Vitamin D Sufficiency Has a Limited Effect on Placental Structure and Pathology: Placental Phenotypes in the VDAART Trial.

Vitamin D insufficiency during pregnancy is widespread. The effects of active vitamin D on the human placenta in vivo are unknown. We test the hypotheses that 25(OH)D sufficiency (arbitrarily defined as 25(OH)D ≥32 ng/mL) modulates placental structure and function in vivo in a population of women whose offspring are at risk for childhood asthma, and that placental pathology is more common in offspring that evolve asthma at age 3. Pregnant volunteers in the St. Louis, MO, cohort of the Vitamin D Antenatal Asthma Reduction Trial (VDAART, NIH grant #HL091528) participated in a nested case-control study and consented for the study of placentas after delivery. Maternal concentrations of 25(OH)D were measured at trial entry and in the third trimester. The histopathology of the placentas from women with sufficient 25(OH)D, versus insufficient, showed no clinically significant differences, but morphometry revealed villi of women with sufficient third-trimester 25(OH)D had a higher villous surface density. Notably, analyses of transcripts, extracted from formalin-fixed paraffin-embedded specimens, revealed higher expression of INTS9, vWF, MACC1, and ARMS2, and diminished expression of the CNTN5 genes in the insufficient group. A larger proportion of placentas showed chronic chorioamnionitis in offspring with versus without asthma at age 3. These findings suggest that maternal 25(OH)D insufficiency has a limited effect on human placental villous histopathology and morphometry, but attenuates a small number of placental gene expression profiles in this selected population. The association of placental chronic chorioamnionitis and offspring asthma is worthy of further study.

Does Neospora caninum cause reproductive problems in pigs?

Neospora caninum is known to cause reproductive disturbances in several animal species, such as cattle, sheep, and goats. However, research on the effects of N. caninum on reproduction in pigs is limited. The objective of this study was to verify the transplacental transmission of N. caninum in pigs during several gestational stages. Twelve healthy Toxoplasma gondii and N. caninum seronegative female pigs were selected and separated into four groups of three animals each. Group A was maintained as a control group. Groups B, C, and D were inoculated intravenously with 2.9 × 107 tachyzoites of the N. caninum strain Nc1, 30 days before conception and at 45 and 90 days of gestation, respectively. Blood samples were collected from females periodically through IFAT for IgG and IgM screening to confirm the infection. At birth, after blood samples were collected from the piglets, they were then euthanized for the collection of the brain, heart, lung, liver, and diaphragm, which were then subjected to PCR. All inoculated gilts seroconverted (IgG) from the seventh day after inoculation. Nine of the 12 females expelled 24 mummified fetuses at the time of delivery, two in group A (eight), two in group B (four), three in group C (nine), and two in group D (three). Of the 24 mummified fetuses, nine were positive for N. caninum (one (25%) fetus of group B, seven (77.8%) of group C, and one (33.3%) of group D). A total of 126 live piglets were born. When the organs of the piglets from the inoculated females were analyzed by PCR for N. caninum, 88 (93.61%) were positive. All gilts inoculated produced at least one positive piglet. This demonstrates that there is transplacental transmission of N. caninum in all phases of gestation, regardless of the time of infection.

Putative Primo-Vascular System in Rabbit Placenta.

The primo vascular system (PVS) is a very important topic of study nowadays because of their role in transport and regeneration of tissue and in cell migration and cancer metastasis. The PVS was detected in different organs of the rabbit but not in the placenta. In this work, we observe the PVS inside the blood vessels of the placenta for the first time. The main characteristic features of the primo vessels (PVs) from the rabbit placenta were in agreement with the PVS in different organs of animals, including the rod-shaped nuclei and their arrangement.

Antioxidant Supplementation Modulates Age-Related Placental Bed Morphology and Reproductive Outcome in Mice.

