Prepuberal ovine mammary development is unaffected by ovariectomy.
Crossbred ewe lambs were used in a 2 x 2 x 2 factorial design to determine the effect of ovariectomy, age, and estrogen administration on prepuberal mammary development. Intact (I, n = 20) and ovariectomized (OVX, n = 17) lambs were sacrificed at 6 and 13 wk of age after 1 wk of either estrogen 0.1 mg/kg BW/day, s.c.) or vehicle injections. Ovaiectomies were performed at 10 +/- 1 d of age. At sacrifice, one mammary gland was dissected into parenchymal and stromal fractions for biochemical analyses. Parenchymal explants from the remaining gland were labeled with [3H]thymidine for histoautoradiography. Neither ovariectomy nor estrogen treatment affected body weight, total gland weight, or parenchymal weight (P > 0.05). However, means for each of these variables increased between 6 and 13 wk (P < 0.01). Analysis of relative mammary growth showed significant positive deviations from isometry. However, no significant difference in parenchymal allometry was observed between I and OVX groups. Exogenous estrogen stimulated an increase (P < 0.05) in epithelial cell labeling with [3H]thymidine, but neither ovariectomy nor age at sacrifice had any effect (P > 0.2) on epithelial labeling. These results demonstrate that prepuberal allometric mammary growth in the ewe lamb does not require the presence of the ovary.
Department of Dairy Science Virginia Polytechnic Institute.
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Ellis
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McFadden
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Akers
D000375:Aging / Q000502:physiology; D000818:Animals; D004958:Estradiol / Q000494:pharmacology*; D005260:Female; D008321:Mammary Glands, Animal / Q000187:drug effects / Q000254:growth & development*; D010052:Ovariectomy / Q000662:veterinary*; D010053:Ovary / Q000502:physiology*; D012756:Sheep / Q000254:growth & development / Q000502:physiology* / Q000601:surgery; D014599:Uterus / Q000187:drug effects / Q000254:growth & development
D004958:Estradiol