NEURAL STRUCTURES IN AN INSECT EMBRYO (SCHISTOCERCA-GREGARIA) REVEALED BY AN ANTISERUM AGAINST A VERTEBRATE GLIAL GLYCOPROTEIN

A number of specific molecular cues play important roles in guiding pa rticular axons towards selected target locations in the nervous system . It is remarkable that many of these well-known molecules, whether re ceptors or chemoattractants/repulsants are highly conserved among inve rtebrates and vertebrates. Here, we demonstrate labeling of the grassh opper Schistocerca gregaria embryo with an antiserum raised against bo vine Reissner's substance, a glycoprotein which is described in verteb rates as a secretory product of radial glial cells. The Reissner's sub stance-like immunoreactivity shows temporal expression during embryoni c development of the central nervous system in the grasshopper. The ea rliest labeling is on processes of the midline precursor 2 progeny at approximatly 29% of embryonic development. At more advanced stages the antigen revealed localisation in the main axon scaffold of the brain and segmentally repeated ganglia. Apparently, the relevant molecule is produced from cells located dorsally of the neural lamina and is accu mulated in the extracellular matrix of the ganglionic neuropil. We sug gest that the labeled antigen has molecular mutualities and relations to the glial glycoprotein of vertebrates. The early and common express ion favours a basic function in correlation with the development of a complex nervous system throughout the animal kingdom.