The number of women who delay their first childbirth is increasing. This demographic shift is an important health issue because advanced maternal age is a risk factor for reproductive capacity loss and the occurrence of placental bed disorders that may lead to placenta abruption, preeclampsia, and placenta insufficiency. A redox imbalance status, resulting from the enhanced production of reactive oxygen species or their deficient neutralization, is proposed to occur in this setting. Thus, uterine redox status was evaluated in young (8- to 12-wk-old) and reproductively aged (38- to 42-wk-old) mice. In addition, it was hypothesized that specific dietary antioxidant supplementation would restore the balance and improve the reproductive outcome of aging female mice. To test this hypothesis, two different antioxidants, the nicotinamide adenine dinucleotide phosphate oxidase (NOX) inhibitor apocynin and the superoxide dismutase mimetic 4-hydroxy-2,2,6,6-tetramethylpiperidinyloxy (TEMPOL), were added to the drinking water of female mice prior to and during pregnancy. Compared to younger females, uteri from reproductively aged nonpregnant mice exhibited areas of endometrial cystic dilation, increased level of NOX1 expression, and enhanced protein carbonylation, especially in the apical surface of the luminal epithelium. Both antioxidants decreased protein carbonylation level in the uterus of reproductively aged mice. When reproductively aged females became pregnant, the litter size was smaller and fetuses were heavier. The change was accompanied by a significant decrease in decidua thickness. Provision of apocynin significantly increased litter size and restored decidua thickness. Reproductively aged mice provided with TEMPOL did not evidence such benefits, but whereas apocynin normalized fetal birth weight, TEMPOL further increased it. These findings emphasize that uterine redox balance is important for reproductive success and suggest that age-related redox imbalance might be compensated by specific antioxidant supplementation.

Primo vascular system in human umbilical cord and placenta.

The primo vascular system (PVS) has been observed in various animals such as mice, rats, rabbits, dogs, swine, and cow, but not in humans. In this work, we report on the observation of a human PVS on both the epithelial fascia and inside the blood vessels of the umbilical cord (UC). The main morphological characteristics of the primo vessels (PVs) and primo nodes (PNs) from the human UC were in agreement with those of the PVS in various animal organs, including the thicknesses and the transparency of the PVs, the sizes of the PNs, the broken-line arrangement of the rod-shaped nuclei, the sparse distribution of nuclei, and the presence of hollow lumens in the central inner parts of the PNs. It was rather surprising that the human PV was not thicker than the PVs from small animals. The difference between the PVS and blood/lymph vessels was confirmed using immunofluorescence staining of von Willebrand factor, CD31, LYVE-1, and D2-40. The positive expression of the PVS to proliferating cell nuclear antigen, a cell-proliferation marker, was consistent with the recent finding of very small embryonic-like stem cells in the PVS of mice.

Maternal serum 25-hydroxyvitamin D and measures of newborn and placental weight in a U.S. multicenter cohort study.

CONTEXT: Inconsistent associations between maternal vitamin D status and fetal size have been published in small studies. OBJECTIVE: Our objective was to examine the association between maternal 25-hydroxyvitamin D [25(OH)D] levels and measures of newborn and placental weight. DESIGN AND SETTING: We measured maternal 25(OH)D in mothers from the Collaborative Perinatal Project, an observational cohort conducted in 12 U.S. medical centers from 1959 to 1965. PARTICIPANTS: Women delivering singleton, term, live births with 25(OH)D measured at a gestation of 26 wk or less (n = 2146). MAIN OUTCOME MEASURES: Birth weight, ponderal index, placental weight, the placental to fetal weight ratio, and small for gestational age were measured. Hypotheses were formulated after data collection. RESULTS: After confounder adjustment, mothers with 25(OH)D of 37.5 nmol/liter or greater gave birth to newborns with 46 g [95% confidence interval (CI), 9-82 g] higher birth weights and 0.13 cm (0.01-0.25 cm) larger head circumferences compared with mothers with less than 37.5 nmol/liter. Birth weight and head circumference rose with increasing 25(OH)D up to 37.5 nmol/liter and then leveled off (P < 0.05). No association was observed between 25(OH)D and ponderal index, placental weight, or the placental to fetal weight ratio. Maternal 25(OH)D of 37.5 nmol/liter or greater vs. less than 37.5 nmol/liter in the first trimester was associated with half the risk of small for gestational age (adjusted odds ratio 0.5; 95% CI 0.3-0.9), but no second-trimester association was observed. CONCLUSIONS: Maternal vitamin D status is independently associated with markers of physiological and pathological growth in term infants. Adequately powered randomized controlled trials are needed to test whether maternal vitamin D supplementation may improve fetal growth.

