Human brain basal ganglia, and related structures. The diencephalon gives rise to the thalamus and hypothalamus. The hindbrain also splits into two areas – the metencephalon and the myelencephalon. The metencephalon gives rise to the cerebellum and pons. The myelencephalon gives rise to the medulla oblongata. Also during the fifth week, the brain divides into repeating segments called neuromeres. These are known as rhombomeres seen in the hindbrain. A characteristic of the brain is gyrification (wrinkling of the cortex). In the womb, the cortex starts off as smooth but starts to form fissures that begin to mark out the different lobes of
Cerebellum are, however, a number of respects in which the structure of the cerebellum is compartmentalized. There are large compartments that are generally known as "zones"; these can be divided into smaller compartments known as "microzones". The first indications of compartmental structure came from studies of the receptive fields of cells in various parts of the cerebellar cortex. Each body part maps to specific points in the cerebellum, but there are numerous repetitions of the basic map, forming an arrangement that has been called "fractured somatotopy". A clearer indication of compartmentalization is obtained by immunostaining the cerebellum for certain types of