Showing papers on "Fetus published in 1977"

Morphological effects of chronic tracheal ligation and drainage in the fetal lamb lung.

Abstract: The relationship between lung liquid flow and fetal lung development has been studied at the cellular level using ultrastructural techniques. Continuous in utero tracheal ligation and drainage (over a period of 21-28 days) both result in malformations of the developing fetal lamb lung. Ligated lungs are larger, and drained lungs are smaller, than normal lungs at a similar gestational age. These changes are not merely due to altered lung liquid volume, but actual tissue growth thas been affected. Future alveolar wall thinning is enhanced in ligated lungs and inhibited in drained lungs, whilst the presence of differentiated alveolar type II cells (probably related to surfactant production) is decreased in ligated lungs and markedly enhanced in drained lungs. These results indicate the importance of fetal lung liquid in the regulation of pulmonary development in the fetus.

Catecholamine release in the newborn infant at birth.

Abstract: Catecholamines were determined by a fluorimetric technique in umbilical blood which was collected from newborn infants immediately after birth. The mean catecholamine concentration was 62.1 nmol/liter in the umbilical artery and 29.3 nmol/liter in the umbilical vein of newborn full term infants delivered uneventfully. This value is considerably higher than in resting adults. Similar levels of catecholamines were seen after elective cesarean sections, whereas considerably higher levels were found after breech deliveries. In the full term asphyxiated infants about a 4-fold increase of the catecholamine concentration was found in both the umbilical arterial and venous blood. The amine concentration level correlated inversely to the pH below 7.25 (10 log catecholamine concentration versus pH, r = -0.71). Preterm infants had, in general, lower amine levels than full term infants both after uneventful deliveries and after intrauterine asphyxia. The catecholamine levels were considerably increased in the newborn infants who showed some kind of abnormal fetal heart rate variation during the last hour before birth; in particular baseline changes were associated with high levels whereas only a moderate increase was seen after loss of beat-to-beat variation.

Human pancreatic carcinoma (MIA PaCa-2) in continuous culture: sensitivity to asparaginase.

Abstract: An undifferentiated human pancreatic carcinoma has been established in continuous culture and is grown in Dulbecco's modified. Eagle's medium fortified with 10% fetal calf serum and 2.5% horse serum. The established cell line (MIA PaCa-2) has a doubling time of 40 h. The cells are large with abundant cytoplasm, exhibit a high degree of aneuploidy and have a tendency to grow on top of other cells. MIA PaCa-2 grows in soft agar with a colony-forming efficiency of 19%. Both MIA PaCa-2 cells and a cell line from another pancreatic carcinoma obtained from National Cancer Institute (NCI) are sensitive to asparaginase, a property not shared by several other human tumor cell lines tested.

hCG Binding and Stimulation of Testosterone Biosynthesis in the Human Fetal Testis

Abstract: The role of hCG in the regulation of testicular steroid production in human fetuses from 14 to 20 weeks gestational age was studied. Saturable binding of 125I-hCG to testicular homogenates was demonstrated, and physiologic concentrations of hCG were able to stimulate testosterone formation in testicular minces without the addition of exogenous precursors. In five fetses of 16-20 weeks gestational age, the capacity to bind hCG varied from 25.6 to 42.2 pg/mg wet tissue. The association constant of binding was 1.07+/-0.12 X 10(10) M-1. Testicular minces from six other fetuses (gestational age 14-19 weeks) were incubated in the presence of concentrations of 0, 0.5, 5 or 50 ng/ml NIH-hCG (1 mg=10,000 IU), which are within the physiologic range. Preincubation of 30 min in excess buffer was necessary to observe clear differences in testosterone production rates between controls and hCG stimulated testicular tissues. The greatest increase in testosterone production occurred when the hCG concentration was increased from 0.5 to 5 ng/ml. Little additional stimulation was observed at a concentration of 50 ng/ml. Maximal production rates of up to 12 ng/mg tissue/h were seen. It is concluded that human fetal testes bind hCG, and that physiologic levels of hCG stimulate fetal testicular testosterone formation in vitro at this stage of gestation.

The placental transfer of propylthiouracil, methimazole and carbimazole.

