The anatomy of the nervous system, from the standpoint of development and function . Fig. 20.—A, Transverse section through the spinal cord of a chick embryo of the third dayshowing neuraxons (F) developing from neuroblasts of the neural tube and from the bipolarganglion cells, d. B, Neuroblasts from the spinal cord of a seventy-two-hour chick. The three tothe right show neurofibrils; C, incremental cone. (Cajal, Prentiss-Arey.) thickened patches of the superficial ectoderm, known as placodes, with which the ganglia ofthese nerves come in contact at an early stage in their embryonic developmen
The anatomy of the nervous system, from the standpoint of development and function . Fig. 20.—A, Transverse section through the spinal cord of a chick embryo of the third dayshowing neuraxons (F) developing from neuroblasts of the neural tube and from the bipolarganglion cells, d. B, Neuroblasts from the spinal cord of a seventy-two-hour chick. The three tothe right show neurofibrils; C, incremental cone. (Cajal, Prentiss-Arey.) thickened patches of the superficial ectoderm, known as placodes, with which the ganglia ofthese nerves come in contact at an early stage in their embryonic development. Theacoustic ganglion of the eighth nerve seems also to have a similar origin, i. c. from the cellsof the otic vesicle which is formed by a process of invagination from the superficial ectoderm. The neuroblasts of these ganglia become bipolar through the developmentof a primary process at either end (Fig. 21). Originally bipolar, a majority ofthese sensory neurons in the mammal become unipolar through the fusion ofthe two primary processes for some distance into a single main
Size: 1049px × 2384px
Photo credit: © The Reading Room / Alamy / Afripics
License: Licensed
Model Released: No
Keywords: ., bookcentury1900, bookdecade1920, booksubjectnervoussystem, bookye
