Small Granule-containing Cells Research Articles

Histological and Ultrastructural Studies of the Unique Hemopoietic-Endocrine Organ of the Grass Carp, Ctenopharyngodon idella (Valenciennes, 1844).

Specific features of the immunohistochemical and ultrastructural organization of the hemopoietic head-kidney (HK) in adult Ctenopharyngodon idella (Valenciennes, 1844) were investigated using light and transmission electron microscopy. The HK of grass carp possessed all developmental stages of leucocytes and erythrocytes, as well as dendritic cells and epithelial reticular cells. The rodlet cells were expressed α-smooth muscle actin (SMA). In addition, macrophages were the most numerous cells in the HK, which aggregated into structures called melanomacrophage centers (MMCs). On contrary, the chromaffin and interrenal cells (ICs) were mixed and organized into large anastomosing cords, which lined the posterior cardinal veins of the HK, and associated with many blood capillaries. The ICs displayed the characteristic features of steroid-producing cells. Three types of chromaffin cells: adrenaline, noradrenaline, and small granule-containing cells were observed in the HK. Glial fibrillary acidic protein (GFAP)-positive sustentacular cells were marked among the chromaffin cells. Hemopoietic cells, immune cells, MMCs, rodlet cells, in addition to three types of chromaffin cells and one type of interrenal cells in the HK were correlated with the functional significance of the fish concerned.

Nitric Oxide and Endothelin-1 in Coronary and Pulmonary Circulation

Since the discovery of the vasorelaxant properties of nitric oxide and the vasoconstrictor effect of endothelin-1, there have been many studies of the distribution and functional significance of these agents in various vascular beds. In the coronary and pulmonary circulation nitric oxide and endothelin-1 actions have been largely investigated in terms of an imbalance between the opposing effects of these vasoactive agents leading to pathophysiological conditions. This article review functional and immunocytochemical studies with emphasis on the ultrastructural localization of nitric oxide synthase and endothelin-1 in the coronary and pulmonary vascular beds. Localization of nitric oxide synthase (type III or I or II) has been shown in endothelial cells, smooth muscle, and perivascular nerves of the coronary and pulmonary vascular beds and in the neurons, nerve fibers, and the small granule-containing cells within cardiac ganglia. Endothelin-1 was mainly localized in subpopulations of coronary and pulmonary endothelial cells. These immunocytochemical studies provide information about the sources of nitric oxide and endothelin-1 that contribute to the vasomotor control of cardiac and pulmonary circulation under normal and pathophysiological conditions.

Nitric oxide synthase-containing neurones and nerve fibres within cardiac ganglia of rat and guinea-pig: an electron-microscopic immunocytochemical study.

The nitric oxide synthase-immunoreactivity and NADPH-diaphorase activity of intracardiac neurones in the rat and guinea-pig was studied at the ultrastructural level. While some nitric oxide synthase-containing intracardiac neurones were very heavily labelled, with electron-dense immunoprecipitate distributed throughout the neuronal cell bodies and their processes, most of the labelled neurones exhibited a lighter and more patchy distribution of nitric oxide synthase-immunoreactive material. Synapses made by nitric oxide synthase-negative nerve fibres with labelled intracardiac neurones were seen. Conversely, many nitric oxide synthase-containing nerve fibres that made synaptic contacts with unlabelled intracardiac neurones were also observed. Some small granule-containing cells were nitric oxide synthase-immunoreactive and were associated with unlabelled nerve terminals, while non-immunoreactive small granule-containing cells that were innervated by nitric oxide synthase-immunoreactive nerves were also seen. Small patches of osmiophilic electron-dense material were observed in the cytoplasm of NADPH-diaphorase-positive intracardiac neurones. This is the first description of the ultrastructural distribution of nitric oxide synthase-immunoreactivity and NADPH-diaphorase activity in a subpopulation of intracardiac neurones of rat and guinea-pig heart and provides further evidence in support of a role for nitric oxide in the local control of the heart by intrinsic neurones.

