Number Of Placentomes Research Articles

Evaluation of Placentome Morphology in the Last Two Periods of Pregnancy in Hair Goats (Capra aegagrus hircus).

This study was carried out on pregnant uteruses obtained from healthy Hair goats (Capra aegagrus hircus). A total of thirteen pregnant uteruses, six second and seven third trimesters, were used. Morphometrically, placentome numbers, lengths, widths and depths were measured. Randomly selected placentomes from the second and third trimesters were stained with the triple staining method. Caruncular and cotyledonary areas, capillary numbers and areas were measured using Qupath v0.5.0 software. The Minitab (version 21.4.1) was used for statistical analysis. While no statistical difference was observed in the number of placentomes between trimesters (p > 0.05), placentome length, width and depth were higher in the third trimester compared to the second trimester (p < 0.001). No difference was observed in the number of caruncular and cotyledonary capillaries in the second trimester. In the second trimester, the caruncular capillary area was higher than the cotyledonary capillary area (p < 0.05). Both caruncular and cotyledonary capillary area parameters were higher in the third trimester than in the second trimester (p < 0.001). In the third trimester, the caruncular capillary area was higher than the cotyledonary capillary area (p < 0.001). The number of caruncular capillaries and cotyledonary capillaries was statistically significantly higher in the third trimester compared to the second trimester. In addition, the number of cotyledonary capillaries was higher than that of caruncular capillaries in the third trimester (p < 0.001). A positive and significant correlation was found between the day of pregnancy and the number of placentomes in the second trimester (p < 0.05). No correlation was observed between the day of pregnancy and the number of placentomes in the third trimester. Vascular area density showed a faster development in foetal tissue than in maternal tissue. Placentome size and angiogenesis increased with the progression of pregnancy.

PSII-12 Influence of Dietary Methionine and Guanidinoacetic Acid on Estrous Cycles and Early Pregnancy in Beef Heifers

Abstract Interest is growing in methods to apply precision nutritional supplements strategically during the peri-conceptual period to enhance progeny performance of beef females. Studies where supplemental methionine (MET) was provided to bovine females in the peri-conceptual period demonstrated epigenetic modifications in muscle of the progeny. Guanidinoacetic acid (GAA) has been fed directly to livestock to increase creatine synthesis, but has not been evaluated for use in fetal programming. We fed MET and GAA to cross-bred heifers during the peri-conceptual period as a 2 x 2 factorial design to influence carcass characteristics of their steer calves. It was, therefore, important to determine if the interactions of dietary MET and GAA in the peri-conceptual period would alter reproductive efficiency. The null hypothesis was that these supplements would not alter reproductive efficiency of beef heifers when fed in the peri-conceptual period. Heifers were divided into four breeding groups for management purposes. On day -63, heifers (n = 20/diet, age = 384.1 ± 1.1 d) were assigned HeatTime collars and individually fed MET (10 g/d), GAA (40 g/d), the combination (MET + GAA), or ground corn carrier (CON) for 126 days. On day -9, heifers received 100 mg of gonadotropin releasing hormone and a CIDR. On day -2, the CIDR was removed and luteolysis was initiated with 25 mg of prostaglandin F2a. All heifers were inseminated with male sexed semen from a single sire and administered a second 100 mg injection of gonadotropin releasing hormone on day 0. On day 63, a blood sample was collected from all pregnant heifers (CON n = 10; MET n = 8; GAA n = 7; MET + GAA n =10) to evaluate circulating progesterone concentrations. Reproductive tracts were collected to determine CL weight, gravid uterine weight, and placentome number. Data were analyzed using the MIXED procedure of SAS with group, MET, GAA, and the interaction of MET and GAA as fixed effects. Days to first estrus were greater and number of estrus events prior to synchronization were fewer in CON heifers compared with supplemented heifers (P &amp;lt; 0.05). Luteal weight tended to be greater in heifers supplemented with MET compared with CON and GAA heifers (P = 0.09), but peak intensity of estrus, concentration of progesterone at day 63 of pregnancy, gravid uterine weight, and placentome number did not differ due to diet (P &amp;gt; 0.10). Supplementation with MET or GAA may improve onset of puberty but does not negatively alter reproductive performance in cross-bred beef heifers. These supplements can be used for fetal programming of muscle development in steer progeny without negatively impacting reproductive performance in the breeding herd. USDA is an equal opportunity provider and employer. Funded in part by USDA-NIFA-AFRI # 2022-67015-36196.

