Pre-postnatal morphogenesis of rat hippocampal pyramidal cells

OBJECTIVE: To follow-up the morphological changes of the neuroblasts as they develop to pyramidal cell in the hippocampal cerebral cortex beginning from 15 days prenatal and ending 14 days postnatal. Particular metric and numerical estimations of the dendrites developed from these cells were carried out.

METHODS: Fifty pregnant rats classified into 5 groups were used to obtain 15 and 18 day embryos; birth, 7 day and 14 day pups. Brains of these animals were processed for histological examination using iron hematoxylin and golgi mixed methods of staining from paraffin sections. Multiplicity and length of the dendrites were assessed. The practical work was carried out in the Anatomy Department of the School of Medicine, King Saud University, Riyadh, Kingdom of Saudi Arabia during the year 2002.

RESULTS: At 15 days prenatal, a few pyramidal cells appeared which greatly increased at 18 days prenatal with the development of their beaded apical dendrites. At birth, the dendrite stem became shorter but had more branches and beads. Postnatal one and 2 weeks consecutively witnessed the arise of axons and basal dendrites.

CONCLUSION: These results showed the very early postnatal full morphological development of the hippocampus cortex pyramidal cells. The progressive increase in length of the apical dendrites during the period from 18 days prenatal when they first appeared to 14 days postnatal was highly significant (P< 0.00).