title: An ultrastructural and developmental analysis of the corpus allatum of juvenile hormone deficient mutants ofDrosophila melanogaster.
abstract: The ultrastructure of the corpus allatum of theapterous mutantsap4andap56fofDrosophila melanogaster during larval-pupal-adult metamorphosis and adult life was correlated with the gland's ability to synthesize juvenile hormone in vitro. During the early wandering period of the third instar of both mutants, a high concentration of smooth endoplasmic reticulum, mitochondria and mitochondrion-scalariform junction complexes are typical features of an active corpus allatum cell. Juvenile hormone biosynthesis by the glands is high at that time and, in fact, only slightly lower than that of wild type glands. In contrast to the wild type gland, the cells of the pupal and pharate adult corpus allatum of both mutants contains highly electron dense mitochondria with tubular cristae but no whorls of smooth endoplasmic reticulum nor glycogen clusters. The frequency and size of the lipid droplets, putatives depots of the juvenile hormone precursors, in cells of theap56fgland is a function of the insect's age, but both are lower than in wild type gland cells. Juvenile hormone biosynthesis by both mutant glands remains at the basal level when compared to increased synthesis by the wild type gland. The frequency and density of lipid droplets in cells of theap4corpus allatum are much lower than in theap56fglands. During adult life, the ultrastructural profile of theap56fcorpus allatum is similar to that of the wild type gland although the in vitro production of juvenile hormone by the former is much lower than that of the wild type gland. The ultrastructural features of the adult corpus allatum ofap4homozygotes reveal precocious degeneration and support the view that this non-vitellogenic mutant is a juvenile hormone deficient mutation.
authors.affiliation: Department of Biology, CB 3280 Coker Hall, University of North Carolina, 27599-3280, Chapel Hill, NC, USA.
authors.forename: Ji-da
authors.initials: JD
authors.lastname: Dai
authors.affiliation: Department of Biology, CB 3280 Coker Hall, University of North Carolina, 27599-3280, Chapel Hill, NC, USA.
authors.forename: Lawrence I
authors.initials: LI
authors.lastname: Gilbert
keywords: Apterous mutation; Corpus allatum; Juvenile hormone; Ring gland