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J Zimmer

Publications and source records attributed to J Zimmer.

At least 163 records · Page 9Linked to original sources
PubMed1984

Cellular and connective organization of slice cultures of the rat hippocampus and fascia dentata.

This study examined the cellular and connective organization of hippocampal tissue taken from 6-8-day-old rats and cultured by the roller tube technique for 3-6 weeks. In the cultures containing the fascia dentata and the hippocampus proper (CA1, CA3, CA4) the main cell and neuropil layers were organotypically organized when observed in ordinary cell stains. The normal distribution of smaller cell populations of AChE-positive neurons and somatostatin-reactive neurons was demonstrated by histochemical and immunohistochemical methods. Both cell types were mainly confined to str. oriens of CA3 and CA1 and the dentate hilus (CA4). Individual dentate granule cells and hippocampal pyramidal cells were injected with lucifer yellow and HRP, revealing great stability of the dendritic patterns of these cells in the culture condition. The same was found for the axonal branching and termination of HRP-filled mossy fibers arising from an HRP-injected granule cell. The preservation of organotypic afferent patterns in the cultures was also shown by Timm staining of the terminal distribution of the mossy fiber system. Mossy fiber terminals, with characteristic ultrastructural features verified in the electron microscope, were thus found in the hilus (CA4) and along the CA3 pyramidal cell layer onto the CA3-CA1 transition. Depending on the amount of dentate tissue relative to CA3 the terminals could stop before reaching CA1 (small fascia dentata) or take up additional intra and infrapyramidal locations along CA3 (small CA3). In cultures with a gap in the CA3 pyramidal cell layer some mossy fiber terminals were found in contact with the CA3 pyramidal cells beyond the gap. In all cultures there was an aberrant projection of supragranular mossy fibers. This projection is analogous to the one known from lesion and transplant studies to form in the absence of the entorhinal perforant path input to the dentate molecular layer. Also, in accordance with these studies the Timm staining pattern of the outer parts of the dentate molecular layer and the entire molecular layer of the hippocampus was altered corresponding to the spread of afferents normally confined to the inner zone of the dentate and str. radiatum of CA3 and CA1. Possibly as a consequence of the lack of normal targets for projections from CA1, this subfield contained an unusually dense Timm staining suggestive of autoinnervation.(ABSTRACT TRUNCATED AT 400 WORDS)

Acetylcholinesterase↗
PubMed1984

The architecture and some of the interconnections of the rat's amygdala and lateral periallocortex.

The connections between the cerebral cortex and amygdala were studied in the rat by means of silver degeneration techniques. To help define the sites of origin and termination of cortico-amygdaloid connections, the architecture of the cortex and the amygdala was studied in sections from normal brains stained for cells, fibers, acetylcholinesterase activity, and heavy metals (Timm staining). The amygdalopetal cortex on the dorsal and lateral surfaces of the rat brain is limited to a narrow strip of periallocortex that forms the dorsal wall and lip of the rhinal sulcus. Histochemical stains indicate that this cortex comprises several stages of cortical differentiation that are intermediate between the ventrally adjacent allocortices and the dorsally adjacent neocortices. The lateral periallocortex consists of two major divisions, the agranular insula (area 13) anteriorly, and a temporal agranular cortex (areas 35 and 36) posteriorly. The principal amygdaloid target for this cortex is the lateral nucleus. Anterior area 13 and posterior area 35 project to the anterior and posterior halves, respectively, of the medial division of this nucleus, while posterior area 13 and anterior area 35 projects to the lateral division of this nucleus. All divisions of periallocortex also send projections to a part of the putamen that surrounds the lateral half of the central nucleus. All of area 13 also sends efferents to the anterior part of the basal nucleus, while the anterior half of area 13 sends an additional projection to the central nucleus. Comparison of these data with those obtained in the cat and monkey suggests that a constant feature of eutherian brains is the existence of a subset of efferents from each of the four neocortical sensory systems that is routed so as to provide subcortical limbic structures with modality-specific information. The initial sequence in this sensorilimbic system consists of one or more modality-specific corticocortical relays that originate in the primary sensory cortices and terminate in one of four topographically adjacent, modality-specific areas of the insular and temporal cortices. These insular and temporal areas then each establish modality-specific connections within the amygdaloid complex. The final set of relays presumably comprises the connection that each of these amygdaloid areas makes with the autonomic and endocrine nuclei of the brain.

