Polygordius
“Diagrams of stages in the metamorphosis of Polygordius, a primitive annelid. Ectoderm throughout is represented as nucleated without cell boundaries; the entoderm has the cell-boundaries shown, and the mesoderm is diagonally shaded. A, gastrula; B, same with blastopore closed; C and D represent formation of stomodaeum and proctodaeum from ectoderm; E, Trochosphere stage showing formation of segments in the posterior portion; F, adult (sagittal); G, adult (transverse). a, archenteron; bp., blostopore; br, brain; c, coelom; d, dorsal; di, dissepiments; m, mesenteron; pr., proctodaeum; s.c., segmentation cavity; st, stomodaeum; v.n., ventral nerve chain; z, zone of formation of nerve segments.” -Galloway, 1915
Keywords
Stomodaeum, Sagittal, mesoderm, Ectoderm, Entoderm, archenteron, Blastopore, gastrula, mesenteron, coelom, worm stages, segmentation cavity, polygordius stages, annelid metamorphosis, primitive annelid life, proctodaeum, trochosphere, blostoporeGalleries
WormsSource
Thomas Walton Galloway Textbook of Zoology (Philadelphia, PA: P. Blakiston's Son & Co., 1915)
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