| 1. |
- A Hulten, Maj, et al.
(författare)
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On the origin of the maternal age effect in trisomy 21 Down syndrome: the Oocyte Mosaicism Selection model
- 2010
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Ingår i: Reproduction. - 1470-1626 .- 1476-3990. ; 139:1, s. 1-9
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Forskningsöversikt (refereegranskat)abstract
- We have recently documented that trisomy 21 mosaicism is common in human foetal ovaries. On the basis of this observation we propose that the maternal age effect in Down syndrome (DS) is caused by the differential behaviour of trisomy 21 in relation to disomy 21 oocytes during development from foetal life until ovulation in adulthood. in particular, we suggest that trisomy 21 oocytes, lagging behind those that are disomic, may escape the timed pruning of the seven million in foetal life to the 300-400 finally selected for ovulation. The net effect of this preferential elimination will be an accumulation of trisomy 21 oocytes in the ovarian reserve of older women. We here highlight the implications of this Oocyte Mosaicism Selection (OMS) model with respect to the prevalent view that the maternal age effect is complex, dependent on many different biological and environmental factors. We examine conclusions drawn from recent large-scale studies in families, tracing DNA markers along the length of chromosome 21q between parents and DS children, in comparison to the OMS model. We conclude that these family linkage data are equally compatible with the maternal age effect originating from the accumulation of trisomy 21 oocytes with advancing maternal age. One relatively straightforward way to get to grips with what is actually going on in this regard would be to compare incidence of trisomy 21 oocytes (and their pairing configurations) in foetal ovaries with that in oocytes at the meiosis I stage from adult women.
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| 2. |
- Bertram, Michael, et al.
(författare)
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Reproduction in a polluted world: implications for wildlife
- 2020
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Ingår i: Reproduction. - 1470-1626 .- 1741-7899. ; 160, s. R13–R23-
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Forskningsöversikt (refereegranskat)abstract
- Environmental pollution is an increasing problem for wildlife globally. Animals are confronted with many different forms of pollution, including chemicals, light, noise, and heat, and these can disrupt critical biological processes such as reproduction. Impacts on reproductive processes can dramatically reduce the number and quality of offspring produced by exposed individuals, and this can have further repercussions on the ecology and evolution of affected populations. Here, we illustrate how environmental pollutants can affect various components of reproduction in wildlife, including direct impacts on reproductive physiology and development, consequences for gamete quality and function, as well as effects on sexual communication, sexual selection, and parental care. We follow with a discussion of the broader ecological and evolutionary consequences of these effects on reproduction and suggest future directions that may enable us to better understand and address the effects of environmental pollution.
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| 3. |
- Bourlev, Vladimir, et al.
(författare)
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The relationship between microvessel density, proliferative activity and expression of vascular endothelial growth factor-A and its receptors in eutopic endometrium and endometriotic lesions
- 2006
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Ingår i: Reproduction. - : Bioscientifica. - 1470-1626 .- 1476-3990 .- 1741-7899. ; 132:3, s. 501-509
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Tidskriftsartikel (refereegranskat)abstract
- Studies were performed to elucidate the possible relationship between microvessel density, proliferative activity and angiogenesis in eutopic endometrium from women with and without endometriosis and peritoneal endometriotic lesions. The question whether changes in these parameters in endometriotic lesions were reflected by the level of vascular endothelial growth factor-A (VEGF-A) in serum and peritonea fluid was also studied. Biopsy specimens of both eutopic endometrium and peritoneal endometriotic lesions from women with endometriosis (n=25) as well as eutopic endometrium from women without endometriosis (n=14) were analysed immunohistochemically regarding microvessel density, proliferative activity, and expression of VEGF-A and its receptors vascular endothelial growth factor receptors 1 and 2 (VEGFR-1 and VEGFR-2) in stroma, glands and blood vessels. The VEGF-A concentration was measured in peritoneal fluid and serum. Secretory phase eutopic endometrium from women with endometriosis had significantly higher microvessel density, expression of VEGF-A in glandular epithelium and VEGFR-2 in endometrial blood vessels than those from women without endometriosis. Endometriotic lesions with high proliferative activity had a higher microvessel density and showed higher vascular expression of VEGFR-2 as well as being accompanied by higher levels of VEGF-A in peritoneal fluid and serum, compared with lesions with low proliferative activity. In conclusion, there seems to be a dysregulation of angiogenic activity in the eutopic endometrium of women with endometriosis and endometriotic lesions with high proliferative activity were accompanied by higher local angiogenic activity and higher levels of VEGF in serum and peritoneal fluid.
