The specificity of retinotectal connections studied by retinal grafts onto the optic tectum in chick embryos

[摘要] Piecesofretinafromknownquadrantsof4-daychickembryoeyesweregraftedontothesurfaceoftheoptictectumof6-or7-dayembryos(thecontralateraleyeofthehostshavingbeenexcisedinanearlieroperationtopreventthenormalcomplementofopticfibersfromreachingthetectum).Theembryoswithgraftswereincubated5days,thenpreparedforhistologicalstudy.ExaminationofserialsectionsstainedwithProtargolrevealedthattheretinalgraftshaddifferentiatednormallyandproducedfiberswhichpassedontothesurfaceofthetectumasasinglebundle,orasparallelfascicles.Thesecoursedforvaryingdistancesonthesurfacemembraneabovethetectum,endinginmanycasesbypiercingthemembraneandenteringthesuperficialtectallayers.Thelocationofthegraftonthetectalsurfaceandthecourseandlengthofthefiberbundleswererecorded,andtheresultsgroupedaccordingtothequadrantoforiginoftheretinalgraft.Fibersfromaparticularquadrantofretinapreferentiallygrewtowardspecificareasofthetectum(dorsalretinatolateroventraltectum;ventralretinatodorsaltectum;nasalretinatoposterodorsaltectum;temporalretinatoanterodorsaltectum).Thesefindingscorrelatedwiththeknownretinotopicdistributionofnormalopticfiberprojectionsontothetectum.Possiblemechanismsmediatingthespecificguidanceoffibersarediscussed.

[学科分类] 生物科学（综合）