Fig 1.
Murine and human adult soft palates are highly homologous.
(A-D) Histological sections of a 4-month-old mouse soft palate stained with hematoxylin & eosin at the level of the TVP (A), LVP (B), MPC and PLP (C), and SPC and PLP (D). *: pharyngotympanic tube cartilage, Apo: palatine aponeurosis, Epi: epiglottis, GH: greater horn of the hyoid bone, LVP: levator veli palatini, MG: mucous glands, MP: medial pterygoid muscle, MPC: middle pharyngeal constrictor, NP: nasopharynx, PLP: palatopharyngeus, PP: pterygoid plate, PTT: pharyngotympanic tube, SB: sphenoid bone, TT: tensor tympani, TVP: tensor veli palatini. The schematic drawing indicates the orientation and the position of each section. Scale bars: 200μm.
Fig 2.
The morphology and attachment points of soft palate muscles in newborn mice appear fully developed.
(A-D) Histological sections of soft palates from newborn mice stained with hematoxylin & eosin at the level of the TVP and PLG (A), TVP and LVP (B), LVP and MPC (C), and SPC and PLP (D). (E, F) MHC immunostaining (green) of sagittal (E) and transverse (F) sections of soft palates from newborn mice. *: tendon of the TVP, Apo: palatine aponeurosis, Epi: epiglottis, GH: cartilage primordium of the greater horn of the hyoid bone, HB: cartilage primordium of the hyoid bone, IPC: inferior pharyngeal constrictor, LC: longus capitis, LVP: levator veli palatini, MP: medial pterygoid muscle, MPC: middle pharyngeal constrictor, NP: nasopharynx, PLG: palatoglossus PLP: palatopharyngeus, PP: pterygoid plate, PTT: pharyngotympanic tube, SPC: superior pharyngeal constrictor, T: tongue, TC: thyroid cartilage, TG: trigeminal ganglion, TVP: tensor veli palatini. The schematic drawings indicate the orientation and the position of each section. Scale bars: 200μm.
Fig 3.
Differentiation of the soft palate muscles proceeds from the lateral regions to the midline.
(A-L) MHC (green) along the antero-posterior axis of the mouse soft palate at E13.5 (A-C), E14.5 (D-F), E15.5 (G-I), and P0 (J-L) at the level of the TVP and PLG (A, D, G, J), LVP (B, E, H, K), and PLP and SPC (C, F, I, L). (A) Dashed lines indicate the outline of the palatal shelf and tongue epithelium. Red arrows indicate the differentiated TVP. (D-E) In the inset, dashed lines correspond to the basal lamina of the palatal shelf epithelium, and the asterisk indicates the epithelial seam during the fusion process. Arrows indicate the medial region of the palatal shelf negative for mature myocytes until newborn stage. LVP: levator veli palatini, MP: medial pterygoid muscle, PLG: palatoglossus PLP: palatopharyngeus, SPC: superior pharyngeal constrictor, T: tongue, TT: tensor tympani, TG: trigeminal ganglion, TVP: tensor veli palatini. The schematic drawings indicate the orientation and the position of each section. Scale bars: 200μm.
Fig 4.
Soft palate innervation is primarily oro-medial and complements the differentiated muscle pattern.
(A-L) MHC (green) and β3-tubulin (red) co-immunostaining along the antero-posterior axis of the mouse soft palate at E13.5 (A-C), E14.5 (D-F), E16.5 (G-I), and P0 (J-L) at the level of the TVP and PLG (A, D, G, J), LVP (B, E, H, K), and PLP and SPC (C, F, I, L). Dashed lines indicate the outline of the palatal shelf and tongue epithelium. Arrows indicate the nerve fibers innervating the palatal shelves in a pattern complementary to the differentiated muscle, mainly located orally in the medial region. The schematic drawings indicate the orientation and the position of each section. Scale bars: 200μm.
Fig 5.
Soft palate vascularization is closely related to innervation and located mainly in oro-medial regions.
(A-L) MHC (green) and CD31 (red) co-immunostaining along the antero-posterior axis of the mouse soft palate at E13.5 (A-C), E14.5 (D-F), E16.5 (G-I), and P0 (J-L) at the level of the TVP and PLG (A, D, G, J), LVP (B, E, H, K), and PLP and SPC (C, F, I, L). Dashed lines indicate the outline of the palatal shelf and tongue epithelium. Arrows indicate blood vessels supplying the palatal shelves in a pattern similar to that of innervation and complementary to the differentiated muscle, mainly located orally in the medial region. The schematic drawings indicate the orientation and the position of each section. Scale bars: 200μm.
Fig 6.
The pharyngeal region constitutes an anatomical boundary between neural crest- and mesoderm-derived tissues.
(A-F) MHC (red) immunostaining and co-immunostaining with Col1a1 (green) of coronal sections of soft palates from E15.5 Wnt1-Cre;Zsgreenfl/fl mice. Positive ZsGreen signal indicates cells are neural crest-derived. (G, H) MHC (red) immunostaining of transverse sections of soft palates from E18.5 Wnt1-Cre;Zsgreenfl/fl samples mice at the level of the PLG (G) and the pharyngotympanic tube (H). Apo: palatine aponeurosis, Epi: epiglottis, LC: longus capitis, LVP: levator veli palatini, NP: nasopharynx, OP: oropharynx, PLG: palatoglossus PLP: palatopharyngeus, PTT: pharyngotympanic tube, SPC: superior pharyngeal constrictor, T: tongue, TVP: tensor veli palatini. The schematic drawings indicate the orientation and the position of each section. Scale bars: 200μm.