title: Rat intermediate lobe in culture: a histological and biochemical characterization.
abstract: The histology, immunohistochemistry, peptide synthesis and secretion as well as proliferation rate of rat intermediate lobe (IL) were studied in primary cultures. The cultures contained two populations of cells: melanotrophs either organized in free floating lobules or in lobules which attached to the dishes and formed a monolayer. Both populations retained their in vivo morphology: polyhedral cells with smooth, ovoid nuclei and a large number of cytoplasmic secretory coated vesicles, a well developed Golgi apparatus, abundant mitochondria and extensive areas of rough endoplasmic reticulum. The melanotrophs stained with varying intensity for alpha-MSH and in situ hybridization showed the presence of pro-opiomelanocortin (POMC) mRNA. 35S-methionine incorporation combined with 2-D gel electrophoresis demonstrated POMC peptide synthesis and radioimmunoassay confirmed its secretion into the medium. 3H-thymidine uptake in the attached melanotrophs was considerably higher than that in the free-floating melanotrophs, demonstrating the dependency of proliferation rate on the cytoarchitecture of the explant. The retention of melanotroph morphology, biosynthetic and proliferative capacity in vitro affords a valid model system for studying POMC gene expression.
authors.affiliation: Experimental Therapeutics Branch, National Institute of Neurological and Communicative Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892.
authors.forename: B M
authors.initials: BM
authors.lastname: Chronwall
authors.forename: J F
authors.initials: JF
authors.lastname: Bishop
authors.forename: D R
authors.initials: DR
authors.lastname: Gehlert
mesh_terms: D000818:Animals; D002455:Cell Division / Q000502:physiology; D046508:Culture Techniques; D005353:Fibronectins / Q000032:analysis; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D010452:Peptide Biosynthesis; D010455:Peptides / Q000378:metabolism; D010902:Pituitary Gland / Q000033:anatomy & histology* / Q000737:chemistry / Q000378:metabolism; D011333:Pro-Opiomelanocortin / Q000096:biosynthesis / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D013936:Thymidine / Q000378:metabolism
chemical_list: D005353:Fibronectins; D010455:Peptides; D011333:Pro-Opiomelanocortin; D013936:Thymidine