Golgi Study Research Articles

Morphological alterations of hippocampal pyramidal neurons heterotopically transplanted into the somatosensory cortex of adult rats: a quantitative Golgi study.

A characteristic feature of hippocampal organization is the laminated termination of extrinsic and intrinsic afferents. At present, it is not known to what extent these layer-specific fiber projections modulate the development and final shape of the dendritic arbor of hippocampal target neurons. In the present study, pieces of late embryonic (E18) rat hippocampus were transplanted heterotopically into a cavity in the somatosensory cortex of 6-8 week-old recipient rats. Here, the transplanted neurons differentiated and survived up to several months in the absence of their specific extrinsic afferents. Moreover, tracing of transplant connections with the carbocyanine dye DiI revealed only a limited projection between the transplant and the host neocortex. Golgi-impregnated transplants were used to analyze the postsynaptic structures (dendrites and spines) of hippocampal pyramidal cells quantitatively. Compared with controls, the transplanted pyramidal neurons showed a significant reduction of apical primary dendrites and basal dendritic branches, i.e. of peripheral dendritic portions that originate farther from the soma. In contrast, the number of basal primary dendrites originating directly from the perikaryon was enhanced. Spine density on the main apical dendritic shaft was significantly lower in all peripheral dendritic segments in transplanted neurons. We conclude from our results that the absence of layer-specific extrinsic afferents that normally terminate on peripheral parts of the dendritic arbor of hippocampal pyramidal neurons caused a reduction of these peripheral dendrites and spines. In contrast, the increase of dendrites and spines near the cell body might be induced by intrinsic fibers that normally terminate on these proximal dendritic portions and are known to sprout under transplant conditions.

Prenatal development of fibrous (white matter), protoplasmic (gray matter), and layer I astrocytes in the human cerebral cortex: A Golgi study

The prenatal developmental histories of layer I, fibrous (white matter), and protoplasmic (gray matter) astrocytes have been studied in the human neocortex by the rapid Golgi method. The developmental route followed by each of these astrocytes is a distinct process which evolves from a specific precursor, occurs at a different time, and is linked to a specific event. The differentiation of layer I astrocytes is linked to the neocortex external glial limiting membrane (EGLM), that of fibrous astrocytes to the early white matter vascularization and maturation, and that of protoplasmic astrocytes to the late gray matter ascending vascularization and maturation. At the start of development, three glial precursors are established in the neocortex: 1) original radial neuroectodermal cells with nuclei above the primordial plexiform layer (PPL) by losing their ependymal and retaining their pial attachments become early astrocytes of layer I and EGLM components; 2) neuroectodermal cells with nuclei below the PPL that retain their pial and ependymal attachments become type I radial glial cells which are committed to the guidance of neurons and the early EGLM maintenance; and, 3) neuroectodermal cells that lose their pial but retain their ependymal attachment are transformed into type II radial glial precursors. By progressively losing their ependymal attachment, type II radial glia precursors become freely migrating cells, establish vascular contacts, and differentiate into fibrous astrocytes (and into oligodendrocytes?) throughout the subplate, developing white matter, and paraventricular regions. After the formation of the gray matter, additional layer I astrocytes are needed for the EGLM late prenatal and postnatal maintenance because type I radial glia cells start to regress and to reabsorb their EGLM endfeet. A late ependyma-to-pia migration of glial precursors progressively repopulates layer I with additional astrocytes and establishes the ephemeral subpial granular layer (SGL) of Ranke. From the 15th week of gestation to the time of birth, late astrocytes of layer I lose their EGLM attachments, migrate freely into the maturing gray matter, establish vascular contacts, and differentiate into protoplasmic astrocytes. The protoplasmic astrocytes of the gray matter evolve from transformation of layer I astrocytes rather than from radial glia cells as is generally believed.

Substance P-immunoreactive neurons in the human retina.

