The localization of acetylcholinesterase activity in the spinal ganglia of the adult fowl studied by electron microscope histochemistry

Ultrastructural changes in acetylcholinesterase activity in the deafferented spinal trigeminal nucleus

Acetylcholinesterase (AChE) activity was investigated in synaptic areas of the cat spinal trigeminal nucleus (pars interpolaris and pars caudalis) ipsilateral and contralateral to complete retrogasserian rhizotomy. Vibratome sections of tissue taken from animals of 1, 3, 6, 14, and 21 days survival were examined by electron microscopy following a histochemical reaction for AChE activity employing a method based on the Karnovsky-Roots technique for demonstrating reaction product. As degeneration progressed with survival time, enzymatic activity was initially reduced in synaptic clefts of injured afferent terminals and subsequently was enhanced throughout the extracellular space, including within synaptic clefts of possibly reinnervated sites. These changes in enzymatic activity with primary deafferentation are discussed in relation to the process of reinnervation, the development of neuronal hyperactivity, and possible noncholinergic functions of AChE.

Acetylcholinesterase activity and type C synapses in the hypoglossal, facial and spinal-cord motor nuclei of rats. An electron-microscope study

Using the electron-microscope technique of Lewis and Shute, we studied the localization of the acetylcholinesterase (AChE) activity in the hypoglossal, facial and spinal-cord motor nuclei of rats. The technique used selectively detects synapses with subsynaptic cisterns (type C synapses) as well as heavy deposits of reaction products in the rough endoplasmic reticulum, in fragments of the nuclear envelope, in some Golgi zones and on parts of the pericaryal plasma membrane, the axolemma and the dendritic membrane. In C synapses, AChE activity was located in the synaptic cleft and on the membrane of presynaptic boutons. Some C synapses exhibited distinct synaptic specialization in the form of multiple 'active zones'. These zones were characterized by dense presynaptic projections, short dilations of the synaptic cleft, and postsynaptic densities localized between the postsynaptic membrane and the outer membrane of the subsynaptic cistern. Within the postsynaptic densities, rows of rod- or channel-like structures were observed. The subsynaptic cisterns were continuous with the positive rough endoplasmic reticulum. The results are discussed in terms of the possible role of C synapses in the regulation of AChE synthesis in postsynaptic cholinergic neurons and/or in the regulation of AChE release into the extracellular space as well as in the establishment of new synaptic contacts.

Fibre population of the vestibulocochlear anastomosis in humans

The vestibulocochlear anastomosis in the adult human was studied by light and electron microscopy. It was found to contain both myelinated and unmyelinated axons. The number of myelinated axons ranged from 223 to 695, with a mean of 360, while the unmyelinated axons varied from 638 to 1453, with a mean of 1005. The ratio of unmyelinated to myelinated axons varied from 2.1 to 4.4, with a mean of 3.0.

Morphometric study of pre- and post-hatching nerve cell bodies of lumbar spinal ganglia of Gallus domesticus

A cytomorphometric study was performed in lumbar spinal ganglia neurons of Gallus domesticus on the 10th and 18th incubation days and 8th, 35th, 61st, and 120th post-hatching days. The absolute volume of nucleus and relative volume of cytoplasm were respectively estimated by the Bach caryometric method and by point-counting volumetry, carried out in 0.5 micrometer thick araldite sections. The relative volume, the surface-to-volume ratio and the total surface of RER, SER, mitochondria, dense bodies, Golgi complex and the relative volume of hyaloplasm inside and outside the Nissl bodies were estimated from electronmicrographs by the Weibel et al. method. The conclusions were: a) there was an increase of the cell volume and a decrease of the nucleo-cytoplasmic ratio, particularly between the first two ages; b) the relative volumes of RER and SER change inversely with respect to each other: the RER increases before hatching, decreasing progressively afterwards; the changes of relative volume of dense bodies are similar to those of the RER, and the mitochondria show relatively small variations concerning the same parameter; c) the relative volume of hyaloplasm inside the Nissl bodies decreases while those outside increases; d) the surface-to-volume ratio drops sharply for all organelles from the 10th to the 18th day of incubation; after hatching, a tendency to increase is observed; e) the membrane surface-to-cytoplasmic volume ratio decreases for all organelles from the 10th to the 18th day of incubation; after hatching, this ratio increases slightly for mitochondria and Golgi complex, sharply for SER, dropping for dense bodies. The RER values alternate regularly.

Combination of cholinesterase staining of nerves and stereoscopic viewing for three-dimensional study of skin innervation on whole mounts

A histochemical staining technique for cholinesterases is reported for the visualization of skin innervation on whole mounts in the chick. A method for realization of stereoscopic pictures showing the nerve fiber pattern in the full thickness of preparations is described. The combination of these 2 techniques allows an excellent three-dimensional demonstration of skin innervation.

