ISSN:
0003-276X
Keywords:
Life and Medical Sciences
;
Cell & Developmental Biology
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Medicine
Notes:
A functional dependency between the nongravid uterus and the ovaries is essential to luteolysis and the return to estrus in the pig. After mating of gilts, the corpora lutea develop, and they are required for the maintenance of pregnancy to a normal duration of about 114 days. Hysterectomy of luteal phase (day 6) nongravid gilts results in persistence of the corpora lutea to 150 days. We report that these corpora secrete greater quantities (P 〈 0.025) of progesterone than during the later half of gestation (days 54-108). Although aging corpora lutea remain functional for at least an additional 35 days, an abrupt reduction by half in progesterone secretion (16 ng/ml) occurs about day 114 in hysterectomized gilts that coincides with the prepartum decrease to basal serum levels (〈0.5 ng/ml) at parturition (day 114) and during lactation. Aging corpora lutea remain large (averaging 〉 450 mg) on days 124 and 136 in hysterectomized gilts, whereas they regress (averaging 〈 75mg) in the lactating dams. Mitochondria continue to increase in size in aging corpora lutea of hysterectomized gilts until day 136; in contrast, they decrease during the postpartum period in lactating dams. A precisely timed signal, possibly of ovarian origin or form the CNS and pituitary gland, entrains in hysterectomized and pregnant pigs at day 113 that results in marked shifts in relaxin and progesterone secretion. Progesterone secretion and mitochondrial features suggest that procine corpora lutea seem genetically controlled and are preprogrammed at estrus for the duration of pregnancy, regardless of the presence of conceptuses or absence of the uterus.
Additional Material:
3 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/ar.1092230303
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