The development and pattern of innervation of the avian cornea☆

[摘要] Theinvolvementofnervesinthedevelopmentoftheaviancorneaispoorlyunderstood,primarilybecausethedemonstrationofcornealnerveshasprovedtobeelusive.Inthepresentstudy,thedevelopmentofcornealinnervationisdemonstratedbytheapplicationofamodifiedBodianstainingtechnique(J.Lewis,1978,Zoon,6,175–179).Onthe6thdayofembryonicdevelopment,numerouslargefasciclesofaxonsareobservedarrivingattheventrotemporalaspectofthecornea,withintheperiocularmesenchyme.Thesefasciclessubdivideintotwodistinctgroupswhichmigratebothventrallyand,moreextensively,dorsallyaroundthecornea.Progressivemigrationofnervefasciclesaroundthecorneaoccursthroughthe7thand8thdaysofdevelopment,andbythe10thdaythecorneaisensheathedwithinaringofnerves.Concomitantwithringformation,nervesareobservedleavingthemainnervefasciclesandmigratingtowardthecornea.Numerousnerveprocesses,whichenterthroughthemid-stroma,areobservedmigratingtowardthecenterofthe12th-daycornea.Innervationoftheepitheliumisdetectedonthe12thday,beginningattheperipheryandincreasingdramaticallywithdevelopment.Innervationoftheepitheliumisalmostcompleteonthe16thdayandpenetrationofnervesintothecentralstromaoccursonthe18thdayofdevelopment.Onthe16thday,thebasalepithelialcellsbegintodemonstratesilver-stainingproperties.Thelevelsofthisstainingincreasewithdevelopment,andinthehatchlingthesquamouscellsdemonstrateacharacteristicsilver-stainingpattern.Innervationofthecornealendotheliumisnotobserved.Theseresultsindicatethattheaviancorneaanditsepitheliumbecomeinnervatedoverthesamedevelopmentalperiodinwhichthemajortransitionfromcornealopacitytotransparencyisachieved.

[学科分类] 生物科学（综合）