Maternal weight and body composition during pregnancy are associated with placental and birth weight in rural Bangladesh.

Placental growth is a strong predictor of fetal growth, but little is known about maternal predictors of placental growth in malnourished populations. Our objective was to investigate in a prospective study the associations of maternal weight and body composition [total body water (TBW) estimated by bioelectrical impedance and fat and fat-free mass derived from upper arm fat and muscle areas (UAFA, UAMA)] and changes in these with placental and birth weights. Within a cluster-randomized trial of maternal micronutrient supplementation, a subsample of 350 women was measured 3 times across gestation. Longitudinal analysis was used to examine independent associations of ∼10-wk measurements and ∼10-20 wk and ∼20-32 wk changes with birth outcomes. Weight, TBW, and UAMA, but not UAFA, at ∼10 wk were each positively and independently associated with placental weight and birth weight (P < 0.05). Of the maternal ∼10-20 wk changes in measurements, only TBW change and placental weight, and maternal weight and birth weight were positively associated (P < 0.05). Gains in weight, TBW, and UAMA from 20 to 32 wk were positively and UAFA gain was negatively associated with placental weight (P ≤ 0.01). Gains in weight and UAMA from 20 to 32 wk were positively associated with birth weight (P ≤ 0.01). Overall, higher maternal weight and measures of fat-free mass at ∼10 wk gestation and gains from 20 to 32 wk are independently associated with higher placental and birth weight.

Effects of antioxidant vitamins on newborn and placental traits in gestations at high altitude: comparative study in high and low altitude native sheep.

The present study evaluated the hypothesis that the effects of hypoxia on sheep pregnancies at high altitude (HA) are mediated by oxidative stress and that antioxidant vitamins may prevent these effects. Both HA native and newcomer ewes were maintained at an altitude of 3,589 m during mating and pregnancy. Control low altitude (LA) native ewes were maintained at sea level. Half of each group received daily oral supplements of vitamins C (500 mg) and E (350 IU) during mating and gestation. Near term, maternal plasma vitamin levels and oxidative stress biomarkers were measured. At delivery, lambs were weighed and measured, and placentas were recovered for macroscopic and microscopic evaluation. Vitamin concentrations in supplemented ewes were two- or threefold greater than in non-supplemented ewes. Plasma carbonyls and malondialdehyde in non-supplemented ewes were consistent with a state of oxidative stress, which was prevented by vitamin supplementation. Vitamin supplementation increased lamb birthweight and cotyledon number in both HA native and newcomer ewes, although placental weight and cotyledon surface were diminished. Placentas from vitamin-supplemented HA ewes were similar to those from ewes at sea level, making these placental traits (weight, number and diameter of cotyledons) similar to those from ewes at sea level. Vitamin supplementation had no effect on LA pregnancies. In conclusion, supplementation with vitamins C and E during pregnancy at HA prevents oxidative stress, improving pregnancy outcomes.

Effect of weight and adiposity at conception and wide variations in gestational dietary intake on pregnancy outcome and early postnatal performance in young adolescent sheep.

