New strategies for the treatment of Parkinson's disease hold considerable promise for the future management of neurodegenerative disorders.

Neurodegenerative diseases are often considered incurable with no efficient therapies to modify or halt the progress of disease, and ultimately lead to reduced quality of life and to death. Our knowledge of the nervous system in health and disease has, however, increased considerably during the last fifty years and today, neuroscience reveals promising new strategies to deal with disorders of the nervous system. Some of these results have been implemented with success in the treatment of Parkinson's disease, a common neurodegenerative illness affecting approximately 1% of the population aged seventy or more. Parkinson's disease is characterized by a massive loss of dopaminergic neurons in the substantia nigra, leading to severe functional disturbance of the neuronal circuitry in the basal ganglia. A thorough description of basal ganglia circuitry in health and disease is presented. We describe how the functional disturbances seen in Parkinson's disease may be corrected at specific sites in this circuitry by medical treatment or, in advanced stages of Parkinson's disease, by neurosurgical methods. The latter include lesional surgery, neural transplantation and deep brain stimulation, together with future treatment strategies using direct or indirect implantation of genetically modified cell-lines capable of secreting neurotrophic factors or neurotransmitters. Advantages and disadvantages are briefly mentioned for each strategy and the implications for the future and the possible use of these interventions in other neurodegenerative diseases are discussed, with special emphasis on deep brain stimulation.

Oriented sectioning of irregular tissue blocks in relation to computerized scanning modalities: results from the domestic pig brain.

We present a new method allowing direct comparison between images obtained by present digital scanning modalities and histological sections from the same object. More specifically the paper illustrates how to orientate, embed, and section large irregular tissue blocks after magnetic resonance imaging (MRI) in such a way that accurate correlation of the digital data sets to histological sections is possible. The functionality and capability of the described procedure and slicing machine is illustrated by results from the pig brain. Accordingly, three pigs were MR-scanned, followed by perfusion fixation. The brains were removed, oriented according to the MR scans, embedded in alginate, and cut on a newly developed slicing machine. The tissue blocks were then stained to reveal grey and white matter and photographed before final sectioning on a cryostat into 80 microm thick sections which were Nissl-stained with toluidine. The results demonstrate how our method enables direct comparison between the pig brain MR images and the later obtained histological sections. The alginate embedding method and slicing machine offer the same possibilities for other parenchymateous organs and soft tissues and may, in addition, be of use in stereological analysis.

Convergence of thalamic and cholinergic projections in the 'dentate area' of lizards.

The small-celled part of the medial cortex (Cxms) in lizards is comparable to the hippocampal area dentata in mammals. As in mammals, most of the afferents to this cortical area are arranged in sharply delimited laminae. In reptiles this lamination pattern is species-specific. In the lizard Tupinambis nigropunctatus projections from the multisensory dorsolateral thalamic nucleus (Dla) terminate in the middle one-third of the outer plexiform layer throughout the whole rostrocaudal extent of Cxms. In Podarcis hispanica the thalamic projections terminate not only in the middle one-third of Cxms but also in the inner plexiform layer. To find out whether the species-related variation of thalamic projections to Cxms is a solitary phenomenon or is related to variations of other afferents of Cxms, we studied the relationships between the thalamic and cholinergic projections from the basal telencephalon in the medial cortex of three lizard families: the Lacertidae, the Teiidae and the Gekkonidae. In the gekkonid lizards Gekko gecko and Eublepharius macularius, Dla projections were studied with the anterograde tracer Phaseolus vulgaris-leucoagglutinin. Projections were found in only the rostral one-third of Cxms where the fibers terminate in the superficial half of the outer plexiform layer and in the deep half of the inner plexiform layer. From acetylcholinesterase staining in the Cxms of representatives of these three lizard families, it appeared that the main cholinergic afferents terminate in the same subregions and the same laminae as the Dla projections. Therefore, there seems to be a close association between thalamic and cholinergic afferents in the Cxms of lizards, irrespective of their precise location in the cortex of the various species. This suggests a functional relationship between these two afferents of the dentate area in lizards.

