Ependymal cells surface of human third brain ventricle by scanning electron microscopy.

OBJECTIVES: The ependymal lining of the human brain ventricular system displays distinct structural differences and functional heterogeneity among individual ependymal cells (ECs). To date, multi-ciliated ECs (E1 cells), bi-ciliated ECs (E2 cells), uni-ciliated ECs (E3 cells), ECs without cilia, and ECs with cytoplasmic protrusions have been described in human brain ventricles. METHOD: Using scanning electron microscopy (SEM), we evaluated ependymal samples from 6 defined regions of the third ventricle from 9 human brains. These regions were strictly defined according to the periventricular structures they neighbour with. RESULTS: We observed different structures on the apical surface of the ECs. Various ECs differed from each other by the presence of microvilli, secretory bodies, and a variable number of cilia, which led us to divide the ECs into several exactly specified types according to their apical morphology. CONCLUSION: We found all types of ECs in every examined region with a predominance of particular types of apical surface of ECs in the individual areas (Tab. 4, Fig. 7, Ref. 22).

Labelling of individual ependymal areas in lateral ventricles of human brain: ependymal tables.

Different types of ependymal areas were studied and labelled in the human brain lateral ventricle. Periventricular structures were included in coining the names of the ependymal areas because they represent a basic and stable part of brain nerve structures suitable for the sake of clarity of localization of the ependyma. The labelling of individual ependymal areas was composed from letters: "Lv" (lateral ventricle); "E" (ependymal area) and letters for abbreviations of the closest periventricular structure, e.g. the septum pellucidum is "sp". The labelling for ependymal area over the septum pellucidum is thus "LvE-sp". The studied types of ependymal areas were arranged in so­called ependymal tables for cornu anterius, pars centralis, cornu inferius and cornu posterius of the human lateral ventricle. Labelling of individual ependymal areas allows for better localization and characterisation of these areas in future studies carried out by various methods (e.g. morphological, biological, molecular) and will prevent from using misnomers with different types of ependymal areas in norm as well as in pathology (Tab. 5, Fig. 6, Ref. 22). Text in PDF www.elis.sk.

Ependymal cells variations in the central canal of the rat spinal cord filum terminale: an ultrastructural investigation.

OBJECTIVE: The ependymal cells, considered today as an active participant in neuroendocrine functions, were investigated by electron microscopy in the central canal of the lowest spinal cord, the filum terminale (FT), in adult rats. In this area of the spinal cord, the central canal is covered by a heterogeneous population of ependymal cells. The aim of the present work was to compare the regional features of the ependymal cells in two different parts of the FT with a special regard to their ultrastructure. METHODS: Two parts of the FT were selected for the ultrastructural observations: the rostral (rFT) and the caudal (cFT) ones. The rTF was removed at the level of the immediate continuation of the conus medullaris, while the cFT 30 mm further caudally. After formaldehyde fixation, the spinal cord was removed and cut into small blocks for electron microscopic processing. The material was embedded into durcupan, contrasted with uranyl acetate, lead citrate as well as osmium tetroxide, and investigated under JEOL 1200 EX electron microscope. RESULTS: In the rFT, the ependymal lining is pseudostratified and one-layered in the cFT, whereas the shape of the ependymal cells may vary from cuboidal to flatten in the rostro-caudal direction. The basal membrane of many ependymal cells possesses deep invaginations, so called "filum terminale labyrinths". Many neuronal processes occur in the pericanalicular neuropil. In contrast to the rFT, the cFT is less rich in the neuropil particles. Some of the ependymal cells concurrently reach both the intracanalicular and extracanalicular cerebrospinal fluid (CSF), thus they may represent a new variant of the ependymal cells designated as "bridge cells of the FT". CONCLUSIONS: The present data indicate that the FT ependymal cells exhibit clear differences in anatomy as well as ultrastructure that may reflect their distinct functional activity. Therefore, observations presented here may serve for the better understanding of the physiological role of the individual ependymal areas in this special portion of the rat spinal cord.