Cytochemical localization of acetylcholinesterase in the rat striatum

An attempt was made to determine the subcellular localization of AChE in rat striatum with several Cu-thiocholine procedures using slices of intact tissue and in isolated organelles obtained by gradient centrifugation. Regardless the method used the reaction product, indicating the localization of AChE activity shows the usual intracellular and extracellular distribution. Although AChE activity was present at the extrajunctional axolemma of the nerve endings almost no enzyme activity was observed in the junctional region either in tissue sections or on isolated synaptosomes.

Light and electron microscopic localization of acetylcholinesterase activity in the rat renal nerves

Acetylcholinesterase activity is shown in the renal nerves of the rat with the technique of Karnovsky and Roots. By light microscopy, the acetylcholinesterase-positive nerves are seen in association with blood vessels, including the glomerular arterioles, and occasionally with renal tubules. By electron microscopy the precipitate appears extracellularly around axons and varicosities. DFP inhibits the deposition of precipitate. Previous demonstration by serial section electron microscopy in the rat revealed that all nerves around the glomerular arterioles contain small dense-cored vesicles characteristic of adrenergic nerves, indicating that the acetylcholinesterase-positive nerves demonstrated here are likely to be adrenergic nerves containing acetylcholinesterase.

Acetylcholinesterase activity of synaptic structures in the spinal trigeminal nucleus

The electron microscope has been used to study the localization of acetylcholinesterase (AChE) activity in the spinal trigeminal nucleus of normal cats with special emphasis on the distribution near synaptic structures. Reaction product is found around both round and flattened synaptic vesicle-containing axon terminals, particularly in synaptic clefts and often specifically associated with the presynaptic, or less frequently the postsynaptic membrane. The presence of reaction product at these specific sites suggests that these are areas of high AChE activity and that acetylcholine may be important in neurotransmission in these regions.

Enzymatic organization of the subcommissural organ

In the subcommissural organ (SCO) of the guinea pig, rat, golden hamster, and mouse the activity and distribution of enzymes related to the energy-supplying metabolism and of some marker enzymes of different cell organelles have been investigated by means of mostly modified histochemical methods. The results were compared with findings in the ciliated ependyma of the ventricular wall and with those in the ependyma of the choroid plexus of the third ventricle. In the ependymal part of the SCO only a moderate activity of hexokinase is observed in its specialized columnar cells whereas a high activity is present both in the ciliated ependyma and the choroid plexus. - The staining pattern of glucose-6-phosphatase is similar to that of hexokinase but this enzyme is found is the SCO only. - Likewise hexokinase, glycogen granules and enzymes related to glycogen metabolism (phosphoglucomutase, uridine-diphosphoglucose pyrophosphorylase, glycogen synthetase and phosphorylase) are regularly found most numerous and active in the nuclear and supra-nuclear area of the ependymal part. These enzymes are less active in both the other ependymal regions. - Uridine-diphosphoglucose dehydrogenase could not be demonstrated in the SCO. The NADP-linked enzymes of the pentose phosphate shunt, glucose-6-phosphate and 6-phosphogluconate dehydrogenase, show a moderate activity which decreases also from the nuclear towards the apical area of the ependymal cells of the SCO. Enzymes of the glycolytic pathway, such as glucosephosphate isomerase, fructose-6-phosphate kinase, fructose-I,6-diphosphate aldolase, glyceraldehyde-3-phosphate and lactate dehydrogenase, are highly active in the SCO and are located mainly in the supranuclear area, too. Fructose-1,6-diphosphatase could not be demonstrated thus indicating that in the SCO the pathway is most probably only glycolytic but not gluconeogenetic. Compared to the ependyma of the ventricular wall and of the choroid plexus, in the SCO the M type subunits of lactate dehydrogenase predominate. Glycolytic enzymes are also very active in the choroid plexus but less in the ciliated ependyma. Compared to the ciliated ependyma and especially to the ependyma of the choroid plexus, the activities of enzymes which are only present in mitochondria (NAD-linked isocitrate dehydrogenase, succinate dehydrogenase, NAD-linked malate dehydrogenase after preextraction, cytochrome oxidase, 3-hydroxybutyrate and glycerolphosphate and glutamate dehydrogenase) are relatively low. Mitochondria are accumulated near the superior pole of the nuclei as well as in the most apical part of the ependymal cells. - The staining pattern of NADP-linked isocitrate and malate dehydrogenase as well as of NADH dehydrogenase suggests that these enzymes are localized both in and out of mitochondria. The extramitochondrial activity of the first two enzymes might be localized in the cytosol. The extramitochondrial activity of NADH dehydrogenase might be localized in the endoplasmic reticulum...