Synthesis of the mesoglea by ectoderm and endoderm in reassembled hydra.

Abstract

The structure and synthesis of the mesoglea was investigated in "reassembled" hydra-hydra regenerating from ectoderm and endoderm previously isolated from each other and then recombined. During tissue isolation and reassembly the mesoglea remains attached to the endoderm. It is observed to be quite elastic and resilient. The mesoglea disappears by 6-8 hr after reassembly, having apparently been digested by endoderm. "New" mesoglea is undergoing synthesis by 12 hr after reassembly. It trilaminar appearance at this time suggests an origin from both epithelia. Interepithelial contact, by cell processes of epithelial cells, is reestablished within the mesoglea between 24 and 48 hr after reassembly. Mesoglea appears normal 48 hr after reassembly. Autoradiographic experiments, performed during the reassembly manipulations, conclusively demonstrate that the mesoglea originates from both epithelia. Mesoglea precursors, amino acids, are incorporated within the mesoglea about 5-6 hr after initial acquisition by epithelia, but subsequent turnover of these amino acids is slow.