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Live-bearing without placenta: Physical estimation indicates the high oxygen-supplying ability of white shark uterus to the embryo.

ABSTRACT: One of the mysteries of shark aplacental viviparity is the ability of the embryos to acquire oxygen from their mothers without a placental connection. It has been assumed that embryonic respiration in aplacental viviparous shark depends on oxygen from the uterine wall, although this hypothesis has not been confirmed quantitatively. Morphological observations of the uterine wall of white shark (Carcharodon carcharias) provided the first quantitative evidence to support the ability of the uterus to supply ample oxygen to the embryo of viviparous elasmobranchs. The uterine surface of the white shark is characterized by (1) uterine lamellae that develop perpendicular to the uterine wall, (2) uterine lamellae folded in an accordion-like fashion, and (3) numerous micro-ridges on the lamellar surface. These modifications result in increased uterine surface are to up to 56 folds compared to the uterus with a smooth surface. Histological observations revealed that the diffusion barrier of the uterine wall is approximately 12?µm. By using these values, the oxygen-diffusion capacity of 1?cm² of the uterine wall of white shark was estimated to be 63.6?nmol·min^-1·torr^-1. This value is 250-400 times greater than that observed in other aplacental viviparous sharks (Squalus spp.) and is comparable with that of fish gills.

SUBMITTER: Tomita T

PROVIDER: S-EPMC5603572 | biostudies-literature | 2017 Sep

REPOSITORIES: biostudies-literature

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Live-bearing without placenta: Physical estimation indicates the high oxygen-supplying ability of white shark uterus to the embryo.

Tomita Taketeru T Nozu Ryo R Nakamura Masaru M Matsuzaki Shohei S Miyamoto Kei K Sato Keiichi K

Scientific reports 20170918 1

One of the mysteries of shark aplacental viviparity is the ability of the embryos to acquire oxygen from their mothers without a placental connection. It has been assumed that embryonic respiration in aplacental viviparous shark depends on oxygen from the uterine wall, although this hypothesis has not been confirmed quantitatively. Morphological observations of the uterine wall of white shark (Carcharodon carcharias) provided the first quantitative evidence to support the ability of the uterus t ...[more]

PMID: 28924159

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Project description:Leptin (Lep) is known for its involvement in the regulation of reproductive functions. It is important for uterine receptivity, implantation, placental growth and maternal energy homeostasis in several species, but Lep's function in the pregnant dog has not been investigated.Pregnant bitches were ovariohysterectomized at pre-implantation, post-implantation, mid-gestation and prepartum luteolysis. Two additional groups were treated with aglepristone in mid-gestation, and ovariohysterectomized 24 or 72 h later. Lep and leptin receptor (LepR) gene expression was detected by semi-quantitative real-time PCR in pre-implantation and inter-placental uterine sections (Ut) and in utero-placental compartments (Ut/Pl). Immunohistochemistry and in situ hybridization (ISH) were performed for Lep and LepR protein and mRNA localization. Parametric one-way ANOVA, paired t-test and Wilcoxon signed-rank test were used for statistical analysis.In the Ut/Pl, Lep expression was higher at post-implantation and prepartum luteolysis than at mid-gestation, while in the Ut, Lep mRNA levels did not change during pregnancy. LepR expression in the Ut/Pl was up-regulated at prepartum luteolysis compared to the earlier stages. In the Ut, highest LepR mRNA was found at pre- and post-implantation. LepR expression was down-regulated in the Ut/Pl compared to the Ut at post-implantation and at mid-gestation. Aglepristone treatment resulted in a decrease of Lep mRNA levels from 24 to 72 h in the Ut without concomitant changes in the Ut/Pl or in LepR levels. Lep and LepR immunoreactivities were strong in the luminal and glandular epithelium in the Ut with abundant LepR signals in the subepithelial stroma. In the Ut/Pl, fetal trophoblasts stained stronger for Lep and LepR than decidual cells, and signals for both proteins were also detected in the glandular chambers. The myometrium, blood vessel media, and sporadically also the endothelium stained for Lep and LepR. ISH showed similar signal distribution in the Ut and Ut/Pl.Lep and LepR are differentially expressed in the canine uterus and placenta during pregnancy, and their presence in various cell types indicates paracrine/autocrine roles. The Lep signaling system may be one of the pathways involved in feto-maternal cross-talk, implantation and maintenance of pregnancy, and may have a regulatory role around parturition.

