The relief of the luminal surface of the sinuses in the mammalian cranial dura mater]

In Mammalia with different types in organization of blood outflow in the dura mater venous sinuses: vertebral (tiger), jugular (fur-seal, cat, rabbit) and mixed (rat, dog, man) the internal surface relief of these sinuses has been studied. The total plan of the relief in all the species studied is principally the same. It is characterized with presence of visually determined macro-relief structures: Pacchionian bodies, trabeculae, bars, eminences and excavations in places, where the sinuses fuse, initial folds (micro-relief) and, at last, formations composed by the nucleus and the external membrane of endotheliocytes (ultra-relief). The micro-relief depends on the type of the venous outflow from the brain. In the animals with the jugular type of the outflow the longitudinal folds are more expressed; in the animals with the vertebral type--there occur folds with transversal orientation. For the representatives with the mixed type--multilayered elastic carcass is specific. At the same time, the development degree of the micro-relief with a similar type of blood outflow is different. The relief of the luminal surface of the longitudinal venous sinus of the mammalian dura mater is supposed to be determined by presence of extravascular formations, by the muscular structures tonus, by construction of the wall elastic carcass and by activity of the luminal part of the external membrane of endotheliocytes.     

Localization of biogenic monoamines in the dura mater of the rat brain

Quantitative and qualitative composition of catecholamines (noradrenaline and dophamine) and indolalkylamines (serotonin and tryptamine) and their localization have been studied in cells and neural fibers of the rat dura mater. Luminiscent-cytophotometric and electron microscopic methods have revealed two types of cells depositing biogenic monoamines. As demonstrate the experiments with rausedil injection, monoaminocytes of the first type (mast cells) contain predominantly indolalkylamines and a small amount of dophamine. Monoaminocytes of the second type (chromaffin cells) synthesize mainly serotonin and, perhaps, tryptamine. In adrenergic neural fibers only noradrenaline has been found to be present.     

Effect of bioabsorbable osseous fixation materials on dura mater and brain tissue

Bioabsorbable materials are frequently used in pediatric cranial surgery, but the effects of these materials on neural tissue are not known. The authors assessed the histologic alterations to dura mater and brain tissue associated with bioabsorbable plates. Fifteen Sprague-Dawley rats were given sham cranial surgery; an additional 30 underwent placement of 8 x 8-mm polylactic acid/poly-glycolic acid plates. The rats were assessed weekly for neurologic or behavioral changes suggesting neural damage. A portion of each group was killed at 3, 6, and 12 months for histologic analysis of cranium, dura mater, and brain tissue by standard hematoxylin and eosin stain. None of the animals showed any behavioral changes or neurologic deficits. The plates were gradually hydrolyzed over the study period, and all had disappeared by 12 months. The histologic examination showed fibrous encapsulation around the plates, accompanied by foreign body giant cell reaction and calcification. Focal gliosis, where evident, was mild and confined primarily to the superficial cortex of the brain beneath the plate. The infiltration of the dura mater and underlying brain parenchyma was negligible. In conclusion, the neurologic and histologic effect of bioabsorbable plates on neural tissue may be considered negligible in the early postoperative period.     

Sinuses of the dura mater in dogs]

Sinuses of the dura mater were studied in 50 preparations of the venous system in mongrel dogs--10 moist, 40 corrosive prepared from plastics AKP-7 and AKP-15. Sinuses of the fornix--superior, sagittal, straight, transversal, occipital sinusal gutter, and sinuses of the basis--cavernous, intracavernous, petrous-basal, occipital and marginal were detected and their connections were described. Emissary and diploid veins and extracranial venous plexus are demonstrated to mediate a close connection between the sinuses of the dura mater. Common features in the sinusal structure of the human dura mater and those of the animals studied are noted; comparative-anatomical differences which should be taken into account when planning the experiment are presented.     

Organizational features and morphometric characteristics of the hemomicrocirculatory bed of the human brain dura mater

By means of silver nitrate impregnation and hematoxylin -- eosin staining the microcirculatory bed of the human brain dura mater (the second half of the mature age) has been investigated. Owing to the analysis of the morphometrical data of module organization of the hemomicrocirculatory bed, an objective quantitative characteristics of its peculiarities in various layers and areas of the dura mater is presented. In three layers of the dura mater in the fornix and skull basis area, falx cerebri and tentorium cerebelli venular links predominate. Most of all morphometrical parameters of the venular vessels increase in the internal layer of the dura mater in the skull basis area. Conditions of functioning for the human brain dura mater are reflected in its blood bed, its specificity manifesting at the microcirculatory level.     