Placental insufficiency and heavier placentas in sheep after suppressing CXCL12/CXCR4 signaling during implantation†.

During implantation, trophoblast cell invasion and differentiation is predominantly important to achieving proper placental formation and embryonic development. The chemokine, C-X-C motif chemokine ligand 12 (CXCL12) working through its receptor C-X-C motif chemokine receptor 4 (CXCR4) is implicated in implantation and placentation but precise roles of this axis are unclear. Suppressing CXCL12/CXCR4 signaling at the fetal-maternal interface in sheep reduces trophoblast invasion, disrupts uterine remodeling, and diminishes placental vascularization. We hypothesize these negative impacts during implantation will manifest as compromised fetal and placental growth at midgestation. To test, on day 12 postbreeding, osmotic pumps were surgically installed in 30 ewes and delivered intrauterine CXCR4 inhibitor or saline for 7 or 14days. On day 90, fetal/maternal tissues were collected, measured, weighed, and maternal (caruncle) and fetal (cotyledon) placenta components separated and analyzed. The objectives were to determine if (i) suppressing CXCL12/CXCR4 during implantation results in reduced fetal and placental growth and development and (ii) if varying the amount of time CXCL12/CXCR4 is suppressed impacts fetal/placental development. Fetal weights were similar; however greater placental weight and placentome numbers occurred when CXCL12/CXCR4 was suppressed for 14days. In caruncles, greater abundance of fibroblast growth factor 2, vascular endothelial growth factor A, vascular endothelial growth factor A receptor 1 (FLT-1), and placental growth factor were observed after suppressing CXCL12/CXCR4. Similar results occurred in cotyledons except less vascular endothelial growth factor in 7day group and less fibroblast growth factor in 14day group. Our data underscore the importance of CXCL12/CXCR4 signaling during placentation and provide strong evidence that altering CXCL12-mediated signaling induces enduring placental effects manifesting later in gestation.

Slaughter of pregnant Tanzania shorthorn Zebu cattle at Morogoro abattoir: Prevalence, fetal wastage, and placentome morphology

Slaughtering pregnant cattle for meat is unethical, impends food security, and brings animal cruelty. A six-month study spinning from June and December 2020 was carried out to determine the number of Tanzania shorthorn zebu (TSHZ) slaughtered cattle, level of fetal wastage, number, size, and morphology of placentomes and their relationship with fetal age, sex, weight, and location in uteri. Results showed that 15,239 cattle were slaughtered, of which 99% (n=15,087) were TSHZ aged above three years. 61.38% (n= 9,353) of slaughtered cattle were female cattle, of which 2,599 (27.79%) were pregnant at varied gestation periods, and only 5,886 (38.63%) were males. Recovered fetuses were 1,450 (55.79%) males and 1,149 (44.21%) females, with a total of 1,081 (41.59%), 919 (35.36%), and 599 (23.05%) recovered in the first, second and third trimester, respectively. Fetal ages varied from 2.2 to 8.9 months, with body length (crown-crump) ranging from 13.7 to 83.1 cm. Fetus weight ranged from 1.1 kg to 23.2 kg. A total of 1545 (59.45%) pregnancies were localized in the right uterine horn, whereas 1054 (40.55%) were in the left uterine horn. The number of placentomes was significantly larger (P &lt; 0.05) in gravid horns ranging from 71 to 115, than in non-gravid horns (5-28). Placentomes in gravid horn were greatly vascularized, large in size, convex in shape, and measured 7 cm in length and 2 cm in width. In non-gravid horns, placentomes were pale, small, and flat and measured 4 cm in length and 1 cm in width. At the microscopic level, the fetal cotyledons comprised a chorionic plate with a smooth external surface of cuboidal epithelium. From the chorionic plate's internal surface, numerous primary villi sprout inside in a pinnate fashion, producing secondary and tertiary villi. A significant fetal loss was resulting from the slaughter of pregnant animals warrants stepping up routine veterinary ante-mortem inspection of traded animals to salvage the high level of fetal wastage.

Effects of administering exogenous bovine somatotropin to beef heifers during the first trimester on conceptus development as well as steroid- and eicosanoid-metabolizing enzymes.

