Morphological and functional characteristics of satellite glial cells in the peripheral nervous system.

Satellite glial cells are specialised cells that form a functional perineuronal sheath around sensory ganglion neurons. There are a large number of studies that reveal the morphological and functional characteristics of these cells. Satellite glial cells have been studied both in intact ganglions and in tissue cultures, using light and transmission electron microscopy, immunohistochemical and other methods. Satellite glial cells have polygonal form; they are mononuclear and have developed synthetic organelles, numerous receptors, adhesion molecules and ion channels, which enable them to interact with adjacent neurons, as well as transmit signals in the ganglions of the peripheral nervous system. Based on the literature data, satellite glial cells thanks to their characteristics can receive signals from other cells and react to changes in their surroundings. Previous studies have investigated the potential role of satellite glial cells in the formation of the blood-nervous tissue barrier of the peripheral nervous system, as well as in the neuropathic pain genesis. Some recent discoveries support the fact that satellite glial cells can participate in controlling of local viral infections and protecting pseudounipolar neurons from mentioned infections.

Arterial supply of the trigeminal ganglion, a micromorphological study.

BACKGROUND: In this study, we explored the specific microanatomical properties of the trigeminal ganglion (TG) blood supply and its close neurovascular relationships with the surrounding vessels. Possible clinical implications have been discussed. MATERIALS AND METHODS: The internal carotid and maxillary arteries of 25 adult and 4 foetal heads were injected with a 10% mixture of India ink and gelatin, and their TGs subsequently underwent microdissection, observation and morphometry under a stereoscopic microscope. RESULTS: The number of trigeminal arteries varied between 3 and 5 (mean 3.34), originating from 2 or 3 of the following sources: the inferolateral trunk (ILT) (100%), the meningohypophyseal trunk (MHT) (100%), and from the middle meningeal artery (MMA) (92%). In total, the mean diameter of the trigeminal branches was 0.222 mm. The trigeminal branch of the ILT supplied medial and middle parts of the TG, the branch of the MHT supplied the medial part of the TG, and the branch of the MMA supplied the lateral part of the TG. Additional arteries for the TG emerged from the dural vascular plexus and the vascular network of the plexal segment of the trigeminal nerve. Uniform and specific intraganglionicdense capillary network was observed for each sensory trigeminal neuron. CONCLUSIONS: The reported features of the TG vasculature could be implied in a safer setting for surgical approach to the skull base, in relation to the surrounding structures. The morphometric data on TG vasculature provide anatomical basis for better understanding the complex TG blood supply from the internal and external carotid arteries.

Vascularisation of the geniculate ganglion.

BACKGROUND: Lack of the relevant data in the literature and possible clinical significance of the geniculate ganglion vasculature inspired us to examine the vessels of this ganglion. MATERIALS AND METHODS: Twelve temporal bones were taken during autopsy and microdissected. Four geniculate ganglions were taken as well, serially sectioned and used for haematoxylin-eosin and trichrome staining, and for CD34 immunostaining. RESULTS: The geniculate ganglion was supplied by the petrosal artery, which averaged 1.1 in number, 0.44 mm in the outer diameter, 0.24 mm in the luminal diameter, and 17.1 mm in length. The artery approached the greater petrosal nerve, giving off 1-3 twigs to it with a mean diameter of 24 µm, and entered the nerve hiatus or a small bone opening close to the ganglion. Before the artery continued to the tympanic segment of the facial nerve, it gave rise to 1 (8.33%), 2 (75.00%) or 3 (16.67%) branches to the geniculate ganglion, which ranged in diameter between 18 µm and 56 µm (mean 29 µm). From the formed superficial network, several twigs penetrated the ganglion and built an intraganglionic plexus. The counting, performed in microscopic fields, each measuring 341.7 µm × 250.0 µm in size, contained between 20 and 38 (mean 28.1) ganglion cells, as well as from 87 to 143 microvessels (mean 99.8), so that the neuron/vessel ratio was 1:3.6. CONCLUSIONS: This is the first detailed examination of the geniculate ganglion vasculature. The obtained data could be of clinical importance, especially in relation to the Bell's palsy, ganglionitis, geniculate neuralgia, petrous bone imaging, and operations in the same region.

Duplication of the superior vena cava associated with atrial termination of the left hepatic vein.

Duplication of the superior vena cava (SVC), associated with an aberrant left hepatic vein (LHV), was found in one of the 58 dissected specimens. The right SVC virtually showed a typical appearance. The persistent left SVC, which drained into the right atrium via the enlarged coronary sinus, was formed by the persistence of the left anterior cardinal vein. The LHV opened into the right atrium, due to the persistent left hepatocardiac channel. The left common carotid artery arose from the brachiocephalic trunk as a consequence of a regression of the embryonic aortic sac. The revealed venous and arterial variations seem to be the first reported vascular combination of this type.

Anatomic and clinical correlations of the lenticulostriate arteries.

The authors examined the lenticulostriate (perforating) arteries in the vascular casts of 48 middle cerebral arteries (MCA), as well as in the MRI or CT scans of 32 patients with cerebral infarcts in the MCA territory. The lenticulostriate arteries ranged between two and 12 in number, and from 80 microm to 1,400 microm in size. They originated from the main trunk, terminal trunks, bifurcation site, and/or leptomeningeal branches of the MCA, either separately or from common trunks (70.8%). The extreme variations of the supplying region of the perforators were noted in seven anatomic specimens. In addition to the basal ganglia, the genu, and the anterior limb of the internal capsule, the lenticulostriate arteries seemed to supply only the rostral portion of the superior part of the posterior limb of the capsule. The patients presented with occlusion of all the lenticulostriate arteries, individual arteries, or only their twigs. Complete occlusion of these arteries resulted in a huge central hemispheric infarct. Occlusion of an individual artery most often caused a large ganglionic-capsular infarct. The authors concluded that the lacunar infarcts usually follow occlusion of a terminal or a side branch of the lenticulostriate arteries.

The acidophilic nature of neuronal Golgi impregnation.

The mechanisms of Golgi impregnation of neurons has remained enigmatic for decades. Recently, it was suggested that divalent (di)chromate anions play a role in the Golgi impregnation process. Therefore, we incubated slices of (para)formaldehyde-fixed rat brain tissue in solutions of potassium (di)chromate, phosphate, chloride or nitrate at pH 6 or 7. Slices were then immersed in solutions of silver nitrate and processed for light microscopical analysis. At pH 6, dichromate probes resulted in dense and homogeneous impregnation of neuronal cytoplasm (typical impregnation). At pH 7, chromate probes showed solely partial cytoplasmic and heavy nuclear-region neuron impregnation (atypical impregnation). Phosphate probes at pH 6 resulted in typical impregnation, whereas at pH 7 phosphate probes gave atypical impregnation. Both at pH 6 and 7, chloride and nitrate probes did not yield any Golgi impregnation. These findings confirmed the pH-dependence of silver-chromate Golgi impregnation as well as the correctness of corresponding acidic silver-phosphate impregnation. Our study revealed a previously unknown, strong anion-dependence of Golgi impregnation, suggesting that hydrogenated monovalent anions are carriers of the neuron impregnation.