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| 4. |
- Carlsson, IB, et al.
(författare)
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Kit ligand and c-Kit are expressed during early human ovarian follicular development and their interaction is required for the survival of follicles in long-term culture
- 2006
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Ingår i: Reproduction (Cambridge, England). - : Bioscientifica. - 1470-1626 .- 1741-7899. ; 131:4, s. 641-649
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Tidskriftsartikel (refereegranskat)abstract
- The receptor tyrosine c-Kit and its cognate ligand, c-Kit ligand (KL, stem cell factor, SCF), are involved in ovarian follicular development in several animal species. We studied the expression of KL and c-Kit usingin situhybridization and immunohistochemistry in donated human ovarian cortical tissue. The KL transcripts were expressed in granulosa cells of primary follicles, whereas the expression of c-Kit was confined to the oocyte and granulosa cells in primary and secondary follicles. We employed an ovarian organ culture using firstly serum-containing and then serum-free medium to study the effects of KL and an anti-c-Kit antibody, ACK2, on the development and survival of ovarian folliclesin vitro. Culture of ovarian cortical slices for 7 days resulted in a 37% increase in the number of primary follicles and a 6% increase in secondary follicles. The proportion of viable follicles decreased in all cultures. The addition of KL (1, 10 and 100 ng/ml) into the culture media did not affect the developmental stages of the follicles or the proportion of atretic follicles. Inclusion of ACK2 (800 ng/ml) in the culture medium significantly increased the proportion of atretic follicles on days 7 (49 vs 28% in control cultures) and 14 (62 vs 38%) of culture. In conclusion, c-Kit and KL are expressed in human ovaries during follicular development. Blocking the c-Kit receptor induces follicular atresia. The KL/c-Kit signaling system is likely to control the survival of human ovarian follicles during early follicular development.
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| 5. |
- Coward, K., et al.
(författare)
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Phospholipase C zeta, the trigger of egg activation in mammals, is present in a non-mammalian species
- 2005
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Ingår i: Reproduction. - : Bioscientifica. - 1470-1626 .- 1476-3990 .- 1741-7899. ; 130:2, s. 157-163
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Tidskriftsartikel (refereegranskat)abstract
- The activation of the egg to begin development into an embryo is triggered by a sperm-induced increase in intracellular egg Ca2+. There has been much controversy about how the sperm induces this fundamental developmental event, but recent studies suggest that, in mammals, egg activation is triggered by a testis-specific phospholipase C: PLC zeta. Since the discovery of PLC zeta, it has been unclear whether its role in triggering egg activation is common to all vertebrates, or is confined to mammals. Here, we demonstrate for the first time that PLC zeta is present in a non-mammalian vertebrate. Using genomic and cDNA databases, we have identified the cDNA encoding a PLC zeta orthologue in the domestic chicken that, like the mammalian isoforms, is a testis-specific gene. The chicken PLC zeta cDNA is 2152 bp in size and encodes an open reading frame of 639 amino acids. When injected into mouse oocytes, chicken PLC zeta cRNA triggers Ca2+ oscillations, indicating that it has functional properties similar to those of mammalian PLC zeta. Our findings suggest that PLC zeta may have a universal role in triggering egg activation in vertebrates.
