Effects of ovarian steroids on bovine mammary epithelial cells: in vitro and in viro evidence of indirect stimulation of proliferation

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dc.contributor.authorWoodward, Terry L.en
dc.contributor.departmentDairy Scienceen
dc.date.accessioned2014-03-14T21:31:47Zen
dc.date.adate2009-03-14en
dc.date.available2014-03-14T21:31:47Zen
dc.date.issued1991en
dc.date.rdate2009-03-14en
dc.date.sdate2009-03-14en
dc.description.abstractThree studies were conducted to determine the effects of ovarian steroids on bovine mammary epithelial cell proliferation. In a first study, estrogen (E), progesterone (P), or E+P were administered to prepubertal beef heifers and biopsied mammary parenchyma taken before and following treatment were compared for growth by evaluation of histoautoradiographic incorporation of thymidine. Estrogen increased epithelial cell growth by 24 h, and fibroblasts to a lesser magnitude by 48-96 h. Estrogen and P was less effective and P was ineffective in increasing proliferation in all cell types studied. Proliferation of adipocytes was not altered. A second study characterized hormone responsive proliferation of Mac-T cells, a recent clonal bovine mammary epithelial cell strain. Mac-T cells responded to all hormones tested as would be expected in vivo. Additionally, passage, harvesting, quantification, freezing, and co-culture techniques were modified to facilitate uncomplicated, timely, inexpensive, effective testing of growth responsiveness to hormones or growth factors. In a third study E and P alone, together, with or without serum were unable to increase Mac-T cell proliferation. Serum from prepubertal Holstein heifers after E treatment did not increase growth of Mac-T cells over serum before treatment. Conditioned media from Mac-T or Fib-T (mammary bovine fibroblast cell line) with or without steroids were tested for ability to increase Mac-T cell proliferation. Growth of Mac-T cells was greatest in Fib-T + E conditioned media followed by Fib-T, then Mac-T and lastly fresh media. Steroid exposure did not enhance the ability of Mac-T cell conditioned media to increase Mac-T cell proliferation. In conclusion, E appears to be the primary ovarian steroid involved in initiating bovine mammogenesis. However, estrogen’s action is not direct and may be caused by paracrine release of growth factors.en
dc.description.degreeMaster of Scienceen
dc.format.extentxi, 131 leavesen
dc.format.mediumBTDen
dc.format.mimetypeapplication/pdfen
dc.identifier.otheretd-03142009-040811en
dc.identifier.sourceurlhttp://scholar.lib.vt.edu/theses/available/etd-03142009-040811/en
dc.identifier.urihttp://hdl.handle.net/10919/41629en
dc.language.isoenen
dc.publisherVirginia Techen
dc.relation.haspartLD5655.V855_1991.W662.pdfen
dc.relation.isformatofOCLC# 25119956en
dc.rightsIn Copyrighten
dc.rights.urihttp://rightsstatements.org/vocab/InC/1.0/en
dc.subject.lccLD5655.V855 1991.W662en
dc.subject.lcshMammary glandsen
dc.subject.lcshOvariesen
dc.subject.lcshSteroid hormonesen
dc.titleEffects of ovarian steroids on bovine mammary epithelial cells: in vitro and in viro evidence of indirect stimulation of proliferationen
dc.typeThesisen
dc.type.dcmitypeTexten
thesis.degree.disciplineDairy Scienceen
thesis.degree.grantorVirginia Polytechnic Institute and State Universityen
thesis.degree.levelmastersen
thesis.degree.nameMaster of Scienceen

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