Induction of corticospinal target finding by release of a diffusible, chemotropic factor in cervical spinal grey matter.
The outgrowth of corticospinal tract axons in rat spinal cord primarily occurs during the first postnatal week. Axons originating from a group of layer V pyramidal cell bodies situated in the anterior part of the cerebral sensorimotor cortex project mainly to the cervical gray matter (Joosten et al., Dev. Brain Res., 36 (1987) 121-130). By co-culturing explants of the anterior part of the sensorimotor cortex and of cervical spinal gray matter in 3-D collagen gels, a target-specific directional growth of cortical axons towards the cervical spinal gray explant could be demonstrated. After retrograde filling with the fluorescent tracer 1,1-dioctadecyl-3,3,3',3'-tetramethyl indocarbocyanine perchlorate (DiI), in vivo as well as in vitro, most of the DiI-labelled cortical neurons were located in layer V of the cortical explant, and were characterized by a pyramidal shape. These data suggest that the cervical spinal gray matter target area becomes innervated by corticospinal axons through the release of a diffusible chemotropic factor.
Joosten
E A
EA
Department of Anatomy and Embryology, Faculty of Medicine, University of Nijmegen, The Netherlands.
van der Ven
P F
PF
Hooiveld
M H
MH
ten Donkelaar
H J
HJ
D000818:Animals; D000831:Animals, Newborn / Q000502:physiology; D001369:Axons / Q000502:physiology; D002232:Carbocyanines; D003094:Collagen; D003584:Cytological Techniques; D005456:Fluorescent Dyes; D005782:Gels; D009333:Neck; D011712:Pyramidal Tracts / Q000502:physiology*; D051381:Rats; D011919:Rats, Inbred Strains; D013116:Spinal Cord / Q000378:metabolism / Q000502:physiology*
D002232:Carbocyanines; D005456:Fluorescent Dyes; D005782:Gels; C064633:1,1'-dipropyl-3,3,3',3'-tetramethylindocarbocyanine; D003094:Collagen