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
