. Comparative embryology of the vertebrates; with 2057 drawings and photos. grouped as 380 illus. Vertebrates -- Embryology; Comparative embryology. TYPES OF CLEAVAGE 313 cerning the cleavage phenomena in the turtle. The information given below is to be correlated also with the developing pigeon's egg.) The germinal disc (blastodisc) of the hen's egg at the time that cleavage begins measures about 3 mm. in diameter. Its general relationship to the egg as a whole is shown in figure 157A. 1) Early Cleavages. The first cleavage furrow makes its appearance at about four and one-half to five hours
. Comparative embryology of the vertebrates; with 2057 drawings and photos. grouped as 380 illus. Vertebrates -- Embryology; Comparative embryology. TYPES OF CLEAVAGE 313 cerning the cleavage phenomena in the turtle. The information given below is to be correlated also with the developing pigeon's egg.) The germinal disc (blastodisc) of the hen's egg at the time that cleavage begins measures about 3 mm. in diameter. Its general relationship to the egg as a whole is shown in figure 157A. 1) Early Cleavages. The first cleavage furrow makes its appearance at about four and one-half to five hours after fertilization at the time when the egg reaches the isthmus of the oviduct (figs. 155A; 157C, D). The first. Fig. 155. Cleavage in the chick blastoderm, surface views. (C after Olsen. '42; the rest after Patterson, MO.) (A) First cleavage is approximately meridional. (B) Second cleavage is at right angles to first. (C) Third cleavage planes are vertical as indicated and approximately parallel to one of the other cleavage planes. Considerable inequality may exist at this time. (This figure slightly modified from original.) (D) Seventeen- cell stage. Observe central and marginal cells. (E) Stage approximating 32-cell con- dition. (F) Surface view of 64-cell stage; 41 central and 23 marginal cells. (G) Surface view of blastoderm in lower portions of oviduct; 31 marginal and 123 central cells. (H) Later blastoderm, showing 34 marginal and 312 central 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 Nelsen, Olin E. (Olin Everett), b. 1898. New York, Blakiston
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Keywords: ., bookcentury1900, bookcollectionameri, bookcollectionbiodiversity
