SWELLING OF CALYX-LIKE NERVE-ENDINGS IN MACULAE AND CRISTAE OF QUAIL EMBRYOS EXPOSED TO WEIGHTLESSNESS

The results of our morphological analysis show that the vestibular app aratus of quail embryos, that developed in weightlessness from 1-12 da ys age, are formed normally. Thus, the specific stimulus of gravity is apparently not a prerequisite of the formation of the structural orga nization of the vestibular apparatus at the early stages of ontogenesi s of the lower and higher vertebrates. However, the space flight facto rs can produce some structural modifications in the otolithic organ an d cristae. Light microscopy revealed a marked swelling of calyx-like n erve endings throughout the sensory epithelium. We suggest that ionic changes in inner ear could cause the swelling of these nerve calyces. We suppose that these rearrangements arise only after weightlessness a nd/or a strong sensory cell stimulation.