{"id":{"repo_id":"london-metro","oai_identifier":"oai:repository.londonmet.ac.uk:3392"},"canonical_url":"https://search.dev.ndltd.org/etd/london-metro/oai:repository.londonmet.ac.uk:3392","repository":{"repo_id":"london-metro","name":"London Metropolitan University","base_url":"https://repository.londonmet.ac.uk/cgi/oai2"},"display":{"title":"Evidence for the formation of supplementary corpora lutea in the pregnant and pseudopregnant rat","abstract":"In a series of experiments investigating a possible post-coitum contraceptive, it was observed that the numbers of corpora lutea (CL) of pregnant Sprague-Dawley (CD) rats were greater than in cyclic, unmated control females (p<0.001). The ontogeny of these supplementary CL (SCL) was established by the recording the mean number of CL in pregnant Sprague-Dawley rats on days 1 to 9 post-coitum (day 1 being the first day post-coitum) using the gross phological dissection of the ovary. Compared to cyclic controls, an initial significant increase in mean CL numbers was recorded on day 1 post-coitum (p<0.05) with a further significant increase between days 5 and 7 (p<0.001). This phenomena was neither Sprague-Dawley strain, nor pregnancy specific, as a similar increase was also recorded for Wistar rats between days 4 and 7 postcoitum and identical increases in mean CL numbers were recorded in pseudopregnant rats of both strains. Histological studies of ovarian tissue confirmed the presence of newly formed CL on day 5 and 6 post-coitum and an absence of entrapped ova; follicular development was also present in early pregnancy with Graafian follicles evident on day 4 post-coitum. Plasma progesterone determinations revealed no increase in circulating progesterone as a result of SCL formation in either pregnant or pseudopregnant rats. Supplementary ovulations may be initiated by the preimplantation surge of oestrogen, on day 4 post-coitum, as treatment with the anti-oestrogen. Tamoxifen, inhibits their formation. Investigations into the presence of an appropriately-timed preovulatory surge of gonadotrophins in the early stages of pregnancy however, proved inconclusive. Supplementary ovulation occurs therefore between day 4 and 7 post-coitum in both pregnant and pseudopregnant Wistar and Sprague-Dawley rats, probably initiated by a consistent physiological event. This phenomena therefore obviously has an impact on the estimation of embryo mortality studies in this species.","abstract_html":"In a series of experiments investigating a possible post-coitum contraceptive, it was observed that the numbers of corpora lutea (CL) of pregnant Sprague-Dawley (CD) rats were greater than in cyclic, unmated control females (p&lt;0.001). The ontogeny of these supplementary CL (SCL) was established by the recording the mean number of CL in pregnant Sprague-Dawley rats on days 1 to 9 post-coitum (day 1 being the first day post-coitum) using the gross phological dissection of the ovary. Compared to cyclic controls, an initial significant increase in mean CL numbers was recorded on day 1 post-coitum (p&lt;0.05) with a further significant increase between days 5 and 7 (p&lt;0.001). This phenomena was neither Sprague-Dawley strain, nor pregnancy specific, as a similar increase was also recorded for Wistar rats between days 4 and 7 postcoitum and identical increases in mean CL numbers were recorded in pseudopregnant rats of both strains. Histological studies of ovarian tissue confirmed the presence of newly formed CL on day 5 and 6 post-coitum and an absence of entrapped ova; follicular development was also present in early pregnancy with Graafian follicles evident on day 4 post-coitum. Plasma progesterone determinations revealed no increase in circulating progesterone as a result of SCL formation in either pregnant or pseudopregnant rats. Supplementary ovulations may be initiated by the preimplantation surge of oestrogen, on day 4 post-coitum, as treatment with the anti-oestrogen. Tamoxifen, inhibits their formation. Investigations into the presence of an appropriately-timed preovulatory surge of gonadotrophins in the early stages of pregnancy however, proved inconclusive. Supplementary ovulation occurs therefore between day 4 and 7 post-coitum in both pregnant and pseudopregnant Wistar and Sprague-Dawley rats, probably initiated by a consistent physiological event. This phenomena therefore obviously has an impact on the estimation of embryo mortality studies in this species.","abstract_has_math":false,"creators":["Garside, Deborah A."],"institution":"City of London Polytechnic","degree_name":"phd","degree_level":"doctoral","degree_discipline":null,"degree_department":null,"school":null,"contributors":[],"advisors":[],"committee_chairs":[],"committee_members":[],"year":1983,"date_issued":"1983-12","date_published":"1983-12","updated_at":"2026-07-24T02:54:30Z","subjects":["590 Animals (Zoology)"],"languages":[],"rights":[],"rights_urls":[],"identifier_entries":[{"key":"dc:identifier.grantnumber","label":"Dc Identifier Grantnumber","values":["N/A"],"render_values":[{"text":"N/A","href":null,"code":true}]}]},"links":{"outbound_url":null,"outbound_label":null,"outbound_source":null},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor.sponsor","label":"Sponsor","values":["London Metropolitan University"]},{"key":"dc:creator","label":"Author","values":["Garside, Deborah A."]