The importance of selenium in the prenatal and postnatal development of calves and lambs.

Selenium deficiency is responsible for Zenker type muscle degeneration in calves, lambs, and foals in the prenatal and postnatal stages of development. Investigations have shown that the selenium GSH Px, and vitamin E content of the maternal and fetal parts of the placenta in cattle are different. Similarly, low concentrations of selenium are present in milk from cows and sheep. In addition to an inadequate supply of selenium and vitamin E as a contributory cause of fetal nutritive muscular dystrophy (FNMD), it is assumed that a placental transport block and/or impaired selenium metabolism in the placenta are also responsible. Postnatal nutritive muscular dystrophy, however, is attributed to either acute selenium and vitamin E deficiency in basic feed or impaired plant absorption of selenium as a result of antagonistic elements, such as sulphur.     

Effects of prenatal ethanol exposure on the lungs of postnatal lambs

Prenatal ethanol exposure increases collagen deposition and alters surfactant protein (SP) expression and immune status in lungs of near-term fetal sheep. Our objectives were to determine 1) whether these prenatal effects of repeated gestational ethanol exposure persist after birth and 2) whether surfactant phospholipid composition is altered following prenatal ethanol exposure. Pregnant ewes were chronically catheterized at 90 days of gestational age (DGA) and given a 1-h daily infusion of ethanol (0.75 g/kg, n = 9) or saline (n = 7) from 95 to 135 DGA; ethanol administration ceased after 135 DGA. Lambs were born naturally at full term (146 ± 0.5 DGA). Lung tissue was examined at 9 wk postnatal age for alterations in structure, SP expression, and inflammation; bronchoalveolar lavage fluid was examined for alterations in surfactant phospholipid composition. At 134 DGA, surfactant phospholipid concentration in amniotic fluid was significantly reduced (P < 0.05) by ethanol exposure, and the composition was altered. In postnatal lambs, there were no significant differences between treatment groups in birth weight, postnatal growth, blood gas parameters, and lung weight, volume, tissue fraction, mean linear intercept, collagen content, proinflammatory cytokine gene expression, and bronchoalveolar lavage fluid surfactant phospholipid composition. Although SP-A, SP-B, and SP-C mRNA levels were not significantly different between treatment groups, SP-D mRNA levels were significantly greater (P < 0.05) in ethanol-treated animals; as SP-D has immunomodulatory roles, innate immunity may be altered. The adverse effects of daily ethanol exposure during late gestation on the fetal lung do not persist to 2 mo after birth, indicating that the developing lung is capable of repair.     

The relative importance of prenatal and postnatal maternal influences on growth in mice

Summary The cross-nursing technique was used to assess the relative importance of prenatal and postnatal maternal influences on growth in mice from an unselected population originated from a cross of four highly inbred strains. Body weights were studied at birth, 7-, 14-, 21- and 42-days, in addition to the weight gains between these ages and tail length at 21 and 42 days of age. At littering, each dam in each nursing set retained two of her own offspring and two were transfereed to each of the other dams in the set, so that each nursed litter contained six young representing three mothers. Prenatal influences accounted for 37, 15, 10, 11 and 13 % of the total variation in the respective body weights, while postnatal influences accounted for 0, 64, 65, 49 and 14% at the respective ages. In the case of weight gains, prenatal influences were responsible for 16, 4, 6 and 30%, while postnatal influences were responsible for 66, 66, 31 and 7% of the total variation in gain during the respective four periods examined. Apparently the individual weight gain from 7 to 14 days was a better measure of the lactational performance of the dam than individual 14-day weight. For tail length, prenatal influences accounted for 6 % and 4 % of the total variation in tail length at 21 and 42 days, respectively, while postnatal influences accounted for 60 % and 24 % at the respective ages. Generally, there was no indication of an important interaction between the nurse and the nursed young at any stage studied.     

