. Human embryology and morphology. Embryology, Human; Morphology. 290 HUMAN EMBRYOLOGY AND MORPHOLOGY. continuous row of lateral fins. If this view is right, then the fore and hind limbs represent highly specialized fin-rays. A section shows each bud to be composed of undifferentiated mesoblast, with a covering of epiblast (Figs. Ill A p. 139, and 237). It represents in structure a process of the undifferen- tiated somatopleure or body-wall. Processes grow into the limb bud from the muscle plate of each segment which is situated opposite the origin of the bud. Each corresponding segment of the
. Human embryology and morphology. Embryology, Human; Morphology. 290 HUMAN EMBRYOLOGY AND MORPHOLOGY. continuous row of lateral fins. If this view is right, then the fore and hind limbs represent highly specialized fin-rays. A section shows each bud to be composed of undifferentiated mesoblast, with a covering of epiblast (Figs. Ill A p. 139, and 237). It represents in structure a process of the undifferen- tiated somatopleure or body-wall. Processes grow into the limb bud from the muscle plate of each segment which is situated opposite the origin of the bud. Each corresponding segment of the spinal cord also sends to the limb bud a nerve process. At least seven body segments contribute to the formation of each limb. Changes in External Conformation.—In the 4 th week (Fig. 234) the limb buds are unsegmented; in the 5 th a constriction , forearm basisofarm frearm \ flm rad. border hand . hi. ulnar border 4th week ^th week 7th week 9th week Fio. 234.—Development of the Upper Limb. (After His.) marks the hand off; the position of the elbow being indicated in the same week. In the 7 th week the fingers appear as thicken- ings in the webbed hand, the middle digit being indicated first. They become free at the end of the second month ; occasionally bash of leg foot leg tib. border. fib. border 4th week. 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 Keith, Arthur, Sir, 1866-1955. London : E. Arnold
Size: 2771px × 902px
Photo credit: © The Book Worm / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1900, booksubjectembryol, bookyear1902
