Glial cell differentiation in neuron-free and neuron-rich regions. II. Early appearance of S-100 protein positive astrocytes in human fetal hippocampus.
The development of the human fetal hippocampus and dentate gyrus has been studied immunocytochemically. The first glial cells to appear are vimentin-positive radial glial cells. A gradual transition from vimentin to glial fibrillary acidic protein (GFAP) reactivity in the radial glial cells occurs at week 8. The GFAP-positive radial glial cells transform into astrocytes from week 14. A population of small S-100-positive somata which morphologically and spatially are distinct from GFAP-positive radial glial cells and their transformed progeny, are found as early as week 9.5 in the hippocampus during the period of peak neurogenesis. The well-defined immunoreactivity of the morphologically homogenous cell subpopulation for S-100 protein, which has been used as an astrocytic marker in the adult hippocampus, indicates that astrocytes may differentiate at very early gestational ages in human fetuses. The S-100-positive astrocytes are thought to be derived from ventricular zone cells, which at the time of their appearance do not express any of the applied astrocytic markers (S-100, GFAP, vimentin). It is suggested that the S-100-positive astrocytic cell population interacts with the first incoming projection fibers, so modulating the pattern of connectivity.
Stagaard Janas
M
M
Institute of Medical Anatomy A, Panum Institute, University of Copenhagen, Denmark.
Nowakowski
R S
RS
Møllgård
K
K
D001253:Astrocytes / Q000737:chemistry / Q000166:cytology*; D015415:Biomarkers; D002454:Cell Differentiation; D005865:Gestational Age; D005904:Glial Fibrillary Acidic Protein / Q000032:analysis; D006624:Hippocampus / Q000737:chemistry / Q000166:cytology / Q000196:embryology*; D006801:Humans; D009024:Morphogenesis; D009418:S100 Proteins / Q000032:analysis*; D014746:Vimentin / Q000032:analysis
D015415:Biomarkers; D005904:Glial Fibrillary Acidic Protein; D009418:S100 Proteins; D014746:Vimentin