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| 6. |
- Gavier-Widén, Dolores
(författare)
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Histological and endocrine characterisation of the annual luteal activity in Eurasian lynx (Lynx lynx)
- 2012
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Ingår i: Reproduction. - 1470-1626 .- 1741-7899. ; 144, s. 477-484
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Tidskriftsartikel (refereegranskat)abstract
- Lynx presents a unique sexual cycle with persistent corpora lutea (CLs) and elevated serum progesterone (P-4) throughout parturition and lactation. In other mammals, CLs normally disintegrate after parturition, therefore the aim of our study was to characterise the annual life cycle of lynx CLs. Ovaries from Eurasian lynxes were obtained from the National Veterinary Institute in Sweden, where tissues from killed lynx were stored at -20 degrees C. Ovaries from 66 animals were weighed; each corpus luteum was segmented for histology and hormone analysis. Ovary and CLs weights were constant throughout the year, peaking during pregnancy. In non-pregnant lynxes, the seasonal level of intraluteal steroids was steady for P-4 (3.2 +/- 1.9 S.D. mu g/g, n = 53) and total oestrogens (18.3 +/- 15.5 S.D. ng/g, n = 53). Within histology slides, structurally intact luteal cells were found throughout the year with the highest incidence in March/April; evidence of luteal regression was predominantly found in post-breeding season. Ovaries from pregnant animals contained two types of CLs. Group A was bigger in size with large luteal cells (P-4, 72.3 +/- 65.4 S.D. mu g/g; oestrogen, 454.0 +/- 52.4 S.D. ng/g). In contrast, group B were smaller, with greater luteal regression and lower steroid concentrations (P-4, 8.3 +/- 2.9 S.D. mu g/g; oestrogen, 31.5 +/- 20.4 S.D. ng/g). Our results suggest that structural luteolysis proceeds throughout the year and into next breeding cycle, resulting in two CLs types on the same ovary. Reproduction (2012) 144 477-484
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| 7. |
- Guo, Yongzhi, et al.
(författare)
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Adipokines as biomarkers of postpartum subclinical endometritis in dairy cows
- 2020
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Ingår i: Reproduction. - 1470-1626 .- 1741-7899. ; 160, s. 417-430
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Tidskriftsartikel (refereegranskat)abstract
- Adipokines emerged as regulators of metabolism and inflammation in several scenarios. This study evaluated the relationship between adipokines (adiponectin, chemerin and visfatin) and cytological (subclinical) endometritis, by comparing healthy (without), transient (recovered by 45 days postpartum (DPP)) and persistent (until 45 DPP) endometritis cows (n = 49). Cows with persistent endometritis had higher adiponectin concentrations in plasma (at 21 DPP, P < 0.05 and at 45 DPP, P < 0.01) and in uterine fluid (at 45 DPP, P < 0.001), and higher chemerin concentrations in plasma (P < 0.05) and uterine fluid (P < 0.01) at 45 DPP than healthy cows. Cows with persistent endometritis had higher gene transcription in the cellular pellet of uterine fluid and protein expression in the endometrium of these adipokines and their receptors than healthy cows. Adiponedin plasma concentrations allowed to discriminate healthy from persistent endometritis cows, in 87% (21 DPP) and 98% (45 DPP) of cases, and adiponectin and chemerin uterine fluid concentrations at 45 DPP allowed for this discrimination in 100% of cases. Cows with concentrations above the cutoff were a minimum of 3.5 (plasma 21 DPP), 20.4 (plasma 45 DPP), and 33.3 (uterine fluid 45 DPP) times more at risk of evidencing persistent endometritis at 45 DPP than cows with concentrations below the cutoff. Overall, results indicate a relationship between adipokine signalling and the inflammatory status of the postpartum uterus of dairy cows, evidencing that adipokines represent suitable biomarkers of subclinical endometritis, able to predict the risk of persistence of inflammation.
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| 8. |
- Humblot, Patrice
(författare)
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Specific expression patterns and cell distribution of ancient and modern PAG in bovine placenta during pregnancye
- 2013
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Ingår i: Reproduction. - 1470-1626 .- 1741-7899. ; 146, s. 347-362
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Tidskriftsartikel (refereegranskat)abstract
- Pregnancy-associated glycoproteins (PAGs) constitute a multigenic family of aspartic proteinases expressed in the trophoblast of the ruminant placenta. In Bos taurus, this family comprises 21 members segregated into ancient and modern phylogenetic groups. Ancient PAGs have been reported to be synthesized throughout the trophoblastic cell layer whereas modern PAGs are produced by binucleate cells of cotyledons. The aim of this study was to investigate modern and ancient PAGs during gestation in cotyledonary and intercotyledonary tissues. To obtain convincing and innovative results despite the high sequence identity shared between PAGs, we designed specific tools such as amplification primers and antibodies. Using real-time RT-PCR, we described the transcript expression of 16 bovine PAGs. Overall, PAGs are characterized by an increase in their expression during gestation. However, we demonstrated a segregation of modern PACs in cotyledons and of ancient PAGs in the intercotyledonary chorion, except for the ancient PAG2 expressed in cotyledons. By raising specific antibodies against the modern PAG1 and ancient PAG11 and PAG2, we established the expression kinetics of the proteins using western blotting. Immunohistochemistry showed that PAGs were produced by specific cellular populations: PAG1 by binucleate cells in the whole trophoblastic layer, PAG11 was localized in binucleate cells of the intercotyledonary trophoblast and the chorionic plate of the cotyledon, while PAG2 was produced in mononucleate cells of the internal villi of the cotyledon. These results revealed a highly specific regulation of PAG expression and cell localization as a function of their phylogenetic status, suggesting distinct biological functions within placental tissues.
