Microvasculature of the cerebral cortex: a vascular corrosion cast and immunocytochemical study.

In mammals, the cerebral cortex microvasculature (CCM) of the neopallium plays important roles in the physiological and pathological processes of the brain. The aim of the present work is to analyze the CCM by use of the SEM-vascular corrosion cast technique, and to examine the immunocytochemical characteristics of the CCM in adult domestic ruminants (cattle, buffalo, and sheep) by using the SEM-immunogold technique. The CCM originated from the very small, finger-like terminal branches of the macrovasculature of the brain. The superficial cortical arterioles were more numerous than the deep straight arterioles which proceeded toward the white matter. The surface casts of the arterioles and capillaries of the cerebral cortex showed ring-shaped formations in the arterioles and at the origin of the capillaries. All capillaries down-stream from these ring-shaped formations were flaccid. Casts of the capillaries showed wrinkles due to the presence of endothelial folds, which is characteristic of varying blood pressure. Formations having intense anti-GIFAP immunoreactivity were frequently evident along the course of the blood capillaries in the cerebral cortex. These formations were probably astrocytes that might regulate the cerebral microcirculation based on physiological and pathological stimuli, such as neuronal activation.

Angiogenesis of buffalo choroid plexuses: structural and immunocytochemical study.

Mammalian choroid plexuses (CPs) are vascularized structures involved in numerous exchange processes that supply nutrients and hormones to the brain, and that remove deleterious compounds and metabolites from the brain. Studies in the adult Mediterranean buffalo have investigated the morphology of CPs using histochemical and immunohistochemical techniques. To date, however, there have been no studies conducted on ruminants regarding this removal process which serves to repair functional vascular damage in the CPs. Each of these vascular repair processes is a very complex and none of these has not yet been completely understood. Then, the aim of the present study is to investigate the morphological processes during angiogenesis in the CPs of healthy adult buffaloes, utilizing transmission electron microscopy (TEM), scanning electron microscopy (SEM), and immunogold-labeling SEM analysis (biomarkers: angiopoietin-2 [Ang-2], vascular endothelial growth factor receptor-3 [VEGFR-3], and CD133). At TEM, the inner surface of the blood capillaries sometimes showed pillar-like cells, which in contact with endothelial cells formed prominences, which in turn formed neo-blood capillaries. With immunogold-labeling SEM analysis, the CP blood capillaries showed Ang-2 and VEGF-3, respectively, in positive particles and spheroid formations. In addition, the external surface of the blood capillaries showed spheroid formations that originated from the neo-vascular capillaries whose terminals formed a capillary network, positive to CD133. On the basis of these results, the following hypothesis can be made, namely, that these CPs are vascular structures which play a fundamental role in maintaining brain homeostasis and self-repairing of functional vascular damage, independently of the presence of rete mirabile in this species.

Nitric oxide (NO) expression during annual reproductive activity in buffalo epididymis: a histochemical and immunocytochemical study.

The buffalo is one of the few domestic animals that has a seasonal mating cycle, influenced by the photoperiod. It is known that the photoperiod regulates gonadal function probably via the pineal and/or hypothalamus-pituitary axis. Moreover, the hypothalamus (melatonin) and gonads influence the production of the signaling transmitter nitric oxide (NO), suggesting that the NO may have an important role in the regulation of gonadotropin-releasing hormone secretion. This further suggests the hypothesis that NO in the epididymis has an important role in the maturation of spermatozoa and their motility and posterior fertilization capacity. The aim of the present study is to investigate the seasonal variations in the morphology of the epididymis by means histochemical and immunocytochemical techniques. We used the NADPH-d, nitric oxide synthase (NOS) I and NOS III to clarify the relationship between epididymis function and NO signaling activity. The results of this work show that NO is present in the caput of epididymis during short photoperiods, i.e., periods of maximum gonadal activity (winter) and absent during long photoperiods, i.e., periods of gonadal regression according to the previously described role of NO in spermatozoa capacitation and motility in the caput epididymis.

Microvasculature of the buffalo (Bubalus bubalis) choroid plexuses: structural, histochemical, and immunocytochemical study.

The choroid plexuses (CPs) in mammals produce the cerebrospinal fluid (CSF). In the literature, the morphology of CPs and the process that regulates the production of CSF are virtually nonexistent for domestic ruminants. Thus this study has two aims: 1. to investigate the morpho-structure of the buffalo CP microvasculature utilizing light microscopy (LM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) techniques, and 2. to investigate the relationship between the blood vessels and both the elongated cells and the cells with multiple protrusions located in the CPs. SEM and TEM analyses of the CPs from buffalo brain showed morphological and structural features similar those reported in other mammalian species. Moreover the blood microvasculature is the major component responsible for the formation of the CSF, secreted by the encephalic CPs. In addition the chemical composition of this fluid depends on several morpho-functional characteristics of the vascularization of the CPs. These characteristics are as follows: two shapes of the vascular organization: lamina-like and ovoid-like elongated cells of the CPs, which connect the ventricular cavities to the blood capillaries; and the CP capillaries have diverse forms. In the present study the employment of NADPHd and NOS I was taken as indirect evidence for the presence of NO for investigation their specific role in CPs. Then NOS I immunoreactivity is found in the walls of CP blood vessels demonstrating indirectly the presence of NO with a vaso-dilatatory and autoregulation function of vascular tone by cholinergic nerve stimulation of blood vessel smooth muscle.

Expression of orexin A and its receptor 1 in the choroid plexuses from buffalo brain.