Nutritional backgrounds prior to pregnancy may interact with subsequent gestational intake to influence pregnancy outcome, particularly in young, growing adolescents. To investigate this interaction, singleton pregnancies were established in two groups of adolescent sheep of identical age but different initial weight and adiposity score, classified as good (G) and poor (P) body mass index (BMI). Thereafter, ewes were offered either an optimal control (C) intake to maintain adiposity throughout pregnancy, undernourished (UN) to maintain weight at conception but deplete maternal body reserves, or overnourished (ON) to promote rapid maternal growth and adiposity, resulting in a 2 x 3 factorial design. Gestation length was independent of BMI and reduced in ON dams. Average placental and lamb birth weights were influenced by initial BMI (G > P) and gestational intake (C > UN > ON), with the highest incidence of growth restriction in ON groups. Metabolic challenges at two thirds of gestation revealed enhanced insulin insensitivity in ON dams (higher glucose postinsulin challenge and higher insulin postglucose challenge), but nevertheless fetal growth was constrained. Initial colostrum yield, total IgG, and nutrient supply were reduced in ON groups, but these low-birth-weight lambs exhibited rapid catch-up growth to weaning. Thus, both maternal BMI at conception and gestational intake have a profound influence on pregnancy outcome in young, putatively growing adolescent sheep and may have implications for the nutritional management of pregnant adolescent humans.

Influence of l-carnitine on metabolism and performance of sows.

In recent years, l-carnitine has been used increasingly as a supplement in livestock animals. The present review gives an overview of the effects of dietary l-carnitine supplementation on the reproductive performance of sows. Results concerning the effect of l-carnitine supplementation during pregnancy on litter sizes are controversial. There are some studies reporting an increased number of piglets born alive per litter, while others could not find such an effect. In contrast, most studies performed show consistently that l-carnitine supplementation to a sow diet low in native carnitine during gestation increases piglet and litter weights at birth and enhances growth of litters during the suckling period. Biochemical mechanisms underlying the favourable effect of carnitine on intra-uterine growth have not been fully elucidated. There is, however, some evidence that carnitine influences the insulin-like growth factor-axis in sows and leads to greater placentae, which in turn improves intra-uterine nutrition, and stimulates oxidation of glucose in the fetuses. These effects may, at least in part, be responsible for higher birth weights of piglets. The stimulating effect of carnitine on growth of the litters might be due to an improved suckling behaviour of piglets born to l-carnitine-supplemented sows, causing the sows' milk production to rise. In conclusion, recent studies have clearly shown that dietary l-carnitine supplementation increases the reproductive performance of sows. These findings suggest that endogenous de novo synthesis of carnitine is insufficient to meet the metabolic requirement of sows during gestation.

Increasing prepartum dietary crude protein using poultry by-product meal dose not influence performance of multiparous Holstein dairy cows.

The aim of this study was to compare the effects of two levels of Crude Protein (CP) using Poultry by-Product Meal (PBPM) fed during late gestation on the performance, blood metabolites and colostrum composition of Holstein cows. Twenty multiparous cows 26 +/- 6 days before expected calving were assigned randomly to two treatments containing 1) 140 g kg(-1) DM CP (34 g kg(-1) DM PBPM) 2) 160 g kg(-1) DM CP (75 g kg(-1) DM PBPM). The cow's BCS was 3.56 +/- 0.5 on average, at the beginning of the trial. Yields of milk, protein, lactose and fat were not affected by prepartum dietary CP level. Colostrum composition (fat, CP and total solids percents), blood metabolites (Ca, glucose, total protein, albumin, globulin, urea N and cholesterol) and metabolic diseases incidence were not influenced by prepartum dietary CP level. There was no significant difference between treatments in body weight and BCS changes. As expected, blood urea N before calving was higher in the cows fed 160 g kg(-1) DM CP diets (p < 0.002). Serum cholesterol during prepartum (p < 0.03) and postpartum (p < 0.01) periods was significantly lower in 160 g kg(-1) DM CP treatment. In general, although postpartum glucose level increased in cows which received 160 g kg(-1) DM CP in the diet, it seems that there is no other obvious advantages over feeding the 140 g kg(-1) DM CP diet. So feeding this level of CP diet to close up cows is recommended.

Early treatment of the pregnant guinea pig with IGFs promotes placental transport and nutrient partitioning near term.

