Comparison of scl, gata1, jak2a,e₁ globin, and βe₃ globinexpression in cloche mutant embryos. Clutches of embryos derived from heterozygous clo parents were raised for 24 hours and assayed for the expression of various hematopoietic and erythroid marker genes: scl (a and b); gata1 (c and d);jak2a (e and f); e1 globin (g and h); and βe3 globin (i and j). Embryos are displayed in a lateral position with anterior to the left and dorsal to the top of each panel. Approximately three quarters of the embryos in a given clutch had the wild-type expression pattern of the gene in question (a, c, e, g, and i); note the prominent staining of the ICM. Approximately one quarter of the embryos in a given clutch showed a near or total absence of all hematopoietic marker gene expression in the ICM (b, d, f, h, and j); presumably, these are clo homozygotes. In approximately one half of mutant embryos, from 5 to 10 cells in the ICM express thescl, gata1, e1 globin, and βe3 globin marker genes (arrow in b, d, h, and j). No jak2aexpression was observed in this area in any mutant embryo (f), ie, an embryo also lacking jak2a expression in the rostral part of the anterior ICM.