Progesterone in utero-ovarian venous plasma during pregnancy in ewes

Pe, Mattner; Thorburn, G. D.

doi:10.1530/jrf.0.0240140

Cited by 13 publications

(4 citation statements)

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“…Recent studies on the origin of plasma progesterone in sheep have shown that up to 110 days gestation the CL is a major contributor, but between 130 days and oirth the ovarian contribution is small (Edgar and Ronaldson 1958;Mattner and Thorburn 1971). Albeit, bilateral oophorectomy at 110--124 days gestation resulted in a 50% reduction of peripheral plasma progesterone concentrations in late pregnancy (Fylling 1970), a difference similar to that seen between the ewes on Yarloop and those on grass pasture.…”

Section: Discussionmentioning

confidence: 62%

Hormone Studies on Ewes Grazing an Oestrogenic (Yarloop Clover) Pasture During the Reproductive Cycle

Obst¹,

Seamark²

1975

Aust. Jnl. Of Bio. Sci.

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The endocrine function of Merino and Corriedale ewes grazing an oestrogenic (Yarloop clover) pasture has been studied during the oestrous cycle, pregnancy and parturition, and the results compared with those from a study of similar ewes grazing a neighbouring grass pasture. Plasma progesterone, oestrogen and corticoids were measured using competitive protein binding assay procedures.During the oestrous cycle clearly anomalous patterns in hormone content were evident in ewes grazing Yarloop, and this related to their significantly poorer (P < 0·001) fertility.The first mating, when ewes were 1 t years of age, was particularly affected. Successful conception took place in only 27% of ewes mated on Yarloop, compared with 95% on grass. Evidence of disturbance in the normal patterns of both plasma oestrogen and progesterone was found in infertile ewes, including a shortened period of luteal function.Disturbance of endocrine function caused by Yarloop clover ingestion was also found in pregnant ewes, with the mean plasma progesterone concentrations during the latter half of pregnancy reduced (P < 0·05) and the plasma oestrogen and corticoid levels tending to be higher in these animals.In detailed hormone studies in the periparturant period, both groups showed a similar fall in plasma progesterone and rise in plasma oestrogen prior to parturition. Where excessive time was taken for parturition (more than 30 min) this was reflected in higher plasma corticoid levels (P < 0·05) within 8 h of birth. IntroductionReproductive difficulties in sheep grazing subterranean clover pastures were first described by Bennetts (1944) and Bennetts et al. (1946). Characteristic signs were ewe infertility, dystocia and uterine prolapse resulting in high ewe and lamb mortality. This syndrome of aberrant reproductive functions on clover pastures is now commonly referred to as 'clover disease' and its occurrence has been widely recognized in association with many different clover species throughout the world (Moule 1961;Moule et al. 1963;Bickoff 1968).The results of extensive studies have revealed that the aetiology relates to oestrogenic isoflavones present in the plants (Batterham et al. 1965). However, the exact way in which these substances exert their adverse effects on reproductive function is as yet unresolved. In the present study, an investigation has been carried out to examine the possibility that the clover acts by causing disturbances in the endocrinology of reproduction.Preliminary investigations (Obst et aT. 1971a) suggested that good indices of reproductive endocrine function for grazing flock sheep can be obtained by using relatively simple radio-ligand assays for plasma hormones. Comparison of these indices throughout the reproductive cycle was, therefore, made between a group of

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Section: Discussionmentioning

confidence: 62%

Hormone Studies on Ewes Grazing an Oestrogenic (Yarloop Clover) Pasture During the Reproductive Cycle

Obst¹,

Seamark²

1975

Aust. Jnl. Of Bio. Sci.

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“…In marked contrast in the giraffe, the lack of 3b-HSD staining in the binucleate cells indicates their inability to convert pregnenolone to other steroids, whereas positive staining of the uninucleate trophoblast cells, particularly in the intercotyledonary regions, suggests they do possess progestagenic capacity. Hence, as in some ruminants such as the sheep (Mattner & Thorburn 1971), the placenta may well support, and even supersede, the maternal (and fetal) ovaries in secreting the progestagens to maintain the pregnancy state. The progestagenic function of the placenta would seem to be supported by the finding of significant concentrations of progestagens in the fetal fluids.…”

Section: Discussionmentioning

confidence: 99%

Ovarian and placental morphology and endocrine functions in the pregnant giraffe (Giraffa camelopardalis)

Wilsher¹,

Stansfield

Greenwood

et al. 2013

Reproduction

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Gross, histological and immunocytochemical examinations carried out on maternal and fetal reproductive tissues from two pregnant giraffes at an estimated 8 and 13.5 months of gestation (termZ15 months) revealed a typically ruminant macrocotyledonary placenta with binucleate trophoblast cells scattered sparsely in the placentome where they stained intensely with a prolactin antiserum. Binucleate cells were present in greater numbers in the intercotyledonary allantochorion where they did not stain for prolactin whereas the uninucleate trophoblast still did. A single large corpus luteum of pregnancy and several small luteinised follicles were present in the maternal ovaries while the fetal ovaries at 13.5 months gestation showed an assortment of enlarging antral follicles and partially and completely lutenised follicles, the granulosa and luteal cells of which stained positively for 3b-hydroxysteroid dehydrogenase (3b-HSD), 17,20 lyase, prolactin, progesterone receptor and androgen receptor, but negatively for aromatase. The uninucleate trophoblast of the placentome and intercotyledonary allantochorion, the epithelium of the maternal endometrial glands, the seminiferous epithelium in the fetal testis at 8 months of gestation and the zonae fasciculata and reticularis of the fetal adrenal at 13.5 months also stained positively for 3b-HSD and negatively for aromatase. Endocrinologically, it appears that the giraffe placenta is more similar to that of the sheep than the cow with a placental lactogen as the likely driver of the considerable degree of luteinisation seen in both the maternal and the fetal ovaries.

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“…This suggests a compensating"response following ovariectomy. Hemispayed pregnant ewes lacking an ovary containing a corpus luteum had higher progesterone levels in the utero-ovarian venous plasma than similar ewes which retained their corpora lutea during the last two months of pregnancy (Mattner and Thorburn, 1971). Bedford et (1972) and Thompson (1973) Peripheral plasma levels of progesterone in the pregnant cow have been reported for several years.…”

Section: Progesteronementioning

confidence: 95%

Physio-pathologic studies in induced parturition in the cow (Bos taurus)

Evans¹

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Progesterone in utero-ovarian venous plasma during pregnancy in ewes

Cited by 13 publications

References 0 publications

Hormone Studies on Ewes Grazing an Oestrogenic (Yarloop Clover) Pasture During the Reproductive Cycle

Hormone Studies on Ewes Grazing an Oestrogenic (Yarloop Clover) Pasture During the Reproductive Cycle

Ovarian and placental morphology and endocrine functions in the pregnant giraffe (Giraffa camelopardalis)

Physio-pathologic studies in induced parturition in the cow (Bos taurus)

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