Title: The Biological bulletin
Identifier: biologicalbullet201mari (find matches)
Year: [1] (s)
Authors: Marine Biological Laboratory (Woods Hole, Mass. ); Marine Biological Laboratory (Woods Hole, Mass. ). Annual report 1907/08-1952; Lillie, Frank Rattray, 1870-1947; Moore, Carl Richard, 1892-; Redfield, Alfred Clarence, 1890-1983
Subjects: Biology; Zoology; Biology; Marine Biology
Publisher: Woods Hole, Mass. : Marine Biological Laboratory
Contributing Library: MBLWHOI Library
Digitizing Sponsor: MBLWHOI Library

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408 H. FURUYA ET AL. a6B,§Bi:. 6B;; . 5B"2 4B'2 SBi1 6A'i: • _ ^- , C A 12'
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5B 5B'1: SB-' 5B:2 5B Figure!. The late-stage vermiform embryos of four species of dicyemids. Scale bar represents 10 ^m. Cilia are omitted. See text for explanations of cell division notations. Other abbreviations: AG. agamete: AX, axial cell; DP. diapolar cell; MP. metapolar cell; PR, propolar cell; PP. parapolar cell; S. syncytium; UP. uropolar cell. Microcyema vespa: (a) a late-stage embryo (sagittal optical section)—note an agamete (5a~) in the cytoplasm of an axial cell (5a'l; (b) a late-stage embryo (sagittal optical section); (c) formed embryo (sagittal optical section)—pairs of 6B", 6B'2. and 6B:i cells form a syncytium (S) that is more conspicuously stained with hematoxylin. Conocyema polymorpha; (d) a late-stage embryo (sagittal optical section)—note an agamete (6a~) incorporated in the cytoplasm of an axial cell (6a'): (e) a late-stage embryo (lateral view); (f) formed embryo (lateral view)—pairs of 4B" and 5B21 cells form propolar cells (PR) that are more conspicuously stained with hematoxylin. Dicyema apalachiensis: (g) 13-cell stage—note an anaphase figure of 4B': cell and a metaphase figure of 4B12 cell; (h) 15-cell stage—the 5B1" and 5B':i pairs form the propolar cells (PR), while the 5B"2 and 5B'22 pairs form another type of polar cell, the metapolar cell (MP); (I) formed embryo (lateral view)— propolar cells and metapolar cells are more conspicuously stained with hematoxylin. Pseudicyema nakaoi: (j) 22-cell stage—note a metaphase figure in 4B12 cell—the plane of this division, in contrast to the divisions of 4B;: pair (Fig. 2g), are oblique to the anterior-posterior axis, and as the result, cells of the propolar tier alternate with cells of the metapolar tier (see Fig. 2k, 1); (k) a late-stage embryo (lateral view); (I) formed embryo (lateral view)—propolar cells and metapolar cells are more conspicuously stained with hematoxylin. conspicuously stained with hematoxylin than the other cells (Fig. Ib). The two parapolar cells cover more than half of the syncytium (Fig. 2c). As peripheral cells are formed, the prospective axial cell, 4a, divides unequally. The large anterior cell, 5a', undergoes no further divi- sions and becomes the axial cell, while the smaller pos- terior cell, 5a2, is incorporated into the axial cell and becomes an agamete (Fig. 2a). At this stage, cilia are first evident on the peripheral cells. Cilia on the external surface of the syncytium are directed anteriorly and are more densely distributed than on other peripheral cells. The fully formed embryo consists of three types of cells: peripheral cells, one syncytial cell, and an axial cell, which contains two agametes (Figs. Ib, 2c). The

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