Substance P (SP) is a neuropeptide that acts as a neurotransmitter or a neuromodulator in the retina. The aim of this study was to identify the type(s) and the distribution of the SP-immunoreactive (SP-IR) cells in the human retina. We have used an antiserum to SP to immunostain neurons in postmortem human retinae. Immunostained retinae were processed with the avidin-biotin complex (ABC) to visualize the cells either whole mounted in glycerol or embedded in plastic. Some retinae were also sectioned at 20 microns in order to obtain radial views of stained cells. SP-IR amacrine cells stain intensely and appear to be of a single type in the human retina. They are large-field cells with large cell bodies (16 microns diameter) lying in normal or displaced positions on either side of the inner plexiform layer (IPL). Their sturdy, spiny, and appendage-bearing dendrites stratify in stratum 3 (S3) of the IPL, where many overlapping, fine dendrites intermingle to form a plexus of stained processes. Either cell bodies or primary dendrites emit an "axon-like" process that, typically, divides into two long, fine processes, which run in opposite directions for hundreds of micrometers in S5 and S3 before disappearing as distinct entities in the stained plexus in S3. Long, fine dendrites also pass from the dendritic plexus to run in S5 and down to the nerve fiber layer to end as large varicosities at blood vessel walls. In addition, fine processes are emitted from the dendritic plexus that runs in S1, and some pass up to the outer plexiform layer (OPL) to run therein for short distances. The SP-IR amacrine cell has many similarities to the thorny, type 2 amacrine cells described from Golgi studies. In addition to the SP-IR amacrine cells, a presumed ganglion cell type is faintly immunoreactive. Its 20-22 microns cell body gives rise to a radiate, sparsely branched, wide-spreading dendritic tree running in S3. Its dendrites and cell body become enveloped by the more intensely SP-IR processes and boutons from the SP-IR amacrine cell type. The SP-IR ganglion cell type most resembles G21 from a Golgi study.

Mechanisms of neural patterning and specification in the developing cerebellum.

The cerebellar cortex is one of the best-studied regions of the CNS. For nearly a century, all of the cerebellar cell types and the patterns of their synaptic connections have been known. Much of this wealth of information comes from Ramon y Cajal's work (1889, 1911, 1960) with Golgi studies. Further infor­ mation on the development (Altman & Bayer 1985a-c, Rakic 1971, Miale & Sidman 1961), anatomy (Palay & Chan-Palay 1974), fiber tracts (BrodaI1981), and circuitry (Llinas & Hillman 1969) of the cerebellar cortex has emerged over the past several decades. The cerebellum provides a unique system for studying CNS development, combining the three classic patterns of CNS development-morphogenetic movements, the formation of ganglionic struc­ tures, and the establishment of neuronal layers-within one brain region. Remarkably simple in its basic plan, the adult cerebellar cortex contains only three layers and two principal classes of neurons. The abundance of one of these principal neurons, the granule cell, has enabled detailed analyses of the molecular mechanisms that underlie the basic steps in neuronal differentiation and has pointed out the role of local community factors in CNS neuronal development. Moreover, studies of naturally occurring mutations (Heintz et al 1993, Sidman 1968) and of targeted gene disruptions that block discrete steps in the development of this region (McMahon 1993, Joyner & Hanks 1991,

A Golgi study on the nucleus sphericus of the striated snake, Elaphe quadrivirgata.

The intrinsic organization of the nucleus sphericus (NS) was studied in the striated snake using the rapid Golgi method. The NS is a large aggregation of cells located in the posterior portion of the telencephalon and is, as a whole, cup-shaped with its hilus oriented in the rostral direction. From the periphery inward, the following three concentric layers were discernible: a marginal layer, mural layer and hilar layer. The marginal layer consists of scattered cells extending dendrites internally toward the hilar layer and externally into the anterior commissure (AC). The mural layer contains densely packed polygonal neurons with dendrites extending internally into the hilar layer and externally toward the marginal layer. The hilar layer consists of scattered cells whose dendrites extend in a transverse direction, distributing mainly in the hilar layer. The axons of the neurons in the marginal and mural layers travel rostromedially, and some axons can be traced into the AC, while those of the neurons in the hilar layer run rostrally, and some are lost among fibers of the accessory olfactory tract (AOT). The afferents to the NS are derived mainly from the AOT and AC. The AOT fibers travel caudally in a thick bundle through the hilus and are distributed totally within the hilar layer, forming a dense fiber plexus. The AC fibers enter the nucleus from the rostromedial aspect and run in an arched course, emitting numerous fine short collaterals.

