The balancers of Triturus italicus: an ultrastructural approach.

Balancer morphology and ultrastructure, with emphasis on changes occurring during development, are described for Triturus italicus, using stereomicroscopy and light microscopy, as well as scanning and transmission electron microscopy. Morphological differentiation of balancers involves elongation, swelling of the distal region of the organ and appearance of secretory cones. The extensive granular endoplasmic reticulum and the well-developed Golgi apparatus characterize the inner cell layer of the mature balancer. Other characteristics include the presence of numerous rounded lipid-like granules and extensive innervation. In the cytoplasm, numerous bundles of tonofilaments can be found, and their amount increases as development progresses. As already stated in previous studies, the general morphology of balancers shows great constancy. [ABSTRACT FROM AUTHOR]