The effect of low-level prenatal X-irradiation on postnatal development in the Wistar rat

The objective of this investigation was to determine the effect of low-dose prenatal X-irradiation on postnatal growth and neurobehavioral development, and whether alterations would manifest at dosages lower than those which produce anatomic malformations from exposure at the most sensitive period of organogenesis. Ninety-eight Wistar strain rats were exposed to 0.1, 0.2, or 0.4 Gy X-radiation of were sham irradiated on the 9th or 17th day of gestation. A conventional teratologic evaluation was completed on half of the animals (572 fetuses). The age of appearance of four physiologic markers and of acquisition of six reflexes was observed in 372 offspring. Exposure during early organogenesis at these levels had no effect on any of these parameters. Prenatal exposure to X-radiation on the 17th day of gestation at dosage levels greater than 0.1 Gy resulted in alterations in the appearance of three postnatal neurophysiologic parameters. Growth retardation throughout the postpartum period also was observed in the offspring. The induction of developmental and reflex alterations had a comparable threshold to the known threshold for anatomic malformations on the 9th day. These results indicate that all of the parameters studied had thresholds either at or above 0.2 Gy acute radiation, and that the postpartum developmental and reflex acquisition measures were not more sensitive indicators of exposure to X-radiation than growth parameters.     

Influences of prenatal and postnatal fraternity size on ovarian development in the mouse

An experiment was conducted to test effects of prenatal and postnatal fraternity size (size of litter in which an individual develops prenatally or is reared postnatally) on ovarian development in mice. Fraternity size treatments were created by standardizing sizes of prenatal and postnatal fraternities in which mice were gestated and reared. Prenatal fraternity size was standardized by surgery on Day 9 of gestation to 6, 10, and 14 fetuses. Postnatal fraternity size was standardized by randomly assigning pups to litters of 5, 10, or 15 pups within 24 h of birth. Female pups were killed at either 3 or 20 wk of age and right ovaries were prepared for histology. Follicles were classified by size and morphology, and numbers of follicles in each class were tabulated. Interaction of postnatal fraternity size and age was observed for number of antral follicles (p less than 0.05). Mice reared in small postnatal fraternities had more antral follicles at weaning (3 wk) and fewer antral follicles at maturity (20 wk of age) than mice reared in large postnatal fraternities. No effect of either prenatal or postnatal fraternity size on other follicle populations was observed (p greater than 0.20). Numbers of Type 2 (primordial), Type 3a, and Type 3b follicles changed with age (p less than 0.01); numbers of primordial follicles declined with age, but numbers of Type 3a and 3b follicles increased. A hypothesis of a negative association between postnatal fraternity size and number of antral follicles at 3 wk of age was supported, but a hypothesis of a positive association between fraternity size and number of primordial follicles was not supported.     

The postnatal development of the genital system in male rats following the prenatal administration of corticosterone

Corticosterone administration to pregnant Wistar rats on days 16 and 18 of pregnancy leads to changes in genital system of male offspring during postnatal ontogenesis: reduction of ano-genital distance in two days old rats, increase of preputial glands' weight in 35 and 70 day old embryos, changes in nature of puberal increase in testosterone blood level from day 35 to day 70 of life. The obtained data suggest that the increase in the corticosteroid level in blood of pregnant females owing to any stress factor can affect the postnatal development of genital system of male offspring.     

The influence of ovarian factors on the somatostatin-growth hormone system during the postnatal growth and sexual development in lambs

