Postnatal development of glial fibrillary acidic protein, vimentin and S100 protein in monkey visual cortex: evidence for a transient reduction of GFAP immunoreactivity.

In the cerebral cortex of some species, the gradual appearance of glial fibrillary acidic protein (GFAP) is often interpreted as reflecting the parallel maturation of neuronal connectivity. We studied the postnatal maturation of astrocytes in the primary visual cortex of Callithrix jacchus using antibodies against GFAP, vimentin and S100 protein as immunohistochemical markers. In the cortical grey matter of this species, the overall GFAP-immunoreactivity (IR) as measured by image analysis is high at birth (130% of the adult value), decreases until about 3 months (80%) and increases again towards adult values (100%). Vimentin-IR was high at birth, and declined towards 3 months and later. In contrast, S100-IR augmented postnatally in neuropil, and showed a laminar shift of maximum IR from layer IV to supragranular layers during ontogenesis. The decrease of GFAP-IR is predominantly due to changes in density of GFAP-positive (+) astrocytes within cortical tissue (newborn: 18,600 GFAP+astrocytes/mm3; 1 month: 11,600/mm3; 3 months: 5,700/mm3; adult: 10,200/mm3), while the overall number of astrocytes remained relatively constant as shown by the number of S100-positive astrocytic cell bodies. At times of low GFAP-IR a reduced area density of intermediate filaments was found in astrocytes by electron microscopy. The period of reduced GFAP-expression coincides with the time of prominent synapse remodeling in the visual cortex of marmosets. These data suggest that GFAP-expression may depend on functional conditions rather than time-dependent maturation.

Pre- and postnatal development of the primary visual cortex of the common marmoset. I. A changing space for synaptogenesis.

The primary visual cortex of Callithrix jacchus occupies a large portion of the occipital neocortex and can be safely delineated from fetal stages onwards. In 20 animals ranging in age from fetal to adult age the morphological development of area 17 was evaluated and compared with the growth of whole brain, skull, and head size. Cortical thickness, surface area, and volume of the area were determined in addition to predominant growth directions. The volume of area 17 approximately doubles between birth (241 mm3) and three months of age (506 mm3). This maximum value marks an overshoot in growth (volume: 180%, surface area: 150%, thickness: 122%), which is followed by a considerable reduction before adult values (100%) are reached. Although these values seem to indicate that the overall reduction in size is fairly isometric, growth and regression are locally anisometric. For example, layers II-IVc contribute disproportionately to the overshoot; thickening is less pronounced than tangential growth and follows a slightly different time course. These data suggest that the developing visual cortex represents a highly dynamic distribution space for the developing synaptic junctions which should be taken into account in studies on synaptogenesis. By comparison it is suggested that this growth dynamic is not restricted to area 17 but also occurs in some other parts of the cerebral cortex. In contrast, most subcortical brain regions apparently do not undergo overshoot growth. Structural changes of the skull compensate the overshoot in cortex growth, so that head size increases steadily.

Tangential organization of the infragranular fiber plexus in rat cerebral cortex.

Cylindrical lesions (diameter 300-500 microns) were formed by poking needles into various parts of the cerebral cortex of adult albino rats. Degenerating axons were visualized in horizontal sections through the 'flattened' cortex using the silver impregnation method of Gallyas et al. [Stain Technol. 55: 291-297 (1980)] which stains degenerating axoplasm. The density and distribution of tangentially oriented axons were evaluated in the infragranular layers by TV image analysis. The sampling fields were concentrically arranged around the lesion at distances of 200, 400, 700 and 1,100 microns. The results indicate that the distribution patterns of degenerating (associational) axons covary with the cytoarchitectonic regions into which the lesions were placed. In the motor cortex, the majority of axons run in the antero-posterior direction. The density is generally lower around lesions in frontal regions than in parietal regions. The most extended degeneration was found around lesions near the border of or within the retrosplenial cortex, indicating an exceptionally strong internal connectivity in this area. Since only few degenerating axons were seen around lesions in the center of area 17, the high density of myelinated axons in the primary visual cortex seems to be due to fibers that originate in peristrate areas. It is concluded that the number and extension of fibers that degenerate tends to covary with some aspects of cortical architecture, but it is not area-specific.

