Histochemical study of biogenic monoamines in early ("Prenervous") and late embryos of sea urchins.

Treatment of the embryos of sea urchins with glyoxylic acid results in the appearance of luminescence which is indicative of the presence of biogenic monoamines. At the early stages of development (cleavage divisions, blastula, gastrula) the histochemical method reveals a tryptamine-like substance which is first found in all embryonic cells and later is concentrated mainly in the cells of the primary gut and ciliary bands. At the stages of prism and pluteus there appear neuron-like cells containing dopamine. The inhibitors of monoamine oxidase and neurotoxins reliably increase the histochemical reaction to monoamines only in late embryos which suggests a change in the properties of monoaminergic systems in the course of embryogenesis.