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Initial stage of fetal development of the pharyngotympanic tube cartilage with special reference to muscle attachments to the tube.

Katori Y, Rodríguez-Vázquez JF, Verdugo-López S, Murakami G, Kawase T, Kobayashi T - Anat Cell Biol (2012)

Bottom Line: In large fetuses, this loose tissue was occupied by an inferior extension of the temporal bone to cover the artery.This later-developing anterior wall of the carotid canal provided the final bony origin of the levator veli palatini muscle.Consequently, the tubal cartilage development seemed to be accelerated by a surrounding muscle, and conversely, the cartilage was likely to determine the other muscular and bony structures.

View Article: PubMed Central - PubMed

Affiliation: Division of Otorhinolaryngology, Sendai Municipal Hospital, Sendai, Japan.

ABSTRACT
Fetal development of the cartilage of the pharyngotympanic tube (PTT) is characterized by its late start. We examined semiserial histological sections of 20 human fetuses at 14-18 weeks of gestation. As controls, we also observed sections of 5 large fetuses at around 30 weeks. At and around 14 weeks, the tubal cartilage first appeared in the posterior side of the pharyngeal opening of the PTT. The levator veli palatini muscle used a mucosal fold containing the initial cartilage for its downward path to the palate. Moreover, the cartilage is a limited hard attachment for the muscle. Therefore, the PTT and its cartilage seemed to play a critical role in early development of levator veli muscle. In contrast, the cartilage developed so that it extended laterally, along a fascia-like structure that connected with the tensor tympani muscle. This muscle appeared to exert mechanical stress on the initial cartilage. The internal carotid artery was exposed to a loose tissue facing the tubal cartilage. In large fetuses, this loose tissue was occupied by an inferior extension of the temporal bone to cover the artery. This later-developing anterior wall of the carotid canal provided the final bony origin of the levator veli palatini muscle. The tubal cartilage seemed to determine the anterior and inferior margins of the canal. Consequently, the tubal cartilage development seemed to be accelerated by a surrounding muscle, and conversely, the cartilage was likely to determine the other muscular and bony structures.

No MeSH data available.


Related in: MedlinePlus

Initial stage of development of the pharyngotympanic tube cartilage: a fetus with 102 mm crown-rump length. Hematoxlyin and eosin staining. Horizontal sections. (A [E]) is the most superior (or inferior) side of the figure: the distance is 3 mm. The posterior or lateral orientation is shown by arrows in (D). (F-H) are higher-magnigfication views of the pharyngotympanic tube (PTT) shown in (B-D), respectively. (A [C]) displays the superior (or inferior) end of the tubal cartilage (C): thus, the initial cartilage, almost 1 mm in diameter, is restricted to the posterior side of the pharyngeal opening of the PTT. The superior end of the levator veli palatini muscle (LVP) is seen 1 mm below the cartilage (D). A thick, band-like mesenchymal condensation or an "adventitia" in the text (triangles) extends between the cartilage and the tensor tympani muscle (TT). A facia (arrows) connects between the tensor veli palatini muscle (TVP) and Meckel's cartilage (MC). The internal cartotid artery (ICA) does not run through the bony carotid canal but is exposed to a large loose space (stars) on the posterior side of the PTT. ATN, auriculotemporal nerve; LP, lateral pterygoid muscle; MN, mandibular nerver; MP, medial pterygoid muscle; OG, otic ganglion; PT, pterygoid process; TMJ, temporomandibular joint. Scale bars in (A)=1 mm (A-E); in (F)=0.5 mm (F-H).
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Figure 1: Initial stage of development of the pharyngotympanic tube cartilage: a fetus with 102 mm crown-rump length. Hematoxlyin and eosin staining. Horizontal sections. (A [E]) is the most superior (or inferior) side of the figure: the distance is 3 mm. The posterior or lateral orientation is shown by arrows in (D). (F-H) are higher-magnigfication views of the pharyngotympanic tube (PTT) shown in (B-D), respectively. (A [C]) displays the superior (or inferior) end of the tubal cartilage (C): thus, the initial cartilage, almost 1 mm in diameter, is restricted to the posterior side of the pharyngeal opening of the PTT. The superior end of the levator veli palatini muscle (LVP) is seen 1 mm below the cartilage (D). A thick, band-like mesenchymal condensation or an "adventitia" in the text (triangles) extends between the cartilage and the tensor tympani muscle (TT). A facia (arrows) connects between the tensor veli palatini muscle (TVP) and Meckel's cartilage (MC). The internal cartotid artery (ICA) does not run through the bony carotid canal but is exposed to a large loose space (stars) on the posterior side of the PTT. ATN, auriculotemporal nerve; LP, lateral pterygoid muscle; MN, mandibular nerver; MP, medial pterygoid muscle; OG, otic ganglion; PT, pterygoid process; TMJ, temporomandibular joint. Scale bars in (A)=1 mm (A-E); in (F)=0.5 mm (F-H).

Mentions: Figs. 1-3 show horizontal sections, Fig. 4 frontal sections and Fig. 5 sagittal sections. The initial appearance of the tubal cartilage is evident in Fig. 1, and a fascial connection between the cartilage and the tensor tympani muscle is evident in Figs. 1 and 2. Likewise, the topographical relationship between the cartilage and the levator veli palatini muscle is shown in Figs. 1, 3, and 4. Finally, Fig. 5 displays the pharyngeal recess. In addition, all the figures show the underdeveloped carotid canal of the temporal bone, in contrast to the late stage (Fig. 5D inset).