Oligodendrocytes in the pons and middle cerebellar peduncle of the cat. Topographical relations to neurons and transverse axon bundles.

Morphology, microtopography and numerical density of oligodendrocytes were analyzed by light microscopy in the pontine gray and middle cerebellar peduncle of adult cats. The cells were selectively stained by use of the dicyanoargentate technique (Ogawa et al. 1975) that visualizes the entire cell population including perikarya and characteristic features of processes. On the basis of different microtopographical relations to neuronal perikarya and/or transversely oriented axon bundles, six groups of oligodendrocytes were separately analyzed: interfascicular, intrafascicular, perifascicular, perineuronal satellite, perifascicular-perineuronal, and "neuropil" cells. The cell morphology did not co-vary with any of these groups, but the shape of oligodendrocytes was on an average more elongated in the peduncle than in the pontine gray. The average cell density was similar in the gray and white matter (55000-56000 cells/mm3). However, 76% of the cells were concentrated near neuronal perikarya and axon bundles in a volume fraction of only 34%. Between adjacent neurons and axon bundles the cell density was even higher suggesting an additive behavior of these two topographical groups of oligodendrocytes. Axon bundles within the pontine gray contained only very few oligodendrocytes (density 6% that of the peduncle). These observations and quantitative data suggest that the perifascicular cells belong to the group of oligodendrocytes that are topographically related to axons (similar to interfascicular glia of the white matter) rather than to neuronal perikarya or neuropil.

Growth of mouse neuroblastoma cell line in a defined medium.

The mouse neuroblastoma tumor line Cl300, clone Neuro-2a, can proliferate in a serum-free synthetic medium supplemented with insulin, transferring, progesterone, selenium and putrescine (N2 medium), with a marked increase in cell number as compared to the optimal 10% serum containing medium. More extensive and elaborate neurite formation with contacts is seen in N2 that in serum supplemented medium. However, electron microscopic studies of the cells grown in N2 lack the formation of synapses, in contrast to the cells grown in serum supplemented medium where at least primitive stages of synaptogenesis are common.

GABA or sodium-bromide-induced plasticity of neurites of mouse neuroblastoma cells in culture. A quantitative study.

Differentiated C1300 mouse neuroblastoma cells were treated with 10(-4)-10(6) M gamma-aminobutyric acid (GABA) and/or sodium bromide (NaBr) for 2 days and then fixed. Quantitative studies revealed an increase in the length and branching of the processes, as well as an increase in the number of cells when compared to the controls. It is suggested that the above changes contribute to the augmentation of specialized contacts between cells and processes as well as the further maturation of the primitive stages of synaptogenesis as discussed.

The temporo-spatial course of degeneration after cutting cortico-cortical connections in adult rats.

Adult albino rats received callosotomies or lesions in the paracingular cortex. Between 12 h and 3 months after injury the structure and topography of the degeneration products were studied by light- and electron-microscopy. The degeneration process was quantified by television-image analysis applied to sections prepared according to a new technique that stains reliably degenerating terminals and lysosomes (Gallyas et al. 1980). All types of cortico-cortical connections show a multiphasic degeneration process: During a precursor stage a small number of dense bodies and mitochondrial granules are stained. These and the few early degenerating axon terminals are much more diffusely distributed than the large number of terminals that degenerate during the following period. The terminal degeneration shows a biphasic time course. One maximum appears at 2-7 days post operation, which corresponds to the well known direct consequence of axotomy. The second peak at 10-20 days post operation could be caused by transneuronal reorganization of the cortical connectivity. Terminal degeneration always begins along the borders between cortical regions and areas, but it may change its laminar and columnar distribution pattern during the second phase. The degeneration products that are phagocytosed by astrocytes seem to be removed by intracellular transport to their perivascular endfeet. The degeneration process ends with fiber degeneration which, especially in laminae I and VI, may form a separate peak after 20 days or more.

Postnatal vascular growth in the neocortex of normal and protein-deprived rats. Morphometric studies.

