| Abstract: | The infundibular organ of adult and larval Branchiostoma was studied by means of the electron microscope. The secretion produced by the infundibular cells is released into the ventricular fluid from secretory vacuoles, fusing with the apical plasmalemma and forming a Reissner's fiber in the ventricle. The basal cell processes reach the external limiting membrane but no basal release of secretory material has been observed. No synapses are in contact with the infundibular cells. The organ seems to function autonomously with neither nervous control from the brain tissue nor chemical regulation from the ventricular fluid. |
