Table 3.

Analysis of notochord development in mD2LIC-/- mutant embryos

StageWild typeClass I (notochord not always distinguishable)Class II (notochord not always distinguishable)Class III
15.8%30.8%19.3%10.2%
235.3%51.4%43.5%42.4%
359.9%17.8%41.2%47.4%
  • Early notochord development can be subdivided into three stages: (1) formation of the notochordal plate; (2) condensation of the notochordal plate to form the notochord; and (3) separation of the notochord basement membrane from that of the endoderm. To characterise the notochord defect in detail, sections from between the level of the heart to the tail bud of 9.5 dpc mD2LIC-/- embryos were examined. These sections were obtained from representative embryos of all three classes, in order to determine how notochord development differs between the different classes of null mutants. Sections were stained by in situ hybridisation for expression of T (n=2) or with Haematoxylin and Eosin (n=2). The appearance of the notochord in each section was classified with respect to its membership one of the three stages outlined above.