The postnatal vascular growth in the neocortical area 18 of normal and pre- and postnatally protein-deprived rats was examined. For control rats the specific length, the specific surface and the volume fraction of vessels increased rapidly between 7 and 20 days of age. Thereafter, only a minor increase was seen. In protein-deprived rats there was no increase in the specific length of vessels between 7 and 10 days of age and this variable was still reduced at 30 days of age compared to controls. This reduction was due to a decrease in the specific length of thin vessels (luminal diameter less than 8.25 mu) whereas the specific length of wider vessels was not affected by the protein deprivation. There were no significant differences in the specific surface or volume fraction of vessels between control and protein-deprived rats. These findings indicate an adaptive increase in luminal diameter of vessels in the protein deprived rats during postnatal development. At 90 days of age no significant differences between vascular variables of control and protein-deprived rats were seen.

Postnatal vascular growth in the cerebellar cortex of normal and protein-deprived rats. Morphometric studies.

The postnatal vascular growth in the cortex of vermis cerebelli folium IX of normal and pre- and postnatally protein-deprived rats was examined. The rate of increase in specific length of vessels seem to parallel the functional maturation of neurons in all cortical layers. From the first postnatal week there is a higher specific length of vessels in the Purkinje cell layer than in the adjoining parts of the molecular and granular layers. The results indicate that such differences are present also after the period of rapid vascular growth. Protein deprivation appears to affect the postnatal increase in specific length of vessels less in the Purkinje cell layer than in the granular and molecular layer where a significant reduction compared to controls was seen for the interval 7--20 days of age. At 90 days of age no significant differences were seen between control and protein-deprived rats.

[Selective and high-contrast staining in nervous tissue (author's transl)]. / Selektive und kontrastreiche Färbungen im Hirngewebe.

Using silver as an impregnating medium and controlling the staining process by physical development, a specific and reliable staining of high contrast can be achieved. These properties represent important prerequisites for automatic and quantitative television image analysis. Specificity depends on appropriate pretreatment. Television image analysis cannot only be used for object analysis, but also to quantify reliability and dependency of contrast on developmental conditions, as demonstrated for stained myelin.

[Ventromedial field of human tuber cinereum. Mechanical morphometry]. / Das ventromediale Feld des menschlichen Tuber cinereum. Ergebnisse maschineller Morphometrie

A quantitative structural analysis of the ventromedial area of the human hypothalamus was performed using an automatic image analysing computer. We divided the ventromedial area into two nuclei, nucleus ventromedialis (N. vm.) and nucleus infundibularis (N. inf.). N. vm. was studied in 6 cases, N. inf. in 7 cases. The following findings were obtained: 1. No significant differences of cell population became apparent between the left and right sides of both nuclei. Aside from a female case above 80 years of age, so far, no correlation with cellular distribution of age and sex, respectively, could be established. 2. In N. vm. the distribution of large and small nerve cells depends on the region within this nucleus. Small nerve cells appear more frequent in the medial region than in the central and in the lateral regions. On the other hand, significant distributional differences of nerve cells in the dorsal, central, and basal regions as well as in oro-caudal direction are absent. Data of individual cases and their mean value are conforming. Cell density (cell number/volume) does not show any regional dependence both in the frontal plane and in the oro-caudal direction; it amounts to approximately 170/mum3 in the entire nucleus. 3. In the frontal plane plane N. inf. does not disclose marked regional differences of cell population. Large neurons are slightly more frequent in the basal-medial region as compared to the dorsal region. An 81-year-old woman displayed a conspicuous increase of large nerve cells in the basal and centrolateral regions, obviously hypertrophy of the potential "subventricular nucleus" as described by SHEEHAN and KOVACS, which is, in our opinion, a part of the N. inf. In young subjects (below the age of 40 years) the frequency of large nerve cells decreases in oro-caudal direction. Identical cell populations suggest that the cuadal end of N. inf. extends to the floor of the mammillary recessus. Cell density in the frontal plane appears higher in the centrolateral region (230/mum3) compared to the dorsal and basal regions (190-200/mum3). Cell density increases in oro-caudal extent; it decreases, however, in the most caudal part.