Differentiation of the nuclear groups in the posterior horn of the human embryonic spinal cord

The formation of nuclear groups in the posterior horns of the human embryonic spinal cord was traced in serial sections of embryos of developmental stages 13 to 23 (32 to 56 postovulatory days). The following observations, new for the human, are presented: 1. The differentiation of the neural tube into 3 zones (germinal, mantle and marginal) is detected in the middle of the 5th week. 2. The primordia of the posterior horns are marked at stage 14 (33 days). 3. In the middle of the 7th week the nucleus proprius and substantia gelatinosa are discerned. 4. Differentiation of the nuclei within the posterior horns proceeds in the ventrodorsal and rostrocaudal gradients. (Folia Morphol 2011; 70, 4: 245–251