Letter: Positive identification of intracellular biogenic amine reaction product with electron microscopic x-ray analysis

Crystalloid structures in retroperitoneal paragangliomas: a light and electron microscopic study

Samples from three clinically functional retroperitoneal paragangliomas were studied by light and electron microscopy. The tumors exhibited a Zellballen pattern histologically, and ultrastructurally all three neoplasms consisted of cells containing catecholamine granules. Prominent cytoplasmic crystalloids were present in all cases. The crystalloids were identified in routine histologic sections, demonstrated eosinophilia, and stained with periodic acid-Schiff, Giemsa, phloxine-tartrazine, and azan stains. Ultrastructurally the crystalloids were osmiophilic, often appeared as slender needles, were membrane bound, and demonstrated a periodicity of 9 nm. The crystalloids, unlike the catecholamine granules, were negative for catecholamine fluorescence. X-ray microanalysis, however, revealed the selective presence of chromium in both catecholamine granules and crystalloids.

A light and fluorescence cytochemical and electron microscopic study of granule-containing cells in the intrapulmonary ganglia of Pseudemys scripta elegans

In the lung of the red-eared turtle, large numbers of intramural ganglia located in the intraparenchymal connective tissue are demonstrated. Numerous cells in close proximity to the principal ganglionic neurons displayed a bright blue-white formaldehyde-induced fluorescence. Microspectrofluorometric analysis revealed the presence of dopamine (DA) in all cells measured. Subsequent light histochemical staining of the fluorescent sections showed the DA-containing cells to display argentaffinity. Electron microscopy of serial sections revealed cells characterized by dense-cored vesicles corresponding to the intensely formaldehyde-induced fluorescent cells. The argentaffin technique performed directly on ultrathin sections selectively stained the dense-cored vesicles. After fixation with glutaraldehyde followed by dichromate, x-ray microanalysis showed the chromium to be incorporated into the dense granules. Cholinergic-type nerve endings formed axosomatic synaptic contacts with the DA-containing cells, which can therefore be considered as intrinsic postganglionic elements. No efferent synapses from the granule-containing cells to the principal ganglionic neurons could be observed. The granule-containing cells occurred solitarily and in clusters, partially invested with satellite cells, and usually located near fenestrated capillaries; they displayed cytoplasmic processes and indicated emiocytotic granule release. Adjacent granule-containing cells were separated by spaces about 20 nm wide, gradually widening to form intercellular channels with apically projecting microvilli and primary cilia. It is concluded that the intrapulmonary granule-containing cells of the red-eared turtle belong to the APUD system. Furthermore, morphologically these cells appeared to possess a special sensory apparatus which designates them as paraneurons. The possible physiological significance of these intrapulmonary granule-containing cells is discussed.

Characterization of chromaffin-like cells in the canine sympathetic chain by enzyme immunohistochemistry and quantitation of their distribution

Some of the paravertebral sympathetic ganglia of the dog contain relatively large amounts of dopamine, which we have suggested previously is localized in dopaminergic neurones. However, the possibility exists that intraganglionic chromaffin-like cells may also be a source of dopamine. In order to resolve this question, we have examined the distribution of chromaffin-like cells in dog paravertebral ganglia (T7-S2) using formaldehyde-induced fluorescence of catecholamines and immunohistochemical localization of dopa decarboxylase, dopamine beta-hydroxylase and phenylethanolamine N-methyltransferase. The results have been compared with levels of the different endogenous catecholamines in equivalent ganglia. Clusters of between 20 and several thousand chromaffin-like cells were randomly present in ganglia at all levels of the chain, and were most common in the more caudal segments (L4 or below); but many ganglia contained no cells. About 24,000 chromaffin-like cells were found in 18 ganglia from six animals which were stained for dopa decarboxylase and dopamine beta-hydroxylase. In 16 of these ganglia, all of the 17,000 cells present contained both enzymes, indicating that they could synthesize noradrenaline. In the remaining two ganglia, 500 out of 7000 cells contained dopa decarboxylase, and therefore were capable of synthesizing dopamine, but appeared to lack the dopamine beta-hydroxylase necessary to convert this to noradrenaline. Five ganglia from three other dogs were stained for dopamine beta-hydroxylase and phenylethanolamine N-methyltransferase. A further 2600 cells were found in these ganglia and both enzymes were present in all of the cells, indicating that they could all synthesize adrenaline. Biochemical estimates of the various catecholamines showed that ganglia containing appreciable amounts of adrenaline had similar distributions to those containing chromaffin-like cells in the same animals. High concentrations of adrenaline were often correlated with high concentrations of noradrenaline but were not correlated with high concentrations of dopamine. It is concluded that paravertebral chromaffin-like cells in the dog store adrenaline, and also perhaps noradrenaline, but not dopamine. The high concentrations of dopamine found in certain ganglia cannot therefore be attributed to the presence of these cells. The erratic distribution of chromaffin-like cells suggests that they are unlikely to fulfil any general role in modulation of ganglionic transmission.