Initial stage of fetal development of the pharyngotympanic tube cartilage with special reference to muscle attachments to the tube.

Katori Y, Rodríguez-Vázquez JF, Verdugo-López S, Murakami G, Kawase T, Kobayashi T - Anat Cell Biol (2012)

Initial stage of development of the pharyngotympanic tube cartilage: a fetus with 102 mm crown-rump length. Hematoxlyin and eosin staining. Horizontal sections. (A [E]) is the most superior (or inferior) side of the figure: the distance is 3 mm. The posterior or lateral orientation is shown by arrows in (D). (F-H) are higher-magnigfication views of the pharyngotympanic tube (PTT) shown in (B-D), respectively. (A [C]) displays the superior (or inferior) end of the tubal cartilage (C): thus, the initial cartilage, almost 1 mm in diameter, is restricted to the posterior side of the pharyngeal opening of the PTT. The superior end of the levator veli palatini muscle (LVP) is seen 1 mm below the cartilage (D). A thick, band-like mesenchymal condensation or an "adventitia" in the text (triangles) extends between the cartilage and the tensor tympani muscle (TT). A facia (arrows) connects between the tensor veli palatini muscle (TVP) and Meckel's cartilage (MC). The internal cartotid artery (ICA) does not run through the bony carotid canal but is exposed to a large loose space (stars) on the posterior side of the PTT. ATN, auriculotemporal nerve; LP, lateral pterygoid muscle; MN, mandibular nerver; MP, medial pterygoid muscle; OG, otic ganglion; PT, pterygoid process; TMJ, temporomandibular joint. Scale bars in (A)=1 mm (A-E); in (F)=0.5 mm (F-H).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3472145&req=5

Figure 1: Initial stage of development of the pharyngotympanic tube cartilage: a fetus with 102 mm crown-rump length. Hematoxlyin and eosin staining. Horizontal sections. (A [E]) is the most superior (or inferior) side of the figure: the distance is 3 mm. The posterior or lateral orientation is shown by arrows in (D). (F-H) are higher-magnigfication views of the pharyngotympanic tube (PTT) shown in (B-D), respectively. (A [C]) displays the superior (or inferior) end of the tubal cartilage (C): thus, the initial cartilage, almost 1 mm in diameter, is restricted to the posterior side of the pharyngeal opening of the PTT. The superior end of the levator veli palatini muscle (LVP) is seen 1 mm below the cartilage (D). A thick, band-like mesenchymal condensation or an "adventitia" in the text (triangles) extends between the cartilage and the tensor tympani muscle (TT). A facia (arrows) connects between the tensor veli palatini muscle (TVP) and Meckel's cartilage (MC). The internal cartotid artery (ICA) does not run through the bony carotid canal but is exposed to a large loose space (stars) on the posterior side of the PTT. ATN, auriculotemporal nerve; LP, lateral pterygoid muscle; MN, mandibular nerver; MP, medial pterygoid muscle; OG, otic ganglion; PT, pterygoid process; TMJ, temporomandibular joint. Scale bars in (A)=1 mm (A-E); in (F)=0.5 mm (F-H).
Mentions: Figs. 1-3 show horizontal sections, Fig. 4 frontal sections and Fig. 5 sagittal sections. The initial appearance of the tubal cartilage is evident in Fig. 1, and a fascial connection between the cartilage and the tensor tympani muscle is evident in Figs. 1 and 2. Likewise, the topographical relationship between the cartilage and the levator veli palatini muscle is shown in Figs. 1, 3, and 4. Finally, Fig. 5 displays the pharyngeal recess. In addition, all the figures show the underdeveloped carotid canal of the temporal bone, in contrast to the late stage (Fig. 5D inset).

Bottom Line: In large fetuses, this loose tissue was occupied by an inferior extension of the temporal bone to cover the artery.This later-developing anterior wall of the carotid canal provided the final bony origin of the levator veli palatini muscle.Consequently, the tubal cartilage development seemed to be accelerated by a surrounding muscle, and conversely, the cartilage was likely to determine the other muscular and bony structures.

View Article: PubMed Central - PubMed

Affiliation: Division of Otorhinolaryngology, Sendai Municipal Hospital, Sendai, Japan.

ABSTRACT
Fetal development of the cartilage of the pharyngotympanic tube (PTT) is characterized by its late start. We examined semiserial histological sections of 20 human fetuses at 14-18 weeks of gestation. As controls, we also observed sections of 5 large fetuses at around 30 weeks. At and around 14 weeks, the tubal cartilage first appeared in the posterior side of the pharyngeal opening of the PTT. The levator veli palatini muscle used a mucosal fold containing the initial cartilage for its downward path to the palate. Moreover, the cartilage is a limited hard attachment for the muscle. Therefore, the PTT and its cartilage seemed to play a critical role in early development of levator veli muscle. In contrast, the cartilage developed so that it extended laterally, along a fascia-like structure that connected with the tensor tympani muscle. This muscle appeared to exert mechanical stress on the initial cartilage. The internal carotid artery was exposed to a loose tissue facing the tubal cartilage. In large fetuses, this loose tissue was occupied by an inferior extension of the temporal bone to cover the artery. This later-developing anterior wall of the carotid canal provided the final bony origin of the levator veli palatini muscle. The tubal cartilage seemed to determine the anterior and inferior margins of the canal. Consequently, the tubal cartilage development seemed to be accelerated by a surrounding muscle, and conversely, the cartilage was likely to determine the other muscular and bony structures.

No MeSH data available.


Related in: MedlinePlus