Fig. 3. In situ hybridization with 33P-labeled antisense SpGsc probe shows that SpGsc mRNA accumulates in oral ectoderm throughout the mesenchyme blastula-pluteus period and transiently during blastula stages in presumptive mesenchyme cells in the vegetal plate. (A,C,E,G,I,K) Bright field images; (B,D,F,H,J,L) corresponding dark field images. (A,B) Egg; (C-H) early mesenchyme blastula; (I,J) gastrula; (K,L) pluteus. The arrowheads in C-H indicate recently ingressed primary mesenchyme cells. The black line in H indicates the approximate plane of section that would produce the hybridization pattern shown in C,D. The locations of oral and aboral ectoderm in I-L are marked with the labels oe and aoe, respectively. The distribution of SpGsc mRNAs is indicated in black in M (blastula) and N (pluteus). cm, coelomic mesenchyme; endo, endoderm; pmc, primary mesenchyme cells; smc, secondary mesenchyme cells. Embryos shown in C-L are oriented with the vegetal pole down. Scale bar: 20 µm.
