THE INITIAL CALCIFICATION PROCESS IN SHELL-REGENERATING TEGULA (ARCHAEOGASTROPODA)

¹ Department of Geology, Florida State University, Tallahassee, FL 32306

Shell regeneration was induced in the marine archaeogastropod, Tegula, by cutting a window in the first body whorl of the shell. At six hour intervals for six days after the shell window was cut, the mantle, foot, and hepatopancreas were prepared for transmission electron microscopy, and the shell window was prepared for scanning electron microscopy. Transmission electron microscopy of the three tissues showed an increase in rough endoplasmic reticulum, Golgi complexes, and mitochondria, followed by the appearance of three types of inclusions. Later, intracellular space increased and spherites were visible. Scanning electron microscopy showed initial crystal deposition in the shell window to be in the form of small doubly-pointed crystallites associated with an organic membrane. These spindle-shaped crystals were frequently aggregated into radiating clusters or rosettes which coalesed until a thin sheet of mineralized material covered the shell window, within six days of shell injury.