engleski

Immunohistochemical study of prenatal development of human indusium griseum

INTRODUCTION Aim of the study was to analyze growth, formation and differentiation of the indusium griseum (IG), the human supracommissural hippocampus (al. girus epicallosus, girus supercallosus) during prenatal development of the human brain. MATERIALS AND METHODS We employed histological and immunohistochemical methods on fixed-paraffinembedded sections of 24 human fetal brains from the 12 th to the 40 th postovulatory week (POW) of development. RESULTS The growth curve of the IG followed the growth of the corpus callosum during its fronto-occipital extension and was most steep between 12 th and 24 th POW. The most intensive differentiation processes of IG development were seen between 20 th and 28 th POW, as revealed by immunohistochemistry related to neuronal, fibrilar, synaptic and glial molecules. The three- layer lamination pattern of the IG in the fetal brains was visible from the 20 th POW onwards, clearly resembling the structural organization of the retrocommissural hippocampus. Glial fibrilar acidic protein (GFAP) show morphological differentiation of the positive cells from the 20 th POW onwards, while fully developed astrocytes could be seen after the 22 nd POW. During this developmental period, neuronal nuclear protein (NeuN), characteristic for early differentiation processes of neurons in the early postmitotic phase, was expressed concomitant with other neuronal markers ; microtubule-associated protein-1b (MAP1b), microtubule-associated protein 2 (MAP2), neurofilaments 200kD (NF-200) and the synaptophysin. From the 22 nd POW different individual Ca-binding proteins positive neurons (calretinin and calbindin) could be identified. In the third trimester of gestation, the expression of the molecular markers of differentiation was slightly weaker and the laminar organization of the IG was not clearly discernible anymore due to the development of its connections. Such a developmental pattern and structural organization of the IG belongs to the earliest corticogenetic processes in the human telencephalon following the development and structural organization of the neighboring retrocommissural hippocampus, which is in correlation with its ontogenetic origin. CONCLUSION Such a developmental pattern and structural organization of the IG belongs to the earliest corticogenetic processes in the human telencephalon following the development and structural organization of the neighboring retrocommissural hippocampus, which is in correlation with its ontogenetic origin.

fetal brain ; indium griseum

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