title: Histopathological findings of cleft palate in rat embryos induced by triamcinolone acetonide.
abstract: Triamcinolone acetonide (TAC), a synthetic glucocorticoid, induces cleft palate resulting from poor development of palatal shelves in mice. However, TAC has no effect on medial edge epithelial cells (MEE cells) in secondary palatal shelves. In the present study, we examined the relationship between the pathogenesis of cleft palate and the effects on MEE cells and palatal mesenchymal cells in rat embryos/fetuses exposed to TAC. Pregnant Wistar Hannover rats were given TAC intramuscularly at 0.5 mg/kg at gestation days (Day) 12, 13, and 14, then embryos/fetuses were harvested on Days 14.5, 15, 16 and 20. The effects of TAC were as follows; an inhibition of palatal mesenchymal cell proliferation on Day 14.5, a decrease in the density of palatal mesenchymal cells and MEE cells, and expression of epidermal growth factor (EGF) receptors in MEE cells on Day 15, and stratified squamous differentiation of MEE cells with expression of cytokeratin and EGF receptors on Day 16. These findings indicated that TAC inhibited the proliferation of mesenchymal cells and affected the differentiation of MEE cells into stratified squamous epithelia in the palatal shelves of rat embryos. However, these stratified squamous MEE cells partially fused with each other. Thus, we suspected that a major contributing factor to the formation of TAC-induced cleft palate might not be the altered differentiation of MEE cells, but the inhibition of mesenchymal cell proliferation.
authors.affiliation: Biological Research Laboratories, Nissan Chemical Industries, Ltd., Minamisaitama, Saitama, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Furukawa
authors.forename: Koji
authors.initials: K
authors.lastname: Usuda
authors.forename: Masayoshi
authors.initials: M
authors.lastname: Abe
authors.forename: Izumi
authors.initials: I
authors.lastname: Ogawa
mesh_terms: D000818:Animals; D002972:Cleft Palate / Q000139:chemically induced* / Q000473:pathology; D004622:Embryo, Mammalian / Q000473:pathology*; D004815:Epidermal Growth Factor; D004847:Epithelial Cells / Q000187:drug effects / Q000473:pathology; D005260:Female; D007150:Immunohistochemistry; D020287:In Situ Nick-End Labeling; D008648:Mesoderm / Q000166:cytology / Q000187:drug effects; D010159:Palate / Q000187:drug effects* / Q000473:pathology; D011247:Pregnancy; D051381:Rats; D017208:Rats, Wistar; D014222:Triamcinolone Acetonide
chemical_list: D004815:Epidermal Growth Factor; D014222:Triamcinolone Acetonide