Limited topographic specificity in the targeting and branching of mammalian retinal axons

摘要: We have studied in rats the topographic targeting of retinocollicular axons anterogradely labeled by focal retinal injections axon tracer DiI. find that developing widely mistarget along both medial-lateral and rostral-caudal axes superior colliculus (SC). In neonatal rats, originating from injection sites temporal periphery covering less than 1% retina grow over most contralateral SC, suggesting growth cones many initially fail to recognize their appropriate target region at rostral SC border. Some these correct errors are retained; do not eliminated. neonates, peripheral nasal transiently develop branches throughout SC. Branches formed later restricted a discrete terminal zone topographically appropriate, caudal At stage, or result increased labeling but this is considerably larger similar stage. Thus, although early projection very diffuse, there some bias for Our findings indicate show only limited specificity branching. conclude mechanisms addition directed required establish order characteristic mature mammalian projections.