Skip to main content
Figure 4 | EvoDevo

Figure 4

From: Evolution of retinoic acid receptors in chordates: insights from three lamprey species, Lampetra fluviatilis, Petromyzon marinus, and Lethenteron japonicum

Figure 4

Expression of the retinoic acid receptor (rar) gene rar2 during development of the European river lamprey, Lampetra fluviatilis, of the sea lamprey, Petromyzon marinus, and of the Japanese lamprey, Lethenteron japonicum. The expression of L. fluviatilis rar2 was characterized by in situ hybridization in embryos at stages (st) 19 (A) and (E), 23 (B) and (F), 25 (C) and (G), as well as 26 (D) and (H). Higher magnifications of the anterior regions of embryos at stages 19, 23, 25, and 26 are shown in (E), (F), (G), and (H), respectively. The cross sections of the embryo at stage 23 (F’) and of the embryo at stage 25 (G’) are through the level of the posteriormost hindbrain. The expression of P. marinus rar2 was characterized by in situ hybridization in embryos at stages 19 (I) and (M), 23 (J) and (N), 25 (K) and (O), as well as 26 (L) and (P). Higher magnifications of the anterior regions of embryos at stages 19, 23, 25, and 26 are shown in (M), (N), (O), and (P), respectively. The cross section of the embryo at stage 23 is through the anterior spinal cord (N’) and those of the embryo at stage 25 are through the mouth region (O’), otic vesicle (O”), and posterior pharynx (O'''). The expression of L. japonicum rar2 was analyzed by in situ hybridization in embryos at stages 24 (Q) as well as 26 (R) and (S). A higher magnification of the anterior region of the embryos at stage 26 is shown in (S). Cross sections of the embryo at stage 26 are through the mouth region (S’) and anterior spinal cord (S”). The exact anteroposterior levels of the sections shown in (S’) and (S”) are indicated by dotted lines in (S). All embryos are oriented with anterior to the left. White arrowheads indicate hindbrain expression and black arrowheads expression in the spinal cord. Black arrows in (G’) and (O''') show pharyngeal expression, while black arrows in (J), (N), and (Q), as well as in (O’) and (S’) highlight mandibular expression. White arrows mark an inconspicuous rar2 expression domain in the anterior P. marinus hindbrain at stages 19 and 23. Scale bars for L. fluviatilis: 100 μm for (A), (B), (C), and (D); 50 μm for (E), (F), (G), (H), (F’), and (G’). Scale bars for P. marinus: 500 μm for (I), (J), (K), and (L); 100 μm for (M), (N), (O), (P), (N’), (O’), (O”), and (O'''). Scale bars for L. japonicum: 500 μm for (Q); 1,000 μm for (R); 100 μm for (S); 50 μm for (S’) and (S”). Abbreviations: h, heart; llp, lower lip; n, notochord; nt, neural tube; ov, otic vesicle; ph, pharynx; sc, spinal cord; tb, tail bud; ulp, upper lip; 1 to 8, pharyngeal pouches 1 to 8.

Back to article page