Abstract: The placental transfer of 35S-labelled methimazole (MMI), carbimazole and propylthiouracil (PTU) has been examined in the rat in late pregnancy and in patients undergoing therapeutic abortion. Although rapid equilibrium of fetal and maternal serum radioactivity (FS:MS ratio 1:1) occurred after iv administration of 35S-carbimazole or 35S-MMI in rats, a persistent fetal to maternal ratio of less than one was observed after 35S-PTU administration. Results from human studies after a single oral dose indicate that, as in the rat, the placenta appeared to be more permeable to 35S-MMI than to 35S-PTU as shown by the marked difference in fetal serum:maternal serum ratios and amounts accumulated in the fetus. Localization of radioactivity in the human fetal thyroid was also observed after administration of 35S-labelled MMI, carbimazole or PTU.

Ontogeny of Amniote Fetal Membranes and Their Application to Phylogeny

Abstract: The extraembryonic or fetal membranes of vertebrates play an important functional role in the nutrition, respiration, excretion, and protection of the embryo and fetus during prenatal life. They are auxiliary structures which develop in continuity with the tissues of the embryo proper, and both embryo and fetal membranes are derived from the same three basic germ layers (ectoderm, mesoderm, and endoderm). The fetal membranes are transitory structures which persist for only a relatively brief period during the ontogeny of the individual; nevertheless, their functional differentiation is essential for the normal development of the embryo during prenatal life. The functional life of the fetal membranes is terminated at the time of birth or hatching; they may become partially resorbed into the body of the newborn, or, more commonly, they become disrupted and degenerate.

Fetal metabolic response to maternal fasting in the rat

Abstract: To determine the fetal response to altered maternal fuel supply, the effects of prolonged maternal fasting, begun 24-96 h before term, were examined and compared with values from normally fed term animals. Fetal weight decreased only after 48 h of maternal fasting. Prolonged maternal fasting was associated with low blood glucose, high blood ketone bodies, and decreased gluconeogenic substrate in the fetus. Plasma insulin was decreased, whereas plasma glucagon was increased in the fetus of fasted mothers. Infusion of [2-3H]glucose into the mother to constant specific activity gave a ratio of maternal to fetal glucose activity of 1.0 in fed and 1.56 in fasted mothers. Fetal liver from fasted mothers showed both increase in activity of key gluconeogenic enzymes (glucose-6-phosphatase and phosphoenolpyruvate carboxykinase) and increased conversion in vitro of lactate, alanine, serine, and glycerol in glucose by liver slices. It is inferred that maternal fasting induces fetal substrate alterations and hormonal changes appropriate to premature appearance of hepatic gluconeogenesis. The priority for endogenous fuel provision in this state leads to impaired fetal growth.

Prenatal exposure to diethylstilbestrol in mice: Toxicological studies

Abstract: The effect of prenatal exposure to diethylstilbestrol (DES) on the postnatal development of male and female genital tract function was studied. The placental transfer or radiolabeled (3H or 14C) DES was studied in pregnant mice. DES-associated radioactivity in the fetal plasma approximated that in maternal plasma 1/2 hr after intravenous administration of [3H]DES; 3H activity corresponding to DES in the fetal genital tract was about threefold higher. The decrease in reproductive capacity of female offspring from mice treated with DES during gestation was dose-related; a low incidence (10% or less) of cancer of the vagina, cervix, and/or uterus was also observed in these mice. Male offspring exposed prenatally to the highest dose (100 microng/kg) of DES in this study also had lower reproductive capacities. Lesions in the genital tract of these mice included epididymal cysts, inflammation, cryptorchidism, and nodular masses in the seminal vesicles and/or prostate gland. Such lesions and sterility were not observed at the lower DES doses. Histological studies with neonatal mice raise the possibility that Mullerian duct tissue may represent a site for the transplacental toxicity of DES in both the male and female fetus.

Viral contamination of bovine foetal serum and cell cultures

Abstract: THE presence of adventitious viruses in cell cultures is well recognised1, and when the cultures are of primate origin there are serious hazards for the production of human viral vaccines2. This is one reason for the increasing use of bovine cell cultures. These cultures, however, are not free from viral contamination3. We found that calf kidney (CK) and calf testis (CT) cells were often infected by non-cytopathic mucosal disease virus (MDV): the cells seemed morphologically healthy but nearly all showed fluorescence with MDV antiserum and rabbit-anti-bovine conjugate. We report here that both the cells and foetal calf serum, an essential growth factor of cell culture medium, are sources of the virus.