Appropriate partitioning of nutrients between the mother and conceptus is a major determinant of pregnancy success, with placental transfer playing a key role. Insulin-like growth factors (IGFs) increase in the maternal circulation during early pregnancy and are predictive of fetal and placental growth. We have previously shown in the guinea pig that increasing maternal IGF abundance in early to midpregnancy enhances fetal growth and viability near term. We now show that this treatment promotes placental transport to the fetus, fetal substrate utilization, and nutrient partitioning near term. Pregnant guinea pigs were infused with IGF-I, IGF-II (both 1 mg.kg-1.day-1) or vehicle subcutaneously from days 20-38 of pregnancy (term=69 days). Tissue uptake and placental transfer of the nonmetabolizable radio analogs [3H]methyl-D-glucose (MG) and [14C]aminoisobutyric acid (AIB) in vivo was measured on day 62. Early pregnancy exposure to elevated maternal IGF-I increased placental MG uptake by>70% (P=0.004), whereas each IGF increased fetal plasma MG concentrations by 40-50% (P<0.012). Both IGFs increased fetal tissue MG uptake (P<0.048), whereas IGF-I also increased AIB uptake by visceral organs (P=0.046). In the mother, earlier exposure to either IGF increased AIB uptake by visceral organs (P<0.014), whereas IGF-I also enhanced uptake of AIB by muscle (P=0.044) and MG uptake by visceral organs (P=0.016) and muscle (P=0.046). In conclusion, exogenous maternal IGFs in early pregnancy sustainedly increase maternal substrate utilization, placental transport of MG to the fetus, and fetal utilization of substrates near term. This was consistent with the previously observed increase in fetal growth and survival following IGF treatment.

The effect of overnourishing singleton-bearing adult ewes on nutrient partitioning to the gravid uterus.

Overnourishing the singleton-bearing adolescent sheep throughout pregnancy promotes maternal tissue synthesis at the expense of the nutrient requirements of the gravid uterus. Consequently, the growth of the placenta is impaired and results in the premature delivery of low-birth-weight lambs relative to moderately fed adolescents of equivalent age. To establish if this phenomenon is unique to the growing animal, singleton pregnancies to a single sire were established by embryo transfer into primiparous adult ewes who had attained the normal mature body size for their genotype. Thereafter ewes were offered a maintenance or a high level of a complete diet throughout gestation. High maternal intakes resulted in elevated maternal insulin, no significant change in growth hormone or glucose, and attenuated progesterone and NEFA concentrations. Live weight gain during the first 93 d of gestation was 48 and 244 g/d, and adiposity score at term was 2.4 and 3.7 in the maintenance and high groups, respectively (P<0.001). In spite of achieving levels of adiposity similar to overnourished adolescents, placental (477 (sem 30) v. 518 (sem 41) g) and fetal (5190 (sem 320) v. 5420 (sem 250) g) weights were equivalent in maintenance and high groups. Gestation length was shorter (P<0.01) and colostrum yield at parturition lower (P<0.05) in high v. maintenance dams. Thus, adult sheep appear to be relatively insensitive to the oversupply of nutrients during pregnancy and have the ability to meet the nutrient requirements for normal conceptus growth in spite of their increased adiposity.

Pregnancy in mice lacking the vitamin D receptor: normal maternal skeletal response, but fetal hypomineralization rescued by maternal calcium supplementation.

