Fig. 6.

Embryogenesis of dorsal lipoma, a pure primary neurulation defect. A and B : Premature disjunction before complete closure of neural plates allows migration of mesenchymal cells into neural groove to establish contact with the ependymal surface. C and D : Formation of fusion line between lipoma, cord, and pia-arachnoid. DREZ and dorsal root are always lateral to the fusion line and thus not entangled in fat. Reprinted from Pang [55] with permission from the Japanese Neurosurgical Society. CE : cutaneous ectoderm, NC : neural crest, Me : mesenchyme, SL : subcutaneous lipoma, DR : dorsal root, IL : intramedullary lipoma, DREZ : dorsal root entry zone, D : dura, P-A : pia-arachnoid, M : muscle, LF : lumbodorsal fascia.