Sympathetic innervation of the amphibian spleen: developmental studies in Xenopus laevis

Spleens from larval and adult South African clawed frogs (Xenopus laevis) were examined using sucrose-potassium phosphate-glyoxylic acid (SPG) histofluorescence for norepinephrine. Innervation of the larval Xenopus spleen is barely detectable at stage 54 and gradually increases during prometamorphosis (stage 57/58) until metamorphic climax (stage 66). This development of innervation late in the larval life of the animal was highly sensitive to environmental conditions and to rapidity at which development occurred. Prevention of overt metamorphosis by sodium perchlorate blockade prevented the development of noradrenergic (NA) splenic innervation in some, but not all, tadpoles examined. Depletion of T-lymphocytes by early larval thymectomy did not alter the kinetics or pattern of splenic NA innervation.