Subsurface cisterns and lamellar bodies in the granule cells of the guinea-pig fascia dentata

Summary Subsurface cisterns (SSC's) and less frequent lamellar bodies (LB's) were identified in the granule cells of the guinea-pig fascia dentata. Both structures, composed of flattened or collapsed agranular cisterns, are continuous with the regular rough endoplasmic reticulum and occasionally connected with each other forming LB-SSC complexes. The SSC's are apposed to glia, synaptic boutons, and nerve cell processes as well as to neighboring granule cells appearing here singly and in confronting pairs. The quantitative analysis of the various cisternal appositions compared to the distribution of the tissue components on the granule cell soma shows that the overwhelming majority of SSC's are related to glial cells.     

Microdensitometry of acetylcholinesterase in subfields of the hippocampal pyramidal layer and fascia dentata.

A quantitative acetylcholinesterase enzyme-histochemical study was performed with microdensitometric methods in the hippocampus of the rat in order to correlate this enzymatic activity with the different zones of the hippocampal pyramidal layer. Higher values of acetylcholinesterase activity were found in the CA3 pyramidal zone. CA1 and CA4 showed the same activity, while the stratum oriens at CA3 showed the highest values among the hippocampal layers studied. The results were correlated with differences in septal afferences.     

Karyomorphological studies of theIxeris dentata complex on Mount Ishizuchi

The karyotypes of four taxa in theIxeris dentata complex collected from Mt. Ishizuchi were investigated.I. dentata subsp.dentata var.dentata f.dentata had 2n=21 in all the examined individuals and its karyotypes were classified into four different types. Var.dentata f.amplifolia showed 2n=21 in all individuals and had three different karyotypes.I. dentata subsp.dentata var.albiflora showed 2n=21 and two different karyotypes.I. dentata subsp.alpicola showed three different karyotypes with 2n=21 and four different ones with 2n=28. Judging from the results of the karyotype analyses, the morphological variation of chromosomes in theI. dentata complex is assumed to be in the process of increasing asymmetry in the shape of chromosomes. Following Levitzky's principle, it can be said that the a-, b-, and c-chromosomes exist in different advanced stages in the process of chromosome variation. The c-group chromosomes are at the most advanced stage in morphological variation, the b-group in the second and the a-group in the least advanced stage. The above-mentioned structural diversity of chromosomes may be related to apomictic reproduction of theI. dentata complex.     

An electron microscope study on the termination of the perforant path fibres in the hippocampus and the fascia dentata

Summary Morphology and distribution of the perforant path fibres in the hippocampus and the fascia dentata of the rat have been studied in the electron microscope. Investigations were carried out on normal tissue as well as on tissue degenerating after entorhinal damage. The perforant path fibres were relatively thin and the terminals small. Two terminal fields were found to be of quantitative importance, one in the middle third of stratum moleculare of the fascia dentata, the other in stratum lacunosum moleculare of regio inferior of the hippocampus. Some of the observations have been expressed in numerical terms.This study was supported in part by Grant NB 02215 from the National Institute of Neurological Diseases and Blindness, U.S. Public Health Service.     

Synaptic contacts of neurons of fascia dentata transplants with nonspecific targets in neocortex of recipients

We carried out an electron microscopy study of possible synaptic contacts of the neurons of intracortical transplants of the rat brain fascia dentata with targets in the recipient somatosensory cortex. The axons of fascia dentata granular cell and their synaptic terminals could be easily identified in the neocortex due to their distinct morphological features (mossy fibers), although the fascia dentate cells normally do not interact with the neocortex. Thin nonmyelenized mossy fibers were found in both an intermediate zone between the transplant and brain and in the adjacent brain. Their presynaptic buds, like in situ, had large size and formed characteristic terminal, intraterminal, and en passant multiple synaptic contacts and desmosome-like junctions. The aberrant nerve fibers used perykaryons, dendrites of varying diameter, and dendrite spikes of the somatosensory cortex pyramidal neurons as postsynaptic targets in the neocortex. In addition to vacant spaces that appeared in the brain as a result of transplantation, the ingrowing axons induced the formation of additional contact sites: deep invaginations of the plasmalemma of perykaryons, somatic spikes, terminal branchings of dendrites, and dendritic outgrowths of complex branched shape. These aberrant contacts were characterized by the presence of polyribosomes, endoplasmic reticulum cisternae, and mitochondria in the postsynaptic loci. Osmiophility and extension of desmosome-like junctions were also enhanced in such synapses. Thus, it was shown that mossy fibers ingrowing in the recipient neocortex were capable of forming cell-to-cell contacts with signs of functional synapses to atypical cell targets.     

A method of multivariate analysis of data in the study of the effects of space flight factors on the rat brain neuron structure]

The usage of some methods of multivariate analysis for neuro-morphological studies is discussed. The alterations of dendritic trees of pyramidal neurons of layer III of visual cortex of the rat exposed to the influence of space flight aboard biosputnik "Cosmos-1887" were studied and the results are described to illustrate the methods power. o-technique of factor analysis was shown to be suitable for processing of the data obtained from an experiment with complex environmental conditions.     

Quantitative immunocytochemical studies on the gonadotrophs isolated from the pituitary of the male rat

Summary Quantitative studies on the population of the gonadotropic cells in the pituitary of adult male rats were performed after trypsic dissociation of the pituitary glands and immunoenzymatic staining with anti--LH or anti--FSH antisera. Number, area and extinction of labelled cells were measured by use of an image analyser and a cytophotometer. The gonadotrophs represent approximately 14% of the pituitary cells. The mean area of gonadotrophs is significantly larger after staining with anti--LH serum than after staining with anti--FSH serum. Planimetric measurement of the gonadotrophs reveals their variability in size ranging between 30 and 160 m². Moreover, the size distribution depends on the staining serum used: more numerous small-sized cells (<75 m²) are stained with anti--FSH serum than with anti--LH serum, which conversely stains more numerous large-sized cells. Cytophotometric measurements indicate that immunostaining varies greatly among cells of the same size class and that the staining intensity appears to increase according to the cell size. These results emphasize the morphofunctional heterogeneity of the gonadotropic cell population.     

Preliminary studies on the primary structure of rat liver dihydropteridine reductase

Cyanogen bromide cleavage of reductively alkylated homogeneous rat liver dihydropteridine reductase afforded several peptide fragments identifiable by polyacrylamide electrophoresis of which 6 (CB-1 to CB-6) could be individually isolated by C8 reverse phase HPLC. Each was characterised by N-terminal amino acid analysis and sequence information was derived for CB-1, CB-4 and CB-6. The blocked N-terminal of the holoenzyme was identified as pyroglutamate and the C-terminal sequence was obtained by sequential degradation.     

镜像神经元研究概况述评

镜像神经元是近来国外认知神经科学研究的热点,通过一系列最新的技术,人们确立了人体内存在镜像神经系统的观点。镜像神经系统在语言进化、动作识别与理解、行为模仿等方面都起着重要的作用。本文就镜像神经系统的研究做一概述。     

Quantitative studies of rat carotid body type I cells

The general structure and results of quantitative studies of rat carotid body type I cells are described. In contrast to previous reports, there was no change in mitochondrial V/v% on stimulating the carotid body with 10% oxygen. The volume of cytoplasm occupied by electron-dense cored vesicles was significantly increased, whilst their density per square micrometre of cytoplasm was decreased during hypoxia. Thus, the size of vesicles is increased by hypoxic stimulation. On the basis of vesicle diameter and density we were unable to find evidence of more than one variety of type I cell.