Figure 5.—

Expression of ttm50 transcripts is developmentally regulated during embryogenesis. In situ hybridization with antisense RNA probes was used to study the tissue specificity of ttm50 transcription at various embryonic stages. (A) Transcripts were ubiquitously distributed during the cleavage stage and are presumably maternally derived. (B) Transcripts temporarily disappeared at the cellular blastoderm stage. (C and D) Expression reappeared in the midgut primordial and weakly in the mesoderm of gastrulas. (E and F) Additional transcripts appeared in the hindgut and Malpighian tubules during germband retraction. The mesodermal expression could be seen in the differentiating skeletal and visceral muscles. (G and H) This expression pattern was retained throughout the duration of organogenesis. In all photos, anterior is to the left and dorsal to the top.