Evidence from thymidine labeling for continuing growth of retina and tectum in juvenile goldfish

摘要: Tritiated thymidine was injected intraperitoneally into juvenile goldfish that were 3 to 6 cm in body length. After h 32 months these fish then killed for autoradiography of retina and tectum. The autoradiographs indicated despite the maturity both tectum still growing by accretion new cells at their margins. As shown Xenopus, retinal added around entire circumference, while tectal principally posterior margin none anteriormost edge. However, this size have a well-defined functional retinotopic projection onto This means newly created ganglion temporal retina, destined send axons anterior tectum, will find only old target locus with which connect. Presumably preexisting terminals must be shifted posteriorly allow synaptic sites.