Presence of biogenic amines in early rat development

Rat ova, zygotes, and (2- to 4-cell) embryos were processed for the fluorescence demonstration of catecholamines and serotonin. Specific endogenous fluorescence, characteristic of catecholamines, was observed in all stages studied. The endogenous fluorescence was intensified by incubation in serotonin or norepinephrine. These observations suggest a role for biogenic amines in early mammalian cleavage, similar to that previously reported in invertebrates.