The morphological research on the developing rat substantia nigra

Objective To observe the morphological changes of the substantia nigra during the development of fetal rat.Methods Continuous coronal sections were prepared from perinatal and adult rat midbrains embedded in paraffin. Nissl staining method was used before the sections were studied by microscopy.Results Two sorts of cells with different polarities were observed in rat midbrain on E13,while the profile of the substantia nigra remained not to be delineated. By the day of E16, the profile of the substantia nigra became evident, with the cells in the ventral part being denser than in the dorsal part. The cytoarchtecture of the substantia nigra changed on E18, and the shape of the cells became mature. According to the distribution and arrangement of the cells, the substantia nigra of this time could be divided into three parts. On birth, the density of the cells in the pars reticulata of the substantia nigra descreased, while that in the pars compacta increased. The shape of the cells appeared mature.Conclusion The maturation of the internal construction of rat substantia nigra is accomplished by birth.