HOW OYSTER FORM PEARLS?

A pearl only forms when there is a stimulus to form a pearl sac. This stimulus can be anything (in natural pearl production) which enters the shell and injures the epithelium of the mantle. The injured epithelium repairs it self, and the epithelium cells of the mantle tissue, or mantle piece, that gets detached from mantle enter the soft tissue of the mollusk's body, this mantle piece then form a sac, by cell division, which is called a pearl sac. Once a pearl sac is formed, the new cells of the sac continue to secrete calcium carbonate crystals that fill up the sac and form a pearl. Concentric layers build up to form the pearl in the same sequence as when the shell is formed in reverse, then the innermost layer of the pearl is made of conchiolin around which there is a prismatic calcite band, with nacreous layers of aragonite outermost.

CULTURED PEARLS

Video above show a mantle piece or SAIBO taken from the epithelium of a donor oyster is grafted into the gonad of a host oyster. The gonad is a sac like organ in oyster's body more commonly known as the pearl pocket. The mantle piece will form a pearl sac within the gonad. Together with the mantle piece a spherical bead is also inserted to serve as the nucleus for the pearl. Once the pearl sac is forms, it encapsulates this nucleus, then the new cells of pearl sac start to secrete the nacreous substance which covers the nucleus.