Investigation of the Blood-Ganglion Barrier Properties in Rat Sympathetic Ganglia by Using Lanthanum Ion and Horseradish Peroxidase as Tracers

Vascular permeability in various rat sympathetic ganglia, including superior cervical ganglia, thoracic ganglia and the celiac-mesenteric ganglia (CMG) complex, was investigated by using lanthanum and horseradish peroxidase (HRP) as tracers with special attention to the neuronal and small granule-containing (SGC) cell area. After lanthanum perfusion, lanthanum tracer was present within the lumen of blood vessels. No lanthanum depositions were found in the extravascular space surrounding neurons in the superior cervical and thoracic ganglia. By contrast, an accumulation of lanthanum was observed in both luminal, abluminal and subendothelial surface of blood vessels in neuronal and SGC cell areas of the CMG complex and surrounding SGC cells in superior cervical ganglia. Injecting HRP revealed that all blood vessels of various sympathetic ganglia, either in neuronal or in SGC cell areas, were impermeable to HRP. HRP reaction product was limited to the vascular lumen and macrophages. The escape of HRP was obstructed by the junctional complex at intercellular clefts of endothelia and also by the diaphragms of the fenestrated capillaries associated with SGC cells. We conclude that there are different properties in the blood-ganglion barriers among rat sympathetic ganglia: (1) continuous capillaries in superior cervical ganglia and thoracic ganglia provide an efficient blood-ganglion barrier that prevents the penetration of tracers, and (2) capillaries in the CMG complex and in regions of the superior cervical ganglia that contain SGC cells possess a selective blood-ganglion barrier that discriminates between tracers based on their molecular sizes.

Morphological observations of small granule-containing (chromaffin) cells in the celiac ganglion of the guinea pig, with emphasis on cell contacts.

Utilizing electron microscopic observation, several contacts between small, granule-containing cells (SGC) and postganglionic neurons (PGN) in the celiac ganglion of the guinea pig have been observed. A SGC in very close association with a PGN was seen to receive a distinct synaptic contact that contained many vesicles with dense cores. This contact was morphologically unlike cholinergic synapses previously reported on chromaffin cells. Because the SGC and PGN were clearly separated by a thin rim of satellite cell cytoplasm mutual to both cells, it is not known how or if the SGC would possibly exert a synaptic or paracrine effect on the PGN. Also, intraganglion SGC existed as large well-vascularized islands within the celiac ganglion. These intraganglion clusters sometimes contained more than 50 cells and perhaps could be considered to function as localized neuroendocrine components within the ganglion by secreting granule products into the nearby blood vessels for local or distant effects, although this certainly is not known. This work reports a unique synaptic ending upon a single-occurring SGC, which, in turn, closely approximates a ganglion neuron in a soma-somatic relationship. In addition, a very close association (but no actual contact) was observed between granule-containing processes, presumably emanating from the intraganglion clusters, and PGN. Whatever the function of ganglionic SGC may be, the exact relationship between SGC and PGN presumably would be of great interest and potential importance.

Small granule-containing (SGC) cells in the hamster adrenal medulla.

In addition to adrenalin (A)- and noradrenaline (NA)-containing cells in the hamster adrenal medulla, a third type of small granule-containing (SGC) cells was identified. These cells were characterized by their small size (about 15 microns in diameter) and location adjacent to A-cells. Numerous pleomorphic dense-cored cytoplasmic granules (306 +/- 44.5 nm x 204.5 +/- 58.3 nm, mean +/- standard error) were present in their cytoplasm. The ultrastructure of these granules were similar to that of NA-containing granules but smaller in size. The granular inclusions of the granules were moderate to high in electrol density. The cytoplasm of the SGC cells contained short profiles of rough endoplasmic reticulum and some free ribosomes.

Glucocorticoid-induced PNMT-immunoreactive sympathetic cells in the superior cervical ganglion of the rat.