Project description:The objective was to elucidate gene expression differences in uterus, caruncle, and cotyledon of ewes with subclinical pregnancy toxemia (SCPT) and healthy ewes, and to identify associated biological functions and pathways involved in pregnancy toxemia. On Day 136 (±1?day) post-breeding, ewes (n?=?18) had body condition score (BCS; 1-5; 1, emaciated; 5, obese) assessed, and blood samples were collected for plasma glucose and ?-hydroxybutyrate (BHBA) analyses. The ewes were euthanized, and tissue samples were collected from the gravid uterus and placentomes. Based on BCS (2.0?±?0.02), glucose (2.4?±?0.33), and BHBA (0.97?±?0.06) concentrations, ewes (n?=?10) were grouped as healthy (n?=?5) and subclinical SCPT (n?=?5) ewes. The mRNA expressions were determined by quantitative PCR method, and prediction of miRNA partners and target genes for the predicted miRNA were identified using miRDB (http://mirdb.org/miRDB/). Top ranked target genes were used to identify associated biological functions and pathways in response to SPCT using PANTHER. The angiogenesis genes VEGF and PlGF, and AdipoQ, AdipoR2, PPARG, LEP, IGF1, IGF2, IL1b, and TNF? mRNA expressions were lower in abundances, whereas hypoxia genes eNOS, HIF1a, and HIF 2a, and sFlt1 and KDR mRNA expressions were greater in abundances in uterus and placenta of SCPT ewes compared to healthy ewes (P?<?0.05). The predicted miRNA and associated target genes contributed to several biological processes, including apoptosis, biological adhesion, biological regulation, cellular component biogenesis, cellular process, developmental process, immune system process, localization, metabolic process, multicellular organismal process, reproduction, and response to stimulus. The target genes were involved in several pathways including angiogenesis, cytoskeletal regulation, hypoxia response via HIF activation, interleukin signaling, ubiquitin proteasome, and VEGF signaling pathway. In conclusion, genes associated with blood vessel remodeling were lower in abundances and that the genes associated with hypoxic conditions were greater in abundances in the uteroplacental compartment of SCPT ewes. It is obvious that the factors that influence placental vascular development and angiogenesis as noted in this study set the course for hemodynamic changes and hence have a major impact on the rate of transplacental nutrient exchange, fetal growth, and health of the dam.

Project description:BackgroundThe two-child policy implemented in China resulted in a surge of high-risk pregnancies among advanced maternal aged women and presented a window of opportunity to identify a large number of placenta accreta spectrum (PAS) cases, which often invoke severe blood loss and hysterectomy. We thus had an opportunity to evaluate the surgical outcomes of a unique conservative PAS management strategy for uterus preservation, and the impacts of magnetic resonance imaging (MRI) in PAS surgical planning.MethodsCross-sectional study, comparing the outcomes of a new uterine artery ligation combined with clover suturing technique (UAL + CST) with the existing conservative surgical approaches in a maternal public hospital with an annual birth of more than 20,000 neonates among all placenta previa cases suspecting of PAS between January 1, 2015 and December 31, 2018.ResultsFrom a total of 89,397 live births, we identified 210 PAS cases from 400 singleton pregnancies with placenta previa. Aside from 2 self-requested natural births (low-lying placenta), all PAS cases had safe cesarean deliveries without any total hysterectomy. Compared with the existing approaches, the evaluated UAL + CST had a significant reduction in intraoperative blood loss (β=-312 ml, P < .001), RBC transfusion (β=-1.08 unit, P = .001), but required more surgery time (β = 16.43 min, P = .01). MRI-measured placenta thickness, when above 50 mm, can increase blood loss (β = 315 ml, P = .01), RBC transfusion (β = 1.28 unit, P = .01), surgery time (β = 48.84 min, P < .001) and hospital stay (β = 2.58 day, P < .001). A majority of percreta patients resumed normal menstrual cycle within 12 months with normal menstrual fluid volume, without abnormal urination or defecation.ConclusionsA conservative surgical management approach of UAL + CST for PAS is safe and effective with a low complication rate. MRI might be useful for planning PAS surgery.Clinical trial registration numberChiCTR2000035202.

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Live-bearing without placenta: Physical estimation indicates the high oxygen-supplying ability of white shark uterus to the embryo.

Publications

Live-bearing without placenta: Physical estimation indicates the high oxygen-supplying ability of white shark uterus to the embryo.

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