Nuclear changes during spermiogenesis in a pulmonate snail.

摘要: Changes in both external form and internal arrangement of nuclear material have been investigated the differentiation sperm pulmonate snail, Otala lactea. Sperm head begins with a flattening previously spherical nucleus thickening envelope covering anterior posterior surfaces that nucleus. Tail filaments can be seen cytoplasm at this time. At slightly later period mitochondria begin to tail filament sheath time elongate direction parallel future axis sperm. same orient itself right angles surface which lines pit occupied by centriole. As elongation proceeds, orientation substance takes on appearance 60 A thick sheets bent axis. Soon fill entire The then twist along its so it starts take mature, flame-shaped form. flat disappear mature they are no longer visible (see Text-fig. 2 B).