. Analysis of development. Embryology; Embryology. SrACCIS ANTCRiCRviEW STACCIS DORSAL View Fig. 145. Relative positions of ectodermal rudiments of the head in neurular stages of Amblystoma punctatum (Carpenter, '37; Harrison, '45).. ? — SOMITE O—ENTODER SR-SINUS » / \ •/ . *• RHOMBOIDALISX / \' / ?"HEART — NEURAL CRESt\ \_y ^ ?/' ©-CHORDA LP-LATERAL PLATE \^ /• 0-NEPHROS -HEAD MESODERM ^«v^ >/ •-ERYTHROCYTES Fig. 146. Map of prospective areas in the primitive streak blastoderm of the chick (Rudnick, '44). a mosaic its differentiation may be adversely affected by relationship with part
. Analysis of development. Embryology; Embryology. SrACCIS ANTCRiCRviEW STACCIS DORSAL View Fig. 145. Relative positions of ectodermal rudiments of the head in neurular stages of Amblystoma punctatum (Carpenter, '37; Harrison, '45).. ? — SOMITE O—ENTODER SR-SINUS » / \ •/ . *• RHOMBOIDALISX / \' / ?"HEART — NEURAL CRESt\ \_y ^ ?/' ©-CHORDA LP-LATERAL PLATE \^ /• 0-NEPHROS -HEAD MESODERM ^«v^ >/ •-ERYTHROCYTES Fig. 146. Map of prospective areas in the primitive streak blastoderm of the chick (Rudnick, '44). a mosaic its differentiation may be adversely affected by relationship with parts of the central nervous system other than the region with which it is normally related (Detwiler and Van Dyke, '50; Detwiler, '51). It has been concluded that the medulla exerts a late morphogenetic influence on the otic vesicle. However, it can be shown that the medulla is not necessary for late differentia- tion. If the hindbrain is removed at an ear plate stage a normal labyrinth forms (Yntema, unpublished). Mechanical factors are of importance, especially the formation of a capsule (Kaan, '38) and a functional endolymphatic sac which may regulate hy- drostatic pressure of the endolymph (Harri- son, '36a). However, presence of capsule and of endolymphatic sac do not in them- selves assure normal development (Detwiler and Van Dyke, '50). The size of the ear in the salamander influences the number of cells in the acoustic area of the medulla (Richardson, '32), and absence of the laby- rinth in the chick results in less marked dif- ferentiation of some associated medullary nuclei (Levi-Montalcini, '49). Neurons of the auditory ganglion are derivatives of the wall of the auditory vesicle (Yntema, '37); hence they serve as an index of differentia-. 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 wor
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Keywords: ., bookcentury1900, bookpublisherphiladelphi, booksubjectembryology
