engleski

Neurogenesis in ganglionic eminence in the last trimester of gestation

It is widely accepted that neurogenesis in humans ends around the middle of gestation. However, the subventricular zone of some focal telencephalic domains continues with neuron production throughout the last trimester. We evaluated Nissl, Golgi and immunohistochemically stained human slides from the Zagreb Neuroembryological Collection to determine if late neurogenesis might also occur in the major proliferative zones of the telencephalon. Between 24-26 postconceptional weeks (pcw) a massive stream of densely packed cells was found leaving the ganglionic eminence (GE), a progenitor domain of the ventral telencephalon that is a major source of cortical GABAergic neurons. Between 32-36 pcw, the GE decreased in size but was clearly distinguishable, and a stream of non-radially oriented MAP-2 positive migratory-like cells still extended towards the dorsal telencephalon. Additionally, volumetric analysis on MRI images was performed to evaluate the developmental pattern of the GE in period from 13 to 34 pcw and found a persistent GE throughout the entire analyzed period. This suggests that the GE maintains its proliferative capabilities up to the end of gestation and that a significant production of cortical GABAergic neurons continues beyond the proliferative period of principal glutamatergic neurons. We propose that protracted neurogenesis from the GE contributes to the disproportional increase in the number of calretinin neurons, the most numerous GABAergic neuron population in primates. We further suggest that late fetal production of neurons is not restricted to neurons within the dentate gyrus and rostral migratory stream.

ganglionic eminence ; neurogenesis

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