Neural cell types surviving congenital sensory deprivation in the optic lobes of Drosophila melanogaster.

Golgi staining of neuronal cell types in the optic lobe rudiments of adult eyeless flies of the sine oculis (so) mutant of Drosophila melanogaster reveals partial independence of optic lobe's development from compound eye formation. (1) Differentiation and maintenance of many neuronal cell types of medulla and lobular complex do not require innervation of the medulla from the retina and the lamina. Neurons derived from the outer and inner optic anlage have been found in adult eyeless flies. (2) The rudiments of ipsilateral medulla, lobula, and lobular plate are isotopically connected with each other. (3) Stratification of the lobular complex is retained. (4) Equivalent parts of the dorsal lobulae are connected by heterolateral small field neurons. (5) The shapes of many tangential neurons of the medulla show sprouting and compensatory innervation of the lobular complex. The basic results reported here for eyeless flies have many parallels in what is known about anophthalmic mice.