Enalapril treatment of proteinuria in normotensive children.

A retrospective study was performed in 48 normotensive proteinuric children to evaluate the effect of enalapril (n = 17), a combination of enalapril and prednisone (n = 11) and prednisone alone (n = 20) on urinary protein excretion and systemic blood pressure. Enalapril treatment was associated with significant and persistent diminution of proteinuria from 1.32 +/- 0.23 to 0.53 +/- 0.11 and 0.44 +/- 0.07 g/day on the 4th and 8th week of treatment, respectively. Combined therapy with enalapril and prednisone resulted in a comparable significant reduction of proteinuria from a pre-treatment value of 2.06 +/- 0.42 to 0.63 +/- 0.22 and 0.52 +/- 0.17 g/day on the 4th and 8th week of treatment, respectively. In contrast to this, in the group treated with prednisone alone, proteinuria decreased significantly only from the 6th week of therapy (p < 0.02). Consequently, these children had significantly higher urinary protein losses at the 4th week of treatment as compared to patients on enalapril treatment (given either alone or combined with prednisone) (p < 0.01 and p < 0.05, respectively). Importantly, the enalapril-induced reduction of proteinuria was unrelated to variations in arterial blood pressure and no significant changes in this parameter were observed. The results indicate that enalapril can be used safety and effectively for symptomatic treatment of proteinuria in normotensive children with preserved renal function. ACE inhibitor provides additive antiproteinuric effect to corticosteroids by accelerating the rate of diminution of proteinuria. Its combination with prednisone may be of particular importance in those cases, where the degree of hypoproteinemia is a concern. (Tab. 2, Fig. 1, Ref. 29.)

Human protein C receptor is present primarily on endothelium of large blood vessels: implications for the control of the protein C pathway.

BACKGROUND: The protein C anticoagulant pathway is critical to the control of hemostasis. Thrombomodulin and a newly identified receptor for protein C/activated protein C, EPCR, are both present on endothelium. EPCR augments activation of protein C by the thrombin-thrombomodulin complex. METHODS AND RESULTS: To gain a better understanding of the relationship between thrombomodulin and EPCR, we compared the cellular specificity and tissue distributions of these two receptors by using immunohistochemistry. EPCR expression was detected almost exclusively on endothelium in human and baboon tissues. In most organs, EPCR was expressed relatively intensely on the endothelium of all arteries and veins, most arterioles, and some postcapillary venules. EPCR staining was usually negative on capillary endothelial cells. In contrast, thrombomodulin was detected at high concentrations in both large vessels and capillary endothelium. Both thrombomodulin and EPCR were expressed poorly on brain capillaries. The liver sinusoids were the only capillaries in which EPCR was expressed at moderate levels and thrombomodulin was low. EPCR and thrombomodulin were both expressed on the endothelium of vasa recta in the renal medulla, the lymph node subcapsular and medullary sinuses, and some capillaries within the adrenal gland. Even in these organs the majority of capillaries were EPCR negative or stained weakly. CONCLUSIONS: These studies suggest that EPCR may be important in enhancing protein C activation on large vessels. The presence of high levels of EPCR on arterial vessels may help explain why partial protein C deficiency is a weak risk factor for arterial thrombosis.

Color flow Doppler imaging and Doppler spectral analysis of the brain of neonatal dogs.

Doppler ultrasonography was performed on the cerebral arteries of 19 neonatal dogs. Vascular structures were identified using anatomic preparations of brains pre-injected with a radiopaque silicone rubber product and cleared using a modified tissue clearing technique. Brain sections were subsequently radiographed or examined under a stereomicroscope. Color flow Doppler imaging was used to facilitate positioning of the Doppler calipers for measurement of peak systolic velocity, minimum diastolic velocity, and resistance index. Blood flow velocities in the internal carotid and middle cerebral arteries were lower when measured in transverse images than in sagittal images. The rostral cerebral arteries could be measured using either plane but values obtained from different locations or using different methods of measurement were statistically different. Blood flow velocities generally increased during the first month after birth. Arterial signals were diphasic with flow throughout diastole. Resistance indices most often were between 0.6 and 0.7 and did not exceed 0.86.

