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Fig. 4. In situ analysis of Xsyn-I RNA expression during development. (A) Animal view of blastula stage embryo (stage 7), showing Xryn-1 mRNA present in the animal hemisphere. (B) Animal-vegetal section of blastula stage embryo, indicating that Xsyn-I is localized to the animal pole of the embryo. Animal pole is to the top. (C) Animal view of an early gastrula (stage 10). Dorsal is to the top. Xsyn-I mRNA is still present in the animal pole. (D) Animal-vegetal section of a midgastrula (stage 11.5). Animal pole is to the top. Xryn-l is expressed in the inner sensorial layer of the ecto- derm, and is absent from vegetal cells and cells which have ingressed through the blastopore lip. Arrowheads denote boundaries of Xsyn-1 expression at the blastopore lip. (E) Lateral view of an early neurula (stage 13); this embryo is not cleared so only surface staining is visible. Dorsal is to the top, anterior is to the right. Xsyn-1 expression is absent from the neural plate and is limited to a band of ectoderm around the embryo. Expression is highest in the posterior ectoderm. nb, boundary of the neural plate. (F) Lateral view of midneurula (stage 15). Dorsal is to the top, anterior is to the right. Xsyn- 1 expression is restricted to a patch of posterior ectoderm and to a patch of anterior ectoderm corresponding to the future cement gland (cg). (G) Ven- tral view of late neurula (stage 20). Anterior is to the right. Xryn-I expression is present in the cement gland (cg) and a small patch of posterior ecto- derm. (H) Lateral view of late tailbud stage embryo (stage 40). Anterior is to the right. High levels of Xsyn-I expression are seen in the anterior endo- derm (ae) and in the cement gland (cg). Xsyn-1 expression is also seen in the phalyngeal mesoderm, and at low levels throughout the epidermis. (I) Stage 40 sense control. Faint background staining is seen in the anterior of the embryo. Sense controls for all other stages showed no background, Bars, 0.5 mm. Bar in (A) applies to (B-F), |