Distribution and morphology of serotonin-immunoreactive neurons in the brainstem of the New Zealand white rabbit.

The aim of the present study was to demonstrate the morphology and distribution of the serotonergic neurons in the brainstem of the New Zealand white rabbit by using a highly specific immunocytochemical procedure. It was possible to divide the serotonergic neurons into a rostral group, which is situated in the mesencephalon and the rostral part of the pons containing four serotonergic nuclei, and a caudal group, which is located in the medulla and the caudal part of the pons containing five serotonergic nuclei. The localization of the serotonergic neurons is presented in a detailed brainstem atlas, and the distribution of the serotonergic neurons is in accordance with results obtained by other authors in different species. Special emphasis was given to the fact that many of the serotonergic neurons were distributed in more lateral parts of the brainstem. The laterally orientated neurons, which were large and multipolar, were morphologically different from the serotonergic neurons in the midline, which were mostly small and relatively nonpolar. The serotonergic system of the New Zealand white rabbit has undergone a major lateralization, like the serotonergic system of man and higher primates, and it may therefore be excellently suited for experimental procedures directed towards the serotonergic system. The difference between serotonergic neurons localized in the midline and those situated laterally may reflect functional differences based on dissimilarity in connectivity and morphology, and this possible subspecialization of the serotonergic system is discussed in the context of present knowledge of serotonergic anatomy and function.

Postnatal development of zinc-containing cells and neuropil in the hippocampal region of the mouse.

The present study describes the postnatal development of zinc-containing boutons and their neurons of origin in the hippocampal region of the mouse. Ages investigated for the development of zinc-containing neuropil were postnatal days 0 (P0), P3, P7, P11, P15, P21, and P28. For zinc-containing cell bodies P7, P15, P21, and P28 were studied. In the area dentata, zinc-containing neuropil appeared first by P3 adjacent to the suprapyramidal limb of the granule cell layer and extended later toward the infrapyramidal limb. By P15, inter- and intralaminar gradients corresponded to those seen in adult animals. The appearance of labeled granule cells followed closely, although temporally delayed, the pattern of granule cell neurogenesis. All granule cells were labeled by P28. In the hippocampus proper, zinc-containing neuropil was seen by P0, but staining of the incipient mossy fiber zone was first visible by P3. Staining pattern and intensity developed gradually until they reached their mature appearance by P15. The distribution of labeled cells was identical to that seen in mature animals by P7 in CA3, but first by P21 in CA1. In the subiculum, neuropil staining first appeared proximally by P7, included all of this area by P11, and appeared mature by P21. A few labeled cells were seen in the proximal subiculum at all ages at which labeled cells were present in CA1. Labeled cells which extended further distally became first visible by P21. Their number and labeling intensity reached mature levels by P28. In the presubiculum, retrosplenial area 29e, and parasubiculum, neuropil staining first appeared by P3. The retrosplenial area 29e could be distinguished by P11. This area and the presubiculum reached their adult appearance by P21. This occurred first by P28 in the parasubiculum due to the late maturation of the parasubiculum a. Labeled cells were first seen by P7 in layer III of the presubiculum and by P15 in the retrosplenial area 29e and the parasubiculum. Cell labeling appeared mature by the same times as the neuropil staining. In the entorhinal areas a very light neuropil stain was apparent in the deeper layers by P0. A distinct rise in staining intensity was first observed by P7 in layers I-III. Thereafter, mature characteristics developed gradually and were attained by P21. Cell labeling was not seen in the medial entorhinal area. A few labeled cells were apparent by P7 in the lateral entorhinal area. After a slight increase by P15, numerous labeled cells were found in layer II and layer VI by P21. Their distribution and labeling intensity appeared mature by P28. Zinc-containing cells appear to represent cells formed late in the course of neurogenesis in all areas aside from the lateral entorhinal area. As far as intrinsic connections are concerned, it is the development of projections from this subset of neurons which is monitored in this study. We suggest that the appearance of zinc may contribute via its different effects on N-methyl-D-aspartate (NMDA) and non-NMDA glutamate receptors to the end of a developmental phase that is permissive to changes in synaptic efficacy. Species differences and alternative functions of zinc are considered.