Enzyme histochemical studies of membrane proteases in rat subfornical organ.

Localization of membrane proteases glutamyl aminopeptidase (EAP), microsomal alanyl aminopeptidase (mAAP), dipeptidyl peptidase IV (DPP IV) and gamma-glutamyl transpeptidase (gamma-GTP) were studied in vessels of the rat subfornical organ (SFO), ependyma which cover the surface of the SFO, and adjacent brain structures. Results of enzyme histochemical reactions showed strong activity for EAP, mAAP, and gamma-GTP, but absence of DPP IV in microvessels of SFO. The ependyma which cover the SFO was positive for gamma-GTP, but negative for other studied proteases. Our results showed that the spectrum of enzymes in the majority of the vessels of SFO is similar to that of the microvessels of the adjacent brain tissue which were positive for EAP, mAAP, and gamma-GTP, but negative for DPP IV. The relative intensity of the enzyme reactions in vessels varied from central to lateral locations in the SFO and the adjacent brain tissue. There was also a difference in the relative reaction intensity from one enzyme to the other. The presence and heterogeneous distribution of the enzymes are consistent with the hypothesis that membrane proteases of the microvascular endothelium constitute an enzyme-barrier between blood and parenchyma of the SFO and between blood and brain tissue, and may be involved in metabolism or modulation of various peptides when they contact the plasma membrane of the endothelial cells of the vessels.

Species differences in the distribution of gamma-glutamyl transpeptidase in choroid plexus of lateral ventricle and microvessels of adjacent brain.

The distribution of gamma-glutamyl transpeptidase in different vascular compartments of the central nervous system was evaluated in several common laboratory animals, i.e., hamster, gerbil, guinea pig, rat and mouse, by enzyme-histochemistry. Microvascular endothelium of the periventricular brain tissue stained positively in all five species. In contrast, the vascular endothelium of the choroid plexus stained positively only in the gerbil, and was negative in the other four species. Positive reactions for the transpeptidase was also found in choroid plexus epithelial cells in guinea pig, rat, and mouse; however no activity could be demonstrated in these cells of hamster and gerbil. The results demonstrate clear species differences in localization of the enzyme and suggest that gamma-glutamyl transpeptidase-promoted amino acid transport in choroid plexus is different in various animal species. It is also suggested that in gerbil, transpeptidase-aided amino acid transport takes place in endothelial cells of choroid plexus, whereas in guinea pig, rat and mouse this occurs in epithelial cells of choroid plexus. In the case of hamster, such aided transport is absent in endothelial as well as in epithelial cells of the choroid plexus. Thus, the hamster and the gerbil showed differences in gamma-glutamyl transpeptidase distribution, whereas the guinea pig, rat, and mouse showed similar enzyme distributions.

Membrane-bound proteases of the gerbil subfornical organ and choroid plexus: an enzyme histochemical study.

Using enzyme-histochemical methods, the membrane-bound peptidases, gamma-glutamyl transpeptidase (gamma-GTP), microsomal alanyl aminopeptidase (mAAP), glutamyl aminopeptidase (EAP), and dipeptidyl peptidase IV (DPP IV), were studied in microvessels of the gerbil subfornical organ (SFO), choroid plexus adjacent to the SFO, and the ependyma of brain ventricle walls in the vicinity of the SFO. Vessels and microvessels of gerbil SFO and choroid plexus were positive for gamma-GTP, mAAP, and EAP, but negative for DPP IV. Blood-brain barrier (BBB) microvessels in the surrounding brain tissue also showed positive reactions for gamma-GTP, mAAP, and EAP but a negative reaction for DPP IV. Both epithelial cells of the choroid plexus and ependymal cells of the ventricle walls were negative for all four studied enzymes. It is suggested that blood-borne peptide hormones which can be substrates for these membrane-bound proteases can be modulated by gamma-GTP, mAAP, and EAP, but not by DPP IV, when they come in contact with the plasma membrane of the endothelial cells of the vessels in gerbil SFO, choroid plexus, and surrounding brain tissue.