The aim of this study was to evaluate the effect of bovine somatotropin (bST) on fetal and placental development during the first third of gestation in beef heifers. Angus heifers (n = 97) were randomly assigned to either receive a 500-mg injection of bST (BST) biweekly on days 0, 15, 29, 43, and 57 of gestation or not receive bST (CTL) throughout the experiment. Body weight (BW) was assessed on days -9, -3, 0, 15, 22, 29, 43, 50, 57, 64, and 77, while blood samples were collected on days 0, 22, 50, and 64. Pregnancy status was determined via transrectal ultrasonography on days 29 and 64. A subset of pregnant heifers (BST, n = 7; CTL, n = 5) were harvested on day 84, and complete gravid reproductive tracts and liver tissue were collected for analysis. Cytochrome P450 1A (CYP1A), 2C (CYP2C), 3A (CYP3A), and uridine 5'-diphospho-glucuronosyltransferase (UGT) activities were determined. Mean change in BW and average daily gain of heifers between fixed-time artificial insemination (day 0) and day 77 did not differ between treatments (P ≥ 0.05). Mean concentrations of insulin-like growth factor 1 (IGF-1) were greater (P < 0.001) in BST (347 ± 27.7 ng/mL) compared with CTL (135 ± 32.8 ng/mL) heifers. Mean placental weight, fetal membrane weight, uterine weight, and ovarian and corpus luteum (CL) weights, as well as fetal morphometric data, did not differ (P ≥ 0.05) between treatments. However, BST heifers had greater (P = 0.03) quantities of combined fetal fluid compared with CTL (521.6 ± 22.9 vs. 429.6 ± 27.14 g, respectively). Tendencies were observed for BST heifers to have reproductive tracts with fewer placentomes (P = 0.08) and fetuses with greater umbilical diameters (P = 0.09) compared with CTL. The activity of CYP1A did not differ (P ≥ 0.05) within the maternal and fetal liver, caruncle, cotyledon, or CL tissue samples between treatments. Furthermore, CYP3A activity was only observed in maternal liver samples and was not different between treatments (P ≥ 0.05). Interestingly, CYP2C activity was greater (P = 0.01) in the liver of BST vs. CTL heifers, and UGT activity was greater (P = 0.02) in the CL from BST heifers compared with CTL. In conclusion, the administration of bST during the first third of gestation increased plasma concentrations of IGF-1, which resulted in an increase in fetal fluid, decrease in placentome number, and greater umbilical diameter, but failed to alter fetal development.

Placenta Morphological and Amniotic Fluid Biochemical Changes Associated with Mid-Gestation Single and Twin Pregnancies in Red Sokoto Goats

Fetal fluids and placentas, which are important in feto-maternal homeostasis, could be affected by the number of developing fetuses. Therefore, placenta morphological and amniotic fluid biochemical changes associated with single and twin pregnancies in Red Sokoto goats were studied. Using Richardson’s formula, 2.1 × [CRL (cm) + 17], 12 intact gravid uteri (7 single-pregnant and 5 twin-pregnant) from mid-gestation [≈70-100 days gestational age (dGA)] pregnant goats were purposively selected. Feto-maternal biometrics [gravid uterine weight (GUW), total placental fluid volume (TPFV), average placentome diameter (APD), mean crown-rump length (MCRL), mean gestational age (MGA), mean fetal weight (MFW), total placentome number (TPN), and average interplacentomal distance (AID)]; amniotic fluid electrolytes [sodium (Na), potassium (K), chloride (Cl), calcium (Ca) and phosphorus (P)]; total protein; glucose; liver markers (AST and ALT); kidney markers (urea and creatinine), and cortisol concentrations were measured. The histology of the placentomes and the interplacentomal areas was also studied. The twin-pregnant (TP) goats had significantly higher (P&lt;0.05) GUW, TPFV, APD, amniotic fluid glucose and cortisol; and lower (P&lt;0.05) Ca levels. The rest of the parameters assessed did not differ between the TP and single-pregnant (SP) groups. Placentomes and the interplacentomal areas from the TP group had more diffuse villous inter-digitations and thicker luminal endothelium, respectively. It was concluded that TP Red Sokoto goats regulated placentome morphology, calcium, glucose and cortisol levels in order to achieve optimal conditions for the dams and the fetuses.

