Structural analysis of the statocyst and nervous system of Praesagittifera naikaiensis , an acoel flatworm, during development after hatching

摘要: Acoel statocysts are fluid-filled chambers formed by two parietal cells underlying basal lamina as a capsule and contain movable statolith cell called lithocyte. The statocyst is needed for geotaxis; however, the mechanism of gravity receptor system has not been elucidated. We focused on geotactic ability acoel Praesagittifera naikaiensis, acquired during development its nervous after hatching, examined three-dimensional relationship between system. was 0 7 days hatching. No major changes in neural structures, namely commissural brain, nerve cords, commissures, were observed juveniles adults. statocyst-associated commissure (stc), brain component, circular located ventral to but connections capsule’s lumen. Fine structures revealed that developed hypothesized needs following conditions: (1) sufficient concentration calcium salt statolith; (2) stc must work afferent neurons; (3) polar cell, which present outside capsule, be sensory stimulated