Distribution of neurons of origin of zinc-containing projections in the amygdala of the rat.

The present study describes the distribution of neurons of origin of zinc-containing pathways in the amygdaloid complex of the rat, using the selenium method for simultaneous retrograde labeling of all zinc-containing neurons. With this method, vesicular ionic zinc is precipitated intravitally with selenium compounds and transported retrogradely to the parent neurons, where it can be visualized by silver amplification. Neurons labeled retrogradely with silver-amplified precipitate were observed in all amygdaloid nuclei except for the lateral olfactory tract nucleus, the accessory olfactory tract nucleus and the central nucleus. Very few labeled cell bodies were seen in the anterior amygdaloid area and the medial nucleus. The amygdalo-hippocampal area and the amygdalo-piriform transition area both showed a substantial number of labeled somata throughout their rostrocaudal extent. In the anterior cortical nucleus, very few labeled cell bodies were found in the rostral pole, whereas they were abundant in the caudal quarter of the nucleus. In the posterolateral cortical nucleus, the number of labeled cell bodies increased gradually; there were none in the rostral pole, but most of the neurons in the caudal part were labeled. The posteromedial cortical nucleus contained a great number of labeled somata, but with some variation in the rostrocaudal extent of the nucleus. Considerable numbers of labeled neurons were observed throughout the lateral nucleus. In the basolateral nucleus, a small number of labeled cell bodies was present in the rostral half, but a gradual increase was observed in the caudal direction. Finally, in the basomedial nucleus, very few labeled cell bodies were present in the rostral two-thirds, whilst a considerable number was encountered in the caudal one-third. Possible functional implications of neuronal zinc are considered. The distribution of neurons of origin of zinc-containing projections has been compared with previously described intrinsic connections of the rat amygdala, and tracts that may possibly be zinc-containing are outlined and discussed. It is concluded that in all probability a substantial proportion of the intrinsic connectivity of the rat amygdaloid complex is zinc-containing.

Cytoarchitecture and staining for acetylcholinesterase and zinc in the visual cortex of the Parma wallaby (Macropus parma).

Cytoarchitecture and distributions of acetylcholinesterase-containing fibers and zinc-containing neuropil are described in the primary visual cortex of a metatherian, the Parma wallaby (Macropus parma). Although some cytoarchitectural features of layer III suggest that a subdivision and a corresponding layer IIIa-c terminology may be employed, neurochemistry is more concisely described using a simple layer I-VI terminology. Horizontal acetylcholinesterase-containing fibers in layer I take on a vertical course as they pass through layer II to form a reticulate pattern in upper layer III. Fibers gather into vertical groups in lower layer III and, markedly, in layer IV. No dominant orientation is seen in layer V, whereas an horizontal course is often seen in layer VI. Zinc-containing neuropil is very dense layers I, II and upper III, where particles are homogeneously distributed. Particles begin to form strands in lower layer III and form conspicuous vertical clusters in an otherwise almost unstained layer IV. There is a sharp transition to a densely and homogeneously stained layer V, a decrease in staining intensity in layer VI, and a further decrease within layer VI towards the white matter. The distribution of acetylcholinesterase-containing fibers in M. parma, a metatherian representative, adds to the number of species-specific patterns observed in eutherians. The distribution of zinc-containing neuropil in M. parma resembles the consistent pattern seen in eutherian species. Thus, pathways incorporating zinc, as a putative neuromodulator of excitatory amino acid receptor responses, may be organized similarly in the cortex of meta- and eutherians.

Histochemical distribution of zinc in the brain of the zebra finch (Taenopygia guttata).

