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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

Pharyngeal recess and the pharyngotympanic tube cartilage: two fetuses. Azan staining. Sagittal sections. (A and B [or C and D]) display fetuses with a crown-rump length of 103 mm (or 100 mm). (A) and (C) are located medially to (B) and (D), respectively. The superior or posterior orientation is shown by arrows in (A). The pharyngotympanic tube (PTT) and the tubal cartilage (C) are located between the pharyngeal recess (PR) and the PTT (A, B). Instead of the bony carotid canal, a loose space (stars in B and D) is evident between the PTT cartilage and the cochlea. Thus, the internal carotid artery (ICA) is exposed to the loose space. An inset (lower angle of D) displays a control specimen (30 wk) in which the bony carotid canal is established: the levator veli palatini muscle (LVP) attaches to the bony part that develops later (asterisks). CPM, constrictor pharyngis medius muscle; CPS, constrictor pharyngis superior muscle; FA, facial artery; HB, hyoid bone; LC, longus capitis muscle; LP, lateral pterygoid muscle; MC, Meckel's cartilage; MP, medial pterygoid muscle; PP, palatopharyngeal muscle; PT, pterygoid process; SG, styloglossus muscle; SH, stylohyoid muscle; SMG, submandibular gland; TVP, tensor veli palatini muscle. Scale bars=1 mm (A-D, inset in D).
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Figure 5: Pharyngeal recess and the pharyngotympanic tube cartilage: two fetuses. Azan staining. Sagittal sections. (A and B [or C and D]) display fetuses with a crown-rump length of 103 mm (or 100 mm). (A) and (C) are located medially to (B) and (D), respectively. The superior or posterior orientation is shown by arrows in (A). The pharyngotympanic tube (PTT) and the tubal cartilage (C) are located between the pharyngeal recess (PR) and the PTT (A, B). Instead of the bony carotid canal, a loose space (stars in B and D) is evident between the PTT cartilage and the cochlea. Thus, the internal carotid artery (ICA) is exposed to the loose space. An inset (lower angle of D) displays a control specimen (30 wk) in which the bony carotid canal is established: the levator veli palatini muscle (LVP) attaches to the bony part that develops later (asterisks). CPM, constrictor pharyngis medius muscle; CPS, constrictor pharyngis superior muscle; FA, facial artery; HB, hyoid bone; LC, longus capitis muscle; LP, lateral pterygoid muscle; MC, Meckel's cartilage; MP, medial pterygoid muscle; PP, palatopharyngeal muscle; PT, pterygoid process; SG, styloglossus muscle; SH, stylohyoid muscle; SMG, submandibular gland; TVP, tensor veli palatini muscle. Scale bars=1 mm (A-D, inset in D).

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)

Pharyngeal recess and the pharyngotympanic tube cartilage: two fetuses. Azan staining. Sagittal sections. (A and B [or C and D]) display fetuses with a crown-rump length of 103 mm (or 100 mm). (A) and (C) are located medially to (B) and (D), respectively. The superior or posterior orientation is shown by arrows in (A). The pharyngotympanic tube (PTT) and the tubal cartilage (C) are located between the pharyngeal recess (PR) and the PTT (A, B). Instead of the bony carotid canal, a loose space (stars in B and D) is evident between the PTT cartilage and the cochlea. Thus, the internal carotid artery (ICA) is exposed to the loose space. An inset (lower angle of D) displays a control specimen (30 wk) in which the bony carotid canal is established: the levator veli palatini muscle (LVP) attaches to the bony part that develops later (asterisks). CPM, constrictor pharyngis medius muscle; CPS, constrictor pharyngis superior muscle; FA, facial artery; HB, hyoid bone; LC, longus capitis muscle; LP, lateral pterygoid muscle; MC, Meckel's cartilage; MP, medial pterygoid muscle; PP, palatopharyngeal muscle; PT, pterygoid process; SG, styloglossus muscle; SH, stylohyoid muscle; SMG, submandibular gland; TVP, tensor veli palatini muscle. Scale bars=1 mm (A-D, inset in D).
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Related In: Results  -  Collection

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Figure 5: Pharyngeal recess and the pharyngotympanic tube cartilage: two fetuses. Azan staining. Sagittal sections. (A and B [or C and D]) display fetuses with a crown-rump length of 103 mm (or 100 mm). (A) and (C) are located medially to (B) and (D), respectively. The superior or posterior orientation is shown by arrows in (A). The pharyngotympanic tube (PTT) and the tubal cartilage (C) are located between the pharyngeal recess (PR) and the PTT (A, B). Instead of the bony carotid canal, a loose space (stars in B and D) is evident between the PTT cartilage and the cochlea. Thus, the internal carotid artery (ICA) is exposed to the loose space. An inset (lower angle of D) displays a control specimen (30 wk) in which the bony carotid canal is established: the levator veli palatini muscle (LVP) attaches to the bony part that develops later (asterisks). CPM, constrictor pharyngis medius muscle; CPS, constrictor pharyngis superior muscle; FA, facial artery; HB, hyoid bone; LC, longus capitis muscle; LP, lateral pterygoid muscle; MC, Meckel's cartilage; MP, medial pterygoid muscle; PP, palatopharyngeal muscle; PT, pterygoid process; SG, styloglossus muscle; SH, stylohyoid muscle; SMG, submandibular gland; TVP, tensor veli palatini muscle. Scale bars=1 mm (A-D, inset in D).
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