Light and electron microscopic immunocytochemical techniques were used to study the effect of glucocorticoids on the development of phenylethanolamine-N-methyltransferase (PNMT)-immunoreactive cells in the superior cervical ganglion (SCG) of early postnatal rats. Rats were injected daily with hydrocortisone acetate on postnatal days 2-6. The first PNMT-immunoreactive cells were detected 6 hours after the first glucocorticoid injection and their number increased after subsequent injections. No PNMT-immunoreactive cells were detected in uninjected controls. PNMT-immunoreactive fibres were seen in the ganglion 6 hours after the first glucocorticoid injection. The PNMT-immunoreactive cells consistently showed processes 2 days after beginning the glucocorticoid treatment, and long processes and fibre networks were seen in ganglia of 7-day-old rats. However, no PNMT-immunoreactive fibres were seen in the iris, which is innervated by the SCG. Ultrastructurally, most of the PNMT-immunoreactive cells had the look of small granule-containing (SGC) cells, including heterochromatin clumps along the nuclear envelope and in the center of the nucleoplasm as well as dense core vesicles. SGC cells, nonimmunoreactive to PNMT antiserum, also were seen. However, some PNMT-immunoreactive cells showed ultrastructural characteristics of nerve cells. In contrast to the SGC cells, these cells were characterized by a voluminous cytoplasm, dispersed nuclear heterochromatin, and a lack of granular vesicles. These results demonstrate that glucocorticoids induce PNMT immunoreactivity both in SGC cells and also in cells with characteristics of principal neurons.

Small granule-containing cells in the heart of the toad (Bufo melanostictus).

This study reveals the presence of small granule-containing cells in the heart of the toad, Bufo melanostictus. The cells were small in size (5-25 microns in diameter) and located in the interatrial septum. The small cells occurred singly or in small clusters within the cardiac ganglia or near the myocardial cells. They were characterized by numerous large dense core vesicles (80-300 nm) in their cytoplasm. With 5-hydroxydopamine treatment, the granularity of the large dense core vesicles was greatly intensified. The large dense core vesicles were variable in size and shape and extended into the long and short processes of the cells. Some of these processes were in close contact with myocardial cells. Other cytoplasmic organelles included rough endoplasmic reticulum, free ribosomes, randomly distributed mitochondria and glycogen particles. Individual cells or cell clusters were usually ensheathed by a thin layer of cytoplasm from sheath cells. The small granule-containing cells in the present study correspond to the catecholamine-containing (SIF) cells described by earlier workers. These cells presumably regulate muscular and ganglionic activities by virtue of their close association.

New synapses associated with the granule-containing cells of rat sympathetic ganglia.

The synapses of the rat superior cervical sympathetic ganglion were studied with both conventional and ultrastructural histochemical methods. Besides the cholinergic synapses polarized from preganglionic fibers to sympathetic ganglion neurons, two morphologically and functionally different types of synapses were observed in relation to the small granule-containing (catecholamine-containing) cells of the rat superior cervical ganglion. The first type is an efferent adrenergic synapse polarized from granule-containing cells to the dendrites of the sympathetic ganglion neurons. This type of synapse might mediate the inhibitory effects (slow inhibitory postsynaptic potentials) induced by catecholamines on the sympathetic neurons. The second type is a reciprocal type of synapse between the granule-containing cells and the cholinergic preganglionic fibers. Through such synapses, these cells could exert a modulating effect on the excitatory preganglionic fibers. Therefore, we propose that these cells, through their multiple synaptic connections, exhibit a local modulatory feedback system in the rat sympathetic ganglia and may serve as interneurons between the preganglionic and postganglionic sympathetic neurons.

