Human embryology

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Macmillan, 1897 - 815 pages
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Acanthias embryo of 17 mm under side
Blastoderm of a dogfish acanthias with commencing concrescence
Longitudinal median section of a recently hatched larva of petro uiyzon
Median section of the head of a rabbit embryo of thirteen and one half days
Hisembryo A 7 5 mm
Reconstruction of the face of His embryo Sell
View of the roof of the mouth of a human embryo
Frontal section of the oral and nasal chambers of a young cow embryo
Frontal section of the nasal and oral cavities of a human embryo of three months
Dental papilla of a dermal tooth of an acanthias embryo of 10 cm
Section of part of the lower jaw of a human embryo of 40 mm
Explanation in text
Vertical section of a molar toothgerm of a human embryo of 160 mm
Part of the enamel organ of a newborn child incisor germ
Odontoblasts from cow embryos A of 30 cm B of 24 cm
Section of the submaxillary gland of a human embryo of sixty three to sixtyeight days
Reconstruction of the pharynx of a human embryo
The Nervous System
Chick embryo of twentynine hours
Crosssection through the forebrain and optic vesicles of a lepidos teus embryo of eight days
Brain of embryo No 22 p 297
The Sense Organs
The Eutodermal Canal
Part of the intestine of a human embryo of about six months
Section of a rabbit embryo of thirteen days through the region
Diagram of the human mesentery in its primitive relations 709
Lungs of a human embryo of five months

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Page 220 - ... by a very thin layer of protoplasm, which is very easily overlooked, especially if the preparation is not suitably stained; this explains, I think, the statement made by Balfour (Works, Vol. i) and others that the blood corpuscles consist only of nuclei. By following the development along further we find that the protoplasm enlarges for several days, and that during the same time there is a progressive diminution in size of the nucleus, which, however, is completed before the layer of protoplasm...
Page 85 - It is almost universally admitted that cells, or the units of the body, propagate themselves by self-division or proliferation, retaining the same nature and ultimately becoming converted into the various tissues and substances of the body. But besides this means of increase, I assume that cells before their conversion into completely passive, or
Page 85 - They are supposed to be transmitted from the parents to the offspring, and are generally developed in the generation which immediately succeeds, but are often transmitted in a dormant state during many generations and are then developed. Their development is supposed to depend on their union with other partially developed cells or gemmules which precede them in the regular course of growth.
Page 85 - I assume that cells, before their conversion into completely passive or "formmaterial," throw off minute granules or atoms, which circulate freely throughout the system, and when supplied with proper nutriment multiply by self-division, subsequently becoming developed into cells, like those from which they were derived...
Page 21 - Eiitwickelungsgeschichle (Third edition, pp. 216-217, fig. 147). Leopold holds that the epithelioid layer is the reflexa, but what has just been said suffices, I think, to show that this view is untenable. That the membrana decidua reflexa should degenerate and disappear no longer seems strange since recent investigations have shown that in many placental mammals there occurs an extensive pseudo-pathological destruction of the mucosa uteri during gestation. These changes, which are best known in...
Page 85 - It is universally admitted that the cells or units of the body increase by self-division or proliferation, retaining the same nature, and that they ultimately become converted into the various tissues and substances of the body. But besides this means of increase I assume that the units throw off minute granules which are dispersed throughout the whole system ; that these, when supplied with proper nutriment, multiply by self-division, and are ultimately developed into units like those from which...
Page 20 - ... persistence of the reflexa involve the further and very improbable assumption that the degenerated tissue is removed and replaced by fully organized cellular decidual tissue. It Is obviously more in accordance with our knowledge of degenerative changes to assume that the hyaline metamorphosis is necrotic and is succeeded by the disintegration and removal of the tissue. This accounts in a satisfactory manner for the absence of the decidua reflexa during the sixth and seventh month. The relations...
Page 19 - ... being a thin membrane, and the thinnest point being opposite the placenta. The examination of sections shows that the entire reflexa is undergoing degeneration , which is found to be the more advanced the more remote the part examined is from the placenta. The chorion laeve lies very near the reflexa, being separated only by chorionic villi, which are very much altered by degeneration, their ectoderm having become a hyaline tissue, which stains darkly and their mesoderm showing clearly the partial...
Page 223 - Tbe above review shows that the vertebrate blood corpuscles are of three kinds: (1) red cells; (2) white cells; (3) plastids. The red and white cells occur in all (?) vertebrates; the plastids are confined to the mammals. The red cells present three chief modifications; whether the primitive form occurs in any living adult vertebrate I do not know ; the second form is persistent in the Ichthyopsida, the third form in the Sauropsida. According to this we must distinguish : A. — One-celled blood,...
Page 220 - AccordIng to the above description we can distinguish three principal stages : — 1, young cells with very little protoplasm; 2, old cells with much protoplasm and granular nucleus ; 3, modified cells with shrunken nucleus which colors darkly and uniformly.

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