166
PAUL BRIEN
FIG. 10. Polypidian budding from the ectomesodermal wall of a cystid of
Plumatella fungosa. (A) Beginning of proliferation of ectoderm (Ect.) forming a
button, at first solid, covered by pleuroparietal cells. (B) The bud has grown. The
blastogenic button is hollowed out into an enclosed vesicle. The inner epithelium,
derived from ectoderm, will form all the organs of the polypide. The peripheral
layer is of pleuroparietal origin and will give rise to the coelomic epithelium of the
young zooecium (refer to Fig. 18 for organogenesis). (Brien, 1960.)
PAUL BRIEN
FIG. 10. Polypidian budding from the ectomesodermal wall of a cystid of
Plumatella fungosa. (A) Beginning of proliferation of ectoderm (Ect.) forming a
button, at first solid, covered by pleuroparietal cells. (B) The bud has grown. The
blastogenic button is hollowed out into an enclosed vesicle. The inner epithelium,
derived from ectoderm, will form all the organs of the polypide. The peripheral
layer is of pleuroparietal origin and will give rise to the coelomic epithelium of the
young zooecium (refer to Fig. 18 for organogenesis). (Brien, 1960.)