An imaginal disc is a sac like epithelial structure found inside the larva of insects that undergoes metamorphosis.
In metamorphosis, the cells divide and differentiate during the third larval stage in a synchronous wave, called the morphogenetic furrow.
The cells passes across the disc resulting in a linear array of cells in well-defined stages of division and differentiation.
Therefore, once the larva turns into a pupa, almost all the larval tissues degenerate and the imaginal discs turns into the external structures of the head, thorax , limbs and genitalia.
Uses: The imaginal discs are widely used to study regulatory mechanisms of cell proliferation during regeneration and eases genetic manipulation.