PMC

Axial CT scans of 4 different patients at the level of arytenoid cartilages. A, Bilateral nonmineralized arytenoid cartilages (block arrows). B, Calcified right (arrow) and sclerotic left (arrowhead) arytenoid cartilages. C, Ossified right (curved arrow) and sclerotic left (arrowhead) arytenoid cartilages. D, Bilateral sclerotic arytenoid cartilages (arrowheads).

Overview of the diversity of adrostral cartilages among anurans. Ventral view of the jaw region of selected anuran larvae. a Bombina orientalis shows a typical anuran condition of the jaw region consisting of paired infrarostral cartilages, a plate-like suprarostral cartilage and horizontally oriented Meckel’s cartilages. b In Pelobates fuscus (drawn after Nikitin 1986) two so-called adrostral cartilages can be observed lateral to the paired suprarostral cartilages. c Heliophryne orientalis possesses two additional cartilages in the lower jaw. The submeckelian cartilages lie beneath Meckel’s cartilages and the adrostral cartilages are situated lateral to the suprarostral cartilage. In Ly-294,002-treated Xenopus laevis larvae (d) the ectopic cartilages arise lateral to the palatoquadrate and are free from any muscle insertion or origination similar to P. fuscus and H. orientalis

Exposure to acetaminophen, but not a non-hepatoxic analog, disrupts the development and morphology of craniofacial cartilages. (A–N) Ventral views of 6-dpf larvae stained with alcian blue. Compared to untreated larvae (A), those treated continuously with 3-acetamidophenol (3.9 mM), a non-hepatotoxic acetaminophen analog (B), have a reduced body size but with all craniofacial cartilages intact. (C–N) APAP treatment (3.9 mM) was initiated at the timepoints indicated then continuously through 6 dpf. The effects on the cartilages of the viscerocranium (labeled in (A)), in both their presence and morphology, are generally less severe as the initiation of treatment is delayed (C–N). In a larva treated with APAP from 2 hpf (C), all cartilages of the viscerocranium are missing, making visible cartilages of the neurocranium, most prominently the ethmoid plate (ep) and the bilateral trabeculae (tr). These cartilages were clearly visible in all larvae in all treatment groups. Incrementally delaying treatment results in the restoration of cartilages derived from the first and second pharyngeal arches (e.g., Meckel’s cartilage) earliest, followed by cartilages derived from the third through seventh pharyngeal arches (ceratobranchial cartilages). With treatment delayed to 10 hpf, the palatoquadrate (pq) and ventral ceratohyal (ch) cartilages are more frequently present (black and white arrowheads in E, respectively). When treatment is delayed to at least 20 hpf, the ventral ceratohyal cartilages tend to be oriented posteriorly rather than anteriorly (compare yellow arrowhead in (G) with morphology in (A)), and Meckel’s cartilage (mc) becomes more frequent (blue arrowhead in (G)) though misshapen. The ventral ceratohyal cartilages also begin to be oriented anteriorly (green arrowhead in (I)). Treatment at 28 hpf restores a reduced number of ceratobranchial cartilages in most larvae (red arrowhead in (I)), though they can appear as early as with a 24 hpf treatment. One representative larva is shown from each treatment group, though the effects vary within each treatment group. Scale bar (in (A)) for (A–N), 250 µm.

Mid-sagittal tissue sections of tracheobronchial cartilages. a The mid-sagittal tissue section showing tracheobronchial cartilages at phase 1 and phase 2 (CS20_1, CRL 17.5 mm). In phase 1, mesenchymal cells line up beneath the tracheal epithelium, while boundaries with surrounding tissue are unclear. In phase 2, cartilage cells line up, and boundaries with the surrounding tissue become evident. Note that the several tracheal cartilages at the cranial side occurred at phase 2 while the remaining were at phase 1. bThe mid-sagittal tissue section trachea showing tracheobronchial cartilages at phase 2 (CS20_2, CRL 19.1 mm). All 18 tracheal cartilages were similarly observed at phase 2, indicating that no difference of the histological differentiation was noted. The first tracheal cartilage is larger than the remaining cartilages. cc, cricoid cartilage; dt, digestive tract; tc, thyroid cartilage; th, thymoma.