The distribution of lacZ transcripts is identical to that of ph transcripts. The protein pattern is similar but some pattern elements last longer due to perdurance. ph transcripts are expressed in two domains extending from 50-90% egg length and from 10-30% egg length in cellular blastoderm embryos. During gastrulation and in germ band extended embryos, ph is expressed uniformly. At this time, segmental lateral stripes are observed on the ectoderm. In late germ band extended embryos, expression is strong in the CNS.