{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,19]],"date-time":"2026-10-19T10:54:24Z","timestamp":1792407264723,"version":"4.4.0"},"reference-count":0,"publisher":"Oxford University Press (OUP)","issue":"1","license":[{"start":{"date-parts":[[1993,9,1]],"date-time":"1993-09-01T00:00:00Z","timestamp":746841600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/academic.oup.com\/pages\/standard-publication-reuse-rights"}],"content-domain":{"domain":["reproduction-online.org"],"crossmark-restriction":true},"short-container-title":[],"published-print":{"date-parts":[[1993,9,1]]},"abstract":"<jats:p>Progesterone, oestradiol and oestrone were measured in plasma from four captive muskoxen during three consecutive pregnancies (1983\u20131984, 1984\u20131985 and 1985\u20131986). Jugular blood samples were collected weekly (1983) or on an alternating 3:4 day schedule (1984\u20131986) during the first 12\u201315 weeks and last 6\u201310 weeks of pregnancy. Sampling during mid-pregnancy was at intervals of 2 weeks (1983 and 1985) or 1 week (1986). Duration of gestation was about 34 weeks (235 \u00b1 4 (sd) days (n = 10), range 230\u2013242 days). Progesterone remained at concentrations similar to those found during the luteal phase of the oestrous cycle for the first 10\u201312 weeks (mean \u00b1 sem 1.6 \u00b1 0.1 ng ml\u22121) after which it rose to a peak (mean 5.5 \u00b1 0.65 ng ml\u22121) between weeks 12 and 20. In all ten pregnancies progesterone concentrations declined dramatically between weeks 20 and 22 to luteal phase values where they remained until parturition. The decline was accompanied by an increase in oestradiol and oestrone concentrations which reached mean peak values of 199.23 \u00b1 87.23 pg ml\u22121 and 980.48 \u00b1 203.91 pg ml\u22121, respectively. Corpora lutea collected from wild muskoxen between 45 and 80 days gestation all showed histological evidence of regression, while corpora lutea from mid-gestation (112\u2013125 days) were in advanced stages of involution. Repeated ovarian ultrasonography of captive muskoxen during the first 100 days of pregnancy confirmed these findings. The unusual, early regression of the corpus luteum of pregnancy indicates that progesterone and oestrogen of mid- and late pregnancy are probably of placental origin. The temporal relationship between the concentrations of these hormones during late pregnancy differs from those of domestic species and is apparently unique among ruminants.<\/jats:p>","DOI":"10.1530\/jrf.0.0990007","type":"journal-article","created":{"date-parts":[[2004,3,20]],"date-time":"2004-03-20T01:55:52Z","timestamp":1079747752000},"page":"7-13","update-policy":"https:\/\/doi.org\/10.1530\/rep\/crossmarkpolicy","source":"Crossref","is-referenced-by-count":13,"title":["Endocrine changes and luteal morphology during pregnancy in muskoxen (\n                    <i>Ovibos moschatus<\/i>\n                    )"],"prefix":"10.1093","volume":"99","author":[{"given":"J. E.","family":"Rowell","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"R. A.","family":"Pierson","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"P. F.","family":"Flood","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"286","published-online":{"date-parts":[[1993,9,1]]},"container-title":["Reproduction"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/academic.oup.com\/reproduction\/article-pdf\/99\/1\/7\/64815566\/jrf_99_1_002.pdf","content-type":"application\/pdf","content-version":"vor","intended-application":"syndication"},{"URL":"https:\/\/academic.oup.com\/reproduction\/article-pdf\/99\/1\/7\/64815566\/jrf_99_1_002.pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,1,7]],"date-time":"2026-01-07T19:09:04Z","timestamp":1767812944000},"score":1,"resource":{"primary":{"URL":"https:\/\/academic.oup.com\/reproduction\/article\/99\/1\/7\/8278203"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[1993,9,1]]},"references-count":0,"journal-issue":{"issue":"1","published-print":{"date-parts":[[1993,9,1]]}},"URL":"https:\/\/doi.org\/10.1530\/jrf.0.0990007","relation":{},"ISSN":["1470-1626","1741-7899"],"issn-type":[{"value":"1470-1626","type":"print"},{"value":"1741-7899","type":"electronic"}],"subject":[],"published-other":{"date-parts":[[1993,9,1]]},"published":{"date-parts":[[1993,9,1]]}}}