Fig. 2. Effects of Noggin on facial morphogenesis. (A) Lateral view and (B) palatal view of a normal skull with mandible removed. The palatine bone extends and contacts the triangular maxillary bone. The jugular process of the maxillary bone extends dorsally and contacts the jugal bone. (C) Embryo treated with one Noggin bead in maxillary prominence at stage 22 and two beads in the globular process at stage 26. Lateral view with mandible attached, showing bifurcated maxillary bone (asterisk). The palatine process of the maxillary bone is connected to the superior branch of the duplicated bone. (D) Palatal view of embryo in (C), showing truncation of palatine bone (asterisk) on the right-hand side. Maxillary bone and premaxilla are outside the field of view towards the right. (E) A side view of the stage 36 beak, showing a disruption in the normally smooth edge (arrow). The absence of palatal shelves can be seen on the treated side. The beak has extended fully, a premaxilla is present and the outer surface is capped with an egg tooth. (F) Palatal view of embryo treated with four beads of Noggin. Asterisk indicates absent maxillary bone. There is also no palatine bone present on the right-hand side. (G) Frontal SEM view of a stage 28 embryo, 12 hours after the second set of beads was implanted. The decreased size of the maxilla on the treated side is evident (arrow), as well as a slight reduction of the globular process of the frontonasal mass (asterisk). (H) Superior view of stage 30 face treated with four beads. Fusion has not occurred on the right, treated side (arrow), whereas normal development is taking place on the contralateral side. (I) Treated and (J) control sides of an embryo stained with BrdU antibody and counterstained with Malachite Green. Dashed line in (I) indicates a zone of low proliferation. (K) Decrease in msx1 expression in the maxillary prominence six hours after the first set of beads (arrow, stage 22+) and (L) 12 hours after the second set of beads (lower arrow, stage 28). Frontonasal mass expression has started to recover in the older embryo (upper arrow). (M) Increased expression in the mesenchyme 12 hours after the first set of beads (arrows, stage 22+). (N) Increased expression in the globular process on the treated side 12 hours after the second set of beads (arrow, stage 28). Scale bars: 3 mm in A-D,F (bar in C can be used for D); 500 µm for E,G,H,K,L,M,N; 100 µm for I,J. Abbreviations: et, egg tooth; fnm, frontonasal mass; j, jugal; lnp, lateral nasal prominence; md, mandibular prominence; mx, maxillary prominence, mxb, maxillary bone, n, nasal bone, nc, nasal chonchae, p, palatine bone, pmx, premaxilla, pp, palatine process of the maxillary bone, ps, palatal shelf.