Immunocytochemical analysis of bipolar cells in the macaque monkey retina

Transfer of visual information from photoreceptors to ganglion cells within the retina is mediated by specialized groups of bipolar cells. At least 10 different morphological types of bipolar cells have been distinguished in Golgi studies of primate retina. In the present study, bipolar cell populations in the macaque monkey retina were identified by their differential immunoreactivity to a spectrum of antibody markers. This enabled their spatial density and photoreceptor connections to be analysed. An antibody against the beta isozyme of protein kinase C (PKCA beta) labelled many cone bipolar cells. Invaginating (presumed ON) cone bipolar cells and rod bipolar cells were preferentially labelled with a monoclonal antibody raised against rabbit olfactory bulb. Flat (presumed OFF) bipolar cells were labelled with an antiserum against the glutamate transporter protein (GLT-1). Different populations of diffuse cone bipolar cells, which contact 5-10 cones, could be distinguished. The GLT-1 antiserum preferentially labelled the flat diffuse bipolar cell type DB2 (Boycott and Wässle, 1991, Eur. J. Neurosci. 3:1069-1088) as well as flat midget bipolar cells. Antibodies to calbindin (CaBP D-28K) labelled the flat diffuse bipolar cell type DB3 and (possibly) the invaginating diffuse bipolar cell type DB5. An antibody against the alpha isozyme of PKC labelled an invaginating diffuse bipolar cell type (DB4) as well as rod bipolar cells. Comparison of the spatial density of cone bipolar cell populations with that of photoreceptors suggests that each bipolar cell class provides a complete coverage of the cone array (each cone is contacted by at least one member of every bipolar cell class). These results support the classification scheme of Boycott and Wässle (1991) by showing that different diffuse bipolar cell classes express different patterns of immunoreactivity, and they reinforce the view that different spatial and temporal components of the signal from the photoreceptor array are processed in parallel within the primate retina.

Quantitative mapping of cytovhrome oxidase activity in the central auditory system of the gerbil: a study with calibrated activity standards and metal-intensified histochemistry

The objective was to obtain detailed topographic determinations of cytochrome oxidase activity in the gerbil central auditory system at the light microscopic level. Quantitative techniques were developed using (1) tissue standards calibrated to express histochemical measures as actual enzyme activity units, (2) densitometry and image analysis of histochemical reaction product formation, (3) spectrophotometry of cytochrome oxidase activity, and (4) a cobalt-intensified staining procedure compatible with autoradiography and other techniques requiring fresh-frozen brains without perfusion-fixation. Linear relationships between incubation time, section thickness, and activity of dissected brain regions, with their reaction product measured densitometrically were determined. Auditory structures with the high activities showed about 8 times the labeling intensity of the white matter or control sections inhibited with cyanide, glutaraldehyde, or heat. This indicated the high sensitivity of the method without loss of specificity. Specific activity for each of the 18 auditory structures measured were all above the units measured for whole brain homogenates, supporting the notion that basal levels of oxidative metabolism are greater for the auditory system. There was a progressive decrement in activity from brain stem to forebrain auditory structures. The more peripheral nuclei also showed a higher proportion of somatic as compared to neuropil reactivity. In contrast, auditory midbrain and thalamocortical regions were characterized primarily by neuropil reactivity. Comparison of intrinsic patterns of activity with morphological schemes to subdivide nuclei, showed a good correspondence with classical subdivisions derived from Golgi studies. The reported activities may provide a base of normative data in the gerbil for subsequent studies of central auditory functions. The method presented fulfilled established quantitative criteria and provided a more sensitive approach for regional mapping studies of brain cytochrome oxidase activity.

Dendritic and histochemical development and ageing in patients with Down's syndrome

Mental retardation and dementia characteristic of Down's syndrome (DS) have a complex pathogenesis. Golgi and immunohistochemical studies were done on DS patients and controls from foetuses and elderly adults. Golgi studies on the cerebral cortex revealed that the postsynaptic spines on the basal dendrites increase from neonate to 15 years of age and gradually decrease after 20 years in controls, but poorly increase in children and rapidly decrease in adults with DS. This deficient synaptogenesis and dendritic atrophy may be related to mental retardation. On the other hand, immunohistochemistry on proteins, whose genes are located on chromosome 21, revealed that c-terminal protein of beta-amyloid appears in neurons of DS, S-100-positive glia increases in the hippocampus of neonates and adults, and membrane protein OK-2 is expressed earlier and is more widespread in the DS brains. The overexpression and early appearance of gene products in DS brains may be related to the pathogenesis of or predisposition to mental disorders or to dendritic hypogenesis.