Neuropeptide Y (NPY)-like immunoreactivity in rat sympathetic neurons and small granule-containing cells

The distribution of neuropeptide Y-like immunoreactivity (NPY-LI) was examined in the rat superior cervical and hypogastric ganglia. NPY-LI was localized in the majority of the sympathetic neurons, a few small granule-containing (SGC) cells and nerve terminals. Most of the NPY-immunoreactive sympathetic neurons were also tyrosine hydroxylase (TH)-immunoreactive but in hypogastric ganglia few neurons with NPY-LI were devoid of TH-immunoreactivity. Electron microscopically NPY-LI was found in the Golgi complexes of sympathetic neurons, in large cytoplasmic granules (100–150 nm in diameter) of the SGC cells and in large dense-cored vesicles (80–100 nm in diameter) of the nerve terminals. NPY-LI coexists mainly with noradrenaline in sympathetic neurons, and may have regulatory functions in sympathetic ganglia and in target organs.

Culture of intramural cardiac ganglia of the newborn guinea-pig. I. Neuronal elements.

The ultrastructure of cultured intrinsic neurones and SIF (small intensely fluorescent) cells dissociated from the atria and interatrial septum of newborn guinea-pig heart has been studied for the first time and compared with these cells in situ. Mononucleate and binucleate neuronal somata and their processes were observed in the culture preparation; their ultrastructure was similar to that of neurones in intracardiac ganglia observed in situ. The number of neurites associated with neuronal cell bodies increased after the first week in culture. A subpopulation of intracardiac neurones showed abnormalities in culture, comparable to the changes previously described in neurones of the monkey heart after unilateral vagotomy in situ. Small granule-containing cells were observed in culture, corresponding to those described in the heart in situ. One type of large process in the culture preparation containing densely packed mitochondria has not been seen in situ, suggesting that changes in cell ultrastructure due to the conditions of culture cannot be discounted. However, the ultrastructure of the cultured cells was, for the most part, consistent with that of the same cell type in situ, indicating that the culture preparation may be a useful model for investigation of the roles and interactions of intramural neurones in the heart, which are inaccessible for such studies in situ.

Outgoing synapses of small granule-containing cells in the rat superior cervical ganglion after post-ganglionic axotomy.

Small granule-containing cells are intrinsic and interneurone-like in the rat superior cervical ganglion, being innervated by preganglionic axons and giving outgoing synapses of asymmetrical type to the principal neurones. A quantitative ultrastructural investigation has been made of the effect on these outgoing synapses of axotomy of the major post-ganglionic nerve trunks 18.5 h-390 days previously. Cutting, or cutting and ligating, the internal and external carotid nerves 2-3 mm from the ganglion in rats aged 1.5-5.5 months resulted in a statistically significant mean loss of up to 85% of the asymmetrical synapses given by small granule-containing cells in the injured ganglion. The reduction of synapses was maximal 5-9 days post-operatively, and thereafter the incidence of synapses showed significant signs of progressive recovery. The time course and magnitude of the change in incidence of these synapses resembled those found earlier (Matthews & Nelson, 1975) for the loss of preganglionic synapses to principal neurones in the same ganglia, and after an identical post-ganglionic lesion. Control experiments showed that there was no loss of outgoing synapses from the small granule-containing cells as a result of surgical stress or of simple ageing. Older rats (5.5 and 13 months) showed a small but significant increase in the incidence of these synapses. Unilateral post-ganglionic axotomy produced the same reaction in the injured ganglia as did bilateral lesions. Uninjured ganglia contralateral to unilateral axotomies, however, also showed some deficit of outgoing synapses from small granule-containing cells, but this was slight, amounting to 9.9% over-all in comparison to normal values in young rats, and this difference did not reach statistical significance. Cutting the cervical sympathetic trunk to produce preganglionic denervation 2 days before surgical removal of ganglia for analysis did not alter the incidence of outgoing synapses of the small granule-containing cells, either in ganglia post-ganglionically axotomized 5-128 days earlier or in contralateral ganglia, indicating that at no stage was any significant proportion of these synapses given to preganglionic axons. These findings suggest that most of the outgoing synapses from the intra-ganglionic small granule-containing cells are directed to principal neurones whose axons leave with the injured branches, the internal and external carotid nerves.(ABSTRACT TRUNCATED AT 400 WORDS)

Incoming synapses and size of small granule-containing cells in a rat sympathetic ganglion after post-ganglionic axotomy.