Amygdala↗
PubMed1984

Intraocular grafts of fresh and freeze-stored rat hippocampal tissue: a comparison of survivability and histological and connective organization.

Intraocular grafts of rat hippocampal tissue, grafted either directly from the immature donor brains (fresh) or after storage in liquid nitrogen at -196 degrees C (freeze-stored), were compared with regard to survivability and histological and connective organization. For direct grafting, pieces of hippocampal tissue from rat embryos (embryonic day 19, E21) and newborn rats (PO) were placed in the anterior eye chamber of adult rats immediately after dissection. For grafting after deep-freeze storage, pieces of hippocampal tissue were taken from rat embryos (E16-E21) and newborn rats (PO), frozen at a cooling rate of 1 degrees C/min in CO2 or N2 vapours after addition of the cryoprotective agent dimethylsolfoxide (DMSO), and stored in liquid nitrogen for 1 to 33 days before thawing and intraocular grafting. From 20 to 68 days after grafting, the recipient rats were sacrificed, their eyes sectioned, and the sections stained with thionine for cell bodies, Timm's sulphide silver method for hippocampal fiber systems and terminal fields, and acetylcholinesterase (AChE) for cholinergic fibers and AChE-positive neurons. When examining the 101 grafted eyes (34 grafted with fresh and 67 with freeze-stored tissue) a significantly lower survival rate of the freeze-stored tissue was found (28 vs. 88%). The survivability of the freeze-stored tissue was age-dependent with no survival at donor ages E16 and PO, while tissue from E18-E21 had a 50% survival rate. The grafts of the freeze-stored tissue were also smaller and showed an increased tendency for fragmentation. When evaluating the structure of the grafts, the deep-freeze storage was found primarily to have been harmful to the dentate granule cells and their precursors. The organization of intrinsic fiber connections followed the pattern known from lesion and intracerebral transplant studies. While demonstrating that immature brain tissue can survive deep-freeze storage and subsequent intraocular grafting, the study also indicates that different schemes may have to be used to get optimal survival of different neuronal populations.

Animals↗
PubMed1984

Neuropeptides and astroglia in intracerebral hippocampal transplants: an immunohistochemical study in the rat.

The rat hippocampus and fascia dentata contain neurons and terminal fields that react immunohistochemically with antisera raised against the peptides somatostatin, cholecystokinin (CCK), and enkephalin. Neurons with overlapping distribution synthesize acetylcholinesterase (AChE) as shown histochemically after systemic administration of diisopropylfluorophosphate (DFP). We used these techniques to examine the organization of peptidergic neurons and fibers and AChE-positive neurons in transplants of late embryonic and early postnatal rat hippocampi inserted into the brain of immature and adult rats. The astroglial organization was examined using an antibody raised against the astroglial marker, glial fibrillary acidic protein (GFAP). Eighty percent of the transplants were recovered. Within the transplants the peptidergic neurons, and the AChE-producing neurons retained their characteristic distributions. An organotypical astroglial pattern was also retained with some indication of a higher than normal density of cells and processes. The transplant neuropil displayed characteristic patterns of terminal field-like staining with the enkephalin and CCK antibodies. An enkephalin-like reactivity characteristic of the large mossy fiber terminals was found in the normal mossy fiber zones. A similar staining, but of smaller particle size, was found in and above the granule cell layer. It corresponded to the aberrant, supragranular mossy fiber projection, known to form after denervation of the dentate molecular layer. Also the CCK-like reactivity of the transplant neuropil was distributed in laminar patterns characteristic of the different subfields. Deviations from the normal patterns again followed known principles for lesion-induced aberrant nerve growth. Normalization of the enkephalin and CCK staining patterns in the dentate molecular layer was observed in transplants with intimate contact with the host dentate molecular layer or entorhinal cortex, but only in immature recipients, and not in every case. The staining was typically of the enkephalin-reacting lateral perforant path and the CCK-reacting medial perforant path and distributed in normal, mutually exclusive laminae in the dentate molecular layer. An invasion of the transplant dentate molecular layer by heterologous, host enkephalin- and CCK-like reacting afferents in transplants located in the host basal ganglia was limited at most. Outgrowth of CCK and enkephalin reacting transplant fibers into the host brains was not observed in this study.(ABSTRACT TRUNCATED AT 400 WORDS)

