Xenbase Image ID: 84094

Fig. 1. A quantitative analysis of Isl1+ primary sensory neurons in the Xenopus embryo. In all figures, embryos are shown with anterior to the right. (A). The Xenopus embryo expresses Isl1 in columns either side of the midline (m) predominantly in primary sensory neurons (black arrowheads). The Isl1+ primary sensory neurons (enlarged in insert) are found at equal density along the length of the posterior neurectoderm. The anterior border for Isl1+ primary sensory neurons (black and white arrowheads) is a short distance caudal to rhombomere 5 shown by double labelling with the rhombomere marker krox-20 which identifies rhombomeres 3 and 5 (marked on the figure). Scale bars: main image 120 μm, inset 20 μm. (B). Time course of formation of Isl1+ primary sensory neurons. The mean number of Isl1+ primary sensory neurons per side of an embryo was determined for more than 10 embryos at each developmental stage. The bars represent the standard error of this calculation. At stage 22 there was a mean of 120 Isl1+ primary sensory neurons on each side of the embryo. (C). The effect of applied RA on the numbers of Isl1+ primary sensory neurons. The mean number of Isl1+ primary sensory neurons for one side of an embryo was calculated for at least ten embryos at stage 17 over a range of applied RA concentrations, bars represent the standard error of the calculation. In untreated embryos there was a mean of 82 (SE 3.5) and in embryos grown from the late blastula stage in 10−7 M RA there was a mean of 95 (SE 3.0) Isl1+ primary sensory neurons. (D). There is no asymmetry in the formation of Isl1+ primary sensory neurons. The ratio of the number of Isl1+ primary sensory neurons on the left compared to the right side of the embryo was determined from mid to late neurula stages for more than 8 embryos at each stage. There was no significant difference in the number of neurons on one side compared to the other. Image published in: Sharpe C and Goldstone K (2000) Copyright © 2000. Image reproduced with permission of the Publisher, Elsevier B. V. Larger Image Printer Friendly View

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