Kh. Joplin et al., CELLULAR DIFFERENCES IN RING GLANDS OF FLESH FLY PUPAE AS A CONSEQUENCE OF DIAPAUSE PROGRAMMING, Tissue & cell, 25(2), 1993, pp. 245-257
The ultrastructure of the ring gland (corpus cardiacum (CC), prothorac
ic gland (PG) and corpus allatum (CA)) was examined in diapausing and
nondiapausing flesh fly pupae. The diapause developmental state, which
is environmentally regulated and coordinated by the brain-ring gland
complex, is associated with differences in the ultrastructure of PG an
d CA cells but not in the CC. During diapause the PG and CA cells have
extensive arrays of rough endoplasmic reticulum and spherical mitocho
ndria. The PG cells also contain lipid droplets surrounded by an elect
ron dense amorphous coat not seen in PG cells from nondiapausing pupae
. In nondiapausing pupae, the PG and CA cells contain large amounts of
ribosomes throughout the cytoplasm but very little rough endoplasmic
reticulum and elongated mitochondria. The fact that ring glands from d
iapausing pupae readily incorporate S-35-methionine indicates that the
gland is actively synthesizing proteins, thus the contrasts in ring g
land ultrastructure are not due to cellular quiescence during diapause
but reflect fundamental cellular and physiological differences betwee
n the diapause and nondiapause developmental program.