The distribution of zinc was studied in the brain of the zebra finch (Taenopygia guttata) by means of the selenium histochemical method. A specific pattern was seen, which usually correlated with the main known architectonic subdivisions. In addition, a few as yet unidentified structures were observed. In the telencephalon, the pallial components were stained with moderate to strong intensity. The only exceptions were the hyperstriatum intercalatus superior, a small medial area in the hyperstriatum accessorium and in the dorsolateral cortex, and the dorsomedial part of the hippocampal complex, which were virtually devoid of staining. Staining of the dorsal ventricular ridge components varied considerably. The archistriatum, the nucleus accumbens, the nucleus of the stria terminalis, the hyperstriatum ventrale and the lateral septum showed moderate to strong staining. The medial septum was weakly stained. The neostriatum showed a rather complex pattern of staining with unstained areas, such as the magnocellular nucleus of the anterior neostriatum, and other parts intensely stained, especially in its caudal region. Both paleostriatii primitivum and augmentatum showed a rostro-caudal gradient that was increasingly stained. We also observed an intensely stained area ventral to the fasciculus prosencephali lateralis and lateral to the tractus septomesencephalicus, a weakly to moderately stained band ventral to the lobus parolfactorius, an intensely stained zone along the lateral ventricle in the hyperstriatum ventrale, and an unstained almond-shaped nucleus in the lateral hyperstriatum ventrale. In the diencephalon, the hypothalamus showed a moderate to strong, rather uniform staining, whereas the thalamus was usually weakly to moderately stained, with the exception of a few unstained nuclei. Only the lateral nucleus of the habenula was stained, and with strong intensity. Most of the mesencephalon stained rather uniformly with a moderate to strong intensity. The most intense staining was seen in the substantia grisea centralis, the substantia grisea et fibrosa periventricularis, the torus semicircularis and the nucleus intercollicularis. The tectum opticum was virtually devoid of stain except for two light bands in the stratum griseum et fibrosum superficiale. The formatio reticularis was moderately stained. All the other structures were either weakly stained or unstained. Some staining was seen in the Purkinje and the granular layers of the cerebellum, as well as around its internal nuclei. The pons and the medulla oblongata showed an overall moderate to intense staining, with the exception of a few unstained nuclei. When compared in three bird species belonging to different genera, zinc distribution shows remarkable similarities, despite species, age and methodological differences.(ABSTRACT TRUNCATED AT 400 WORDS)

Cholecystokinin-, enkephalin-, and substance P-like immunoreactivity in the dentate area, hippocampus, and subiculum of the domestic pig.

The distribution of cholecystokinin-like, enkephalin-like, and substance P-like immunoreactivities is described in the dentate area, hippocampus, and subiculum of the domestic pig (Sus scrofa domesticus) as a baseline for future experimental studies. The distributions in the pig are compared with previous observations in other species. Cholecystokinin-like immunoreactive nerve cell bodies were intensely stained and present in large numbers in all subfields studied. Cholecystokinin-like immunoreactive terminals appeared as stained puncta, whereas fibers were only rarely encountered. The puncta were mainly seen in the dentate molecular layer and dentate granule cell layer, the pyramidal cell layer of the hippocampal regio inferior, stratum moleculare of the hippocampal regio superior, and in the subiculum. Enkephalin-like immunoreactive nerve cell bodies were faintly stained and generally present in very small numbers, except for some pyramidal cells in the subicular cell layer. Enkephalin-like immunoreactive fibers were few in number, whereas stained puncta appeared with variable densities. Puncta of particularly high densities were found in the dentate molecular layer, whereas they appeared of moderate density in the dentate hilus, stratum moleculare of the hippocampal regio superior, and in the subiculum. Substance P-like immunoreactive nerve cell bodies were few and very faintly stained. They primarily occurred in the dentate hilus, stratum oriens of the hippocampus, and in the subicular cell layer. Stained fibers were few in number, whereas stained puncta were present in abundant numbers corresponding to the mossy fiber projection in the dentate hilus and the layer of mossy fibers of the hippocampal regio inferior, and in moderate numbers in stratum moleculare of the hippocampal regio superior and in the subiculum. For all three neuropeptides there were consistent and very characteristic variations in the distribution of immunoreactivity along the septotemporal axis of the hippocampus. When viewed in a comparative perspective the distribution of enkephalin-like and substance P-like terminals in the domestic pig displayed striking differences from the basic pattern observed in other species. This contrasted with the distribution of cholecystokinin-like neurons and terminals, which resembled more closely these species.

