. Carnegie Institution di Washington la pubblicazione. 40 LA MATURAZIONE DELL'UOVO DEL MOUSE. In alcune delle uova da un topo ha ucciso circa 33 ore p.p. e non inseminate, ci sembrano pochi citoplasmatici di radiazioni a mandrino poli, da cui i corpi circumpolare sono scomparsi. Anche nell'uovo illustrato in fig. 29a, i granuli citoplasmatici intorno alla estremità interna del mandrino sono orientati con i loro assi lungo una direzione radiale; ma per il resto le prove di radiazioni citoplasmatica attorno ai poli del secondo mandrino di maturazione è stata carente. Come già detto per quanto riguarda la fi

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. Carnegie Institution of Washington publication. 40 THE MATURATION OF THE EGG OF THE MOUSE. In some of the eggs from a mouse killed about 33 hours p.p. and not inseminated, there appear a few cytoplasmic radiations at the spindle poles, from which the circumpolar bodies have vanished. Also in the egg illustrated in fig. 29a, the cytoplasmic granules around the inner end of the spindle are oriented with their long axes in a radial direction; but otherwise the evidence of cytoplasmic radiations about the poles of the second maturation spindle has been lacking. As already stated regarding the first spindle, the clear region around the spindle exists at the same time with the circumpolar bodies, except that it may appear a little before them (fig. 19), and sometimes persists longer (fig. 30). It can usually be found surrounding the spindles of eggs which have been only a short time in the oviduct (figs. 20, 21, 22, 23, 24), but in most eggs in which the circumpolar bodies have vanished, it has likewise disappeared (figs. 25, 26, 27). It becomes quite faint (figs. 29, 30), or is altogether gone, after the chromosomes have divided. 5. Position and Orientation of second Maturation spindle. The second maturation spindle always lies near the surface of the egg—in fact, sometimes so near that its flatness (fig. 20) is apparently due to pressure. There is no satisfactory evidence that it moves through the cytoplasm, although it is found at different distances from the first polar cell when that is present. This topic will be taken up later (pp. 44 and 63). There is less variation in the orientation of the second spindle than in that of the first. Very rarely, indeed, can it be found perpendic- ular to the surface; occasionally it is oblique, but in the majority of cases it is parallel to the surface. It is parallel in all instances in which the daughter chromosomes have separated and have reached, or nearly reached, the poles before the abstriction of the second polar cell

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• bookauthorcarnegie
• bookcentury1900
• bookdecade1910
• bookyear1911