TYROSINE-HYDROXYLASE-POSITIVE AND DOPAMINE-BETA-HYDROXYLASE-POSITIVE NEURONS AND FIBERS IN THE DEVELOPING HUMAN CEREBELLUM - AN IMMUNOHISTOCHEMICAL STUDY

Six human fetuses of gestational ages 16-28 weeks were employed. The i mmunocytochemical avidin-biotin-peroxidase complex method combined wit h the silver Bodian technique was used to evaluate the presence of tyr osine hydroxylase and dopamine-beta-hydroxylase neurons and afferent a nd efferent fibres in the cerebellum during development. Our results i llustrated that by 16-18 weeks, immunoreactivity of the Purkinje cells and the granule cells was evident. By 23 weeks, the positive Purkinje cells were tightly packed together and the perinuclear granules began to extend into the processes. The positive cells next to Purkinje cel ls were the basket cells and stellate cells. By 26-28 weeks, all posit ive cells increased in number and size. Messy and climbing fibres appe ared early in development (16-18 weeks of gestation) and were seen syn apsing with the positive granule cells. At the same time, some paralle l fibres were observed. At later stages, the tyrosine hydroxylase- and dopamine-beta-hydroxylase-positive Purkinje cells were surrounded by abundant climbing fibres, while parallel fibres were also evident in t he molecular layer. In the deep cerebellar nuclei, positive tyrosine h ydroxylase and dopamine-beta-hydroxylase neurons were present by 16-18 weeks of development. Those in the dentate nucleus were more polymorp hic but smaller in size. Some afferent fibres were also spotted around 16-18 weeks of gestation and their numbers increased later. Positive efferent fibres were present by 26 weeks. All these observations point to an early presence of tyrosine hydroxylase and dopamine-beta-hydrox ylase components in cerebellar development.