In vitro experiments on axon guidance demonstrating an anterior-posterior gradient on the tectum.
Axonal growth cones originating from explants of embryonic chick retina were simultaneously exposed to two different cell monolayers and their preference for particular monolayers as a substrate for growth was determined. These experiments show that: (1) nasal retinal axons can distinguish between retinal and tectal cells; (2) temporal retinal axons can distinguish between tectal cells that originated from different positions within the tectum along the antero-posterior axis; (3) axons originating from nasal parts of the retina have different recognizing capabilities from temporal axons; (4) the property of the tectal cells, which is attractive for temporal axons, has a graded distribution along the antero-posterior axis of the tectum; and (5) this gradient also exists in non-innervated tecta.
D000818:Animals; D001370:Axonal Transport; D001369:Axons / Q000502:physiology*; D002642:Chick Embryo; D009924:Organ Culture Techniques; D012160:Retina / Q000196:embryology / Q000637:transplantation*; D013477:Superior Colliculi / Q000196:embryology / Q000502:physiology*