Presence of a Substance Rich in Protein-bound Cystine or Cysteine in the Neurosecretory System of an Insect

Abstract

COMPARISONS have been drawn between the hypothalamo-hypophysial neurosecretory system of vertebrates and corresponding systems in invertebrates; for example, the pars intercerebralis-corpus cardiacum neurosecretory system of insects¹. Such comparisons are supported by the demonstration in both groups² of a deeply staining chrome–alum–hæmatoxyphil neurosecretory material. In the dog, this material has been described as a glycolipoprotein ‘bearer-substance’, soluble in lipid-solvents, and for this reason clearly to be differentiated from the posterior pituitary principles³. There is, however, an alternative view⁴, namely, that chrome–alum–hæmatoxyphil vertebrate neurosecretory material, or material in its exact distribution, is essentially a protein, which, in tissues which have not been fixed in formalin, is soluble in water rather than lipid solvents, and which for these reasons, and because of its high cystine content, could well be closely akin to the posterior pituitary principles. The present investigation is concerned with the nature of neurosecretory material in the intercerebralis–cardiacum system of the cockroach, Leucophaea maderae.