A quantitative ultrastructural study has been made of the reaction of the incoming synapses of small granule-containing cells after axotomy of the major post-ganglionic branches of the superior cervical ganglion of the young adult rat. These cells are intrinsic and interneurone-like in this ganglion, receiving a preganglionic input and giving outgoing synapses to principal post-ganglionic neurones. Unlike their outgoing synapses, which are lost after post-ganglionic axotomy (Case & Matthews, 1986), the incoming synapses of the small granule-containing cells in axotomized ganglia increased in incidence post-operatively. The increase first became clearly evident 5-7 days post-operatively and was greater, being both more sustained and progressive, after bilateral than after unilateral axotomy. After bilateral axotomy the incidence of incoming synapses rose to more than four times that of normal ganglia and was still elevated at 128 days post-operatively, but was within normal limits at 390 days. After a unilateral lesion, increases of similar extent and time course to those in the axotomized ganglia were seen in the incoming synapses of small granule-containing cells in the uninjured contralateral ganglia. The incoming synapses of the small granule-containing cells are multifocal, i.e. show several points or active foci of synaptic specialization. The increase in synapses expressed itself both through an increased incidence of these synaptic active foci per nerve terminal and through an increase in the number of presynaptic nerve terminal profiles associated with the cells. Control observations indicated that the increase in synapses was not due to surgical stress, nor was it attributable solely to post-operative ageing. The nerve terminals which were presynaptic to the small granule-containing cells post-operatively were all of preganglionic origin: no incoming synapses or presynaptic nerve terminals remained at 2 days after a preganglionic denervation of axotomized or contralateral ganglia, at whatever stage this was performed throughout the range of survival intervals. There was some evidence that the synapses had increased by sprouting, including terminal sprouting, of the preganglionic nerve fibres. In the shorter term there was an increase in the proportion of small nerve terminal profiles. In the longer term the mean size of the terminal profiles increased, and very large terminals of unusual form were seen. After post-ganglionic axotomy, and in particular after a bilateral lesion, the small granule-containing cells became hypertrophied.(ABSTRACT TRUNCATED AT 400 WORDS)

Denervation-induced formation of adrenergic synapses in the superior cervical sympathetic ganglion of the rat and the enhancement of this effect by postganglionic axotomy