Commissural connections of the cat periaqueductal gray matter studied with anterograde and retrograde tract-tracing techniques

The commissural connections of the periaqueductal gray matter were investigated by light and electron microscopy by using the anterograde tracer Phaseolus vulgaris leucoagglutinin and the retrograde tracer horseradish peroxidase. In the first group of seven animals (1–7), single injections of Phaseolus vulgaris leucoagglutinin were performed iontophoretically (4.5 μA for 30 min) into various subdivisions of the periaqueductal gray matter. On light microscopic examination, injection sites were characterized by several immunolabeled neurons of different sizes and morphology, with the cytoplasm, nucleus and neuronal processes intensely stained. Many labeled fibers turned from injection sites toward all contralateral periaqueductal gray matter subdivisions, but anterograde labeling was densest in the regions homotopic to those injected. Commissural fibers bore along their course many en passant boutons of different sizes and morphology, and gave off spine-like processes, at the end of which one terminal bouton was observed. Labeled fibers branched into numerous collaterals which ended in a terminal array of 10–20 en passant and en grappe boutons. At the electron microscopic level, commissural axons were observed in close proximity to the cytoplasmic membranes of cells. Axon terminals formed symmetric or asymmetric synapses mainly on dendritic shafts of neurons and rarely on vesicle-containing profiles. Horseradish peroxidase experiments were carried out in four cats (1–4). The tracer was injected iontophoretically into different regions of the periaqueductal gray matter of three cats (1–3). Retrogradely labeled neurons giving rise to commissural connections had a morphology similar to that of polygonal, triangular and fusiform cells described in previous Golgi studies. The perikaryal cross-sectional area of commissural neurons was smaller than that of neurons projecting outside the periaqueductal gray matter (mean value of commissural neurons 149.77 μm 2 vs 261.19 μm 2 for projecting neurons), which were retrogradely labeled by pressure-injecting horseradish peroxidase into several targets of periaqueductal gray matter (4). Moreover, since the distribution of sizes of the two populations of the periaqueductal gray matter overlapped in the range of 90–300 μm 2, a considerable number of projecting neurons were as small as commissural neurons. The present results suggest that commissural fibers could reciprocally connect zones of the periaqueductal gray matter with similar functions, and originate from small and medium-sized neurons, some of which are also projecting neurons.

Synapses on axon collaterals of pyramidal cells are spaced at random intervals: a Golgi study in the mouse cerebral cortex

Synapses on axon collaterals of pyramidal cells are spaced at random intervals: a Golgi study in the mouse cerebral cortex

Synapses on axon collaterals of pyramidal cells are spaced at random intervals: a Golgi study in the mouse cerebral cortex.

In this study we investigated the arrangement of synapses on local axon collaterals of Golgi-stained pyramidal neurons in the mouse cerebral cortex. As synaptic markers we considered axonal swellings visible at high magnification under the light microscope. Such axonal swellings coincide with synaptic boutons, as has been demonstrated in a number of combined light and electron microscopic studies. These studies also indicated that, in most cases, one bouton corresponds precisely to one synapse. Golgi-impregnated axonal trees of 20 neocortical pyramidal neurons were drawn with a camera lucida. Axonal swellings were marked on the drawings. Most swellings were 'en passant'; occasionally, they were situated at the tip of short, spine-like processes. On axon collaterals, the average interval between swellings was 4.5 microns. On the axonal main stem, the swellings were always less densely packed than on the collaterals. Statistical analysis of the spatial distribution of the swellings did not reveal any special patterns. Instead, the arrangement of swellings on individual collaterals follows a Poisson distribution. Moreover, the same holds to a large extent for the entire collection of pyramidal cell collaterals. This suggests that a single Poisson process, characterized by only one rate parameter (number of synapses per unit length), describes most of the spatial distribution of synapses along pyramidal cell collaterals. These findings do not speak in favour of a pronounced target specificity of pyramidal neurons at the synaptic level. Instead, our results support a probabilistic model of cortical connectivity.

Calcium-binding protein parvalbumin-immunoreactive neurons in the rat olfactory bulb. 1. Distribution and structural features in adult rat.

