title: Stability of the glandular morphogenesis produced by retinoids in the newborn hamster cheek pouch in vitro.
abstract: Retinoids can induce alterations in differentiation and morphogenesis in the hamster cheek pouch. In order to determine the stability of these changes, explants of neonatal pouch were exposed to 6 micrograms/ml of either retinyl acetate (RAc: 1.8 x 10(-5) M) or all-trans retinoic acid (RA: 2.0 x 10(-5) M) for an initial 3 of 7 days, out of a total of 21 days in organ culture. Three days of RAc or RA caused a delay in the differentiation and keratinization of the epithelium at least up to day 7 of culture. Additionally, two out of ten explants exposed to RA showed small downgrowths of epithelium into the stroma at 7 or 14 days. Seven days of exposure to either retinoid led to inhibition of epithelial keratinization, and produced a mucous metaplasia which was still seen at the end of the 21-day culture period. Periodic acid-Schiff (PAS)-positive, diastase-resistant material was present in the metaplastic epithelium, in intercellular, and in some instances, intracellular locations. An excess of either RAc or RA, for 7 days, induced persistent glandlike downgrowths of epithelium, suggesting that a stable alteration in the developmental program of the epithelium may have occurred. Many of these downgrowths possessed a lumen which was lined by cuboidal epithelium and contained PAS-positive, diastase-resistant secretory material. RA appeared more potent than RAc in inhibiting keratinization, in producing a mucous metaplasia, and in initiating glandlike downgrowths. The persistence of glandular downgrowths suggests that retinoids, either directly or indirectly, act in a manner similar to that of an embryonic inductor.
authors.affiliation: Department of Biomedical Sciences, University of Guelph, Ontario, Canada.
authors.forename: H A
authors.initials: HA
authors.lastname: Covant
authors.forename: M H
authors.initials: MH
authors.lastname: Hardy
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D003238:Connective Tissue / Q000187:drug effects; D006224:Cricetinae; D004224:Diterpenes; D004848:Epithelium / Q000187:drug effects; D005088:Exocrine Glands / Q000187:drug effects*; D008647:Mesocricetus; D009024:Morphogenesis / Q000187:drug effects; D009092:Mucous Membrane / Q000187:drug effects; D009093:Mucus; D009924:Organ Culture Techniques; D012176:Retinoids / Q000494:pharmacology*; D000084562:Retinyl Esters; D014212:Tretinoin / Q000494:pharmacology; D014801:Vitamin A / Q000031:analogs & derivatives / Q000494:pharmacology
chemical_list: D004224:Diterpenes; D012176:Retinoids; D000084562:Retinyl Esters; D014801:Vitamin A; C009166:retinol acetate; D014212:Tretinoin