Number of cells in embryo developmental stage # 14-15

Value 17800 cells/embryo Range: ±500 cells/embryo
Organism African clawed frog Xenopus laevis
Reference Cooke J. Properties of the primary organization field in the embryo of Xenopus laevis. IV. Pattern formation and regulation following early inhibition of mitosis. J Embryol Exp Morphol. 1973 Aug30(1):49-62.PubMed ID4729951
Method Operations were of two types, and were performed synchronously with the onset of blockage of the cell cycle. In one, a second stage 10 organizer was grafted into the marginal zone of a stage 10+ or 10.5 gastrula, at an angle of about 100° as described in Paper I. Typical results of such operation are described in Paper II (Cooke, 1972b). In the other, the head organizer region was simply excised, as from the donor in the previous operation, but from a stage 10+ gastrula. Control embryos at the time of blockage, and control and blocked, operated embryos at stages 14-15 and stages 22-24, were disaggregated in pairs in Ca2+- and Mg2+-free Holtfreter at pH 8-2, containing 150 mg/1 EDTA. After dissecting free the endodermal mass of large fragile and yolky cells from gastrulae, or their well-known derivatives from later stages, the remaining cell sheets, incorporating neurectoderm, mesoderm and a little head endoderm were transferred rapidly to 0-5 ml of the disaggregation solution per pair. After 10 min they were pipetted gently to a single-cell suspension with a Spemann pipette, and counted immediately.
Comments Cell number per embryo, excluding yolky endoderm. Visual observation of early blastulae, and counting of cell suspensions from the late blastula and subsequent stages of Xenopus development, have shown that exposure to either colcemid or mitomycin C can sustain blockage of the mitotic cycle, and hence prevent the normal increase in cell number.
Entered by Uri M
ID 104148