The hypothalamic peptide orexin A, deriving from the proteolytic cleavage of the precursor molecule prepro-orexin, has a wide range of physiological effects including the regulation of feeding behaviour, neuroendocrine functions, sleep-wake cycle, and energy homeostasis. Lowered excretion of orexin A into the cerebrospinal fluid (CSF) plays a pathological role in animal and human narcolepsy. Altered levels of orexin A into the CSF have been also found in numerous disorders of the central nervous system, including Parkinson's and Huntington's disease, dementia, and depressive disorders. While the localization of orexin A and its receptor 1, OX(1), has been elicited in many regions of the mammalian brain and in peripheral organs, there are no information on the expression of the neuropeptide and its receptor 1 in the choroid plexuses (CPs) producing the CSF. In this study, we investigated the expression of orexin A and OX(1) in the CPs from the brain of an adult mammalian species, Bubalis bubalis, by immunogold-labelling in scanning electron microscopy. Both orexin A and OX(1) immuno-reactivity appeared to be widely distributed on the surface of choroid epithelium. Interestingly, a marked orexin A labelling was detected in the areas surrounding the CP blood capillaries. The expression of prepro-orexin and OX(1) mRNA transcripts of 200 and 300 bp, respectively, was assessed in the CPs by reverse-transcription polymerase chain reaction, while Western blotting analysis confirmed the presence of these two proteins in the tissue. Our findings provide the first evidence for orexin A and OX(1) expression in the CPs from mammalian brain, and suggest that the levels of orexin A into the CSF are probably regulated by CP activity.

Expression of the serotonin transporter (SERT) in the choroid plexuses from buffalo brain.

Choroid plexuses (CPs) play pivotal roles in a wide range of processes that establish, survey, and maintain the biochemical and cellular status of the central nervous system. Mammalian CPs contain a very high density of serotonin receptors, and serotonin has been shown to affect CP functions. The serotonin transporter (SERT) regulates the entire serotonergic system, including serotonin receptors by means of modulation of serotonin concentration in the extracellular fluid. In this study, the expression of SERT in the CPs from the brain of a mammalian species, Bubalis bubalis, was established. By immunogold labeling in scanning electron microscopy, SERT immunoreactivity was found to be localized on the apical surface of the choroid epithelium. In particular, SERT positivity was detected on the apical portion of villi, and both on the membrane and in the cytoplasm of grouped cells on the surface of the choroid epithelium. Significantly, no SERT was detected in blood vessels irrigating the CPs. The expression of SERT mRNA transcripts of 440 bp in the CPs was detected by reverse-transcription polymerase chain reaction, and Western blotting analysis revealed the presence of three isoforms of the protein with molecular masses of approximately 70, 80, and 140 kDa, respectively, probably corresponding to differently glycosylated SERT. Our findings provide the first report of SERT detection in the CPs of buffalo brain and indicate that this protein is locally synthesized from the choroid epithelial cells. We suggest that SERT might have an important role in mammalian CPs, possibly regulating the serotonin flow between brain and rest of the body.

Structural and functional features of choroid epithelium from buffalo brain.

Choroid plexuses (CPs) play pivotal roles in many processes that establish, survey, and maintain the biochemical and cellular status of the central nervous system (CNS). Changes in the anatomy and physiology of CPs have been linked to several CNS diseases. However, CP structure and function are not definitely known. Here, we report structural and functional features of choroid epithelium from buffalo brain never described before. Mixed with common epithelial cells, two novel cell types were identified by scanning and transmission electron microscopies. The first peculiar cells showed a globular apical portion projecting into the ventricular cavities, and a basal peduncle in direct contact with blood capillaries underlying the epithelium. The second type of cells resulted to be formed by a globular body from which depart numerous processes; these cells, localized deeply in the choroid epithelium, strictly contact neighboring epithelial cells. No synaptic contacts were detected between these cell populations and common epithelial cells. To gain some insight into the functional properties of choroid cells, NADPH diaphorase (NADPHd) and neuronal nitric oxide synthase (nNOS) activities were evaluated. Of interest, whereas a strong NADPHd activity was detected in all cell types of choroid epithelium, nNOS was only detected in the first type of peculiar cells. The presence of nNOS in the CPs was confirmed by Western blotting. These results suggest that nitric oxide may serve as a signal for the regulation of CP multiple functions.

Microvasculature of the buffalo epididymis.

The microvasculature of the water buffalo (Bubalus bubalis) epididymis was investigated using light (LM), scanning electron (SEM), and transmission electron (TEM) microscopy techniques. SEM analysis of the buffalo epididymis showed fenestrations that occupied ovoid inside the endothelium of the postcapillary venules located in the caput, corpus, and cauda. They varied in shape and dimension, but more importantly, they connected the venules of the blood vascular system to the capillaries of the peripheral lymphatic vascular system. Morphofunctional analysis of these connections suggests that the microvasculature of the buffalo epididymis plays a role in facilitating the circulation of biologically active substances, and the absorption and secretion processes necessary for the survival and maturation of spermatozoa. The lymphatic capillaries at the connection points formed a network of variously sized polygonal links. These capillaries then converged to form the precollector lymphatic vessels, which in turn converged with the larger vessels originating from the testis. It was further noted that in the capillary endothelium there were no fenestrations, and in the large veins there were many diverticula. These diverticula appear to play a role in the regulation of the seasonal variations of the blood reflux. In general, the microvascular architecture of the buffalo epididymis, particularly its connection to the lymphatic vascular system, appears to play an important role in the absorption and secretion processes of the epididymal epithelium.