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["1983-12"]},{"key":"dc:date.issued","label":"Date","values":["1983-12"]},{"key":"dc:publisher.department","label":"Dc Publisher Department","values":["School of Human Sciences (SHSC)","Department of Biological Sciences"]},{"key":"dc:publisher.institution","label":"Dc Publisher Institution","values":["City of London Polytechnic"]},{"key":"dc:relation.isreferencedby","label":"Dc Relation Isreferencedby","values":["https://repository.londonmet.ac.uk/3392/"]},{"key":"dc:type","label":"Dc Type","values":["Thesis"]},{"key":"dc:type.qualificationlevel","label":"Dc Type Qualificationlevel","values":["doctoral"]},{"key":"dc:type.qualificationname","label":"Dc Type Qualificationname","values":["phd"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["590 Animals (Zoology)"]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier.grantnumber","label":"Dc Identifier Grantnumber","values":["N/A"]},{"key":"dc:identifier.uri","label":"Identifier URI","values":["https://repository.londonmet.ac.uk/3392/1/347864.pdf"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description.abstract","label":"Abstract","values":["In a series of experiments investigating a possible post-coitum contraceptive, it was observed that the numbers of corpora lutea (CL) of pregnant Sprague-Dawley (CD) rats were greater than in cyclic, unmated control females (p<0.001). The ontogeny of these supplementary CL (SCL) was established by the recording the mean number of CL in pregnant Sprague-Dawley rats on days 1 to 9 post-coitum (day 1 being the first day post-coitum) using the gross phological dissection of the ovary. Compared to cyclic controls, an initial significant increase in mean CL numbers was recorded on day 1 post-coitum (p<0.05) with a further significant increase between days 5 and 7 (p<0.001). This phenomena was neither Sprague-Dawley strain, nor pregnancy specific, as a similar increase was also recorded for Wistar rats between days 4 and 7 postcoitum and identical increases in mean CL numbers were recorded in pseudopregnant rats of both strains. Histological studies of ovarian tissue confirmed the presence of newly formed CL on day 5 and 6 post-coitum and an absence of entrapped ova; follicular development was also present in early pregnancy with Graafian follicles evident on day 4 post-coitum. Plasma progesterone determinations revealed no increase in circulating progesterone as a result of SCL formation in either pregnant or pseudopregnant rats. Supplementary ovulations may be initiated by the preimplantation surge of oestrogen, on day 4 post-coitum, as treatment with the anti-oestrogen. Tamoxifen, inhibits their formation. Investigations into the presence of an appropriately-timed preovulatory surge of gonadotrophins in the early stages of pregnancy however, proved inconclusive. Supplementary ovulation occurs therefore between day 4 and 7 post-coitum in both pregnant and pseudopregnant Wistar and Sprague-Dawley rats, probably initiated by a consistent physiological event. This phenomena therefore obviously has an impact on the estimation of embryo mortality studies in this species."]},{"key":"dc:format","label":"Dc Format","values":["text"]},{"key":"dc:title","label":"Title","values":["Evidence for the formation of supplementary corpora lutea in the pregnant and pseudopregnant rat"]}]}],"canonical_facts":{"dc:contributor.sponsor":["London Metropolitan University"],"dc:creator":["Garside, Deborah A."],"dc:date":["1983-12"],"dc:date.issued":["1983-12"],"dc:description.abstract":["In a series of experiments investigating a possible post-coitum contraceptive, it was observed that the numbers of corpora lutea (CL) of pregnant Sprague-Dawley (CD) rats were greater than in cyclic, unmated control females (p<0.001). The ontogeny of these supplementary CL (SCL) was established by the recording the mean number of CL in pregnant Sprague-Dawley rats on days 1 to 9 post-coitum (day 1 being the first day post-coitum) using the gross phological dissection of the ovary. Compared to cyclic controls, an initial significant increase in mean CL numbers was recorded on day 1 post-coitum (p<0.05) with a further significant increase between days 5 and 7 (p<0.001). This phenomena was neither Sprague-Dawley strain, nor pregnancy specific, as a similar increase was also recorded for Wistar rats between days 4 and 7 postcoitum and identical increases in mean CL numbers were recorded in pseudopregnant rats of both strains. Histological studies of ovarian tissue confirmed the presence of newly formed CL on day 5 and 6 post-coitum and an absence of entrapped ova; follicular development was also present in early pregnancy with Graafian follicles evident on day 4 post-coitum. Plasma progesterone determinations revealed no increase in circulating progesterone as a result of SCL formation in either pregnant or pseudopregnant rats. Supplementary ovulations may be initiated by the preimplantation surge of oestrogen, on day 4 post-coitum, as treatment with the anti-oestrogen. Tamoxifen, inhibits their formation. Investigations into the presence of an appropriately-timed preovulatory surge of gonadotrophins in the early stages of pregnancy however, proved inconclusive. Supplementary ovulation occurs therefore between day 4 and 7 post-coitum in both pregnant and pseudopregnant Wistar and Sprague-Dawley rats, probably initiated by a consistent physiological event. This phenomena therefore obviously has an impact on the estimation of embryo mortality studies in this species."],"dc:format":["text"],"dc:identifier.grantnumber":["N/A"],"dc:identifier.uri":["https://repository.londonmet.ac.uk/3392/1/347864.pdf"],"dc:publisher.department":["School of Human Sciences (SHSC)","Department of Biological Sciences"],"dc:publisher.institution":["City of London Polytechnic"],"dc:relation.isreferencedby":["https://repository.londonmet.ac.uk/3392/"],"dc:subject":["590 Animals (Zoology)"],"dc:title":["Evidence for the formation of supplementary corpora lutea in the pregnant and pseudopregnant rat"],"dc:type":["Thesis"],"dc:type.qualificationlevel":["doctoral"],"dc:type.qualificationname":["phd"]},"updated_at":"2026-07-24T02:54:30Z"}