Study on parturition of beef cattle in small holder farm: stage, placental weight, and placentomes

Scientific data on the length of parturition stage, placental weight, and the number of placentomes in Ongole (PO), Simental Ongole (SimPO), Limosin and Ongole (LimPO) breeds in Yogyakarta Province are not yet known. This research aimed to study parturition stage, placental weight, and placentomes number on beef catlle in small holder farm. This research was carried out on small farmers in the Special Region of Yogyakarta Province. There were 22 PO, 7 simpo, and 4 limpo cattle. The first study determined length stage of parturition. The second study determined the weight of the placenta and the number of placentomes. Data collected were analyzed descriptively. The results of first stage in PO, SimPO, and LimPO cattle were 73.7, 44.5, and 62. 9 hours. The duration of second stage in PO, SimPO, and LimPO cattles were 58.1, 78.7, and 24.5 minutes. The duration of third stage in PO, SimPO, and LimPO cattle were 4.3, 4.8, and 3.5 hours. The placenta weight in PO and SimPO cattle showed that the average of placenta weight was 4.1 and 3.6 Kg. The number of placentomes in PO, SimPO, dan LimPO cattle were 92.5, 92.8, and 102.6. This research showed that the average of stage I in PO was longer than SimPO and LimPO, stage II and stage III in SimPO was longer than PO and LimPO. In addition, the average of placenta weight in PO was heavier than SimPO and LimPO cows. The average number of placentomes in LimPO was higher than PO and SimPO cattle.

Morphology of placentome in Korean water deer Hydropotes inermis argropus.

The placenta of the Korean water deer was anatomically examined to accumulate basic information regarding its reproductive system. The convex placentomes with five to nine well-developed pedicles were observed in the whole uterine horns, and therefore, the placenta was classified as oligocotyledonary. The evidence indicating the migration of binucleate cells (BNCs) from trophectoderm to the uterine epithelium led to the histological classification of the placenta as synepitheliochorial. The number of fetuses was markedly higher than that in other ruminant species. However, the number of placentomes was found to be similar to the other Cervidae species. Therefore, these results suggest that the Korean water deer may possess special mechanisms or structures at the fetus attachment site to maintain this unusally high number of fetuses.

Effects of fetal and maternal genotype on placentome morphology in sheep

Both maternal and fetal genotypes contribute to conceptus development. The objective was to determine how placentome number, size, and type and fetal weight was influenced after reciprocal embryo transfer in Columbia and Romanov sheep. Reciprocal embryo transfer was conducted between Columbia and Romanov ewes where a single embryo was transferred into Romanov and Columbia recipients [Romanov embryo in a Romanov uterus (RinR, n = 9); Romanov embryo in a Columbia uterus (RinC, n = 7); Columbia embryo in a Columbia uterus (CinC, n = 8); Columbia embryo in a Romanov uterus (CinR, n = 4)]. On day 130 of gestation, fetuses were weighed and placentomes were morphologically typed, weighed, and measured.Regardless of maternal genotype, Romanov fetuses were smaller (P < 0.05) compared to Columbia fetuses. Moreover, CinC fetuses were larger (P < 0.05) than CinR fetuses. There was a tendency (P = 0.12) for a fetal by maternal genotype interaction on total placentome weight, but main effects were significant for fetal genotype (P = 0.04) and maternal genotype (P < 0.01). The number of Type A placentomes was greater than any other types. Type A placentomes had a greater (P < 0.05) contribution to total placentome weight within the Romanov uterus, or when associated with a Romanov fetus, than within the Columbia breed, in which placentome type was evenly distributed. The hypothesis that the Romanov uterus would limit the growth of a Columbia conceptus is accepted; however, the Romanov conceptus did not experience augmented growth when transferred into a Columbia uterus as predicted.

Evolution of placentation in cattle and antelopes.

Bovids have enjoyed great evolutionary success as evidenced by the large number of extant species. Several important domestic animals are from this family. They derive from both subfamilies: cattle and their kin belong to Bovinae and sheep and goats to Antilopinae. The premise of this review, therefore, is that evolution of reproduction and placentation is best understood in a context that includes antelope-like bovines and antelopes. Many key features of placentation, including hormone secretion, had evolved before bovids emerged as a distinct group. Variation nevertheless occurs. Most striking is the difference in fusion of the binucleate trophoblast cell with uterine epithelium that yields a transient trinucleate cell in bovines and many antelopes, but a more persistent syncytium in wildebeest, sheep and goat. There is considerable variation in placentome number and villus branching within the placentome. Many antelopes have right-sided implantation in a bicornuate uterus whilst others have a uterus duplex. Finally, there has been continued evolution of placental hormones with tandem duplication of PAG genes in cattle, differences in glycosylation of placental lactogen and the emergence of placental growth hormone in sheep and goats. The selection pressures driving this evolution are unknown though maternal-fetal competition for nutrients is an attractive hypothesis.