Detection of herpes simplex virus in the ependyma of experimentally infected mice.

Forty-five Swiss albino mice were inoculated with HSV-1 (strain McKrae) by the corneal route. The spread of HSV to the brain stem and the ventricular ependyma was investigated. The polymerase chain reaction (PCR) was used to detect HSV-DNA in the CSF during the course of infection. The ependyma of the third and fourth ventricle and the central canal contained viral antigen at a late stage of infection in up to 60% of mice. At this stage we found that many animals gave a positive PCR in the CSF although no antigen could be detected in the ependymal cells. The presence or absence of antigen containing cells could not be related to detection of HSV-DNA in the CSF. The results show that infection of the ventricular wall is not important for the spread of HSV to the CSF.

[A scanning electron microscopy study of the ependyma in the lateral cerebral ventricle in humans]. / Stúdium ependýmu v bocnej mozgovej komore cloveka v rastrovacom elektrónovom mikroskope.

The apical surface of ependymal cells in the cornu anterius of the lateral ventricle of the brain was studied in man. The surface of ependymal cells displays varied differentiation, the cells have microvilli, spherical processes, and cilia. In the cornu anterius ependymal cells without cilia as well as with one cilium and even several cilia were observed. Different types of cells occur in groups forming so-called ependymal areas, which are constituents of the lining of the ventricular walls. Ependymal areas with a large number of cilia were recorded along with areas without cilia and so-called transitory ependymal areas with a small number of cilia. There are no sharp borderlines between the individual areas.

Histochemistry of proteases in ependyma, choroid plexus and leptomeninges.

Aminopeptidase M (APM), aminopeptidase A (APA), dipeptidyl peptidase IV (DPP IV) and gamma-glutamyl transferase (GGT) were demonstrated histochemically in cryostat sections of the rat brain to show the reaction pattern of ependyma, choroid plexus and leptomeninges. GGT was only demonstrable in the cell membranes of ependymal cells and in the leptomeninges; however, APA, APM and DAP IV showed a variable degree of activity in the capillary endothelium of the choroid plexus as well as in the leptomeninges. On the basis of these results, it is postulated that peptides in the cerebrospinal fluid can be cleaved extraventricularly by the enzymes demonstrated in the leptomeninges.

The nucleolar channel system of nerve cell. Short communication.

The nucleolar channel system which belongs to less known nuclear components has been described in nerve cells of dog dorsal root ganglia. This structure is formed by a system of twisted tubules. Till now this structure was not observed in all mammalian cells.

Incidence of degenerate fibres in the dorsal column nuclei after ligation of the abdominal aorta.

It was investigated the incidence of damaged nerve fibres in the gracile nucleus and the cuneate nucleus of the dog following an intermittent ligation of the abdominal aorta and 3-day survival. The incidence of damaged fibres was studied at three levels, i.e. the caudal part of the gracile nucleus, the cell-nest region of the gracile nucleus and the region just before the beginning of the central canal. The largest number of disintegrated nerve fibres was found in the cell-nest region. It was observed, that the incidence of damaged fibres diminished both caudally and cranially. When comparing the region just before the beginning of the gracile nucleus with the caudal part of the gracile nucleus it was stated, that the higher density of decomposed fibres was in the region just below the obex. In common there were fewer disintegrated fibres in the cuneate than in the gracile nucleus.