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Regular Manuscript

Neuronal maturation in an experimental model of brain tissue heterotopia in the lung

¹ University of Sao Paulo
² Ribeirão Preto School of Medicine - University of Sao Paulo

^* To whom correspondence should be addressed. E-mail: lcperes{at}fmrp.usp.br.

	Abstract

Neural maturation involves diverse interaction and signaling mechanisms which are essential to the development of the nervous system. However, little is known about the development of neurons in heterotopic brain tissue in the lung, a rare abnormality occasionally observed in malformed babies and fetuses. The aim of this study was to identify the neurons and to investigate their maturation in experimental brain tissue heterotopia both during fetal and neonatal periods. The fetuses from twenty four pregnant female Swiss mice were used to induce brain tissue heterotopia on the 15th gestational day. Briefly, the brain of one fetus of each dam was extracted, disaggregated and injected into the right hemithorax of siblings. Six of these fetuses with pulmonary brain tissue implantation (PBI) were collected on the 18th gestational day (group E18) and six other on the 8th postnatal day (group P8). The brain of fetuses from dams not submitted to any experimental procedure was collected on the 18th gestational day (group CE18) and on the 8th postnatal day (group CP8) to serve as a control of neuronal quantification and maturation. Immunohistochemical staining for NeuN was used to assess neuron quantification and maturation. NeuN Labeling Index (LI) was greater in postnatal than fetal period both for the experimental and control groups (P8 > E18 and CP8 > CE18), although there were fewer neurons in experimental than in control groups (P8 < CP8 and E18 < CE18) (P<0.005). These results indicate that fetal neuroblasts/neurons not only survive a dramatic event such as mechanical disaggregation, in the same way as it happens in human cases, but they keep their development in heterotopia irrespective of local tissue influences.

Key Words: Heterotopic tissue, experimental model, neuronal maturation, NeuN, mouse