INVITRO EFFECTS OF IMPLANTED SPINAL GANGLIA ON CARTILAGE CELLS IN XENOPUS-LAEVIS FORELIMB REGENERATES

Following forelimb amputation in Xenopus laevis froglets a heteromorphic cartilaginous spike regenerate develops. It has been shown that the peripheral innervation of a forelimb is essential throughout the regeneration process; in its absence a regenerate undergoes resorption and subsequent stumping. This study examined the in vitro effects of spinal ganglion implants from siblings on forelimb regenerates of froglets. Perichondrial cells and chondroblasts of the regenerates incorporated tritiated thymidine, which suggests a causal relationship between the presence of implanted sensory nerves and cell proliferation. Presumably, a neurotropic factor(s) of low molecular weight is produced which can diffuse through the extracellular and cartilage matrices and exert its effect on the perichondrium and the developing cartilage within the spike regenerate. From our histological observations it appears that the innervated explants underwent appositional (perichondrial) as well as interstitial (cartilaginous) growth.