Origin and Early History of the Primordial Germ-cells in the Chick ... |
Common terms and phrases
21 somite chick 33 somites acetic acid acid fuchsin amoeboid Anat aorta appearance area pellucida at.sp Bensley Bensley's acetic-osmic-bichromate Berenberg-Gossler 12 bl.c bl.v blood cell blood vessel bryo centrosomes chromatin coelomic angle coelomic epithelium containing osmic acid cytoplasm Dantschakoff dial germ-cells differentiated Eigenmann embryo as figure embryo with 25 embryos possessing entodermal wander-cells epithelial cells fixation and Meves fore-brain four and one-half germ-cells are found germ-wall entoderm germinal epithelium gonad groups head region Hoffman 93 hypoblast indifferent gonad iron-hematoxylin stain JOURNAL OF ANATOMY lumen of blood mesentery methyl green micra migration mitochondria mordial germ-cells neighboring cells notochord nucleus Nussbaum 01 older embryos oogonia origin of primordial pairs of somites plate of mesoderm Portion pr.o primitive streak stage primor primordial germ primordial germ-cells arise seen sex-cells somite chick embryo sp.m splanchnic mesoderm splanchnic plate teleost tissues transverse section Wolffian body Wright's stain yolk material yolk spheres younger
Popular passages
Page 514 - The primordial germ-cells arise anterior and antero-lateral to the embryo in a specialized region of germ-wall entoderm just at the margin of the area pellucida. This region has roughly the shape of a crescent and the germ-cells arise during the primitive streak stage and until the embryo has about 3 somites. The concavity of this crescent is towards the embryo and the horns extend cauclalward on either side.
Page 488 - Nussbaum was correct when in 1880 he formulated the hypothesis that "the sexual cells do not come from any cells that have given up their embryonic character or have gone into building any part of the body, nor do sexual cells ever go into body formation.
Page 514 - ... first are in the space between entoderm and ectoderm. Later, thanks to their amoeboid power, they enter the mesoderm and the forming blood vessels of the mesoderm. 3. They are at first carried by their own movement, and later by that of the blood to all parts of the embryo and vascular area. They remain generally distributed in this way until the embryo has about 20 somites. 4. In embryos with about 20 to 22 pairs of somites, the primordial germ-cells, while generally distributed throughout the...
Page 515 - An important period in the history of the sex-cells of Rana pipiens. Anat. Anz., Bd.
Page 515 - In embryos possessing about 26 to 29 somites the primordial germcells are found in the splanchnic mesoderm near the radix mesenterii. 7. In embryos with 30 to 33 somites the primordial germ-cells are in the radix mesenterii and coelomic epithelium on both sides of the coelomic angle. They remain in this position until the formation of the gonad begins when they gradually pass into that organ.
Page 485 - Wolffian body not having been modified at this age, yet in these he found primordial germ-cells far removed from the site of the future sex-gland, in the splanchnic plate of mesoderm, in the region between splanchnic mesoderm and entoderm and in the entoderm.
Page 514 - This increase in the number of the germ-cells in the vessels of the splanchic mesoderm may be in part only apparent, that is, a degeneration of some may have occurred elsewhere, or, it may be a real increase due to some influence, probably of a chemotactic nature, exerted in the region of the future gonad. At this period the great majority of the cells are found in the vessels, but a few, chiefly in the splanchnic mesoderm, are present in the tissues.
Page 485 - ... in the modified coelomic epithelium. In the three species mentioned above, he found at the proper time, numbers of primordial ova in the germinal epithelium.
Page 515 - Contribution a 1'etude de la formation des organes sexuels chez les Insectes.
Page 486 - ... Chrysemys embryos of this stage, the extremes being given as 158 and 415. This number is much closer to my own count (see chart, page 323) for Caretta. In Lepidosteus the primordial germ-cells have a very similar origin. They are described as migratory to a high degree. In Amia they are said to arise from the entoderm of the roof and margin of the floor of the subgerminal cavity. The history of the germ-cells in Chrysemys is practically identical with that above described for Caretta. However,...