Distribution of acetylcholinesterase in the hippocampal region of the mouse. III. The area dentata.

The distribution of acetylcholinesterase (AChE) was examined in the area dentata of the adult mouse (Mus musculus domesticus). A distinctly stratified distribution of the enzyme was observed and was compared in detail with cytoarchitectural fields and layers. In the stratum moleculare, bands of relatively high AChE activity were seen immediately beneath the pia, at the borders between the outer, middle, and deep portions of the stratum moleculare, and superficial to the granule cell layer. AChE activity was low in the intervening parts of the stratum moleculare. In contrast to the rat, three sublaminae could be discerned in the hilus of the mouse at most septotemporal levels: a limiting subzone, a hilar plexiform layer, and a deep hilar cell mass. Deep to the granule cell layer, AChE activity was high in the limiting subzone and, septally, in the hilar plexiform layer. The deep hilar cell mass stained lightly towards the septal pole of the region but darker at more temporal levels. Numerous AChE-stained cells were seen in the hilus, with the exception of the most temporal levels. A comparative analysis of the AChE pattern of the area dentata reveals that 1) AChE-intense supra- and infragranular bands are found in all mammals, whereas 2) considerable difference between various strains of mice and between species are seen in the stratum moleculare. The functional significance of the AChE pattern is discussed in relation to species differences and connectivity and also with respect to possible activities of the enzyme other than hydrolysis of ACh, which may be involved in growth-related functions and in the plastic and degenerative processes observed in Alzheimer's disease.

Diversity of relative intensities of acetylcholinesterase staining within the laminae of the visual cortex of four mammals.

The histological staining patterns of acetylcholinesterase fibers in the visual cortex of the hamster, bank vole, yellow necked wood mouse, and rabbit are described. Between the species there are variations in staining intensities of the laminae in the visual cortex. In the hamster and bank vole layers IV, V, and VI are intensely stained. The yellow necked wood mouse demonstrates little difference in staining intensity between the layers of the visual cortex. The rabbit evidences a dense precipitate in the lower portion of layer IV and also in layer V. Staining intensity patterns suggest that the cholinergic afferents to the visual cortex may develop preferential innervation to laminae which receive low sensory stimulation during the formative period.

Histochemical distribution of zinc in the brain of the rainbow trout, Oncorhynchos myciss. II. The diencephalon.

The distribution of zinc in the diencephalon of the rainbow trout, Oncorhynchos myciss, is described in the present paper, which is the second in a series of three reporting for the first time the distribution of a heavy metal in the fish brain. The Neo-Timm method was used for the histochemical demonstration of zinc. The staining was essentially confined to the neuropil, in all probability representing stained axon terminals, but stained nerve cell bodies were observed in the nucleus lateralis geniculatus and the nucleus cerebellosus hypothalami. Stained fibers were never seen. The staining gave rise to a consistent, specific distribution pattern, which accorded well with the diencephalic nuclei defined on the basis of cytoarchitectural criteria. The diencephalon was in general stained with much higher intensity than the telencephalon, in surprising contrast to the state of affairs in the mammalian, reptilian, and avian brain. In species of these classes, high staining intensities are observed almost exclusively in the telencephalon. The Neo-Timm staining was predominantly distributed in the nuclei of the periventricular zone, but some internal (migrated) nuclei did show a positive staining reaction, namely the nucleus lateralis geniculatus, the anterior thalamic nucleus, the nucleus diffusus tori lateralis, and the nucleus cerebellosus hypothalami. The zinc distribution pattern has been compared with the terminal fields of afferent projections, known from experimental studies, and with the distribution of substance P. The possible function of zinc in synaptic vesicles is considered.

Somatostatin- and neuropeptide Y-like immunoreactivity in the dentate area, hippocampus, and subiculum of the domestic pig.

