Expression of traf4a from the end of gastrulation to the beginning of somitogenesis. (A) traf4a is first detected weakly at 75% epiboly in the enveloping layer (EVL). (B) At the 3 somite stage, transcripts accumulate in the eye field (EF), the polster (PO), and in the trigeminal placode (TP). (C,D) More posterior views, expression of traf4a is detected in anterior trunkal neural crest (NC), the paraxial mesoderm (PM), the adaxial cells (AD), the dorsal and the ventral neurons (DN and VN). (E–G) similar expression is observed at 5 somite stage. (H,I) Histological transverse sections at the level of the adaxial cells and more posteriorly showing a presence of traf4a transcripts in the endoderm (EN). (A) lateral view, (B–F) dorsal views. In each panel, anterior is to the left. (G) optical cross-section at the level of the paraxial mesoderm. (H,I) histological transverse sections. N, notochord.

Expression of traf4a at midsomitogenesis. (A–C) At the 10 somite stage, traf4a is seen in the eyes (E), the epidermis (EP), the trigeminal placode (TP), the presumptive branchial arches (PBA), the anterior trunkal neural crest (NC), the adaxial cells (AD) and the dorsal neurons (DN). (D,E) At the 15 somite stage, in addition to the expression in the eye, the anterior trunkal neural crest and the dorsal neurons, an expression of traf4a is detected in the endoderm (EN), the somites (S), the tail bud (TB) and the branchial arches (BA). (F) Focus on the tail of the embryo seen in (D) showing traf4a staining in the tail bud, in the somites and in the dorsal spinal cord neurons (DSN). (G) An optical section at the trunk level shows expression of traf4a in the dorsal spinal cord neurons and in the paraxial mesoderm (PM). (H) In the paraxial mesoderm, traf4a expression encompasses the proximal part of the somite (S) but is excluded from the adaxial cells (AD) as confirmed in (I) on a transverse thick section. (A–C,E) dorsal views, (D,F) lateral views. In each panel, anterior is to the left. (G) optical section, (H) dorsal view of a flat mount after removal of the yolk, (I) thick section. N, notochord; NT, neural tube.

Expression of traf4a at 24 and 36 hpf. (A) At 24 hpf, traf4a expression is detected in the telencephalon (TE), tegmentum (TG), cerebellum (CE), hindbrain (HB), spinal cord (SC), somites (S) and the axial vasculature (AV). (B) Higher magnification of the same embryo showing the same territories of expression than in (A), additional expression can be detected in the diencephalon (DI) and the adenohypophyse (AH). (C) High magnification of the trunk region of the embryo in (A) showing expression in interneurons (IN), in the dorsal aorta (DA) and in the posterior cardinal vein (PCV). (D) Thick section of the same embryo at the level of the trunk confirming the expression of traf4a in the interneurons, the dorsal aorta and the posterior cardinal vein. (E) High magnification of the tail region showing expression of traf4a in the dorsal spinal cord (DSC), the somites (S), the proctoderm (PR) and the tail bud (TB). Traf4a is excluded from the muscle pioneers (MP). (F) Histological transverse section at the level of the tail pointing out that traf4a is expressed in the dorsal part (DS) and in the ventral part (VS) of the somites but is excluded from the muscle pioneers (MP) and from the slow muscle fibers (SMF). (G–I) At 36 hpf, traf4a transcripts are present in the cerebellum (CE), the telencephalon (TE), the diencephalon (DI), the tectum (TC), the hindbrain (HB), the branchial arches (BA), the statoacoustic ganglia (AG), the pectoral fins (PF), the liver primordium (LP) and the pancreas (P), but are excluded from the central nervous system ventricular zone (VZ). (J) Focus on the eye of an embryo at 36 hpf showing an expression of traf4a in the lens (LE) and in the anterior ventral retina (AVR) just in front of the choroïd fissure (CF). (K) Histological section highlighting the staining in the ventral otic vesicles (VOT), in the statoacoustic ganglia (AG), in the lateral hindbrain (LHB) and in the dorsal hindbrain (DHB). (L) Histological section at the level of the anterior spinal cord focusing on the expression of traf4a in the interneurons (IN) and in the liver (L). (A–C,E,J) lateral views, (H,I) dorsal views, (G) oblique view. In each panel, anterior is to the left. (D) thick section, (F,K,L) histological transverse sections. N, notochord; NT, neural tube.

Expression of traf4a at 40, 48 and 60 hpf. (A–C) At 40 hpf, traf4a expression is detected in the telencephalon (TE), the tectum (TC), the tegmentum (TG), the cerebellum (CE), the diencephalon (DI), the hindbrain (HB), the adenohypophyse (AH) and the anterior spinal cord (ASC). (D) In the eye, traf4a is expressed in the lens (LE) and in cells of the retina (R) close to the lens. (E,F) Additional expression of traf4a is observed in the liver (L) and in the pectoral fins (PF). (G–I) At 48 hpf, expression of traf4a in the brain is still detected in the telencephalon (TE), the tegmentum (TG), and the diencephalon (DI) with strong labeling in oligodendrocytes (OL). A staining is observed in the pectoral fin muscles (PFM), the hypaxial muscles (HM). In the eye, expression is observed in the lens (LE) and in the ganglion cell layer (GL). (J–L) At 60 hpf, expression of traf4a is mainly observed in the oligodendrocytes (OL) and the branchial arches (BA). (A,K) lateral views, (B,C,G,H,J) dorsal views, (E) oblique view, (D,F,I,L) histological transverse sections, (C) optical cross section. For dorsal, lateral and oblique view anterior is to the left and for transverse sections dorsal is up.