Central nervous system axons are often seen ectopically crossing the midline in Sac1¹/Sac1²¹⁰⁷ embryos.

Homozygous embryos have dorsal anterior holes in the cuticle. Sac1²¹⁰⁷/Df(3L)Fpa2 embryos have dorsal anterior holes in the cuticle and puckering of the dorsal cuticle. Cells towards the ends of the amnioserosa have a smaller apical surface area than cells in the middle of the amnioserosa in stage 13 homozygous or Sac1²¹⁰⁷/Df(3L)Fpa2 embryos, in contrast to wild-type embryos at this stage, in which the apical surface area of cells is fairly uniform throughout the amnioserosa. This distinction between the end and middle amnioserosa cells in terms of the degree of apical constriction which is seen at the onset of dorsal closure in mutant embryos is similar to that seen in wild-type embryos midway through dorsal closure, suggesting that morphogenesis of the amnioserosa cells is occurring prematurely in the mutant embryos.