. The development of the chick : an introduction to embryology. Embryology; Chickens -- Embryos. 216 THE DEVELOPMENT OF THE CHICK forward to form the tip of the upper jaw. The two mandibular arches have also fused in the middle line and begin to project forward to form the lower jaw. This projection of upper and lower jaw causes a great increase in the depth of the oral cavity (Fig. 148). The upper jaw is thus composed of three mdependent parts: viz., the median part formed from the naso-frontal process and Fig. 126. — Head of an embryo of about 5 days from the oral surface. (N. L. 8
. The development of the chick : an introduction to embryology. Embryology; Chickens -- Embryos. 216 THE DEVELOPMENT OF THE CHICK forward to form the tip of the upper jaw. The two mandibular arches have also fused in the middle line and begin to project forward to form the lower jaw. This projection of upper and lower jaw causes a great increase in the depth of the oral cavity (Fig. 148). The upper jaw is thus composed of three mdependent parts: viz., the median part formed from the naso-frontal process and Fig. 126. — Head of an embryo of about 5 days from the oral surface. (N. L. 8 mm.) ch. F., Choroid fissure. E. L., Eye-lid (nic- titating membrane), ex. nar., External nares. 1. Gr., Lachrymal groove. Other abbreviations as before. the two lateral parts formed from the maxillary processes. The former becomes the intermaxillary and the latter the maxillary region. II. Embryonic Membranes General. The extension of the blastoderm over the surface of the yolk goes on very rapidly up to the end of the fourth day of incubation (Fig. 33), at which time there is left a small cir- cumscribed area of uncovered yolk, that may be called the umbilicus of the yolk-sac, which remains uncovered for a long time. Its final closure is associated with the formation of the 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 Lillie, Frank Rattray, 1870-1947. New York : Henry Holt
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Keywords: ., bookauthorlilliefrankrat, bookcentury1900, booksubjectembryology