Acetylcholinesterase↗
PubMed1984

Toward a complete linkage map of the human X chromosome: regional assignment of 16 cloned single-copy DNA sequences employing a panel of somatic cell hybrids.

Closely linked restriction fragment length polymorphisms (RFLPs) are potentially useful as diagnostic markers of genetic defects, and, in principle, RFLPs can be employed to construct a complete linkage map of the human genome. On the X chromosome, linkage studies are particularly rewarding because in man more than 120 X-linked genes are known. Thus, it is probable that each X-specific RFLP will be of use as a genetic marker of one or several X-linked disorders. To facilitate the search for closely linked RFLPs, we have regionally assigned 16 cloned DNA sequences to various portions of the human X chromosome, employing a large panel of somatic cell hybrids. These probes have been used to correlate genetic and physical distances on Xp, and it can be extrapolated from these data that the number and distribution of available Xq sequences will also suffice to span the long arm of the X chromosome.

Animals↗
PubMed1983

Commissural fibers terminate on non-pyramidal neurons in the guinea pig hippocampus -- a combined Golgi/EM degeneration study.

The combined Golgi/EM method was applied to guinea pig hippocampi with acute anterograde degeneration of the commissural afferents in order to identify possible synaptic contacts between commissural terminals and non-pyramidal neurons. Degenerating, electron-dense terminals of commissural origin were found in synaptic contact with both perikarya and dendrites of two identified non-pyramidal neurons in regio superior, namely a basket cell and a bipolar neuron in stratum oriens. The observed connection may form the morphological basis for the physiologically observed feed-forward inhibition of the pyramidal cells.

Animals↗
PubMed1983

Lesion-induced mossy fibers to the molecular layer of the rat fascia dentata: identification of postsynaptic granule cells by the Golgi-EM technique.

The axons of the dentate granule cells, the hippocampal mossy fibers, sprout "backward" into the dentate molecular layer when this is heavily denervated. Using the combined Golgi-electron microscopy (EM) technique we now demonstrate that these aberrant supragranular mossy fibers at least in part terminate on granule cell dendrites. Sprouting of mossy fibers into the dentate molecular layer was induced in adult rats by simultaneous surgical removal of the commissural and entorhinal afferents to the fascia dentata. After at least 7 weeks survival, the presence of mossy fiber terminals in the inner part of the dentate molecular layer was demonstrated by light microscopy. In the electron microscope the mossy fiber terminals were identified by their unique structural characteristics, namely, the unusually large size of the terminals, the dense packing of clear synaptic vesicles with a few dense core vesicles intermingled, the presence of asymmetric synaptic contacts with spines and desmosome-like contacts with dendritic shafts, and the continuity with a thin unmyelinated preterminal axon. Golgi-stained granule cells were first identified in the light microscope, and then, after deimpregnation, the same cells were examined in the electron microscope. In ultrathin, serial sections lesion-induced mossy fiber terminals were found in synaptic contact with spines on proximal dendritic segments of such identified Golgi-impregnated granule cells. From this we conclude that the aberrant, supragranular mossy fibers can innervate dendrites of the parent cell group, the dentate granule cells. The results, moreover, provide an example of reactive synaptogenesis where both the sprouted afferents and its postsynaptic element have been identified.

Animals↗
PubMed1983

Cellular, histochemical and connective organization of the hippocampus and fascia dentata transplanted to different regions of immature and adult rat brains.

