{"id":{"repo_id":"vt","oai_identifier":"oai:vtechworks.lib.vt.edu:10919/41561"},"canonical_url":"https://search.dev.ndltd.org/etd/vt/oai:vtechworks.lib.vt.edu:10919/41561","repository":{"repo_id":"vt","name":"Virginia Tech","base_url":"https://vtechworks.lib.vt.edu/oai/request"},"display":{"title":"An investigation into hormonal regulation of ovine mammary gland growth during pregnancy","abstract":"Prepartum, multiparous ewes were randomly assigned to experimental groups and sacrificed at 50(n=5), SO(n=4),115(n=5), and 140(n=4) days of gestation. Serum harvested the week prior to slaughter was assayed for progesterone (PG), prolactin (PRL) and growth hormone (GH) concentrations. Mammary tissue obtained at slaughter was assayed for receptor concentrations of progesterone (PGr), prolactin (PRLr) and insulin (Ir). Quantitative biochemical, histological and autoradiographical analyses were used to measure mammary gland growth and indicated no significant glandular growth occurs prior to 8O days of gestation. However, a major phase of parenchymal growth occurred between 8O and 115 days which coincided with significant increases in PG, PGr and PRLr concentrations. Parenchymal growth continued further into late pregnancy. GH and Ir concentrations did not change significantly during pregnancy and were not strongly correlated to growth measurements. These results suggest that mammary gland growth is receptor-mediated and direct or indirect regulation of PGr and PRLr is primarily responsible for the observed growth phenomenon.","abstract_html":"Prepartum, multiparous ewes were randomly assigned to experimental groups and sacrificed at 50(n=5), SO(n=4),115(n=5), and 140(n=4) days of gestation. Serum harvested the week prior to slaughter was assayed for progesterone (PG), prolactin (PRL) and growth hormone (GH) concentrations. Mammary tissue obtained at slaughter was assayed for receptor concentrations of progesterone (PGr), prolactin (PRLr) and insulin (Ir). Quantitative biochemical, histological and autoradiographical analyses were used to measure mammary gland growth and indicated no significant glandular growth occurs prior to 8O days of gestation. However, a major phase of parenchymal growth occurred between 8O and 115 days which coincided with significant increases in PG, PGr and PRLr concentrations. Parenchymal growth continued further into late pregnancy. GH and Ir concentrations did not change significantly during pregnancy and were not strongly correlated to growth measurements. These results suggest that mammary gland growth is receptor-mediated and direct or indirect regulation of PGr and PRLr is primarily responsible for the observed growth phenomenon.","abstract_has_math":false,"creators":["Smith, James Joseph"],"institution":"Virginia Tech","degree_name":"Master of Science","degree_level":"masters","degree_discipline":"Dairy Science","degree_department":"Dairy Science","school":null,"contributors":[],"advisors":[],"committee_chairs":["Akers, Robert Michael"],"committee_members":["Gwazdauskas, Francis C.","Beal, Wilfred E.","White, John M."],"year":1985,"date_issued":"1985-05-05","date_published":"1985-05-05","updated_at":"2026-07-22T22:20:20Z","subjects":["Mammary glands"],"languages":["en"],"rights":["In Copyright"],"rights_urls":["http://rightsstatements.org/vocab/InC/1.0/"],"identifier_entries":[{"key":"dc:identifier.other","label":"Dc Identifier Other","values":["etd-03122013-040148"],"render_values":[{"text":"etd-03122013-040148","href":null,"code":true}]}]},"links":{"outbound_url":"http://hdl.handle.net/10919/41561","outbound_label":"Handle","outbound_source":"dc:identifier.uri"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.committeechair","label":"Committee Chair","values":["Akers, Robert Michael"]},{"key":"dc:contributor.committeemember","label":"Committee Member","values":["Gwazdauskas, Francis C.","Beal, Wilfred E.","White, John M."]},{"key":"dc:contributor.department","label":"Department","values":["Dairy Science"]},{"key":"dc:creator","label":"Author","values":["Smith, James Joseph"]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date.accessioned","label":"Dc Date Accessioned","values":["2014-03-14T21:31:33Z"]},{"key":"dc:date.available","label":"Dc Date Available","values":["2014-03-14T21:31:33Z","2013-03-12"]},{"key":"dc:date.issued","label":"Date","values":["1985-05-05"]},{"key":"dc:publisher","label":"Institution","values":["Virginia Tech"]},{"key":"dc:type","label":"Dc Type","values":["Thesis"]},{"key":"dc:type.dcmitype","label":"Dc Type Dcmitype","values":["Text"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Dairy Science"]},{"key":"thesis:degree_level","label":"Degree Level","values":["masters"]},{"key":"thesis:degree_name","label":"Degree Name","values":["Master of Science"]},{"key":"thesis:institution_name","label":"Thesis Institution Name","values":["Virginia Polytechnic Institute and State University"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Mammary glands"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language.iso","label":"Language (ISO)","values":["en"]},{"key":"dc:rights","label":"Dc Rights","values":["In Copyright"]},{"key":"dc:rights.uri","label":"Rights URI","values":["http://rightsstatements.org/vocab/InC/1.0/"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier.other","label":"Dc Identifier Other","values":["etd-03122013-040148"]},{"key":"dc:identifier.uri","label":"Identifier URI","values":["http://hdl.handle.net/10919/41561"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["Prepartum, multiparous ewes were randomly assigned to experimental groups and sacrificed at 50(n=5), SO(n=4),115(n=5), and 140(n=4) days of gestation. Serum harvested the week prior to slaughter was assayed for progesterone (PG), prolactin (PRL) and growth hormone (GH) concentrations. Mammary tissue obtained at slaughter was assayed for receptor concentrations of progesterone (PGr), prolactin (PRLr) and insulin (Ir). Quantitative biochemical, histological and autoradiographical analyses were used to measure mammary gland growth and indicated no significant glandular growth occurs prior to 8O days of gestation. However, a major phase of parenchymal growth occurred between 8O and 115 days which coincided with significant increases in PG, PGr and PRLr concentrations. Parenchymal growth continued further into late pregnancy. GH and Ir concentrations did not change significantly during pregnancy and were not strongly correlated to growth measurements. 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