Fetal mineralization appears to be driven by the pregnancy-induced stimulation of intestinal Ca absorption. We thus hypothesized that mineralization would be impaired in fetuses of mice that lack the vitamin D receptor (VDR). Here we report on the maternal response to pregnancy, and the fetal mineralization, in mice with a homozygous disruption of the VDR gene (VDR-/-) mated with wild-type (wt) males. We found that VDR-/- mice show mild hypocalcemia, clear rickets and osteomalacia on bone histomorphometry, lower cortical bone density on quantitative tomography, and reduced concentrations of calbindin-D9k (CaBP-D9k) in duodenal mucosa and kidney. The skeletal response to pregnancy was comparable in wt and VDR-/- mice; duodenal CaBP-D9k concentrations increased during pregnancy in VDR-/- as in wt mice, but remained 40% lower than in wt mice. We confirmed our hypothesis that mineralization is defective in d18.5 VDR+/- fetuses of VDR-/- mice, both by whole-body Ca determination and histomorphometric evaluation; the number of osteoclastic cells in bone was increased. The fetuses were hypercalcemic and had a 5-fold increase in circulating 1,25(OH)2D3. We then studied pregnancies in VDR-/- females, mated with wt males, fed a high Ca/P/lactose rescue diet during pregnancy. The rescue diet normalized the mineralization, the number of osteoclastic cells, and plasma Ca and 1,25(OH)2D3 concentrations in the fetuses. We interpret the data as evidence that, to ensure normal fetal mineralization, the maternal VDR-dependent intestinal Ca absorption can be substituted by passive Ca absorption entrained by a higher Ca intake. Alternatively or additionally, elevated 1,25(OH)2D3 in utero may disturb bone development.

Placental triage of the singleton placenta.

Triage is the sorting and allocation of treatment according to a system of priorities in order to maximize treatment. Placental triage promptly after delivery of the placenta, with documentation of the findings in the medical record, only takes a few minutes, and allows for the identification of abnormal placentas to be submitted for detailed gross and microscopic pathology examination. It requires familiarity with normal gross placental anatomy and variations of normal, and the development of a systematic procedure for comprehensive examination of the placental disk as a whole, the umbilical cord, the extraplacental membranes, the fetal surface, the maternal surface, and the parenchyma. This article provides a systematic approach to gross examination of the placenta. It also reviews the clinical and legal impact of placenta examination, and suggests procedures that will optimize the information available in the placenta.

Vitamin C supplementation of the maternal diet reduces the rate of malformation in the offspring of diabetic rats.

An excess of reactive oxygen species (ROS) has been associated with the increased rate of congenital malformations in experimental diabetic pregnancy. Previous in vitro and in vivo studies show that antioxidants can protect the embryonic development in a diabetic environment. In the present investigation we examined the antiteratogenic capacity of vitamin C, an antioxidative agent not previously evaluated as a dietary supplement in diabetic pregnancy. Normal and streptozotocin diabetic rats were either fed a standard diet or a diet enriched with 0.9, 1.8 or 4% sodium ascorbate throughout pregnancy. On gestational day 20, the litters of normal and diabetic rats without vitamin C supplement contained 9 and 12% early resorptions, 2 and 17% late resorptions and 1 and 27% malformations, respectively. Vitamin C treatment reduced the rates of late resorptions and malformations in the diabetic groups in proportion to the dose administered. Thus, in the diabetic group with 4% ascorbate treatment we found unchanged numbers of early resorptions, but only 7% late resorptions (p < 0.05 vs untreated diabetic pregnancy) and 8% malformations (p < 0.05 vs untreated diabetic pregnancy). Maternal diabetes did not alter tissue levels of ascorbic acid in the fetuses at term, whereas vitamin C treatment caused accumulation of ascorbic acid in the placenta, maternal and fetal liver. Vitamin C supplementation yielded increased alpha-tocopherol concentration in the placenta and caused a reduction of the high concentrations of thiobarbituric acid reactive substances (TBARS) in serum of pregnant diabetic rats. Vitamin C treatment reduces the rates of congenital malformations and late resorptions, thereby supporting that ROS are involved in the embryonic dysmorphogenesis of diabetic pregnancy.

Effect of maternal glucocorticoid treatment on ovine fetal fluids at 0.6 gestation.