Development of a surgical procedure for removal of a placentome from a pregnant ewe during gestation

BackgroundIn recent decades, there has been a growing interest in the impact of insults during pregnancy on postnatal health and disease. It is known that changes in placental development can impact fetal growth and subsequent susceptibility to adult onset diseases; however, a method to collect sufficient placental tissues for both histological and gene expression analyses during gestation without compromising the pregnancy has not been described. The ewe is an established biomedical model for the study of fetal development. Due to its cotyledonary placental type, the sheep has potential for surgical removal of materno-fetal exchange tissues, i.e., placentomes. A novel surgical procedure was developed in well-fed control ewes to excise a single placentome at mid-gestation.ResultsA follow-up study was performed in a cohort of nutrient-restricted ewes to investigate rapid placental changes in response to undernutrition. The surgery averaged 19 min, and there were no viability differences between control and sham ewes. Nutrient restricted fetuses were smaller than controls (4.7 ± 0.1 kg vs. 5.6 ± 0.2 kg; P < 0.05), with greater dam weight loss (− 32.4 ± 1.3 kg vs. 14.2 ± 2.2 kg; P < 0.01), and smaller placentomes at necropsy (5.7 ± 0.3 g vs. 7.2 ± 0.9 g; P < 0.05). Weight of sampled placentomes and placentome numbers did not differ.ConclusionsWith this technique, gestational studies in the sheep model will provide insight into the onset and complexity of changes in gene expression in placentomes resulting from undernutrition (as described in our study), overnutrition, alcohol or substance abuse, and environmental or disease factors of relevance and concern regarding the reproductive health and developmental origins of health and disease in humans and in animals.

FTY720, a sphingosine analog, altered placentome histoarchitecture in ewes

BackgroundThe lysosphingolipid, sphingosine-1-phosphate, is a well-described and potent pro-angiogenic factor. Receptors, as well as the sphingosine phosphorylating enzyme sphingosine kinase 1, are expressed in the placentomes of sheep and the decidua of rodents; however, a function for this signaling pathway during pregnancy has not been established. The objective of this study was to investigate whether sphingosine-1-phosphate promoted angiogenesis within the placentomes of pregnant ewes. Ewes were given daily jugular injections of FTY720 (2-amino-2[2-(− 4-octylphenyl)ethyl]propate-1,3-diol hydrochloride), an S1P analog.ResultsFTY720 infusion from days 30 to 60 of pregnancy did not alter maternal organ weights nor total number or mass of placentomes, but did alter placentome histoarchitecture. Interdigitation of caruncular crypts and cotyledonary villi was decreased, as was the relative area of cotyledonary tissue within placentomes. Also, the percentage of area occupied by cotyledonary villi per unit of placentome was increased, while the thickness of the caruncular capsule was decreased in ewes treated with FTY720. Further, FTY720 infusion decreased the number and density of blood vessels within caruncular tissue near the placentome capsule where the crypts emerge from the capsule. Finally, FTY720 infusion decreased asparagine and glutamine in amniotic fluid and methionine in allantoic fluid, and decreased the crown rump length of day 60 fetuses.ConclusionsWhile members of the sphingosine-1-phosphate signaling pathway have been characterized within the uteri and placentae of sheep and mice, the present study uses FTY720 to address the influence of S1P signaling on placental development. We present evidence that modulation of the S1P signaling pathway results in the alteration of caruncular vasculature, placentome architecture, abundance of amino acids in allantoic and amniotic fluids, and fetal growth during pregnancy in sheep. The marked morphological changes in placentome histoarchitecture, including alteration in the vasculature, may be relevant to fetal growth and survival. It is somewhat surprising that fetal length was reduced as early as day 60, because fetal growth in sheep is greatest after day 60. The subtle changes observed in the fetuses of ewes exposed to FTY720 may indicate an adaptive response of the fetuses to cope with altered placental morphology.

Maternal periconceptional and first trimester protein restriction in beef heifers: effects on placental parameters and fetal and neonatal calf development.

