0000000000276898
AUTHOR
Norbert Ulfig
Ontogeny of the human amygdala.
Data on the fetal development of the human amygdala is reviewed with special reference to major ontogenetic events. In the fifth gestational month, the inferior portion of the amygdala reveals cell-dense columns merging with the ganglionic eminence (proliferative zone) in Nissl-stained sections. These columns contain vimentin-positive fibers and can therefore be regarded as migrational routes. In the sixth and seventh months, distinct reorganization of the cytoarchitectonics takes place. The sequential occurrence of afferens can be visualized using anti-GAP-43; moreover, outgrowing axons appear to reach the periphery of the ganglionic eminence. The latter may thus represent an intermediate …
Expression of MAP1a and MAP1b in the ganglionic eminence and the internal capsule of the human fetal brain.
The expression of microtubule-associated proteins 1a and 1b (MAP1a and 1b) were investigated in two transient structures, the ganglionic eminence (GE) being a prominent part of the telencephalic proliferative zone and the perireticular nucleus (PR) within the internal capsule (IC). Anti-MAP1a immunolabels PR neurons from 18 weeks of gestation (wg) onwards, whereas anti-MAP1b immunolabels long IC fibers between 18 and 22 wg. MAP1b is further present in thalamic fibers that seem to terminate at the medial margin of the GE, in a moderate number of cells of the GE and its medial extension, the gangliothalamic body (GTB). From 26 to 33 wg MAP1b is expressed in short fiber bundles of the IC, a fe…
Monoclonal antibodies SMI 311 and SMI 312 as tools to investigate the maturation of nerve cells and axonal patterns in human fetal brain
Neurofilaments, which are exclusively found in nerve cells, are one of the earliest recognizable features of the maturing nervous system. The differential distribution of neurofilament proteins in varying degrees of phosphorylation within a neuron provides the possibility of selectively demonstrating either somata and dendrites or axons. Non-phosphorylated neurofilaments typical of somata and dendrites can be visualized with the aid of monoclonal antibody SMI 311, whereas antibody SMI 312 is directed against highly phosphorylated axonal epitopes of neurofilaments. The maturation of neuronal types, the development of area-specific axonal networks, and the gradients of maturation can thus be …
Transient features of the thalamic reticular nucleus in the human foetal brain
The architectonic organization and neuronal types of the human foetal reticular nucleus (RN)--with special reference to transient characteristics--have been investigated using antisera against calretinin, parvalbumin and neurofilament epitopes of somata and dendrites (SMI 311). The RN consists of four subdivisions (clearly distinguishable in the 6/7th gestational month): The main portion appears as a prominent structure on account of its extension and high packing density of neurons which coexpress calretinin and parvalbumin. These two calcium-binding proteins are also expressed by the perireticular nucleus forming a conspicuous grey within the internal capsule. Perireticular cells form clu…
Alterations in the organization of the isocortical layer I in trisomy 22.
The isocortical layer I of human fetal brains obtained from different cases of chromosomal abnormalities (trisomy 18, 21, 22) and controls without pathological disturbances were investigated histologically and immunohistochemically by using the antibodies SMI 311, SMI 35 and SMI 81 (SNAP 25) as well as antibodies against GAP 43 and calretinin. In cases of trisomy 22 the Cajal-Retzius cells in Nissl-sections and in SMI 311-immunopreparations do not reveal any alterations regarding their location or morphology. However, the axonal plexus, selectively labelled with SMI 35, normally located in layer Ib, is malpositioned in Ia. Likewise, SNAP 25- and GAP 43-immunoreactive structures, which were …
Transient expression of synaptogyrin in the ganglionic eminence of the human fetal brain
Summary The ganglionic eminence (GE) representing a conspicuous bulb-like elevation of the telencephalic proliferative zone has recently been shown to be involved in the establishment of cortical connections. This study demonstrates the presence of synaptogyrin-immunoreactivity in a large number of cell bodies of the human GE between 12 and 20 weeks of gestation. From the 20 th week onwards synaptogyrin expression sharply declines. No immunoreactive structures are detectable in the 23 rd week or later. As the GE persists nearly throughout the entire fetal period these results show that its neurochemical features change distinctly in the course of development. The synaptogyrin-immunoreactive…
Distribution patterns of vimentin-immunoreactive structures in the human prosencephalon during the second half of gestation.
Neuronal migration is guided by long radially oriented glial fibres. During late stages of development radial glial cells are transformed into astrocytes. A predominant intermediate filament protein within radial glial cells and immature astrocytes is vimentin. In this study fetal brain sections were used to demonstrate the transient features of vimentin-positive radial glia. In the lower half of the cerebral wall of the 6th gestational month bundles, curvature, and crossing of vimentin-positive fibres are regularly seen. Moreover, fibres terminating on vessels are observed. In the upper half fibres are radially oriented; when ascending towards the pial surface the number and diameter of fi…
Anomalous alterations affecting microglia in the central nervous system of a fetus at 12 weeks of gestation: case report.
We report here on the first documented case of profound alterations specifically affecting the microglial population within the nervous system during the fetal period. This case, derived at gestational week 12, was one amongst a series of second trimester brains currently being investigated with respect to microglial colonization of the human fetal brain. No significant pathological alterations could be identified upon gross macroscopy or following microscopic analysis of serial brain sections stained with cresyl fast violet (Nissl). By contrast, sections stained immunohistochemically to detect MHC class II (CR3/43) and CD68 (PG-M1) antigens revealed a marked pathological change in the morp…