With the principal aim of providing baseline observations for future experimental studies, the distribution of somatostatin-like and neuropeptide Y-like immunoreactivities is described in the dentate area, hippocampus, and subiculum of the domestic pig (Sus scrofa domesticus) and compared with the distribution described in other mammals. Intensely stained somatostatin-like immunoreactive nerve cell bodies were present throughout the region, with highest densities in the dentate hilus, stratum radiatum and stratum oriens of the hippocampal regio inferior, stratum oriens of the hippocampal regio superior, and in the subicular cell layer. Somatostatin-like immunoreactive terminals were represented by both stained fibers and stained puncta. Scattered somatostatin-like immunoreactive nerve fibers were seen in most areas, but regular fiber plexuses were present in the dentate molecular layer and dentate hilus, stratum moleculare of the hippocampus, and in the subicular plexiform layer. Somatostatin-like immunoreactive puncta were seen in the dentate molecular layer, stratum moleculare of the hippocampus, and in the subicular plexiform layer. Neuropeptide Y-like immunoreactive nerve cell bodies were less numerous than somatostatin-like immunoreactive ones. They were mainly seen in the dentate granule cell layer and dentate hilus, stratum radiatum and stratum oriens of the hippocampus, and in the subicular cell layer. Intensely stained neuropeptide Y-like immunoreactive fibers were numerous, and present in all areas examined. They formed fiber plexuses in the dentate molecular layer and dentate hilus, stratum moleculare of the hippocampal regio superior, and in the subicular plexiform layer. Neuropeptide Y-like immunoreactive puncta were present in the dentate molecular layer, stratum moleculare of the hippocampus, and in the subicular plexiform layer. Consistent and very characteristic variation in the distribution of somatostatin-like and neuropeptide Y-like immunoreactivity was found along the septotemporal axis of the hippocampus. The distribution of somatostatin-like and neuropeptide Y-like neurons and terminals in the domestic pig displayed striking similarities with the basic pattern of organization of these neuropeptides in other species, although more subtle species-specific characteristics were also observed in the pig.

Histochemical distribution of zinc in the brain of the rainbow trout, Oncorhynchos myciss. I. The telencephalon.

The present paper which describes the distribution of zinc in the telencephalon of the rainbow trout, Oncorhynchos myciss, is the first report on the distribution of a heavy metal in the fish brain. Zinc was demonstrated histochemically by silver enhancement using the Neo-Timm method. The staining was mainly confined to the neuropil, but both moderately and intensely stained nerve cell bodies were of common occurrence. Stained fibers were never observed. The staining revealed a specific distribution pattern which could easily be correlated with the telencephalic nuclei defined on the basis of cytoarchitectural features. However, the telencephalon stained much more weakly than the rest of the brain, in striking contrast to the situation in the reptilian, mammalian, and avian brain. In these classes, high staining intensities are observed almost exclusively in the telencephalon. The staining was essentially restricted to the nuclei of the ventral telencephalic area. In the dorsal telencephalic area, only the medial and central zones and medial part of the posterior zone showed comparable staining intensities. The Neo-Timm staining pattern lends support to the view that the pallio-subpallial boundary is between the medial and dorsal zones of the dorsal telencephalic area. The distribution of zinc has been compared with the terminal field of afferent projections, known from experimental mapping, and also with the distribution of substance P and vasoactive intestinal peptide. Finally, the possible functional implications of zinc in synaptic vesicles are considered.

Distribution of acetylcholinesterase in the hippocampal region of the mouse: II. Subiculum and hippocampus.

