Previous experiments have established that grafts of embryonic day (E) 16 frontal cortex placed into the occipital cortex of postnatal day (P) 0-P1 @entity35 selectively attract axons from the ventrolateral and ventromedial (VL/VM) thalamic nuclei (Frapp   et al., Exp. Neurol. 169 (2001) 264). The present study was therefore undertaken to identify any possible maturation-promoting activity of the cortex on VL/VM thalamic cells. In a first step, a primary culture of VL/VM thalamic cells taken from P0-P1 @entity35 was developed. Neurons, glial cells and a few immature, nestin immunoreactive cells were identified in the culture. In a second step, VL/VM thalamic cells that had been maintained in vitro for 4-5 days were cultured for 7 additional days in isolation (control condition) or with an @entity23852 or P5 explant of frontal or occipital cortex placed on a microporous membrane. In control conditions, the total cell population and the percentage of @entity19744 immunoreactive neurons were not modified with time. In contrast, the percentage of @entity19744 immunoreactive neurons was increased in @entity23852 cortex co-cultures whereas the total cell population was unchanged and the proliferative activity remained very low. Also, the mean number of neurites per neuron was increased but no effect was found on neuritic length. Similar effects on neuronal maturation were found with @entity23852 frontal or occipital cortex explants, indicating a lack of areal specificity. P5 cortex also produced, but to a lesser extent, an increase in percentage of @entity19744 immunoreactive neurons. Further, P5 cortex had no effect on mean number of neurites per neuron but substantially promoted elongation of neuronal processes. We propose that in addition to their well-established survival promoting effect, diffusible molecules released by embryonic and early postnatal cortex can promote in vitro the maturation of thalamic neurons.

Cortical diffusible factors increase XXXX immunoreactive neuronal population in thalamic cultures.

@entity35 :: ('10116', 'Species') :: ['rats'] @entity19744 :: ('25595(Tax:10116)', 'Gene') :: ['MAP-2'] @entity23852 :: ('50719(Tax:10116)', 'Gene') :: ['E16']
@entity19744 :: (25595(Tax:10116),Gene) :: ['MAP-2']
