Aspects of cuticle formation in Drosophila melanogaster

The molting process and some aspects of puparium formation in Drosophila melanogaster have been examined by electron microscopy and autoradiography. Results indicate clearly alternate phases of production of enzymes involved in cuticle synthesis and enzymes involved in cuticle degradation, in epithelial cells. The synthesis phase begins about four hours before each molt and appears to continue about three hours after puparium formation. Protein which is involved in cuticle structure appears to remain where deposited. On the other hand, metabolic products of tyrosine that are involved in sclerotization and tanning diffuse outward through the cuticle from their origin in the epithelial cells. Channels or canals for transport of materials from cells toward epicuticle have not been observed in larval or prepupal material.