Few studies have investigated the effects of nutrition during the periconception and early gestation periods on fetal and placental development in cattle. In this study, nulliparous yearling heifers (n=360) were individually fed a diet high or low in protein (HPeri and LPeri) beginning 60 days before conception. From 24 to 98 days after conception, half of each treatment group was changed to the alternative high- or low-protein diet (HPost and LPost) yielding four groups in a 2×2 factorial design. A subset of heifers (n=46) was necropsied at 98 days after conception and fetoplacental development assessed. Placentome number and volume decreased in response to LPeri and LPost diets respectively. Absolute lung, pancreas, septum and ventricle weights decreased in LPost versus HPost fetuses, whereas the post-conception diet altered absolute and relative liver and brain weights depending on sex. Similarly, changes in fetal hepatic gene expression of factors regulating growth, glucose output and lipid metabolism were induced by protein restriction in a sex-specific manner. At term, neonatal calf and placental measures were not different. Protein restriction of heifers during the periconception and early gestation periods alters fetoplacental development and hepatic gene expression. These changes may contribute to functional consequences for progeny, but this may not be apparent from gross morphometry at birth.

PSII-7 Uterine artery hemodynamics and placentome quantification during maternal nutrient restriction in beef cattle

Abstract Proper fetal nutrition via adequate uteroplacental blood flow is critical for maximizing fetal development and reducing mortality. However, our understanding of adaptations during maternal nutrient restriction is incomplete. The purpose of this study was to determine the effect of nutrient restriction during mid to late gestation on utero-placental hemodynamics and placentome morphometrics in gestating beef cattle. Animals (n = 10) were randomly assigned one of 2 treatments: Control (CON; 100% NRC Requirements) vs Restricted Feed (NR; 60% of NRC Requirements) from 140 to 240 days of gestation. Hemodynamic parameters were collected by Doppler ultrasonography 1 week prior to slaughter from the ipsilateral and contralateral uterine arteries, after which, total uterine artery blood flow was calculated. Six animals (n = 3 per treatment) were slaughtered on day 240 of gestation (Group 1) and the remaining 4 animals were slaughtered on 265 ± 15 days (Group 2). Placentome tissues were harvested for weight and number determination. Placentome number decreased (P = 0.01) in nutrient restricted (49 ± 6) versus control (83 ± 6) fed dams. There was an interaction between treatment and group in which ipsilateral diameter increased (P &amp;lt; 0.05) in group 2 NR animals versus group 2 CON animals while there was no difference between NR and CON in group 1. There was no difference (P = 0.30) in total uterine artery blood flow in fetal weight, which averaged 212 ± 37 mL/min*kg in nutrient restricted versus 153 ± 34 mL/min*kg in control fed dams. In summary, these data indicate limited alterations in uterine artery blood flow and fetal weight in nutrient restricted dams during the last half of gestation. The decrease in placentome number with no difference in placentome weight could indicate larger placentomes in nutrient restricted dams were able to compensate for the reduction in total number.

Evolution of placentation in cattle and antelopes

Bovids have enjoyed great evolutionary success as evidenced by the large number of extant species. Several important domestic animals are from this family. They derive from both subfamilies: cattle and their kin belong to Bovinae and sheep and goats to Antilopinae. The premise of this review, therefore, is that evolution of reproduction and placentation is best understood in a context that includes antelope-like bovines and antelopes. Many key features of placentation, including hormone secretion, had evolved before bovids emerged as a distinct group. Variation nevertheless occurs. Most striking is the difference in fusion of the binucleate trophoblast cell with uterine epithelium that yields a transient trinucleate cell in bovines and many antelopes, but a more persistent syncytium in wildebeest, sheep and goat. There is considerable variation in placentome number and villus branching within the placentome. Many antelopes have right-sided implantation in a bicornuate uterus whilst others have a uterus duplex. Finally, there has been continued evolution of placental hormones with tandem duplication of PAG genes in cattle, differences in glycosylation of placental lactogen and the emergence of placental growth hormone in sheep and goats. The selection pressures driving this evolution are unknown though maternal-fetal competition for nutrients is an attractive hypothesis.

