ABSTRACT

In recent years, anticholinergic drugs were shown to affect intercellular signals in developing systems. Sea urchin development seems to be regulated by both cytoplasmic heterogeneity and by intercellular communications. In vivo experiments were carried out on the whole development of the sea urchin Paracentrotus lividus, in the Station Zoologique of Villefranche-sur-Mer, by the methods suggested by Fenaux et al. The morphological effects are different according to the mode of action of drugs: atropine miniaturizes the sensitive bands of larvae and the adult rudiments, while carbachol and eserine (that mimic ACh eccess) cause an increased size of the same structures. In ciliated structures, sea urchin larvae exhibit receptors on the external surface, exposed to substances present in the sea water.