The aim of the study was to elucidate the effects of ovarian hormones on somatostatin in the hypothalamic neurons and growth hormone (GH) secretion during the postnatal growth and development of sheep. The study was performed on 9-week-old (infantile) lambs that were ovary-intact (OVI) or ovariectomized (OVX) at 39 days of age, and on 16-week-old (juvenile) lambs that were OVI or OVX at 88 days of age. Hormones in neurons and somatotropic cells were assayed with immunohistochemistry and radioimmunoassay. Following ovariectomy, immunoreactive somatostatin was more abundant (p<0.05) in the hypothalamus of infantile lambs, whereas in juvenile lambs it was more abundant (p<0.05) in the periventricular nucleus but reduced (p<0.01) in the median eminence. In contrast to somatostatin in the hypothalamus, the content of immunoreactive GH in the hypophysis was less in OVX infantile lambs, but greater in OVX juvenile lambs (p<0.05). Basal blood serum concentrations of GH were greater (p<0.05) in OVX infantile lambs, whereas in OVX juvenile lambs, mean and basal concentrations of GH and amplitude of GH pulses were less than in OVI lambs (p<0.05). The postnatal increase in body weight was greatest in middle-late infancy (p<0.01). The body weight did not differ (p>0.05) between OVI and OVX lambs. In conclusion, ovarian factors may inhibit the GH secretion in infantile lambs but enhance the GH secretion in juvenile lambs. Transition to puberty, as related to the growth rate, appears to be due mainly to change in gonadal influence on the somatostatin neurosecretion. A stimulation of somatostatin output in the median eminence by gonadal factors in infancy is followed by a stimulation of somatostatin accumulation after infancy. Thus, ovarian factors modulate mechanisms within the somatotropic system of lambs to synchronize the somatic growth with sexual development.     

Occurrence of lead in placenta--important information for prenatal and postnatal development of child

This work points out consequences of lead on prenatal and postnatal development of child that have not been elaborated in such extent before. Our new method for proof of lead in placenta enabled us to show how lead is from mother's blood erythrocytes in the intervillous space released and received by the villous syncytiotrophoblast. This finding enriches relation between mother's erythrocytes, lead, calcium that is a lead carrier, and syncytiotrophoblast. Our finding of abundant thin terminal villi, that in some places form bunches observed in scanning electron microscope, points out deficiency of O2 and CO2 transport in placenta. This phenomenon is indirect evidence that periphery "starves" for oxygen that participates in maintaining conditions for intact development of child. Behaviour of fibrin deposit layer before the childbirth is also discussed. Attention is paid to possible rise of hyperkinetic syndrome of children as a consequence of mother's dwelling in environment polluted with lead. Presence of lead is verified by infrared spectroscopy.     

The effects of manganese deficiency during prenatal and postnatal development on mitochondrial structure and function in the rat

The influence of manganese deficiency on liver trace element concentration, MnSOD activity, and mitochondrial structure and function during postnatal development was determined in rats. In both normal and manganese-deficient animals, liver manganese concentration increased with time, but in deficient rats liver manganese was lower than in controls at all ages measured. At 9 mo of age, liver manganese concentration in the deficient rats was only 20% that of controls. The developmental pattern observed for MnSOD paralleled that of liver manganese concentration in normal and deficient rats; it was lower than in controls on days 20 and 60. However, at 9 mo of age, MnSOD levels were similar in the two groups. Although there were no differences at 9 mo of age in MnSOD activity between the groups, manganese-deficient rats showed mitochondrial abnormalities in liver. Despite mitochondrial abnormalities, however, oxygen uptake and P/O ratios were normal. We suggest that the mitochondrial damage apparent at 9 mo of age is, at least in part, the result of lower than normal MnSOD activity occurring earlier. The functional significance of the abnormalities remains to be established.     

Androgens in relation to prenatal development and postnatal inversion of the gubernacula in rats.

Exposure of male rats to the anti-androgen flutamide during fetal life, from day 10 after conception to the day of birth, allowed quantitatively unaltered development of the gubernacula. Apparently, androgens play no important role or no role at all in their growth. Castration of newborn male rats did not interfere with the inversion during further postnatal life of the gubernacula to create the muscular parts of the scrotum (cremaster muscles). Prenatal exposure to flutamide, followed by castration immediately after birth, also allowed gubernacular inversion and cremaster muscle growth. Neonatal administration of testosterone, after castration at birth, did not enhance gubernacular inversion or promote cremaster muscle growth in infancy or during adulthood. Apparently, postnatal gubernacular inversion and cremaster muscle growth are independent not only of androgens, but also of all testis hormones. Neonatal administration of the potent androgen 5 alpha-dihydrotestosterone propionate suppressed gonadotrophin secretion and, in intact males, inhibited testicular growth. Administration from the day of birth to day 33 delayed testicular descent and enhanced growth of the genital apparatus, but did not affect the size of the cremaster muscles. These experiments indicate that androgens are not involved in the processes that create the cavities into which testes descend to acquire their full reproductive potential.     