A study has been made at the ultrastructural level of the effects of denervation and axotomy on the synapse population of the rat superior cervical ganglion. Superior cervical ganglia were subjected unilaterally to acute (survival, 48 h) or chronic preganglionic denervation (survival, 41–189 days) by cutting the cervical sympathetic trunk; in chronic denervation experiments regeneration of preganglionic nerve fibres into the ganglion was prevented by suturing the proximal (caudal) stump of the trunk into the sternomastoid muscle. In some chronic experiments the preganglionic denervation was combined with simultaneous crush axotomy of the major postganglionic branches of the ganglion, the internal and external carotid nerves (axotomized-denervated ganglia). Control observations were made in contralateral ganglia and in ganglia from normal rats. After excision and before fixation, ganglia were incubated briefly in the presence of 5-hydroxydopamine to label adrenergic vesicles. Chronic denervation caused a statistically significant 12% decrease from control values in the cytoplasmic minor axes of the principal ganglionic neurones; axotomy combined with chronic denervation led to a 6% increase in this dimension, which was not statistically significant. The minor axes of the neuronal nuclei did not differ significantly from control values in either type of experiment. Axotomy combined with denervation led however to a 36% decrease in the incidence of nucleated neuronal profiles per unit area of ganglion. Counts of synapses were made in the various classes of ganglia and their incidence was expressed per nucleated neuronal profile, to permit comparison within and between experiments. Normal and control ganglia showed a high incidence of synapses of preganglionic cholinergic type. Nerve terminal profiles and synapses containing small dense-cored vesicles, as distinct from the efferent synapses of small granule-containing cells, were not found to be present on the principal neurones or their dendrites in these ganglia, despite strong 5-hydroxydopamine labelling of small dense-cored vesicles within cell bodies and dendrites. After acute denervation extremely few residual synapses were found in the ganglion, in areas remote from small granule-containing cells, and these residual synapses were of the cholinergic type. Acute denervation led to the appearance of vacated or isolated postsynaptic densities; such densities were also found, but were fewer in number, in chronically denervated and axotomizeddenervated ganglia. Chronic denervation was associated with the appearance of new synapses, in the proven absence of regeneration of the preganglionic nerve fibres, amounting overall to 12% of the control incidence of synapses per nucleated neuronal profile. The majority of these synapses arose from nerve endings containing a variable population of small dense-cored vesicles which became specifically labelled by 5-hydroxydopamine, indicating that they were of the adrenergic type. The numerical incidence of these synapses showed a significant correlation with the post-operative survival interval. When chronic denervation was combined with post-ganglionic axotomy, the incidence of synapses per nucleated neuronal profile was 32.6% of the control incidence of synapses. The incidence of synapses from nerve terminals containing small dense-cored vesicles in these ganglia was increased three-fold when compared with that in the chronically denervated ganglia. In comparison with acutely denervated ganglia, both chronically denervated and axotomized-denervated ganglia showed also a statistically significant increase of synapses from nerve terminals containing regular clear vesicles but there was no significant difference in the incidence of these synapses between the two long-term experimental groups. Possible post-operative origins of the two classes of synaptic terminals, the one containing small dense-cored vesicles and the other, regular clear vesicles, are discussed. The most likely source of both is considered to be nerve sprouts arising from the intraganglionic portions of the post-ganglionic axons, of adrenergic and cholinergic neurones, respectively. The possible sources of stimuli for sprouting in the denervated and axotomized-denervated ganglia are discussed. Several sources are likely, including the products of neuronal and nerve degeneration and “sprouting factors” arising from the ganglionic neurones, their satellite cells and, or, their targets; these might interact with or be superimposed upon intrinsic changes in the metabolic machinery of the denervated, or axotomized-denervated, neurones. The source of postsynaptic sites for the novel adrenergic synapses is also discussed.

A quantitative study of structural features, synapses and nearest-neighbour relationships of small, granule-containing cells in the rat superior cervical sympathetic ganglion at various adult stages