Effects of maternal nutrient restriction followed by realimentation during early and mid-gestation in beef cows. II. Placental development, umbilical blood flow, and uterine blood flow responses to diet alterations

The objectives were to examine the effects of maternal nutrient restriction followed by realimentation during early to mid-gestation on placental development and uterine and umbilical hemodynamics in the beef cow. On day 30 of pregnancy, multiparous, non-lactating beef cows (620.5 ± 11.3 kg) were assigned to 1 of 2 dietary treatments: control (C; 100% National Research Council [NRC] recommendations; n = 18) and restricted (R; 60% NRC; n = 30). On day 85, cows were slaughtered (C, n = 6; R, n = 6), remained on control (CC; n = 12) and restricted (RR; n = 12), or were realimented to control (RC; n = 11). On day 140, cows were slaughtered (CC, n = 6; RR, n = 6; RC, n = 5), remained on control (CCC, n = 6; RCC, n = 5), or were realimented to control (RRC, n = 6). On day 254, all remaining cows were slaughtered. Heart rate and umbilical and uterine hemodynamics [blood flow, resistance index (RI), and pulsatility index (PI)] were determined via Doppler ultrasonography. As expected umbilical blood flow increased and fetal heart rate decreased as gestation advanced. Umbilical PI in RRC cows was less (P = 0.01) compared to RCC and CCC. During late gestation, RCC cows had greater (P = 0.02) ipsilateral and total uterine blood flow vs. CCC and RRC. There was an increase in the number and weight of placentomes from R cows (P ≤ 0.02) compared to C cows (i.e. day 85). There were more placentomes (P = 0.03) in RR vs. CC and RC cows, but placentome weight was not affected (P = 0.18) by maternal dietary treatment at day 140. Maternal nutrient restriction during early to mid-gestation increased the weight (by day 85) and number (day 85 and 140) of placentomes, and did not reduce fetal weight compared to control cows. A longer realimentation period may enhance uterine blood flow and individual placentome size during later gestation, which may compensate for reduced nutrients experienced early in gestation.

Maternal undernutrition during the pre- and post-conception periods in twin-bearing hairsheep ewes: effects on fetal and placental development at mid-gestation.

To evaluate the effects of pre- and post-conception undernutrition (UN) on fetal and placental development at mid-gestation, 28 Katahdin × Pelibuey multiparous ewes were blocked by weight and assigned to the following four dietary treatments (n=7 each): ewes fed 100% (control) or 60% of their nutritional requirements 30days before mating (UNPre), 50days after mating (UNPost) or during both periods (UNB). Four twin-bearing ewes were selected per treatment at day 50 post-conception and then slaughtered at day 75 of gestation to analyze their fetuses. Control fetuses were heavier (P<0.05) than UNPost and UNB fetuses in 14.6 and 9.4%, respectively. Organ weights as percentage of the fetal weight (except for liver) and morphometric measurements (except for abdominal girth) were similar between control and UN fetuses (UNPre, UNPost, and UNB). Placental mass was heavier (P<0.05) in control ewes than UNB ewes, but not relative to ewes of other treatments. The number of placentomes per ewe and placental efficiency were unaffected by UN treatments. Compared to control, only UNB ewes exhibited variations (P<0.05) in the proportion of placentomes, specifically for type A (+13.8%) and B (-12.6%). Placentomes of type A and B had lower weight, length, and width of placentas in UNPost and UNB ewes than placentas of control ewes (P<0.05). Overall results indicate that fetal and placental development of ewes carrying twins is mainly altered when nutritional restriction occurs simultaneously before conception and during the first third of pregnancy.

Remodelling of the bovine placenta: Comprehensive morphological and histomorphological characterization at the late embryonic and early accelerated fetal growth stages

IntroductionPlacental function impacts growth and development with lifelong consequences for performance and health. We provide novel insights into placental development in bovine, an important agricultural species and biomedical model. MethodsConcepti with defined genetics and sex were recovered from nulliparous dams managed under standardized conditions to study placental gross morphological and histomorphological parameters at the late embryo (Day48) and early accelerated fetal growth (Day153) stages. ResultsPlacentome number increased 3-fold between Day48 and Day153. Placental barrier thickness was thinner, and volume of placental components, and surface areas and densities were higher at Day153 than Day48. We confirmed two placentome types, flat and convex. At Day48, there were more convex than flat placentomes, and convex placentomes had a lower proportion of maternal connective tissue (P < 0.01). However, this was reversed at Day153, where convex placentomes were lower in number and had greater volume of placental components (P < 0.01- P < 0.001) and greater surface area (P < 0.001) than flat placentomes. Importantly, embryo (r = 0.50) and fetal (r = 0.30) weight correlated with total number of convex but not flat placentomes. DiscussionExtensive remodelling of the placenta increases capacity for nutrient exchange to support rapidly increasing embryo-fetal weight from Day48 to Day153. The cellular composition of convex placentomes, and exclusive relationships between convex placentome number and embryo-fetal weight, provide strong evidence for these placentomes as drivers of prenatal growth. The difference in proportion of maternal connective tissue between placentome types at Day48 suggests that this tissue plays a role in determining placentome shape, further highlighting the importance of early placental development.

