Mosaic dorsal tracheal branches lack a terminal cell in 26% of cases. In 80% of the cases where the terminal cell is missing, a homozygous mutant cell is located in the stalk position nearest the tip.
When homozygous pnt
cardioblast clones are made in the embryo, a small proportion of clones exhibit more cardioblasts than expected, suggesting a slight increase in the proliferative capability of cardioblast precursors.
Mutant embryos show a clear fusion of commissures and frequent disruption of longitudinal connectives. Midline glial cells are either reduce in number or fail to properly migrate in between anterior and posterior commissures. General embryonic morphology is relatively normal, though the PNS shows a slight reduction in sensory neurons and defects in the trajectories of motoneurons.
-positive nerve bundles are seen to cross the midline in mutant embryos, in contrast to wild-type.
The axon bundles of the anterior commissures are not organised into three sub-regions in homozygous embryos, in contrast to wild-type. One or two discrete axon bundles can be seen within the commissure. The commissural axons leave the longitudinal tracts at apparently random, irregular positions along the dorso-ventral axis of the connective.
mutant embryos have narrow denticle bands. The central nervous system is broad and less dense than wild-type. The head skeleton has fused ventral arms.