Configurational and volumetric changes of the early prenatal human cerebellar dentate nucleus.

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 degrees 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 dorso-medial 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.