CALCIUM-ACCUMULATING ORGANELLES IN THE PHOTORECEPTOR CELLS OF THE CRAYFISH ORCONECTES-LIMOSUS

1. By permeabilizing entire retinae with the saponin beta-escin and th en loading the photoreceptor cells of the crayfish Orconectes limosus with oxalate and ATP, we localized calcium-accumulating organelles. Th e Ca-oxalate-deposits were identified with the electron microscope. 2. The photoreceptor cells of crayfish contain three kinds of calcium-ac cumulating organelles: submicrovillar cisternae, mitochondriae and ele ctron dense pigment granules. 3. The submicrovillar cisternae appear t ubelike and are less voluminous than those of other arthropods. 4. The deposits found in the pigment granules support the hypothesis that th ey are involved in calcium regulation. 5. The effect of beta-escin on the electroretinogram was also tested. Beta-Escin causes a diminution in the ERG-amplitude which stays stable for 1 hr.