. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. EARLY DEVELOPMENT IN A LANCELET 89. Figure 8. TEMs of eggs at 10 min after insemination. A. Section through the second polar body (PB), male pronucleus (arrow), and vegetal pole plasm (PP). Black dots in the yolk-free zone around the male pronucleus are mitochondria. The yolk is patchily distributed in the animal hemisphere. Scale bar: 20 yum. B. Section through the same egg as in A, about 10 Mm deeper, which passes through the female pronucleus (double arrow). The yolk-free patch of cytoplasm underlying the male pronucleus
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. EARLY DEVELOPMENT IN A LANCELET 89. Figure 8. TEMs of eggs at 10 min after insemination. A. Section through the second polar body (PB), male pronucleus (arrow), and vegetal pole plasm (PP). Black dots in the yolk-free zone around the male pronucleus are mitochondria. The yolk is patchily distributed in the animal hemisphere. Scale bar: 20 yum. B. Section through the same egg as in A, about 10 Mm deeper, which passes through the female pronucleus (double arrow). The yolk-free patch of cytoplasm underlying the male pronucleus is at lower right (single arrow). Scale bar: 20 pm. C. Higher magnification of the male pronucleus and its cloud of mitochondria in A. The nuclear envelope is complete except in a few spots (arrows). Scale bar: 1 pm. D. Higher magnification of the female pronucleus in B. The nuclear envelope is complete except in a few areas (arrows). The nucleus contains a few dense patches. Scale bar: 1 urn. fontaine (1906), and Conklin (1932) to conclude that the sperm always enters near the vegetal pole. In contrast, our results show that the fertilizing sperm can enter the egg near the animal pole (three out of three observations). although more extensive study would be required to show whether they always do so. The axoneme enters with the nucleus, mitochondrion, and centrioles, but rapidly dis- appears. Then the sperm nucleus undergoes two phases. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original 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. Woods Hole, Mass. : Marine Biological Laboratory
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