Groups and sub-groups (clusters) of small granule-containing cells (“small cells”) were analysed at 3 and 6μm intervals and in serial sections, in rats aged 2–13 months. Fully intraganglionic clusters of small cells were all found to receive an incoming (“afferent”) innervation, of the order of 3–6 afferent terminals per cell, derived from axons of preganglionic type via multifocal. symmetrical, mainly axosomatic synapses. No evidence was obtained of sharing of preganglionic inputs between small cells and principal neurones. Intraganglionic clusters also regularly gave outgoing (“efferent”) synapses of the asymmetrical type, of the order of 2–6 per cell, to intraganglionic nerve elements; 30–50% of these synapses were given from somata, 50–70% from processes of the small cells. Whenever the postsynaptic structure was identifiable these synapses were all found to be given to postganglionic neurones or their dendrites, principally to spine-like processes or slender twigs. In some ganglia a few efferent synapses to other small cells were observed; these were of the symmetrical type. Efferent synapses to nerve profiles resembling chemosensory axon terminals, also of the symmetrical type, were extremely infrequent (fewer than 1% of all efferent synapses) in intraganglionic small cell groups and appeared virtually restricted to glomus-like clusters of small cell, which lay intracapsularly, or in and near the bases of nerves entering or leaving the ganglion. Almost all groups and clusters of small cells were located near to fenestrated capillary vessels, which are not found elsewhere in the ganglion. The implications of possible non-synaptic release of material from small cells via membrane regions not covered by satellite cell cytoplasm, were explored in a nearest-neighbour analysis. These “exposed” regions comprised 1–3% of the small cell surface, a proportion comparable with those engaged in receiving afferent synapses or in giving efferent synapses. The majority of such regions faced toward other nerve profiles (axons and dendrites) ensheathed in satellite cytoplasm (mean, 30%), intraganglionic tissue spaces wider than 3 μm (mean, 30%) or other small cells (mean, 14%); 25% faced toward blood vessels, but of these vascularly directed regions, only one fifth (or 5% of the total) on average faced directly toward fenestrated endothelium, the rest being non-fenestrated and/or separated by pericyte processes from the exposed regions of small cell membrane. Thirty-three percent of the small cells in a sample of 242 lay within 2μm of the nearest blood vessel. Thus the vascular relationship is close, but vascular fenestrations would not appear to provide the major or most direct route for the distribution of secretions from the small cells. Serial section analyses showed variation between small cells within a cluster and also between clusters in the extent of their synaptic and other relationships: some small cells lacked exposed membrane, some gave no efferent synapses, whereas others exhibited both features simultaneously. In older rats (up to 13 months) the afferent synaptic terminals upon the small cells were larger and gave more synaptic foci, though the terminals themselves were not more numerous; points of efferent synapse from the small cells increased in incidence; processes of the small cells increased in volume and incidence; and there was evidence of increasing separation of small cells, with a shift of intercellular attachments from the somata out on to the processes. The proportion and distribution of regions of exposed membrane remained relatively constant. The cytoplasmic volume of the small cells was found to vary according to the incidence of afferent synaptic terminals and to the weight of the rat. These findings are discussed in relation to the possible actions of the small cells. It is concluded that the small granule-containing cells in this ganglion of the rat are consistently both interneurone- and paraneurone-like, exerting a focused synaptic influence upon the principal neurones in addition to a more diffuse non-synaptic influence which may include both preganglionic axons and postganglionic neurones, as well as other small cells and the ganglionic vasculature. Physiological and pharmacological evidence suggests that their effects on ganglionic transmission may be directly inhibitory or indirectly facilitatory, or both; the present observations suggest that these effects can be precisely recruited, possibly differentially from principal neurone activation, and may be directed to selected pathways through the ganglion.

Fine structure of the small, granule-containing cells in the superior cervical ganglia of hydrocortisone-treated early postnatal and adult rats.

Hydrocortisone injections into rats on postnatal days 3-9 caused an increase in the number of small granule-containing cells in the superior cervical ganglia. These cells, corresponding to the small, intensely fluorescent cells, showed an extensive rough endoplasmic reticulum, a large Golgi apparatus and a very large number of granular vesicles. In addition to the granular vesicles, 70-160 nm in diameter, in which the dense core filled most of the vesicle, most cells of the hydrocortisone-injected rats contained also larger granular vesicles, up to 350 nm in diameter, in which the dense core was eccentrically located. A minority of the cells contained only granular vesicles 70-100 nm in diameter, which was the only type seen in the saline-treated control rats. Thirty days after discontinuation of the hydrocortisone treatment, most of the cells with large granular vesicles had disappeared, and only two profiles of such cells were seen on day 40. The other small cells contained only granular vesicles 70-160 nm in diameter, and these cells could not be distinguished from the small granule-containing cells of 40-day-old control rats treated early postnatally with saline. Hydrocortisone treatment, first on days 3-9 and subsequently on days 40-46, caused reappearance of the small granule-containing cells with large granular vesicles up to 350 nm in diameter, the dense core of which was eccentrically located. Hydrocortisone treatment on days 40-46 only was not followed by appearance of such cells in rats treated with saline on days 3-9.