Three paternally imprinted regions are sequentially required in prenatal and postnatal mouse development

正Reproduction in mammals is primarily through fertilization of the oocytes and sperms generated by the females and males, respectively. Fusion of two haploid genomes leads to formation of the diploid zygotes, which sequentially gives rise to the pre-implantation and post-implantation embryos     

Family networks in prenatal and postnatal health

Abstract

This paper examines the effects of kin access on prenatal health practices, birth outcome, and postnatal health practice for infants born to black and white mothers ages 21 to 28 in the U.S. during 1984–86. The data used for this research were compiled from three sources: (1) The National Longitudinal Survey of Youth; (2) The Children of the National Longitudinal Survey of Youth; (3) special kin access data files, which were created specifically for this study. Logistic regression procedures are used to assess the effects of kin proximity, maternal grandmother proximity, and presence of the child's father on health practices (N = 1,030) and birth outcome (N = 1,385), controlling for the mother's educational attainment, work experience, poverty, presence of the child's father, and birth order of the child. We find no evidence supporting the notion that kin access positively affects the prenatal and postnatal health practices of young mothers. The results suggest that young mothers who reside with their mothers or other adult kin, and those who are in close proximity to them, are no more likely to seek prenatal care during the first trimester, or to avoid smoking or drinking during pregnancy. Mothers who live with a sexual partner or husband are, however, somewhat more likely to seek prenatal care and to avoid alcohol use during pregnancy. Closer kin access is associated with a lower probability of breastfeeding. These results suggest that it will not be adequate to rely on kin networks or kin assistance to improve the prospect of healthy birth outcomes.     

Family networks in prenatal and postnatal health

This paper examines the effects of kin access on prenatal health practices, birth outcome, and postnatal health practice for infants born to black and white mothers ages 21 to 28 in the U.S. during 1984-86. The data used for this research were compiled from three sources: (1) The National Longitudinal Survey of Youth; (2) The Children of the National Longitudinal Survey of Youth; (3) special kin access data files, which were created specifically for this study. Logistic regression procedures are used to assess the effects of kin proximity, maternal grandmother proximity, and presence of the child's father on health practices (N = 1,030) and birth outcome (N = 1,385), controlling for the mother's educational attainment, work experience, poverty, presence of the child's father, and birth order of the child. We find no evidence supporting the notion that kin access positively affects the prenatal and postnatal health practices of young mothers. The results suggest that young mothers who reside with their mothers or other adult kin, and those who are in close proximity to them, are no more likely to seek prenatal care during the first trimester, or to avoid smoking or drinking during pregnancy. Mothers who live with a sexual partner or husband are, however, somewhat more likely to seek prenatal care and to avoid alcohol use during pregnancy. Closer kin access is associated with a lower probability of breastfeeding. These results suggest that it will not be adequate to rely on kin networks or kin assistance to improve the prospect of healthy birth outcomes.     

The enzyme activity of carbohydrate metabolism in the liver of swine during the transition from prenatal to postnatal development

Studies have ben been made on the activity of hexokinase, glucokinase, phosphofructokinase, glucose-6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase, as well as NADP-dependent dehydrogenases (malate and citrate) in the liver of foetuses and newborn piglets in relation to their age, fasting and reaction to injection of adaptive hormones (insulin and cortisol). It was shown that postpartum adaptation of carbohydrate metabolism in porcine liver is associated with activation of the glycolysis and with the increase in the activity of NADPH-generating dehydrogenases. In fasting newborn piglets the rate of carbohydrate catabolism increases. The effects of the investigated factors are different in the liver of 1-day piglets (sensitive to fasting) and 5-day animals (less sensitive). In is suggested that low ability of newborn piglets to maintain physiological level of glucose in the blood is associated with active glycolysis in the liver and ineffectiveness of the hormone-substrate mechanisms which control tissue glycaemia.     