The laminar distribution and morphological features of parvalbumin-immunoreactive [PV(+)] neurons, one of the subpopulations of GABAergic neurons, were studied in the rat olfactory bulb at a light microscopic level. In the main olfactory bulb of adult rats, PV(+) neurons were mainly located in the external plexiform layer (EPL), and a few were scattered in the glomerular layer (GL), mitral cell layer (ML), and granule cell layer (GRL); whereas PV(+) neurons were rarely seen in the accessory olfactory bulb. The inner and outer sublayers of the EPL (ISL and OSL) appeared to be somewhat different in the distribution of PV(+) somata and features of PV(+) processes. PV(+) somata were located throughout the OSL, and PV(+) processes intermingled with one another, making a dense meshwork in the OSL; whereas, in the ISL, PV(+) somata were mainly located near the inner border of the EPL, and PV(+) processes made a sparser meshwork than that in the OSL. PV(+) neurons in the EPL were apparently heterogeneous in their structural features and appeared to be classifiable into several groups. Among them there appeared five distinctive types of PV(+) neurons. The most prominent group of PV(+) neurons in the OSL were superficial short-axon cells, located in the superficial portion of this sublayer and giving rise to relatively thick processes, in horizontal or oblique directions, which usually bore spines and varicosities. Another prominent group of PV(+) neurons extended several short, branched dendrites with spines and varicosities, which appeared to intermingle with one another, making a relatively small, spherical or ovoid dendritic field around the cell bodies; most of them resembled Van Gehuchten cells reported in previous Golgi studies. A third distinctive and most numerous group of PV(+) neurons were of the multipolar type; their somata and processes were located throughout the EPL. Their relatively smooth processes with frequent varicosities and a few spines were extended horizontally or diagonally throughout the EPL. A fourth group, which could be a subtype of the multipolar type, were located in or just above th ML and extended several thin, smooth dendrites in the EPL, some of which appeared to reach the border between the GL and EPL. Occasionally, axon-like processes arose from their cell bodies and extended into the ML. This fourth type of PV(+) neuron was named inner short-axon cells. A fifth group of neuron was located in the ML; processes of these neurons were extended horizontally, so they were named inner horizontal cells.(ABSTRACT TRUNCATED AT 400 WORDS)

Growth of ectopic dendrites on cortical pyramidal neurons in neuronal storage diseases correlates with abnormal accumulation of GM2 ganglioside.

Ganglioside analysis and quantitative Golgi studies of the cerebral cortex of cats with ganglioside and nonganglioside lysosomal storage diseases reveal a correlation between the amount of accumulated GM2 ganglioside and the extent of ectopic dendrite growth on cortical pyramidal neurons. This correlation was not observed with any of the other gangliosides assayed for, including GM1 ganglioside. These results suggest a specific role for GM2 ganglioside in the initiation of ectopic neurites on pyramidal cells in vivo and are consistent with the developing hypothesis that different gangliosides have specific roles in different cell types dependent upon the receptor or other effector molecules with which they may interact.

Divergent axon collaterals originate in the estrogen receptive ventromedial nucleus of hypothalamus in the rat.

The ventromedial nucleus of the hypothalamus (VMH) plays a crucial role in the mediation of lordosis by integrating predominantly inhibitory limbic signals with cyclic variation of ovarian steroids and sending a stimulatory output to the midbrain, especially the periaqueductal gray (PAG). Tract-tracing studies have established projections of the VMH and Golgi studies have shown these neurons to frequently give rise to axon collaterals, but the anatomical pattern of shared projections has not been explored. We have used a combination of retrograde tracers to map VMH projections to the medial division of the medial preoptic nucleus (MPNm), posterodorsal division of the medial nucleus of the amygdala (MeApd), and the PAG. Neurons with dual projections were mainly confined to the VMHvl and represented 31%-37% of each projection subset. Neurons simultaneously projecting to the MPNm, MeApd, and PAG represented 7%-9% of each projection subset. By combining tract-tracing with steroid autoradiography, we found that approximately one-quarter of each projection subset in the VMHvl concentrated 3H-estradiol. Thus, some of the VMHvl neurons that communicate a facilitatory signal to the PAG may also act to stimulate lordosis through a feedback suppression of the net inhibition formed by efferent signals from the forebrain. The even distribution of estrogen binding among projection subsets suggests a lack of compartmentalization of estrogen-regulated processes that are relevant to lordosis.