Assessment of the accuracy of estimation of gestational age in cattle from placentome size using inverse regression

AIMS: To assess, in dairy cows between 60–160 days of gestation, whether the agreement between actual gestational age and that predicted by placentome size could be improved by using individual placentome measurements rather than a single average, and to identify how increasing the number of placentomes measured improved the prediction.METHODS: Data were obtained from 58 cows examined using transrectal ultrasonography every 10 days between 60–130 days, and every 15 days between 130–160 days of gestation. For each cow, four to six placentomes in each of the pregnant and non-pregnant horns were examined from the region of the uterus near to the cervix. A mixed-effects model, which included cow as a random effect, and a simple linear regression which ignored within-cow correlation, were fitted to the data. Inverse regression was used to compare the 95% prediction bands obtained for estimating gestational age using the means of three, five or eight placentome measurements.RESULTS: The fit of the mixed effects model was better than a simple linear regression (p<0.001) but the fitted lines from the two models were very similar. Using the simple regression model, for a mean placentome length of 15 mm estimated gestational age was 100 days, with 95% CI of 68–131 days for measurement of three placentomes, and 80–120 days for eight placentomes.CONCLUSIONS: The agreement between placentome size and gestational age was improved by increasing the number of placentomes measured. Direct comparison of these CI with those for other published fetal measures was not possible as similar prediction bands have not previously been calculated for fetal measures; however one study reported a residual SD which had been calculated using size measurements as the predictor variable and age as the response variable. Using these data 95% CI were calculated to be ±9 days for crown-rump length and ±25 days for uterine diameter. These are likely to be an underestimate of the true CI and do not take account of the increase in variance of the difference between predicted and actual gestational age as gestational age increases.CLINICAL RELEVANCE: Placentome measurement may be useful for estimating fetal age in late gestation. Further research is required to better establish the agreement between gestational age and the fetal measurements which are currently used to estimate fetal age.

Intravenous maternal -arginine administration to twin-bearing ewes during late pregnancy enhances placental growth and development.

This study aimed to investigate if intravenous maternal Arg administration to well-fed twin-bearing ewes, from 100 to 140 d of gestation or birth, could enhance placental development and placental nutrient transport. Ewes received intravenous infusions of saline (control) or 345 μmol Arg HCl/kg of BW 3 times daily from d 100 of pregnancy (P100) to d 140 of pregnancy (P140; cohort 1) or from P100 to birth (cohort 2). At P140, ewes in cohort 1 were euthanized and individual placentae per fetus were dissected and placentomes were classed per type (A to D) and size (light to heavy). Placentome number and individual weight were recorded. As an indicator of placental nutrient transport, blood plasma was collected from the uterine ovarian vein (UOV), uterine artery (UA), and umbilical vein and artery at the time of euthanasia and analyzed for metabolites and free AA concentrations. The ewes in cohort 2 were allowed to lamb and lambs were weighed at birth. The expelled placenta was dissected and number of cotyledons and weights of total cotyledons, remaining fetal membranes, and total placenta were recorded. At P140, Arg-infused ewes had a 63% ( = 0.03) greater number of unoccupied caruncles than control ewes. No differences were observed for placental weight at P140. At birth, lambs from Arg-infused ewes tended to have 11% ( = 0.09) greater placental weight and 34% ( = 0.03) greater total cotyledon weight compared with control lambs. Arginine-infused ewes (Arg-infused) had increased concentrations of Arg ( = 0.0001) and ornithine (Orn; = 0.004) but decreased concentrations of Met ( = 0.01) and His ( = 0.02 and = 0.09, respectively) compared with control ewes in plasma UOV and UA. Fetuses from Arg-infused ewes had increased concentrations of Orn ( = 0.005) and decreased concentrations of His ( = 0.006), Met ( = 0.003), and Lys ( = 0.01) but no differences in Arg ( > 0.10) concentrations were found compared with control fetuses in umbilical artery and vein plasma. This study showed that maternal Arg administration of well-fed twin-bearing ewes during late pregnancy tended to improve placental growth and development.