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# proj.
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# Ann.
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| GrayAnatomy |
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THE TERM Embryology, in its widest sense, is applied to the various changes which take place during the growth of an animal from the egg to the adult condition: it is, however, usually restricted to t |
10.7 KB |
2019-12-21 |
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436 |
2024-12-25
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| GrayAnatomy |
03 |
The ova are developed from the primitive germ cells which are imbedded in the substance of the ovaries. Each primitive germ cell gives rise, by repeated divisions, to a number of smaller cells termed |
7.71 KB |
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320 |
2024-12-25
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| GrayAnatomy |
04 |
The spermatozoa or male germ cells are developed in the testes and are present in enormous numbers in the seminal fluid. Each consists of a small but greatly modified cell. The human spermatozoön poss |
4.67 KB |
2019-12-21 |
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195 |
2024-12-25
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| GrayAnatomy |
05 |
Fertilization consists in the union of the spermatozoön with the mature ovum (Fig. 8). Nothing is known regarding the fertilization of the human ovum, but the various stages of the process have been s |
2.71 KB |
2019-12-21 |
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130 |
2024-12-25
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| GrayAnatomy |
06 |
The early segmentation of the human ovum has not yet been observed, but judging from what is known to occur in other mammals it may be regarded as certain that the process starts immediately after the |
9.42 KB |
2019-12-21 |
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336 |
2024-12-25
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| GrayAnatomy |
07 |
In front of the primitive streak two longitudinal ridges, caused by a folding up of the ectoderm, make their appearance, one on either side of the middle line (Fig. 16). These are named the neural fol |
2.79 KB |
2019-12-21 |
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128 |
2024-12-25
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| GrayAnatomy |
08 |
The notochord (Fig. 19) consists of a rod of cells situated on the ventral aspect of the neural tube; it constitutes the foundation of the axial skeleton, since around it the segments of the vertebral |
1.23 KB |
2019-12-21 |
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41 |
2024-12-25
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| GrayAnatomy |
09 |
Toward the end of the second week transverse segmentation of the paraxial mesoderm begins, and it is converted into a series of well-defined, more or less cubical masses, the primitive segments (Figs. |
1.21 KB |
2019-12-21 |
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58 |
2024-12-25
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| GrayAnatomy |
10 |
The embryo increases rapidly in size, but the circumference of the embryonic disk, or line of meeting of the embryonic and amniotic parts of the ectoderm, is of relatively slow growth and gradually co |
1.89 KB |
2019-12-21 |
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87 |
2024-12-25
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| GrayAnatomy |
11 |
The yolk-sac (Figs. 22 and 23) is situated on the ventral aspect of the embryo; it is lined by entoderm, outside of which is a layer of mesoderm. It is filled with fluid, the vitelline fluid, which po |
1.63 KB |
2019-12-21 |
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79 |
2024-12-25
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