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Discussion

As hypothesized and found by Karp and Solursh (1974), embryos raised in a sulfate-free environment do indeed fail to form archenterons. Supporting the findings that sulfate acts only as an adhesive to allow secondary mesenchyme cells to pull the archenteron up through the embryo, sulfate-free embryo cells had differentiated. AP activity indicated that sulfate-free raised embryos have gut cells. These cells simply have not migrated to the correct location. Additionally, the immunofluorescent staining pattern in the sulfate-free embryo appeared to be a ring, suggesting that the cells had invaginated. This finding would further support the hypothesis that sulfate is necessary for the adhesion of secondary mesenchyme cells to the blastocoel wall to extend and form the archenteron. The cells invaginated, but lacked the ability to migrate and form an archenteron. These data support the finding and hypothesis of Karp and Solursh (1974). Interstingly, embryos in this experiment did not feritilixe as well and developed more slowly than eggs from the same donor collected, fertilized, and raised in artificial sea water. Further experiments should be done to determine if sulfate (or the lack thereof) affects fertilization and development processes more generally.

References:
Gilbert, S.F. 2000. Developmental Biology (6th ed). Sinauer Associates, Inc., Massachusetts, p. 238-241.

 Karp, G. C. and M. Solursh. 1974. Acid Mucopolysaccharide Metabolism, the Cell Surface , and Primary Mesenchyme Cell Activity in the Sea Urchin Embryo. Developmental Biology. 41: 110-123

 image from: http://sdb.bio.purdue.edu/dbcinema/images/Miller00.gif

© 2001 Cebra-Thomas
Last Modified: 25 May 2004

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