Stimulation of Shell Regeneration by Crude Extract of Subesophaqeal Ganglionic Mass in Giant African Snails, Achatina fulica (Bowdich)

The distribution of cells that stained positively with paraldehyde fuchsin (PAF) and negatively with chrome-hematoxylin phloxine (CH) in the subesophageal ganglionic mass of Achatina fulica has been mapped. The PAF-positive cells occur in the visceral ganglion, each cell contains electron-dense elementary granules of 1,300 Angstrom in diameter. From serial section, it showed that the PAF-positive cells or neurosecretory cells (NSC) sent axons into the intestinal nerve. The CH-negative cells occurred in the right parietal ganglion, each cell contained electron-dense elementary granules of 1,370 Angstrom in diameter. From serial sections, it showed that CH-negative cells sent axons into the pallial nerve. PAF-positive and CH-negative materials were depleted from cells in 24 hr after shell removal and reappeared by 72 h. Shell regeneration apparently completed within 15 days. Moreover, the subesophageal ganglionic mass homogenate (SGH) had some effects on shell regeneration which suggested that the PAFpositive and CH-negative cells were the neurosecretory cells that control shell regeneration.