title: Transient appearance of tyrosine hydroxylase immunoreactive cells in the midline epithelial seam of the human fetal secondary palate.
abstract: OBJECTIVE
  Transient immunoreactivity for tyrosine hydroxylase, which mediates the conversion of the amino acid L-tyrosine to dihydroxyphenylalanine, in the midline epithelial seam between the bilateral palatal shelves was investigated in human fetuses.
  
  
  METHODS
  Horizontal or frontal paraffin sections of two human fetuses at 9 and 15 weeks of gestation were used to examine the distribution of tyrosine hydroxylase-immunoreactive cells in regions of the entire head other than the brain. Immunohistochemical staining for S100 protein, calretinin, cytokeratin 14, and vimentin was examined using adjacent or near sections.
  
  
  RESULTS
  Tyrosine hydroxylase-immunoreactive cells were large and densely distributed in the midline epithelial seam at the site of palatal fusion in fetuses at 9 weeks but not in fetuses at 15 weeks, in which the midline epithelial seam had already disappeared. No expression of S100 protein, calretinin, or vimentin was detected, but the midline epithelial seam was positive for cytokeratin 14. Tyrosine hydroxylase immunoreactivity was not detected in epithelia during the process of palatal fusion in mice from E 14.0 to 15.0.
  
  
  CONCLUSIONS
  These findings indicate that tyrosine hydroxylase-immunoreactive cells in the midline epithelial seams are nonneural epithelial cells and suggest that the tyrosine hydroxylase is a novel factor involved in normal palatal formation, especially the fate of the midline epithelial seam in humans.
authors: Sendai Medical Hospital, Sendai, Miyagi, Japan
authors: Yukio
authors: Y
authors: Katori
authors: Shunichi
authors: S
authors: Shibata
authors: Tetsuaki
authors: T
authors: Kawase
authors: Baik Hwan
authors: BH
authors: Cho
authors: Gen
authors: G
authors: Murakami
mesh_terms: D000818:Animals; D002102:Cadaver; D064032:Calbindin 2 / Q000378:metabolism; D005333:Fetus / Q000166:cytology; D005865:Gestational Age; D006801:Humans; D007124:Immunoenzyme Techniques; D053547:Keratin-14 / Q000378:metabolism; D051379:Mice; D010159:Palate / Q000166:cytology* / Q000196:embryology / Q000201:enzymology*; D009418:S100 Proteins / Q000378:metabolism; D014446:Tyrosine 3-Monooxygenase / Q000378:metabolism*; D014746:Vimentin / Q000378:metabolism
chemical_list: D064032:Calbindin 2; D053547:Keratin-14; D009418:S100 Proteins; D014746:Vimentin; D014446:Tyrosine 3-Monooxygenase