Local circuit neurons immunoreactive for calretinin, calbindin D‐28k or parvalbumin in monkey prefronatal cortex: Distribution and morphology

In the cerebral cortex, local circuit neurons provide critical inhibitory control over the activity of pyramidal neurons, the major class of excitatory efferent cortical cells. The calcium-binding proteins, calretinin, calbindin, and parvalbumin, are expressed in a variety of cortical local circuit neurons. However, in the primate prefrontal cortex, relatively little is known, especially with regard to calretinin, about the specific classes or distribution of local circuit neurons that contain these calcium-binding proteins. In this study, we used immunohistochemical techniques to characterize and compare the morphological features and distribution in macaque monkey prefrontal cortex of local circuit neurons that contain each of these calcium-binding proteins. On the basis of the axonal features of the labeled neurons, and correlations with previous Golgi studies, calretinin appeared to be present in double-bouquet neurons, calbindin in neurogliaform neurons and Martinotti cells, and parvalbumin in chandelier and wide arbor (basket) neurons. Calretinin was also found in other cell populations, such as a distinctive group of large neurons in the infragranular layers, but it was not possible to assign these neurons to a known cell class. In addition, although the animals studied were adults, immunoreactivity for both calretinin and calbindin was found in Cajal-Retzius neurons of layer I. Dual labeling studies confirmed that with the exception of the Cajal-Retzius neurons, each calcium-binding protein was expressed in separate populations of prefrontal cortical neurons. Comparisons of the laminar distributions of the labeled neurons also indicated that these calcium-binding proteins were segregated into discrete neuronal populations. Calretinin-positive neurons were present in greatest density in deep layer I and layer II, calbindin-immunoreactive cells were most dense in layers II-superficial III, and parvalbumin-containing neurons were present in greatest density in the middle cortical layers. In addition, the relative density of calretinin-labeled neurons was approximately twice that of the calbindin- and parvalbumin-positive neurons. However, within each group of labeled neurons, their laminar distribution and relative density did not differ substantially across regions of the prefrontal cortex. These findings demonstrate that calretinin, calbindin, and parvalbumin are markers of separate populations of local circuit neurons in monkey prefrontal cortex, and that they may be useful tools in unraveling the intrinsic inhibitory circuitry of the primate prefrontal cortex in but normal and disease states.

Terminal patterns of the tegmental afferents in the interpeduncular nucleus: a Golgi study in the mouse

The intranuclear course, distribution and termination of the tegmental afferents in the interpeduncular nucleus (IP) were studied in the mouse by means of the rapid Golgi method. Primarily on the basis of terminal branching patterns and distribution areas, two types of afferents were distinguished. The type 1 fibers distribute mainly within the rostral half in the form of numerous glomerular endings, the size of which corresponds well with that of the tufted terminal dendrites of the IP neurons. On the other hand, the caudal half of the IP has far fewer fibers than the rostral IP and is innervated by the type 2 fibers, which follow a tortuous course, terminating in dense fiber plexus. Thus, the rostral and caudal IP are innervated in a different fashion by different afferents originating from tegmental regions. These results are discussed in relation to the distribution patterns of another conspicuous afferent system of the IP, the fasciculus retroflexus.

A Golgi study of human locus coeruleus in normal brains and in Parkinson's disease

The locus coeruleus (LC) of eight adults without neurodegenerative disease and eight patients with Parkinson's disease was investigated by means of the Golgi-Braitenberg method for formalin-fixed human autopsy material. As with Golgi studies in the rat and cat, two main neuronal classes could be demonstrated in the human LC: (i) medium-sized fusiform and multipolar LC neurons known to contain neuromelanin and (ii) smaller neurons of widely varying somatic shape and dendritic arborization which are considered to be intermingled neurons of adjacent brain stem nuclei not containing neuromelanin. In Parkinson's disease, the Golgi-impregnated medium-sized LC neurons were reduced in number. They showed marked reduction of dendritic length, severe loss of spines, dendritic varicosities and swollen perikarya. The last two findings could be due in part to Lewy-body inclusions. The smaller non-noradrenergic neurons did not show severe pathological changes by the Golgi impregnation technique, which is in line with the fact that only neuromelanin-containing LC neurons are affected in the pathological process of Parkinson's disease.