This study examined the effects of maternal dexamethasone treatment on the volume and composition of fetal fluids, and on placental morphology at 0.6 gestation (80-90 days). Nine pregnant ewes were infused with dexamethasone (D, 0.76 mg h-1 for 72 h) while an additional nine ewes received saline (S, 0.38 mL h-1 for 72 h). Allantoic fluid (ALF) volume was significantly greater (P < 0.01) in the D group (737 +/- 116 mL) than in the S group (190 +/- 55 mL), but there was no difference in amniotic fluid (AMF) volume. The urine flow rate was 11 times higher in three D fetuses. The 51Cr-EDTA infused into the bladders of four fetuses during the final 4-5 h of the 72 infusions was detected in both AMF and ALF. Dexamethasone treatment significantly altered the composition of the fetal fluids but had no affect on fetal body weight, organ weights and placental weight; however, there were fewer cotyledons under 5 g (P < 0.05). In the D group, 3% of cotyledons were of the 'bovine' type in morphology, whereas all cotyledons in the S group were of the 'ovine' type. These findings suggest that prolonged exposure to large doses of glucocorticoids during pregnancy would affect the volume and composition of the fetal fluids and placental morphology, with potentially detrimental effects on the fetus.

Effect of maternal glucocorticoid treatment on fetal fluids in sheep at 0.4 gestation.

Treatment of nine pregnant Merino ewes (64.0 +/- 0.4 days of gestation) with dexamethasone (D; 0.76 mg/h for 48 h) resulted in significant alterations in fetal fluids compared with eight saline-infused control animals (S; 63.0 +/- 0.9 days). There was a substantial increase in allantoic fluid volume (177 +/- 18 ml, D vs. 31 +/- 6, S) but no change in amniotic fluid volume (248 +/- 12 ml, D; 305 +/- 24, S). For allantoic fluid there was a significant decrease in osmolality (213 +/- 4 mosmol/kg water, D; 230 +/- 5, S) and alterations in composition. Amniotic fluid osmolality was unchanged (292 +/- 2 mosmol/kg water, D; 293 +/- 1, S), but amniotic fluid composition was affected. In four fetuses in which bladder and amniotic cannulas were inserted at gestational age 68-75 days, fetal urine flow rate increased from a mean of 4.1 +/- 1.1 to 13.8 +/- 2.6 ml/h after 24 h and 11.8 +/- 3.0 ml/h at 48 h for a similar maternal D infusion, whereas no such increase occurred in four control fetuses. All the fetal urine voided during a 3.5- to 4-h infusion of 51Cr-labeled EDTA into the fetal bladder was directed to the allantois. The results suggest that the increase in allantoic fluid volume resulted from increased fetal urine output into the allantoic compartment, although the composition of the excess allantoic fluid differed substantially from that of fetal urine. There was a greater incidence of abnormal cotyledons in the D-infused ewes.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of hyperbaric oxygen on rat embryos.

The aim of the study was to investigate the toxic effects of hyperbaric oxygen (HBO) on rat embryos. Two groups of Fischer pregnant rats were exposed to oxygen at pressures of 324 and 426 kPa for 90 min per day for 5 consecutive days (8-12 days of gestation). The third group was exposed to normobaric oxygen for 12 h on the eighth day of gestation. Two control groups were used; the first was comprised of intact and the second of sham-treated animals. The HBO treatment did not significantly affect maternal weight gain or reduce litter size, nor did it induce any embryonic abnormalities. However, the fetal body weight was reduced and the placental weight increased in the groups exposed to HBO at pressures of 324 and 426 kPa. When female fetuses which had been exposed to oxygen at 324 or 426 kPa were compared to the intact control group, a reduction in wet weights of 9.2 (p < 0.05) and 12.1% (p < 0.01), respectively, was noted. Male fetuses exposed to oxygen at 324 and 426 kPa displayed a reduced body weight of 11.7 (p < 0.01) and 16.6% (p < 0.01), respectively. Placental weight was increased by 18.9 (p < 0.01) and 23.6% (p < 0.01) in the groups exposed to oxygen at 324 and 426 kPa, respectively. These data suggest that HBO, either at 324 or 426 kPa, is not potent at inducing malformations and that the largest embryotoxic effects are upon fetal body weight and placental weight.(ABSTRACT TRUNCATED AT 250 WORDS)