Golgi-stained sections of the human cerebellar dentate nucleus (DN) at various gestational ages were examined to study the dendritic proliferation and maturation of the DN neurons. Bipolar cells were seen at 14–15 weeks. By 19–20 weeks, three cell types were identifiable: bipolar, hemisphereic and pyriform. The cells of the dorsomedial region matured earlier than those of the ventrolateral region. In addition to the above cell types, multipolar and nuclear boundary cells were observable at 24–25 weeks. The five cell types persisted during subsequent development. At no stage of development was any neuronal organizational pattern apparent. A remarkable dendritic proliferation occurred at 27–28 weeks. Spines and filiform processes were seen at 34 weeks of intrauterine life.

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The three-dimensional configurational and volumetric changes of the human dentate nucleus (DN) during intrauterine life were examined in 11 fetuses (11 to 27–28 weeks of gestation). During intrauterine life, the dentate nuclear profile successively passes through the pongid, cercopithecus and prosimian phases of configuration. The smooth, elongated, crescent-shaped DN of 11 weeks lies along a dorsal-ventral axis. A 45 ° clockwise shift in the position of the nucleus changes the axis to dorsomedial-ventrolateral at 14–15 weeks, which is maintained in subsequent ages. The formation of gyri is preceded by a thinning of the substantia grisea. This begins at 17–18 weeks in the dorsomedial region of the DN. Gyri first make their appearance at 24–25 weeks. The DN of 27–28 weeks resembles the adult human DN. Two regions are discernible at this stage – a microgyric, magnocellular region and a macrogyric, parvocellular region. The DN volume increases with increasing gestational age. Between 14–15, 19–20 and 24–25 weeks the volumetric increase is statistically significant. This is simultaneously accompanied by a modification of the configuration of the DN.

Histological and quantitative studies were carried out in dentate nucleus (DN) of 14 human fetuses of gestational ages ranging from 10 weeks to 28 weeks in Nissl stained sections. The dentate nucleus was already well delineated at 11 weeks, but the adult profile was attained only by 27-28 weeks. The magnocellular dorsomedial region and the parvocellular ventrolateral region became apparent at 17-18 weeks. The numerical density of neurons showed a steady decline with advancing gestational age. However, the absolute neuronal count until 19-20 weeks was 367.1 x 10(3) followed by a count of 249.5 x 10(3) at 22-23 weeks. The reduction in the count between the two periods was significant and coincided with cell death which was striking between 19 and 23 weeks. The glial cell population continued to increase with advancing gestational age. The occurrence of significant neuronal cell death and its probable role in the developing human DN is reported for the first time.

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