The distribution of acetylcholinesterase (AChE) was examined in the subiculum and hippocampus of the adult mouse (Mus musculus domesticus). A distinctly stratified AChE pattern was observed in both areas and was compared in detail with cytoarchitectural fields and layers. In the subiculum, the lateral plexiform layer was lightly stained superficially and moderately stained at depth, where it abutted the lateral, moderately stained cell layer. Medially, a moderately stained deep plexiform layer separated the darkly stained superficial plexiform layer from the equally AChE-intense cell layer. At depth, the subicular cell layer was delimited by a band of very high AChE activity. In regio superior of the hippocampus, AChE-intense bands delimited the moderately stained strata moleculare, radiatum, and oriens toward the subjacent layers. In the stratum pyramidale, precipitate insinuated between the cell bodies gave a dark appearance to the deep part of the layer. The homologous strata of regio inferior appeared darker, but the relative staining intensities corresponded largely to those in regio superior. AChE activity in the layer of mossy fibers was almost absent septally but increased gradually to very high levels temporally. The AChE staining pattern, in conjunction with cytochemical and morphological evidence, strongly suggests a division of the pyramidal cell layer of the mouse and rat into superficial and deep substrata and discourages the definition of a prosubiculum in rodents. A comparative analysis of the AChE pattern reveals that: 1) in the subiculum, differences between species are observed within a generalized pattern of medial darkly staining and lateral lightly staining portions; 2) in the hippocampus, a conservation of the AChE pattern is seen in strata associated with intrinsic hippocampal connection; while 3) numerous interspecific differences are found in the stratum moleculare.

Histochemical demonstration of zinc in the hippocampal region of the domestic pig: III. The dentate area.

The distribution of zinc was described in the dentate area, a part of the hippocampal region, of the domestic pig. A modification of Timm's sulphide silver procedure, the Neo-Timm method, was used for the histochemical demonstration of zinc. The staining of the dentate area exhibited a well-defined stratified pattern, the predominant part of the staining being restricted to the neuropil, although weakly stained nerve cell bodies were observed in the hilus fasciae dentatae. In the molecular layer, three distinct sublaminae were seen at most septotemporal levels. The outer and inner sublaminae displayed medium staining intensity, whereas the intermediate sublamina appeared extremely pale. The granular cell layer was well stained in its superficial two thirds, because of dense masses of staining occupying the interstices between the unstained granular cells. In the hilus fasciae dentatae, extreme differences in staining intensity were seen between the layers, ranging from very intense staining of the outer hilar cell layer to generally weak staining of the inner plexiform layer. The distribution of zinc in the pig was compared with that in the guinea pig and rat, described previously. The staining pattern of the molecular layer showed striking species differences, whereas the granular cell layer appeared very near identical. The stratified staining pattern seen in the hilus of the pig is very similar to the distribution observed in the guinea pig, but differs from the essentially homogeneous staining of the rat hilus.(ABSTRACT TRUNCATED AT 250 WORDS)

Computer-assisted three-dimensional reconstruction of the hippocampal region based on serial sections.

A large series of rabbit hippocampal Neo-Timm stained sections were manually aligned, digitized, and by a modified median filtration noise reduced and reconstructed into a three-dimensional object. From the presented simulated grey tone cuts of this object, the reader may assemble a rabbit hippocampal model, that spatially illustrates its anatomy.

Histochemical demonstration of zinc in the hippocampal region of the domestic pig: II. Subiculum and hippocampus.

The distribution of zinc has been described in two areas of the hippocampal region of the domestic pig, viz., the subiculum and the hippocampus. Zinc was demonstrated histochemically according to the Neo-Timm method, a modification of the sulphide-silver procedure. In each of the examined areas the staining displayed a distinctly stratified pattern which has been compared in detail to fields and layers defined on the basis of cyto- and fibroarchitecture, resulting in a combined chemo- and cytoarchitectonic map. Most of the staining was confined to the neuropil, but a considerable number of stained nerve cell bodies were seen in both the subiculum and the hippocampus. In the subiculum, the plexiform layer was divided into a superficial, weakly stained subzone and a deep, better stained subzone. The cell layer was generally well stained, but displayed a complex staining pattern with differences in staining intensity of both the cell bodies and neuropil. In regio superior of the hippocampus, the stratum moleculare appeared weakly stained, with the exception of a tapering process of more darkly stained tissue projecting from the plexiform layer of the subiculum into the deepest part of the layer. Stratum radiatum and the superficial subzone of stratum oriens showed a weak staining intensity, contrasting to the relatively darkly stained pyramidal cell layer and the intensely stained deep subzone of stratum oriens. In regio inferior, the stratum moleculare was divided into a moderately stained superficial part and an unstained deep part. Stratum radiatum and stratum oriens both appeared weakly stained. The layer of mossy fibers was very intensely stained and appeared almost homogeneously black in its main suprapyramidal part, whereas the infrapyramidal part was looser in character. The pyramidal cell layer was darker than in regio superior. The distribution of zinc in the pig was compared with that in the guinea pig and rat, described previously. The staining pattern is fundamentally similar in all three species, though notable species-specific traits do exist.

