Hormonal control of meiosis reinitiation in starfish oocytes : New evidence for the absence of efficient intracellular receptors for 1-methyladenine recognition

Intracellular Ca²⁺ ions release and Na⁺ pump stimulation are triggered only 1 or 2 min after 1-methyladenine injection into starfish oocytes, whereas both events occur less than 2 sec after external application of the hormone. These data confirm and extend previous observations pointing to the existence of receptors localized on the external side of the plasma membrane. They make unlikely that the two elementary responses to the hormone here studied could be independently triggered through stimulation of eventual intracellular receptors, directly accessible from inside the oocyte.