The morphological changes which take place in the differentiation of the adult Drosophila eye from the larval imaginal disc have been described from a histological and cytological standpoint by Shatoury (1956, 1963) and Shatoury & Waddington (1957). In addition, Gottschewski (1960), Gottschewski & Querner (1961), and Schneider (1964) have studied these processes in eyes and brains in vitro. These latter workers removed eye-antennal anlage with associated structures, and placed them in culture media. Under these conditions, the imaginal discs can apparently undergo most of the normal differentiation processes, finally attaining nearly all of the adult morphology.
The imaginal eye disc can be found in the Drosophila larva as early as the larva's emergence from the egg (Kaliss, 1939), and its size is known to increase during the larval instars primarily through cellular division which, in turn, ceases almost entirely shortly after metamorphosis begins (Hadorn, 1965).
A genetic modifier screen of midline to identify candidate enhancer and suppressor genes that regulate interommatidial bristle formation in the adult drosophila eye