The aims of the present study were to examine the survival and the cellular and connective differentiation of intracerebral transplants of fascia dentata and hippocampus. Pieces of immature dentate and hippocampal tissue were taken from late embryonic (E18) and early postnatal (1-9 days old) rats and transplanted into the brains of 1- to 13-day-old and adult rats. After survival times from 4 days to 2 years the cellular and connective organization of the transplants was monitored in parallel series of sections stained with thionin (cell bodies), Timm's sulphide silver method (terminal fields). Nauta and Fink-Heimer methods (normal and degenerating fibers) and a method for AChE activity (cholinergic afferents). The transplants survived well in all combinations of donor and recipient ages used, and they survived and differentiated in all parts of the recipient brains, although relations to pial and ventricular surfaces appeared to be optimal. Cell differentiation continued after transplantation, and a characteristic laminar organization was retained, although least in embryonic donor tissues. The distribution of intrinsic connections was determined by the types of subfields present in the transplants and interaction with ingrown host afferents. All aberrant intrinsic connections observed corresponded to aberrant connections formed in the hippocampus and fascia dentata denervated in situ and included supragranular mossy fibers in the fascia dentata, aberrant infrapyramidal mossy fibers in CA3, spread of CA4-associated afferents beyond the normal commissural-associational zone in the dentate molecular layer together with ingrowth of CA3-associated and CA1-subiculum-associated afferents. Most transplants received a cholinergic input of host origin irrespective of the localization in the host brain, but also non-cholinergic host pathways innervated the transplants, in particular when the transplants were in close contact with host fiber tracts, and when the recipients were immature. At various transplant locations the non-cholinergic host afferents belonged to the commissural hippocampo-dentate system, the commissural hippocampal system and the callosal system. Other cases suggested innervation of dentate transplant by host entorhinal afferents. The formation and distribution of intrinsic transplant connections and connections between transplant and host appeared to be regulated by the same factors that regulate the development and reorganization of fiber connections in the normal and the in situ denervated hippocampus and fascia dentata. As a special variety of this, the distribution of cholinergic afferents adjusted to the distribution of the major intrinsic and extrinsic non-cholinergic pathways.

Acetylcholinesterase↗
PubMed1982

Astrocyte cultures from adult rat brain. Derivation, characterization and neurotrophic properties of pure astroglial cells from corpus callosum.

It has not as yet been routinely possible to derive primary cultures of glial cells from adult rat brain tissue even when adopting strategies that have proven successful with perinatal tissue. We now report that in response to a surgical lesion and a period of postoperative 'priming' in vivo, proliferating cultures of astroglial cells can be derived from the normally quiescent glia of the corpus callosum region of the adult rat brain. In such cultures the predominance of astroglia and the virtual absence of oligodendroglia and neurons has been established by the use of a variety of cell-type specific antisera. Fibroblasts, the only other cell type identified, when not numerous could be successfully eliminated by treatment of the cultures with anti-Thy-1 antibodies and guinea pig complement. Pure astroglial cells from adult brain have been sub-cultured and maintained for up to 4 months in vitro, providing suitable quantities of cells for studies on the trophic interaction between glia and neurons. In long-term culture the adult astrocytes maintain a flattened undifferentiated morphology but readily assume a stellate shape with long branching processes upon the addition of a crude homogenate from bovine pituitary.

Animals↗
PubMed1982

Differentiation of neurons containing olfactory marker protein in adult rat olfactory epithelium transplanted to the anterior chamber of the eye.

Olfactory marker protein is a cytoplasmic component unique to fully-differentiated olfactory sensory neurons. It has been proposed that expression of this protein occurs only if the neurons make synaptic contact with the central nervous system. In the present experiments, adult olfactory epithelium was transplanted as an autograft to the anterior chamber of the eye. This procedure destroys the mature sensory neurons, which are subsequently replaced by division and differentiation of stem cells. The newly-formed sensory neurons differentiate sufficiently to produce olfactory marker protein, without apparently contacting central nervous tissue. We conclude that contact with the central nervous system is not necessary for expression of olfactory marker protein.

Animals↗
PubMed1981

Lesion-induced sprouting of hippocampal mossy fiber collaterals to the fascia dentata in developing and adult rats.