Fine-structural and degenerative features in adult and aged human synpathetic ganglion cells

Sympathetic ganglia, either cervical and upper thoracic or lumbar, were removed from adult and aged patients suffering from circulatory deficiencies in their upper on lower extremities, respectively. The ganglion cells had several features that can be associated with age. Lipofuscin was ample in all ganglion cells and was usually polarly concentrated. Its amount tended to increase with age and it was present also in the glia cells. Lipofuscin autofluorescence often prevented the visualization of the formaldehyde induced fluorescence for catecholamines. At the electron microscopic level, pigment bodies were seen to be composed of three different kinds of osmiophilic properties: (1) gray component that had (2) dark patches dispersed into it and (3) pale, oval, incorporated droplets. In principal ganglion cells, the frist two formed the major part, the pale one taking over in the small granule-containing cells. Various inclusion bodies included a cylinder-shaped type that had a varying pattern of rod-like structures inside it. Myelin figures (laminar bodies) were sometimes found to fill neurite profiles, occasionally with random mitochondrial accumulations. These bore a distant resemblance to the primitive type of neuritic (senile) plaques, although none of the patients was diagnosed to have, for example, Alzheimer's disease or senile dementia of the Alzheimer type. Nevertheless, it appears to us that it might be possible to find coexistent neuropathological changes in peripheral sympathetic ganglia in diseases affecting primarily the central nervous system.

Basal-granulated cells in human Brunner's glands.

Basal-granulated cells (BGC) in the human duodenal bulb were observed by light and electron microscopy, and both the cell types and their population densities in the duodenal crypts and in the Brunner's glands were compared. The number of the BGC in the Brunner's glands was much smaller than in the crypts. On the basis of their ultrastructural features, nine types of BGC, i.e. an EC cell, N cell, D cell, D1 cell, S cell, I cell, G cell, L cell and P cell were identified in the human duodenal bulb. In the duodenal crypts, as is generally recognized, EC cells were most numerous, making up 40% of the total BGC. N cells and D cells were around 10% of the total, and S cells, I cells and L cells were less than 10%, respectively. By contrast, in Brunner's glands, D cells and small granule-containing cells such as S cells, I cells and D1 cells were predominant, accounting for about 80% of the total BGC. EC cells and N cells were about 10% or less, respectively. These results indicate that the Brunner's glands are definitely different from the ordinary intestinal mucosa in regard to their BGC population, and are considered to have endocrine functions mainly performed by D1 cells, S cells and I cells.

Catecholamine-storing cells in the adrenal medulla of the pre- and postnatal rat. Acetylcholinesterase as a means for early discrimination of cell types.

The development of the rat adrenal medulla was studied at the ultrastructural level with particular emphasis placed on early discrimination of different catecholamine-storing cells. The first granule-containing cells, phaeochromoblasts, were seen at day 15 of gestation migrating into the anlage of the cortex. These cells were characterized by a few small granules (80-120 nm in diameter) and a high nuclear to cytoplasmic ratio. Presumably due to differentiation into chromaffin cells, they were no longer present after the eight postnatal day. Maturation of phaeochromoblasts was indicated by an increase in number and size of their storage granules and a decrease in the nuclear to cytoplasmic ratio. Noradrenaline and adrenaline cell types were first clearly discernible at day 21 of gestation. Another cell type, a giant cell, was also recognized at this stage. In the adult animal, noradrenaline, two morphologically different types of adrenaline, and small granule-containing cells were observed. By applying acetylcholinesterase histochemistry, it was found that at day 17 of gestation a small population of granule-storing cells showed strong positive staining in the endoplasmic reticulum. In the adult animal this cell type was further characterized by small-storage granules. Other chromaffin cells began to show weak staining with the endoplasmic reticulum at day 19 of gestation. This staining appeared more frequently within adrenaline than noradrenaline cells. However, even in the adult animal many cells of both types were completely negative. It is concluded that acetylcholinesterase histochemistry is a useful method for early discrimination of small granule-containing cells in the developing rat adrenal medulla.

Histology and ultrastructure of the adrenal gland ofRhacophorus leucomystax(Amphibia, Anura)

Abstract Each of the two adrenal glands of Rhacophorus consists of a strip lying along the lateral edge of the ventral surface of the ipsilateral kidney. The gland is composed of Interrenal, Stilling and Chromaffin cells. The Chromaffin cells, according to their granule content, may be divided into Adrenaline-, Noradrenaline-, and Small Granule Containing-Cells. The structure of the gland is compared with that in other amphibians; its peculiar affinity with the adrenal gland of Rana is discussed.