. Animal growth and development. Embryology; Growth; Biology; Growth; Embryology; Animals -- growth & development. Fig. 32. Changes in the external form of the amphibian embryo, from the appearance of the neural fold to the completion of the neural tube. DEVELOPMENT OF THE CENTRAL NERVOUS SYSTEM Originally the neural tube is wider at the front end of the embryo. This width is enhanced by local swellings that produce three distinct bulges. These are the forebrain, midbrain, and hindbrain. Now the fore- brain bulges laterally and two cup-like rudiments appear. Simultaneously the surface ecto
. Animal growth and development. Embryology; Growth; Biology; Growth; Embryology; Animals -- growth & development. Fig. 32. Changes in the external form of the amphibian embryo, from the appearance of the neural fold to the completion of the neural tube. DEVELOPMENT OF THE CENTRAL NERVOUS SYSTEM Originally the neural tube is wider at the front end of the embryo. This width is enhanced by local swellings that produce three distinct bulges. These are the forebrain, midbrain, and hindbrain. Now the fore- brain bulges laterally and two cup-like rudiments appear. Simultaneously the surface ectoderm (the epidermis) folds inward to meet the optic cups. Folds are pinched off and ultimately develop into eye lenses. The ears and nostrils also appear at first as epidermal infoldings. In the meantime the spinal cord undergoes considerable growth and cell division. Meso- dermal cells migrate toward the cord and aggregate around it and the un- derlying notochord. They transform into cartilage and ultimately into bone tissue, giving rise to a hollow vertebral column with associated ribs, etc. The spinal-cord cells are at first large and rounded. They now as- sume typical neuron shapes, spinning out long fibers. The cells in the ventral part become motor neurons, and their fibers penetrate peripheral 63. 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 Sussman, Maurice. Englewood Cliffs, N. J. , Prentice-Hall
Size: 3692px × 677px
Photo credit: © Library Book Collection / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, books, booksubjectbiology, booksubjectembryology