A lesion-induced formation of an abnormal projection of hippocampal mossy fiber collaterals to the molecular layer of the fascia dentata was studied in rats. Both immature (1--30 days old) and adult rats were subjected to hippocampal and entorhinal lesions which alone or in combination removed one or more of the major afferents to the dentate molecular layer (commissural, associational, and perforant path). Some lesions in addition transected the main part of the mossy fibers en route from the dentate granule cells to the hippocampal pyramidal cells in regio inferior (CA3). The formation of aberrant mossy fiber terminals in fascia dentata (supragranular mossy fibers) was monitored by the histochemical Timm sulphide silver method, but the presence of aberrant terminals was also observed in the electron microscope. Abnormal amounts of supragranular mossy fiber terminals were found following entorhinal lesions of both immature and adult rats, but not following commissural lesions. Even larger amounts of aberrant terminals were, however, found in immature and adult rats subjected to lesions which removed most of the associational hippocampodentate projection by isolating columns of fascia dentata from major parts of the hilus (CA4). Pure transections of the fascia dentata perpendicular to its longitudinal septotemporal axis did not in itself cause aberrant supragranular terminals, although such lesions partially damaged the associational afferents. When the transections were combined with commissural lesions or entorhinal lesions or both, large amounts of supragranular terminals did, however, form at the denervated levels septal to the transection. After comparison of the amounts and distributions of the aberrant terminals found after the different lesions and in transplants of dentate tissue with different amounts of afferent input, we conclude that it is deafferentation of the dentate molecular layer, and not axotomy of the mossy fibers in the hilus of CA3 (pruning), that causes the aberrant growth of mossy fiber collaterals. Moreover, simultaneous removal of more than one afferent system seems to have a potentiating rather than a simple additive effect on the formation of supragranular mossy fibers.

Afferent Pathways↗
PubMed1981

Activity of steroid sulfatase in fibroblasts with numerical and structural X chromosome aberrations.

In cultured fibroblasts of patients with numerical and structural X chromosome aberrations the activity of steroid sulfatase (STS) is correlated with the number of functional STS gene copies. While normally, this X-linked gene is not inactivated, our data suggest that it may be subject to inactivation when carried on a structurally altered X-chromosome. Similar inactivation patterns have been reported earlier for the Xg locus which, like STS, is located on the distal portion of Xp.

Cells, Cultured↗
PubMed1981

Induction of chromosome shattering by ultraviolet irradiation and caffeine: comparison of whole-cell and partial-cell irradiation.

Synchronized and asynchronously growing cells of a V79 sub-line of the Chinese hamster were either whole-cell irradiated ( gamma, 254 nm) or laser-UV-microirradiated ( gamma, 257 nm). Post-incubation with caffeine (1-2 mM) often resulted in chromosome shattering, which was a rare event in the absence of this compound. In experiments with caffeine, the following results were obtained. Shattering of all the chromosomes of a cell (generalized chromosome shattering, GCS) was induced by whole-cell irradiation at the first post-irradiation mitosis when the UV fluence exceeded a "threshold" value in the sensitive phases of the cell cycle (G1 and S). GCS was also induced by laser-UV-microirradiation of a small part of the nucleus in G1 or S whereas microirradiation of cytoplasm beside the nucleus was not effective. An upper limit of the UV fluence in the non-irradiated nuclear part due to scattering of the microbeam was experimentally obtained. This UV fluence was significantly below the threshold fluence necessary to induce GCS in whole-cell irradiation experiments. In other cells, partial nuclear irradiation resulted in shattering of a few chromosomes only, while the majority remained intact (partial chromosome shattering, PCS). G1/early S was the most sensitive phase for induction of GCS by whole-cell and partial nuclear irradiation. The frequency of PCS was observed to increase when partial nuclear irradiation was performed either at lower incident doses or at later stages of S. We suggest that PCS and GCS indicate 2 levels of chromosome damage which can be produced by the synergistic action of UV irradiation and caffeine. PCS may be restricted to microirradiated chromatin whereas GCS involves both irradiated and unirradiated chromosomes in the microirradiated nucleus.

Animals↗