of the anterior part of the middle and inferior temporal gyri consists of four vascular layers of which the third and fourth have the densest capillary network of the same density. There are all types of arteries in this cortex form A1 to A6 as well as all types of veins from V1 to V5. Fountain-like arteries usually branch into five to six terminal recurrent branches; we have found that there are about two of them in each serial section. The middle temporal visual area has the same features of the vascular network as the above mentioned gyri with one difference only: there are at least six fountain-like arteries in each serial section. The increased number of these arteries might point to a greater sensitivity of this area to hypoxic conditions. The tangential sections of these areas reveal the existence of vertically-oriented vascular units with a centrally located venous vessel surrounded by arterial rings.

[Vascular characteristics of the lamina terminalis of the human hypothalamus]. / Vaskularne karakteristike lamine terminalis hipotalamusa coveka.

The aim of the study is to discover the sources of vascularization, vascular area, the size and density of the capillary network of the vascular organ of the laminae terminalis of the hypothalamus. The brain blood vessels under examination were filled with a mixture of India ink and gelatin. The serial paraffin sections of 30 and 200 um were cleared after Spalteholz. In the vascularization of this neuroendocrine structure of the hypothalamus, two arterial stems take part with their branches: a cerebri anterior and a. communicans anterior. In order to quantify the density of the capillary network, the authors used standard stereologic parameters - volumene density, surface density and mean radius of blood vessels. While the precise functions of the vascular organ have yet to be fully elucidated, the similarity in organization of this region to the median eminence has led several authors to suggest a neurosecretory role for the vascular organ of the lamina terminalis.

[Characteristics of the human lateral geniculate nucleus vascular network]. / Karakteristike vaskularne mreze humanog lateralnog genikulatnog jedra.

The blood supply of the lateral geniculate nucleus (LGN) was studied on ten human brains obtained at autopsy from patients of both sexes with no indication of either psychiatric and neurological disorders or trauma of CNS. The age range was form 30 to 50 years. The brain blood vessels-the basilar artery and the internal carotid artery were injected with a mixture of gelatin and Indian ink. Microdissection revealed that the arterial branches for the LGN arise from anterior choroidal artery and posterior cerebral artery through one of its central branches-lateral posterior choroidal artery. The morphology of arterial network was examined by the analysis of cleared paraffine sections. The arterial branches run in a dorsal to ventral direction of the nucleus, parallely with lines of projection and perpendicularly to the plane of the LGN laminae. Free anastomoses occur between these branches.

[Characteristics of the vascular network in the hypothalamic median eminence in man]. / Karakteristike vaskularne mreze eminentiae medianae hipotalamusa coveka.

The aim of these studies is to determine the sources of vascularization, the vascular areas, the appearance and density of the median eminence capillary network in prenatal human brains of both sexes. The brain blood vessels under examination were filled with a mixture of India ink and gelatin. Serial paraffin sections 20-40 microns thick, cleared after Spaltehol. Two arterial stems take part in median eminence vascularization together with their branches: a. hypophisialis superior and a. hypophisialis inferior. In order to quantify the density of the capillary network, the authors used the standard stereologic parameters--volume density and mean radius of blood vessels. No statistically significant sex-dependent differences were established regarding the appearance and density of the median eminence capillary network of the human brain in the course of the comparative testing of the mean values of these parameters in the male and female sex.

[Morphometric analysis of the vascular network of the suprachiasmatic and paraventricular nucleus in the human brain]. / Morfometrijska analiza vaskularne mreze suprahijazmaticnog i paraventrikularnog jedra mozga coveka.

The aim of the study is to discover, the sources of vascularization, vascular areas, the size and density of the capillary network in the suprachiasmatic and the paraventricular nuclei of postnatal human brains of both sexes. The brain blood vessels under examination were filled with a mixture of India ink and gelatin. The serial paraffin sections of 200 microns cleared after Spalteholz. In the vascularization of the suprachiasmatic and the paraventricular nuclei, two arterial stems, take part with their branches (a. cerebri anterior and a. communicans anterior). In order to quantify the density of the capillary network, the authors used the standard stereologic parameters - volume density, surface density and mean radius of blood vessels. The comparative testing of the mean values obtained in male and female subjects did not reveal any significant sex - dependent differences regarding the size and density of the capillary network in the suprachiasmatic and the paraventricular nuclei of the human brain.

[Morphologic characteristics of the vascular network of the dentate nucleus during development]. / Morfoloske karakteristike krvne mreze zupcastog jedra u toku razvoja.

The development of the blood network of the dentate nucleus was studied on 20 human fetal brains of different crown-rump length (CRL). In the stage of 17 to 20 weeks, the blood network of the dentate nucleus consisted of moderate spiral blood vessels. They anastomosed each other and made irregular elongated polyhedral meshes. From this meshwork, blood vessels of a greater volume arose and extended to the hilum of the nucleus. Between 23 and 25 weeks, a clear segmental vascular pattern was noticed. The capillary network was very dense. Along the outer surface of the nucleus the blood vessels which connected two secondary wrinkles of the gray matter were observed. In all the stages investigated the blood vessels were moderately spiral.

[Morphometric analysis of the vascular network in the preoptic area of the brain in man]. / Morfometrijska analiza vaskularne mreze preopticke areje mozga coveka.

Twenty brains of human beings of both sex aged 17-64 were used for morphometric analysis of the vascular network of preoptic area. Blood vessels of the brain were filled by the mixture od India ink and gelatine. Serial resections 200 microns thick were illuminated by the method of Spalteholz. Standard stereologic parameters--volume density, surface density and the average half diameter of blood vessels were used for the quantification of capillary blood network density. By the comparative test of obtained mean values of males and females no statistically significant differences pertaining to sex and in respect to the size and density of capillary network in preoptic area were confirmed. This fact supported the assumption that although there were no morphologic differences in the blood network changes in various functional states, accompanying neuroendocrine events in the body of adults were in all probability the main and responsible factors inducing greater or less vascularization of specific organs.