Parvalbumin‐containing neurons in the cerebral cortex of the lizard Podarcis hispanica: Morphology, ultrastructure, and coexistence with GABA, somatostatin, and neuropeptide Y

The morphology, fine structure, and degree of colocalization with GABA, somatostatin, and neuropeptide Y of parvalbumin-containing cells were studied with immunocytochemistry in the cerebral cortex of the lizard Podarcis hispanica. Parvalbumin-containing cells make up a morphologically heterogeneous population of spine-free neurons, displaying the morphological features of nonprincipal cells previously described in Golgi studies. Electron microscopically, parvalbumin-immunoreactive cell bodies are similar in all cortical areas and layers. The perisomatic input is moderate in number, and boutons with either round clear vesicles or flattened vesicles were observed making asymmetric or symmetric synaptic contacts, respectively. Parvalbumin-immunoreactive dendrites are smooth and almost completely covered with synaptic boutons of different types, most of which establish asymmetric contacts. Parvalbumin-immunoreactive boutons are concentrated around cell bodies of principal cells. They are large, containing abundant mitochondria and small pleomorphic vesicles, and establishing symmetric synaptic contacts with somata, proximal dendritic shafts, and axon initial segments of principal cells. Colocalization studies revealed that all the parvalbumin-containing cells are GABA-immunoreactive, representing only a fraction of the GABA-immunopositive cell population, and that parvalbumin- and peptide- (somatostatin and neuropeptide Y) containing cells show a negligible overlap. These results demonstrate that in the cerebral cortex of the lizard Podarcis hispanica, parvalbumin-containing cells represent a subset of nonprincipal GABAergic neurons largely involved in perisomatic inhibition, which are different from the peptide-containing cells, and suggest that they may include both axosomatic and axoaxonic cells.

Neuropathological study on cerebellum of macular mutant mouse heterozygote.

The hemizygote of the macular mutant mouse is clinically, biochemically and neuropathologically similar to a patient with Menkes kinky hair disease. The heterozygote of this mutant mouse was biochemically and neuropathologically examined. The copper content in the brain decreased in comparison with that in the normal littermate, although it was more than that in the hemizygote. In the Golgi study, abnormal Purkinje cells with somal sprouts, thick stem dendrites and dendritic focal swellings, which were seen in the hemizygote, were not observed in the heterozygote. Ultrastructurally, abnormal mitochondria were seen in the Purkinje cells in the anterior and middle cerebellar lobe of the heterozygote. Histochemically, cytochrome c oxidase activity decreased, especially at the anterior lobe in the cerebellar cortex of the heterozygote. This activity, as indicated by staining intensity, was in between that in the normal littermate and that in the hemizygote. The heterozygote did not show a mosaic pattern in the distribution of these neuropathological changes, although this mutant mouse shows x-linked recessive inheritance. Thus, our results lead to the conclusion that the neuropathological changes observed in this mutant mouse do not result directly from an abnormal gene in the Purkinje cell, but from the secondary effects of subsequent to presumptive copper deficiency.

Parvalbumin‐immunoreactive structures of the adult human entorhinal and transentorhinal region

Parvalbumin-immunoreactive structures in the entorhinal and transentorhinal region of the adult human brain were studied using the avidin-biotin-peroxidase technique. Parvalbumin-immunoreactive neurons and fibers (axons) were present in all layers (layer nomenclature according to Rose, 1927). The density of fibers was high in the islands of the superficial cell layer pre-alpha and in layer pre-beta and still heavier in pre-gamma. In the subjacent lamina dissecans it diminished abruptly and remained low in all layers of the internal principal stratum (layers pri-alpha, -beta, -gamma). This low density of fibers facilitated recognition of axon cartridges in layers pri-alpha and pri-gamma. Axon cartridges were also present within layers pre-beta and pre-gamma but were obscured by the dense fiber network there. Parvalbumin immunoreactivity was observed in the nerve cell soma and throughout the dendritic tree allowing the distinction of numerous nerve cell types. All parvalbumin-immunoreactive neurons belonged to the class of nonpyramidal neurons. Their lipofuscin pigment patterns differed distinctly from that of the pyramidal and modified pyramidal neurons. Based on their location, soma size, and dendritic arborization, they were grouped as large, medium-sized, and small neurons either of the multipolar or bipolar (vertical or horizontal) type. One type could be identified as an axo-axonic neuron, more specifically as a chandelier neuron generating axon cartridges. The dense fiber net within layer pre-gamma suggested the existence of another neuronal type, probably a neuron with an extended axonal ramification. The identified neurons were compared to neuronal types described in the literature from Golgi studies.