Glucose and mannitol diffusion in human dura mater

An in vitro experimental study of the control of the human dura mater optical properties at administration of aqueous solutions of glucose and mannitol has been presented. The significant increase of the dura mater optical transmittance under action of immersion liquids has been demonstrated. Diffusion coefficients of glucose and mannitol in the human dura mater tissue at 20 degrees C have been estimated as (1.63 +/- 0.29) x 10(-6)cm(2)/s and as (1.31 +/- 0.41) x 10(-6) cm(2)/s, respectively. Experiments show that administration of immersion liquids allows for the effective control of tissue optical characteristics that make dura mater more transparent, thereby increasing the ability of light penetration through the tissue.     

Vasopressin in tissue basophils of the dura mater of white rats

By an indirect immunohistochemical method with fluorescein-isothiocyanate (FITC) and horse radish peroxidase as markers (HRP) the presence of vasopressin was shown in cells of dura mater in white rats. Mast cells were identified after staining with methylene blue by the metachromatic granularity of the cytoplasm. It was shown that the number of cells found by means of FITC luminescence corresponds with their number found by means of methylene blue. The use of conjugate with HRP unveils a lesser number of vasopressin-containing cells.     

Effect of acetylcholine on the mast cells of the dura mater]

The effects of various doses (100 mg/kg, 200 mg/kg and 500 mg/kg) of acetylcholine on the mast cells of the dura mater was studied in white rats by electron microscopy and the Falck fluorescent method. The qualitative and quantitative differences were found in the processes of accumulation and removal of monoamines depending on the drug dosage. The data obtained allow to suggest the stimulating effect of acetylcholine on monoamine secretion.     

Histophysiology of tissue basophils of the cerebral dura mater after laser irradiation

By means of the histochemical and morphometric methods the reaction of the tissue basophils of the brain dura mater has been studied to the one-time and varying-duration (0.5 sec.-3 hr.) irradiation by a helium-neon laser of the wave length 632.8 nm, power density 0.76 mvt/sm2. It has been found, that the laser irradiation had a biostimulating effect upon the tissue basophils; the first peak of activity is in the case of a 3-second continuous irradiation; the second--from 15 min. to 1 hr. In symmetrical parts of the right (irradiated) and left (nonirradiated) regions of the dura very similar changes of the functional activity of the tissue basophils activity were seen.     

Cellular dynamics and tissue interactions of the dura mater during head development

During development and growth of the neurocranium, the dura mater regulates events in the underlying brain and overlying skull by the release of soluble factors and cellular activity. Morphogenesis of the cranial bones and sutures is dependent on tissue interactions with the dura mater, which control the size and shape of bones as well as sutural patency. Development of the brain also involves interactions with dura mater: secretion of stromal derived factor 1 (SDF-1) is a critical event in directing migration of the external granular layer precursors of the cerebellar cortex and the Cajal-Retzius (CR) cells of the cerebral cortex. The dura mater is also required for growth of the hippocampal dentate gyrus. Wnt1Cre/R26R transgenic reporter mice were used to study the origin and fates of the cells of dura mater during head development. The dura mater of mammals is derived entirely from the cranial neural crest. Beginning around neonatal day 10 (N 10), the dura mater is infiltrated by cells derived from paraxial mesoderm, which later come to predominate. Over the course of infancy, the neural crest-derived cells of the dura mater become sequestered in niche-like distribution characteristic of stem cells. Simultaneously, dura mater cells underlying the sagittal suture migrate upward into the mesodermally-derived mesenchyme separating the parietal bones. Although initially the parietal bones are formed entirely from paraxial mesoderm, the cellular composition gradually becomes chimeric and is populated mainly by neural crest-derived cells by N 30. This occurs as a consequence of osteoblastic differentiation at the dura mater interface and intravasation of neural crest-derived osteoclastic and other hematopoietic precursors. The isolated cells of the dura mater are multipotent in vitro, giving rise to osteoblasts, neuronal cells and other derivatives characteristic of cranial neural crest, possibly reflecting the multipotent nature of dura mater cells in vivo.