Amphibian Early Development

phibians, each part of the embryo arises predictably from an identifiable part of the egg, leading embryologists to conclude that the egg's cytoplasm contains spatially organized materials that direct embryonic development. Some have proposed that the variety and organization of these materials must equal the anatomical complexity of the adult itself (the mosaic viewpoint), and that development is the mere point-to-point transformation of egg materials into embryonic materials. Other embryologists have proposed that the egg's organization suffices only for its development to the next immediate developmental stage, which must then make and distribute additional in-