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| 9. |
- Kannisto, P, et al.
(författare)
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Involvement of local adrenergic receptors in the process of ovulation in gonadotrophin-primed immature rats
- 1985
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Ingår i: Journal of Reproduction and Fertility. - : Bioscientifica. - 0022-4251. ; 75:2, s. 62-357
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Tidskriftsartikel (refereegranskat)abstract
- Immature female rats were primed with 4 i.u. PMSG at 08:00 h of Day 26. This results in ovulation in the morning of Day 29. The number of ovulations was counted in terms of newly formed corpora lutea in the morning of Day 30. Various adrenergic drugs were delivered into the ovarian bursa bilaterally in the afternoon of Day 27 to study their effect on ovulation. A methyl cellulose gel solution was used as vehicle to minimize leakage from the bursa. Noradrenaline, terbutaline and 4-aminopyridine significantly enhanced the number of corpora lutea compared to control ovaries injected with gel vehicle alone. The effect of terbutaline was counteracted by propranolol. Phentolamine partly blocked the noradrenaline-induced enhancement and the antagonist alone significantly reduced the number of ovulations. The results indicate that stimulation of alpha-adrenergic receptors (probably via actions in the follicle wall) as well as beta-receptors (influencing steroid-producing cells) may interfere with the ovulation process.
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| 10. |
- Kindahl, Hans
(författare)
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Canine placenta: a source of prepartal prostaglandins during normal and anti progestin-induced parturition
- 2010
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Ingår i: Reproduction. - 1470-1626 .- 1741-7899. ; 139, s. 655-664
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Tidskriftsartikel (refereegranskat)abstract
- Expression of cyclooxygenase 2 (COX2, now known as PTGS2), prostaglandin E2 synthase (PTGES, PGES), and prostaglandin F2 alpha synthase (PGFS), of the respective receptors PTGFR (FP), PTGER2 (EP2), and PTGER4 (EP4) and of the progesterone receptor (PGR, PR) was assessed by real-time PCR, immunohistochemistry (IHC), or in situ hybridization (ISH) in utero/placental tissue samples collected from three to five bitches on days 8-12 (pre-implantation), 18-25 (post-implantation), and 35-40 (mid-gestation) of pregnancy and during the prepartal luteolysis. Additionally, ten mid-pregnant bitches were treated with the antiprogestin aglepristone (10 mg/kg bw (2 x /24 h)); ovariohysterectomy was 24 and 72 h after the second treatment. Plasma progesterone and 15-ketodihydro-PGF2 alpha (PGFM) concentrations were determined by RIA. Expression of the PGR was highest before implantation and primarily located to the endometrium; expression in the placenta was restricted to the decidual cells. PTGS2 was constantly low expressed until mid-gestation; a strong upregulation occurred at prepartal luteolysis concomitant with an increase in PGFM. PGFS was upregulated after implantation and significantly elevated through early and mid-gestation. PTGES showed a gradual increase and a strong prepartal upregulation. PTGFR, PTGER2, and PTGER4 were downregulated after implantation; a gradual upregulation of PTGFR and PTGER2 occurred towards parturition. ISH and IHC co-localized PGFS, PTGFR, PTGES, and PTGS2 in the trophoblast and endometrium. The changes following application of aglepristone were in the same direction as those observed from mid-gestation to prepartal luteolysis. These data suggest that the prepartal increase of PGF2 alpha results from a strong upregulation of PTGS2 in the fetal trophoblast with the withdrawal of progesterone having a signalling function and the decidual cells playing a key role in the underlying cell-to-cell crosstalk. Reproduction (2010) 139 655-664
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