Distribution of acetylcholinesterase in the hippocampal region of the mouse: I. Entorhinal area, parasubiculum, retrosplenial area, and presubiculum.

The distribution of acetylcholinesterase (AChE) was examined in the multilayered posterior part of the hippocampal region of the adult mouse (Mus musculus domesticus), namely, the entorhinal area, the parasubiculum, the presubiculum, and those parts of the retrosplenial cortex that extend into the posterior hippocampal region (area retrosplenialis 29d and 29e). A modification of the Koelle copper thiocholine method was employed for the histochemical demonstration of AChE. The AChE staining resulted in a distinctly stratified pattern, which has been compared in detail with the fields and layers defined by cyto- and fibro-architecture. Most of the enzyme activity was located in the neuropil, but both moderately and intensely stained nerve cell bodies were observed too. In the entorhinal area two main subfields were identified, which have been designated pars medialis and pars lateralis. In pars medialis, the superficial two thirds of layer I, the interstices between the stellate cell bodies in layer II, and layers IV and VI showed moderate to high content of AChE, whereas layer V and, especially, layer III were poor in enzyme activity. A particular feature was the occurrence of cone-shaped, darkly stained areas within layer II and, occasionally, the deep part of layer I. The staining of pars laterais differed in several respects from that of pars medialis, the most prominent feature being a less conspicuous stratification. In addition, intensely stained somata occurred more frequently than in pars medialis, although they still constituted only a very small minority of the total number of nerve cell bodies. In the parasubiculum, a clear cytoarchitectural subdivision into a posterolateral parasubiculum a and an anteromedial parasubiculum b was observed. These subfields showed, however, only minor differences in AChE staining. Thus, in both subfields, layers I and IV stained intensely, whereas layers II and III showed moderate to intense staining. Layers V and VI did not differ in appearance from the corresponding layers of the entorhinal area. The retrosplenial areas 29d and 29e appeared very light in the AChE pattern, area 29e being the better stained. The presubiculum was very rich in AChE, with layers, I, III and IV being particularly intensely stained. The small nerve cell bodies of layer II were unstained, whereas the intervening neuropil was intensely stained. The distribution of AChE in the mouse was compared with that in the rat, guinea pig, and rabbit, described previously. The staining pattern is largely similar in all four species, but striking species-specific differences do exist.(ABSTRACT TRUNCATED AT 400 WORDS)

Distribution of acetylcholinesterase and zinc in the visual cortex of the mouse.

The distributions of acetylcholinesterase (AChE) and zinc-containing boutons and their cells of origin in the visual cortex of the house mouse (Mus musculus domesticus) are described. The primary visual area is defined by both acetylcholinesterase and zinc staining. The AChE staining pattern is dark in upper layer I and layers IV and VI. It is light in layers II/III and V. The lack of a densely stained layer IV in the secondary visual cortices defines the borders between primary and secondary areas. Large, multipolar AChE-positive neurons are located throughout the cortical layers, but preferentially in layer VI. Dense zinc-positive neuropil in the primary visual cortex is apparent in layer Ib, upper layer II/III, and layers V and VI. Neurons that give rise to zinc-containing boutons are situated in layers II/III and VI. The medial and lateral borders can be distinguished by a bold contrast of staining in lower layer II/III; the secondary areas have more zinc-positive neurons, and the neuropil stains darker. A surprising observation of this study is the disparity between the mouse and rat visual cortex of the AChE staining pattern. Layer V is very light in the mouse, whereas a dark stain has been described in layer V of the rat. Layer VI stains heavily in the mouse while less AChE activity has been observed in layer VI of the rat.