. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. NEURAL DIFFERENTIATION 19. Figure 18. Golgi region of a "neural" endodermal interstitial cell in a 48 h planula. Several mitochon- dria and microtubules are seen in close proximity to the Golgi. x37,400. Figure 19. Electron-dense droplets (arrows) in the Golgi region of a developing endodermal ganglionic cell. Such droplets are characteristic of neural differentiation. mid-region of the planula. Interstitial cells destined to form ganglionic cells migrate out from all regions of the central endoderm and ar
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. NEURAL DIFFERENTIATION 19. Figure 18. Golgi region of a "neural" endodermal interstitial cell in a 48 h planula. Several mitochon- dria and microtubules are seen in close proximity to the Golgi. x37,400. Figure 19. Electron-dense droplets (arrows) in the Golgi region of a developing endodermal ganglionic cell. Such droplets are characteristic of neural differentiation. mid-region of the planula. Interstitial cells destined to form ganglionic cells migrate out from all regions of the central endoderm and are evenly distributed along the planular anterior-posterior axis in the ectoderm. Since the interstitial cells and their progeny exhibit a rather precise positioning within the ectoderm, some mecha- nism of directed migration may be operating in the plan- ula. The FMRFamide findings support the notion of di- rected migration. FMRFamide-positive endodermal in- terstitial cells and FMRFamide-positive ectodermal Figure 14. Endodermal interstitial cell in the anterior region of a 48-h planula. This undifferentiated cell contains a centrally located nucleus (N), a few segments of rough endoplasmic reticulum (arrow), a few mitochondria, and numerous free ribosomes. Although not visible in this plane of section, the intersti- tial cell also contains a prominent nucleolus. This interstitial cell has migrated from its site of origin in the central endoderm to the outer endoderm (E) and is in close proximity to the mesoglea (M). x Figure 15. Developing nematoblast in theanteriorendodermofa48-h planula. Interstitial cells travers- ing the nematocyte differentiation pathway are characterized by the appearance of large amounts of rough endoplasmic reticulum (arrow) and by the formation of a nematocyst capsule (C). Such cells eventually emigrate to the ectoderm. N, nucleus. X 10,800. Figure 16. Interstitial cell traversing the neural differentiation pathway in the anterior endoderm of
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
