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The Role of the Ovary for the Maintenance of Pregnancy in Cats
Author(s) -
Tsutsui T,
Suzuki Y,
Toyonaga M,
Oba H,
Mizutani T,
Hori T
Publication year - 2009
Publication title -
reproduction in domestic animals
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.546
H-Index - 66
eISSN - 1439-0531
pISSN - 0936-6768
DOI - 10.1111/j.1439-0531.2009.01452.x
Subject(s) - ovary , cats , pregnancy , andrology , medicine , gynecology , obstetrics , biology , genetics
Contents Plasma progesterone (P 4 ) concentrations are maintained in pregnant cats until parturition, but become low in pseudopregnant cats 40–45 days after infertile mating. This difference in P 4 concentrations is considered to be due to P 4 secretion by the placenta of pregnant cats. Therefore, to clarify these points, we performed ovariectomy (OVX) at various stages of pregnancy, examined the pregnancy status and measured LH and P 4 concentrations in peripheral, ovarian and uterine venous blood. After OVX, abortion occurred in 100% (5/5), 80% (4/5), 40% (2/5) and 60% (3/5) of Groups I (Day 35), II (Day 40), III (Day 45) and IV (Day 50) cats, respectively. In the remaining cats, normal delivery took place on days 63–69 [mean, 66.1 ± 1.1 (SE)] of pregnancy. The time to abortion after OVX was 4–8 (mean, 5.6 ± 0.8), 3–17 (mean, 8.0 ± 3.6), 10 and 11, and 2–4 (mean, 3.0 ± 0.7) days in Groups I, II, III and IV, respectively. The plasma P 4 concentrations were 1–2 ng/ml in all groups on the day after OVX, decreasing to less than 1 ng/ml from the 2nd day onwards. The concentrations of P 4 in ovarian venous blood at the time of OVX decreased with the stage of pregnancy, but were clearly higher than those in peripheral blood. The plasma P 4 concentrations in uterine venous blood were similar to those in peripheral blood. These results suggest that peripheral P 4 in pregnant cats is the result of P 4 secretion secreted only by the ovarian corpus luteum, not by the placenta, but indicate that either P 4 is not essential for the maintenance of pregnancy in cats from day 40–45 of pregnancy onwards, or that the placenta provides a local source of P 4 that does not appear in measurable amounts in the peripheral circulation.