Studies on prenatal and postnatal development in rats exposed to 60-Hz electric fields

A series of three experiments was performed to determine the effects of 30-day exposures to uniform 60-Hz electric fields (100 kV/m) on reproduction and on growth and development in the fetuses and offspring of rats. In the first experiment, exposure of females for 6 days prior to and during the mating period did not affect their reproductive performance, and continued exposure through 20 days of gestation (dg) did not affect the viability, size, or morphology of their fetuses. In the second experiment, exposure of the pregnant rat was begun on 0 dg and continued until the resulting offspring reached 8 days of age. In the third experiment, exposure began at 17 dg and continued through 25 days of postnatal life. In the second and third experiments, no statistically significant differences suggesting impairment of the growth or survival of exposed offspring were detected. In the second experiment, a significantly greater percentage of the exposed offspring showed movement, standing, and grooming at 14 days of age than among-sham-exposed offspring. There was a significant decrease at 14 days in the percentage of exposed offspring displaying the righting reflex in the second experiment and negative geotropism in the third experiment. These differences were all transient and were not found when the animals were tested again at 21 days of age. Evaluation of the reproductive integrity of the offspring of the second experiment did not disclose any deficits.     

Effects of 0.6-Gy prenatal X irradiation on postnatal neurophysiologic development in the Wistar rat

Forty-one pregnant Wistar strain rats were irradiated with 0.6-Gy X rays or were sham irradiated on the 9th or 17th days of gestation to determine if this dosage level would result in alterations in postnatal neurophysiologic development. Half of the mothers were sacrificed at term, and the developmental status of 221 newborns was evaluated. The remaining mothers delivered and raised their litters. The 161 offspring were observed for the age of attainment of the following physiologic parameters: pinna detachment, eye opening, testes opening. Offspring were also tested for the acquisition of the following selected reflexes: surface righting, negative geotaxis, auditory startle, air righting, and visual placing. Term fetal weight was lower than the controls in the group irradiated on the 9th day but was recuperable postnatally. None of the 9 developmental tests performed postnatally were abnormal in the animals irradiated on the 9th day. Thus, at least with regard to these measures, the surviving embryos exposed during the all-or-none period could not be differentiated from the controls. Offspring irradiated on the 17th day exhibited retarded growth which persisted during neonatal life. The three-day-mean neonatal weight was significantly lower in the group irradiated on the 17th day compared to controls. There were no significant maternal body weight or organ/weight differences between the groups. Rats exposed in utero on the 17th day had a significantly delayed acquisition of air righting. These results demonstrate that 0.6-Gy in utero irradiation on the 17th day of gestation can cause subtle alterations in growth and development of the Wistar strain rat during postnatal life.     

Coadaptation of prenatal and postnatal maternal effects

In a wide variety of species, a female's age of first reproduction influences offspring size and survival, suggesting that there exists an optimal timing of reproduction. Mothers in many species also influence offspring size and survival after birth through variation in parental care. We experimentally separated these effects in the burying beetle Nicrophorus vespilloides to test for coadaptation between prenatal and postnatal maternal effects associated with age at first reproduction. Females that reproduced early produced offspring with lower birth weight. The amount of parental care depended on the age of first reproduction of the caretaker, as did the extent of offspring begging. As predicted for a coadaptation of maternal effects, prenatal and postnatal effects were opposite for different-aged mothers, and larval weight gain and survival was greatest when the age of the caretaker and birth mother matched. Thus, prenatal effects intrinsically associated with age of first reproduction can be ameliorated by innate plasticity in postnatal care. A coadaptation of prenatal and postnatal maternal effects may evolve to allow variable timing of the first reproductive attempt. Such a coadaptation might be particularly valuable when females are constrained from reproducing at an optimal age, as, for example, in species that breed on scarce and unpredictable resources.