THE ROLE OF AMOEBOCYTES IN THE REGENERATION OF SHELL IN THE LAND PULMONATE, EUPLECTA INDICA (PFIEFFER)

¹ Department of Zoology, Panjab University, Chandigarh, India

An hour after the damage of the shell in Euplecta indica (Pfieffer) a thin, structureless, basophilic regeneration membrane appears. Thereafter, a large number of amoebocytes precipitate on this membrane. Soon these break up and contribute their cytoplasmic contents to the regenerate. This is positive for glycoproteins, mucoproteins, neutral mucopolysaccharides, acid mucopolysaccharides, proteins, calcium and some lipids. Also, tracts of acid mucopolysaccharides precipitate from the extrapallial fluid and are deposited on the regenerate.

Calcification is initiated by the appearance of seed crystals of calcium carbonate on top of or along areas of cellular precipitation. This leads to a progressive decrease in metachromasia. The crystals grow into large tabular forms, coalesce with the adjacent tabulae and form a calcified sheet of regenerated material. The spaces between the tabulae are later packed by small crystal aggregates of various shapes. More and more amoebocytes continue to arrive, settle on the calcified sheets along with precipitated organic matter from the extrapallial fluid, break up and repeat the calcifying process until a regenerate of the same thickness as the normal shell is formed.