Approximately 80% of flies containing so3 mutant clones can eclose as adults. The flies have small or no eyes, but normal antennae and palp. Head cuticle with antenna-like structures can extend into the eye and some of the small eyes become club-like, suggesting a partial transformation to antenna. Occasional loss of the ocellus is also seen.
so3 mutants do not develop a somatogastric nervous system. However, this does not affect the formation of the pars intercerebralis.
so3 mutant clones in the eye over-proliferate and are non-autonomous.
The stomatogastric nervous system and corpus cardiacum are absent in mutant stage 16 embryos.
Heterozygotes have wild-type eyes.
so9/so3 adult males are viable and fertile, and have normal looking testes with no degenerating spermatocytes.
When clones of so3 homozygous cells are induced in the testis, spermatocyte degeneration is seen. However, this degeneration appears to be independent of the genotype of the spermatocytes in question, suggesting that it is the genotype of cyst cells (not scoreable for technical reasons) that is important in determining spermatocyte degeneration.
Stalk cells are missing in mutant egg chambers.
Bolwig's organ neurons are missing in mutant embryos.
Development of the visual system proceeds normally in mutant embryos until stage 11, when the posterior lip of the optic lobe would normally start to invaginate. Invagination of the optic lobe placode does not occur in mutant embryos.
Cells of homozygous clones in the eye disc overproliferate and fail to differentiate into neurons. The clones retain their epithelial organisation and give rise to abnormal folding of the disc. Cells in the clones subsequently die. Morphogenetic furrow initiation does not occur in clones of the eye disc that encompass the margins. Propagation of the morphogenetic furrow does not occur in homozygous clones in the eye disc. 3% of the R1, R6 and R7 cells are missing in eyes in which homozygous clones have been induced using Scer\FLP1GMR.PP.
so3/so5 transheterozygotes exhibit an extreme eye phenotype, The optic lobe primordium of homozygotes is reduced in size and movement into the head cavity is arrested at an early stage so it fails to invaginate.