Production of oestrone and oestradiol-17  by different regions of the filamentous pig blastocyst

Bate, L. A.; King, G. J.

doi:10.1530/jrf.0.0840163

Cited by 14 publications

(8 citation statements)

References 13 publications

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“…It was thus somewhat surprising to observe such a marked and consistent increase in leukocyte density, evident as early as attachment sites could be identified, through to Day 27, when the placenta was well established. One possible explanation is that local concentrations of trophoblast-derived signaling molecules may be highest near the embryonic disk, as has been reported for estrogen [48]. Variations in the intimacy of maternal-fetal contact may also be a factor.…”

Section: Discussionmentioning

confidence: 88%

Conceptus Influences the Distribution of Uterine Leukocytes During Early Porcine Pregnancy1

Engelhardt

Croy

King

2002

Biology of Reproduction

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Pregnancy in humans and rodents is associated with dramatic changes in leukocyte populations within the uterus. In these species, recruitment of leukocytes, mostly natural killer (NK) lymphocytes, accompanies decidualization of endometrial stroma even in the absence of pregnancy. In the pig, a nondecidualizing species, the predominant lymphocytes in the pregnant uterus are T and/or NK cells, but their distribution relative to embryonic attachment sites has not been reported. The objective of this study was to compare the abundance of leukocytes in porcine endometrium in contact with trophoblast with that between attachment sites during the early postattachment period. Uteri were recovered on Days 15-17 (n = 4), 18 and 19 (n = 4), 21 and 22 (n = 5), and 25-27 (n = 2) of gestation and from cycling pigs during the luteal phase (Day 15; n = 3). Leukocytes were identified in uterus obtained at versus between attachment sites using an antibody reactive with all leukocytes (CD44). In all pregnant animals, leukocytes were diffusely scattered throughout the endometrial stroma but were rare or absent in the luminal epithelium. Leukocyte density was approximately 3-fold greater in endometrium in contact with conceptuses than in endometrium between attachment sites throughout the early postattachment period. Leukocyte density during the luteal phase was similar to that between attachment sites, suggesting that leukocyte recruitment was a localized response to the embryo. The ability of an individual porcine conceptus to recruit maternal leukocytes to the adjacent stroma may be a vital step in early placental development and embryo survival.

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Section: Discussionmentioning

confidence: 88%

Conceptus Influences the Distribution of Uterine Leukocytes During Early Porcine Pregnancy1

Engelhardt

Croy

King

2002

Biology of Reproduction

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“…This missing factor does not seem to be PGE-2 or one of the porcine conceptus secretory proteins (Harney & Bazer, 1989). Alternatively, since a minimum of four embryos is necessary to maintain pregnancy in pigs (Polge et ai, 1966) and elongated conceptuses release oestrogens from all segments (Bate & King, 1988), PGF-2ct synthesis and release is probably modified throughout most of the uterus during prevention of luteolysis in pregnant animals. Beads may have inhibited endocrine release of PGF-2a from immediately adjacent regions, but failed to suppress this from distant regions.…”

Section: Discussionmentioning

confidence: 99%

Effect of intrauterine application of oestradiol-17 and prostaglandin E-2 on the porcine oestrous cycle and uterine endocrinology

Laforest¹,

King²

1992

Reproduction

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Silastic beads were inserted into the uterine lumen on Day 10 after oestrus. Gilts received beads containing oestradiol-17 beta only, oestradiol benzoate, or oestradiol-17 beta+prostaglandin (PG) E-2. Oestrous cycles were slightly longer in treated than in untreated pigs (20.2 +/- 0.4 days), and durations were 22.6 +/- 1.3, 26.2 +/- 1.7 and 23.2 +/- 1.8 days for oestradiol-17 beta, oestradiol benzoate and oestradiol-17 beta+PGE-2 treatments, respectively (P greater than 0.05). Thus, PGE-2 and an oestrogen such as oestradiol benzoate that persist for a longer period cannot prolong the cycle more than oestradiol-17 beta alone. Additional cyclic gilts underwent similar treatments with beads containing oestradiol-17 beta, oestradiol-17 beta+PGE-2 or cholesterol, and cannulation of one utero-ovarian vein on Day 10. Blood samples were collected from the catheter every 15 min from 08:00 until 11:00 h and from 20:00 until 23:00 h for 5 consecutive days starting the day after surgery and peripheral plasma samples were also collected daily. On Day 16, beads containing oestradiol-17 beta were surrounded by endometrial folds whereas cholesterol beads were free. Concentrations of plasma progesterone did not vary significantly from Days 11 to 16 in gilts treated with oestradiol-17 beta or oestradiol-17 beta+PGE-2, but decreased in cholesterol-treated gilts. Concentrations of plasma oestrone and oestradiol-17 beta were more than ten times higher in gilts treated with oestradiol-17 beta or oestradiol-17 beta+PGE-2 than in cholesterol-treated gilts on the day after bead insertion, but decreased rapidly to values comparable to those in cholesterol-treated gilts by Day 14. In contrast, concentrations of oestrone sulphate remained high until Day 16. Concentrations of PGE-2 in the utero-ovarian vein plasma did not differ (P greater than 0.05) between treatments but those of PGF-2 alpha were higher (P less than 0.004) in gilts treated with cholesterol than in those treated with oestradiol-17 beta or oestradiol-17 beta+PGE-2. It is postulated that insufficient oestradiol-17 beta is released by the beads toward the end of a 'recognition period' to prolong the cycle for more than 3-6 days.

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“…The distribution pattern of estrogens in the blastocyst at day 12 corresponds well with the localized and progressive nature of structural changes in the maternal epithelium. A large number of cells in the trophectoderm produce estradiol-17P near the embryonic disc, and the number decreases progressively distally (King and Ackerley, 1985;Bate and King, 1988). Any connection between estrogens and localized chorionic influences on the maternal epithelium remains speculative since it is not yet possible to attribute alterations to specific embryonic products.…”

Section: Discussionmentioning

confidence: 99%

Microscopic examination of porcine conceptus‐maternal interface between days 10 and 19 of pregnancy

Keys

King

1990

Am. J. Anat.

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Conceptus-maternal interactions in the pig were examined at days 10, 13, 16, and 19 of pregnancy. Contact between the chorion and uterine epithelium was not preserved on day 10, but extensive contact occurred in 3 of 5 pregnant gilts on day 13 and was related to localized differentiation of the uterine epithelium. Attachment events occurred earlier and more rapidly than previously reported, commencing in the region of the embryonic disc and progressing toward the extremities of the chorionic vesicle, with stages from apposition through attachment occurring simultaneously along a conceptus at day 13 and thereafter. Apical protuberances on maternal epithelial cells and interposing blunt chorionic processes were evident at sites of early maternal-conceptus interaction, but were reduced at regions exhibiting microvillous interdigitation. Placentation in the pig represents a developmental process consisting of a continuum of sequential events which occur over a broad time frame rather than at specific discrete times.

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Production of oestrone and oestradiol-17 by different regions of the filamentous pig blastocyst

Cited by 14 publications

References 13 publications

Conceptus Influences the Distribution of Uterine Leukocytes During Early Porcine Pregnancy1

Conceptus Influences the Distribution of Uterine Leukocytes During Early Porcine Pregnancy1

Effect of intrauterine application of oestradiol-17 and prostaglandin E-2 on the porcine oestrous cycle and uterine endocrinology

Microscopic examination of porcine conceptus‐maternal interface between days 10 and 19 of pregnancy

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