. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. ANALYSIS OF NEURAL TUBE FORMATION 89 tion is made from the dark and disorganized appearance of the raesenchyme cells. The somites are normal in appearance. It should be emphasized that the effects of radiation on the ectoderm and mesoderm discussed previously are uniform for all wave lengths except 2967 A. As previously stated, the most apparent effect of ultraviolet light is to prevent closure of the neural tube. Furthermore, failure of the neural plate to form a 0015 QOI4 0011 0010 \ O 0006 i 0005 0004 0.
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. ANALYSIS OF NEURAL TUBE FORMATION 89 tion is made from the dark and disorganized appearance of the raesenchyme cells. The somites are normal in appearance. It should be emphasized that the effects of radiation on the ectoderm and mesoderm discussed previously are uniform for all wave lengths except 2967 A. As previously stated, the most apparent effect of ultraviolet light is to prevent closure of the neural tube. Furthermore, failure of the neural plate to form a 0015 QOI4 0011 0010 \ O 0006 i 0005 0004 0002 2400 2500 2600 2700 2800 2900 3000 WAVE LENGTH IN ANGSTROM UNITS 3100 FIGURE 4. Photochemical efficiency curve. Inhibition of closure of the neural tube for a distance of at least one-third its length in 50 per cent of the embryos. Correction for extinction by vitelline membrane based upon transmission measurements with the photocell and quartz microscope. (O) and (X) are symbols for experimentally determined doses stronger and weaker respectively than the calculated end-point doses (A). neural tube seems to be restricted to an effect upon the folding process because radiation does not appear to produce other effects on the neural plate cells. The results presented in Table II show that prolonged incubation leads to closure of the neural tube in regions which were open after 30 hours incubation. This prob- ably can best be interpreted as indicating that material and not the capacity to pro- duce or utilize material is altered. Microscopic observations fail to reveal any ab- normal changes in the cells of the neural tube. The volume of the neural plate or. 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 Marine Biological Laboratory (Woods Hole, Mass. ); Marine Biological Laboratory (Woods Hole
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
