[Presence of indoleamines in the pineal and parapineal organs of Lampetra planeri (Petromyzontidae)].

Using the Falck and Hillarp technique, the precursors of melatonin (5-HT and may be 5-HTP) have been identified in the pineal and parapineal organs of Lampetra planeri (Petromyzontidae). A particular kind of cell, the so-called "cells with residual bodies" (Collin, 1968), is responsible for this neurohormonal activity of the two organs.