| |
Fig. 3. Relationship between Xbra and Xsna expression in Xenopus. Distribution of Xsna or Xbra mRNA shown by in situ hybridisation under dark field illumination, with corresponding bright field views to the right (A,B) or below (CE). Scale bar = 400 pm in CE; 200 pm in A,B. A,B: Stage 10.5. Para-sagittal (A) Xbra is expressed in involuted (i) and uninvoluted (u) mesoderm, to left and right of internal blastopore lip (arrow)respectively. Suprablastoporal endoderm (arrowheads, se) also labelled.B: Xsna is expressed only to left of internal blastopore lip (arrow) in involuted mesoderm (i), including cells migrated towards animal cap (ac). C,D: Stage 12. Mid-embryo transverse section. Xbra transcripts detected only in notochord (arrow, n) and sub-notochordal endoderm (arrowheads, se). D: Xsna expressed in all mesoderm (m) except notochord
(arrow, n). E: Stage 23. Ventral horizontal section. Xbra expressed strongly in posterior (p), in tailbud (tb). a = anterior; ac = animal cap; b
= blastopore lip; bc = blastocoel; d = dorsal; e = endoderm; ec = ectoderm; ep = epidermis; i = involuted mesoderm; Ip = lateral plate mesoderm; m = mesoderm; n = notochord; p = posterior; se = supra-
blastoporal endoderm; tb = tailbud; u = un-involuted prospective mesoderm; us = unsegmented mesoderm; v = ventral. |