X-ray microanalysis of monoaminergic terminals in the nucleus tegmentalis dorsalis of the chicken

X-ray microanalysis after aldehyde-chromate-dichromate treatment served to confirm the presence of monoaminergic terminals in the nucleus tegmentalis dorsalis (NTD) of the chicken. The monoaminergic terminals were represented as neuronal elements with electron-dense vesicles (EDVs) of several different shapes as seen in Eponembedded semi-thin sections. Conventional electron microscopic observations of the adjacent ultra-thin sections showed the EDVs to be comprised of spherical medium-sized (about 80 nm in diameter), large dense-cored (about 120 nm) and elongated granular vesicles (100-220 nm) in the same nerve varicosities. It is probable that the NTD, being a center of catecholaminergic efferent projections, may also receive direct monoaminergic inputs from an unknown area of the brain and/or from recurrent collaterals of the same catecholamine-containing neurons in the NTD.

Electron microscopic cytochemical correlates of histofluorescence

The biogenic amines, norepinephrine and dopamine, have been localized electron microscopically in the substantia nigra, pineal body, adrenal medulla and stellate ganglion of squirrel monkeys. The method of localization has been by the use of a specific cytochemical technique, utilizing a chromium (Cr) complex with an isoquiniline derivative formed by the reaction of the unsubstituted biogenic amine with glutaraldehyde. The final reaction product, i.e., amine-glutaraldehyde-Cr, has been identified using energy dispersive X-ray analysis and the positive Cr reactive sites have been correlated with light microscopy conducted by using glyoxylic acid histofluorescence. All tissues were taken from squirrel monkeys which had either been perfused with the fixative or had been perfused with an F-12 buffer prior to fixation and/or histochemical treatment. The best results were obtained from the F-12 perfusion followed by tissue being taken through the various histochemical-cytochemical procedures. The electron microscopic localization of deposits shows significantly large structures containing the Cr positive amine material. These large deposits have not heretofore been described and correlate well in size and location with what is seen with histofluorescence. This electron microscopic technique should lead to further advances in the study of biogenic amines in nervous tissue when fine structural localization, plus well preserved morphology, are essential.

Use of the analytical electron microscope (AEM) in cytochemical studies of the central nervous system

Central nervous tissues (median eminence and arcuate nucleus) were studied by means of energy dispersive x-ray analysis using electron optical systems (analytical electron microscopy). These studies were conducted after the tissue had been treated specifically for localized biogenic amines (BA). The results indicate that not only is the BA cytochemical reaction highly specific, and that BAs can be localized intraneuronally in areas not previously identified, but also that the analytical electron microscope is a very valuable and potentially powerful tool in the studies of inclusion bodies and organelles in the central nervous system and other tissues. Thus, the nonspecific density production by osmium tetroxide can be elucidated from the specific BA reaction plus other areas of the nervous system containing density producing heavy metals, i.e., iron are readily identifiable.