Nerve terminal distribution in the human tongue intrinsic muscles: An immunohistochemical study using midterm fetuses

Abstract

Desmin and vimentin are intermediate filaments that play crucial roles in maturation, maintenance and recovery of muscle fibers and mesenchymal cells. The expression of these proteins has not been investigated extensively in human fetuses. In the present study, we examined the immunohistochemical expression of intermediate filaments in skeletal muscles of the head, neck and thorax in 12 mid-term human fetuses at 9-18 weeks of gestation. We also used immunohistochemistry to localise expression of the myosin heavy chain, and silver-impregnation to identify the fetal endomysium.Expression of desmin and vimentin was already detectable in intercostal muscle at 9weeks, especially at sites of muscle attachment to the perichondrium. At this stage, myosin heavy chain was expressed throughout the muscle fibers, and the endomysium had already developed. Beginning with punctate expression, the positive areas became diffusely distributed in the muscle fibers. At 15-18 weeks, intermediate filament proteinswere extensively expressed in all of the muscles examined. Expression at the bone-muscle interface was continuous with expression along the intramuscular tendon fibres. These results suggest that the development of intermediate filaments begins in areas of mechanical stress due to early muscle contraction. Their initially punctate distribution, as observed here, probably corresponds to the earliest stage of fetal enthesis formation.

Fetal anatomy of the upper pharyngeal muscles with special reference to the nerve supply: is it an enteric plexus or simply an intramuscular nerve?

“…The nerve density was highest in the CPM. No such cluster of nerves, or plexus, is seen in the fetal tongue at the same stage [11]. We confirmed the curved or recurrent courses of the pharyngeal nerves that had been previously described by Shimokawa et al [6].…”

“…However, in these high-magnification photos, it was difficult to identify the topographical anatomy of the nerve courses. Our recent immunohistochemical study using human fetuses [11] revealed that the pharyngeal muscles are so large at 20-25 weeks of gestation, that the nerves supplying them are clearly identifiable at lower magnifications. Moreover, the fetal upper pharyngeal muscles provide a thick muscle mass, in contrast to the thin, lower pharyngeal wall.…”

Nerves in the intersphincteric space of the human anal canal with special reference to their continuation to the enteric nerve plexus of the rectum

“…This difference occurred in the level above the squamous‐columnar epithelial junction, that is, the lower part of Figure . The typical end‐plate band for striated muscle innervation (Abe et al, ) was seen in the external anal sphincter in three of the 12 cadavers (Fig. B).…”

Fetal development of deep back muscles in the human thoracic region with a focus on transversospinalis muscles and the medial branch of the spinal nerve posterior ramus

“…All these figures are for a 9-week fetus. But beginning at 15 weeks, the linear terminal in the semispinalis muscle developed into a thicker structure, recently termed the 'endplate band' by Mu & Sanders (2010) and Abe et al (2011) (not shown). We attempted to trace the segmental nerve in semiserial sections based on S100 immunostaining, but we were not able to identify a single multifidus muscle bundle innervated by two segmental nerves.…”

“…For each fetus, 50-200 sections were obtained, depending on fetus size. Most sections were stained with hematoxylin and eosin (HE), but some sections (four sections for every 10 sections) underwent immunohistochemical staining for (i) peripheral nerves (S100 protein; Niikura et al 2010;Abe et al 2011), (ii) striated muscle fibers (desmin; Abe et al 2010), (iii) vessels and stromal mesenchyme (CD34; Katori et al 2011a), and (iv) macrophages (CD68; Kim et al 2011). All studies cited for immunostaining applications were recently performed by our group using human fetuses.…”