| OCR Text |
Show 74 in the Three of regions gnathal, indicated. are groove is the three incipient ganglia (Plate VI, Figure 3). thoracic, In the formed. (Plate VI, Figure 3), and thoracic cord, five distinct, base of this groove. or Punctsubstanz) cytoplasm. of granular, and ganglia. neural strand smaller The neural Their appear. generally anterio-posterior gradient a and extremely abundant mitotic divisions. these dividing cells is slightly basophilic. evident formation become soon a nerve to (neuropile neuromeres regions middle or four the associated with abdominal of at formation follows is middle eleven rests neuroblasts fibers gnathal The and Initially each in the fiber voluminous, Two brain mass placed commissures develop shortly is centers or The finely of fiber supraesophageal isolated between the but anteriorly median pair. Large, pale neuroblastic nuclei remain in the brain, but they more are and of fibers the gnathal develop the connect the mandibular transverse substance missures As the thoracic and tissues in the most commissures connect the surface Interganlionic become anterior ends embryos mature, the head The the ectoderm the base of of stomodaeum and the brain with connectives identifiable of ectoderm. Laterally, the surrounding (Plate IX, Figure 5). the at appendages.. posterior fibrillar region ganglion. forms to regions differentiate Individual neuropilar each confined more as the fibrillar earliest ventral and com ganglia. gradually separates |