Effects of Fetal or Maternal Hypophysectomy on Endocrine Organs and Body Weight in Infant Rhesus Monkeys (Macaca mulatta): With Particular Emphasis on Oogenesis

Abstract: The effects of maternal and fetal hypophysectomy on the development of the fetal endocrine glands and oogenesis were studied in the rhesus monkey (Macaca mulatta). Maternal hypophysectomy was carried out between 58-71 days of pregnancy and fetal hypophysectomy was performed between 114-117 days of pregnancy. A generalized retardation of fetal growth was produced by maternal but not fetal hypophysectomy. Maternal hypophysectomy significantly (p less than .05) reduced the mean adrenal though not thyroid weights of term infants. On the other hand fetal hypophysectomy significantly (p less than .05) reduced mean ovarian adrenal and thyroid weights in term infants. The morphology of term infant ovaries was not adversely affected by maternal hypophysectomy. The ovaries of infants showed disrupted oogenesis and atretic oocytes following ablation of the fetal hypophysis. Fetal hypophysectomy resulted in a reduction in total numbers of germ cells and a marked increase in the percentage of germ cells undergoing atresia. The percentage of atretic germ cells in ovaries of term infants under the influence of maternal hypophysectomy was similar to that of intact controls even though the total number of germ cells was about 1/2 that of intact controls. It is concluded that the survival of gametes within the fetal ovaries of this species depends primarily on the secretions of the fetal pituitary.

Morphine and Brain Growth Retardation in the Rat

Abstract: Fetal and infant rats were maternally exposed to morphine sulfate during gestation and lactation. Drug was administered twice daily by i.p. injection, with dosages gradually increased from 10 mg/kg/in

Intra-uterine healing of fetal rat oral mucosal, skin and cartilage wounds.

Abstract: . Orofacial wounds, including rupture of the palate, were surgically created in utero on 19½ day Sprague Dawley rat fetuses. Six hours prior to sacrifice 0.1 mgm/100 gm maternal body weight of colchicine was injected subcutaneously. Five fetuses in each group of operated and unoperated controls were sacrificed at 0, 24, 48 and 72 h postoperatively. Serial histological sections in the frontal plane were stained with hemotoxylin and eosin and modified Mallory's. Rapid and complete epithelialization of oral and skin wounds was observed within the 72 h period. There was a complete lack of inflammatory response, scab formation and involvement of nasal epithelium in healing. Nasal cartilage wounds rapidly rounded off and the perichondrium reformed without evidence of callus formation. These findings are discussed in regard to the etiology of some congenital defects and the prospect of fetal surgical correction of orofacial deformity.

Prenatal Diagnosis of Duchenne's Muscular Dystrophy

Abstract: Two pregnancies at risk for X-linked recessive Duchenne's muscular dystrophy were studied at 18 and 20 weeks. Fetal blood was obtained by placental aspiration for measurement of plasma creatine phosphokinase activity. Activity in the first fetus was 96 IU per liter, as compared to a control range of 0 to 150 IU per liter in 16 pregnancies not at risk for the disorder. The pregnancy continued, and the infant was normal after birth. In the second fetus creatine phosphokinase activity was significantly elevated to 540 IU per liter (P<0.001). Fetal blood also showed considerable hemolysis, an unusual observation in placental blood sampling. After abortion, examination of fetal muscle by light, phase and electron microscopy showed characteristic features of Duchenne's muscular dystrophy, including wide variation in muscle-fiber diameter and reduction in the number of fibers per fasciculus. These cases illustrate the potential usefulness of fetal plasma for prenatal diagnosis and, specifically, of crea...

Autonomic control of cardiovascular functions during neonatal development and in adult sheep.

Abstract: We studied the autonomic control of resting heart rate of systemic and pulmonary vascular blood pressures (BP) in chronically instrumented neonatal lambs 1-8 weeks of age. The maximum response to ganglionic blockade and sympathetic and parasympathetic antagonists was taken as an index of the magnitude of the total neural, adrenergic, and cholinergic tones. The reactivity of the circulatory parameters to adrenergic and cholinergic agonists also was investigated. All findings were compared with those in adult nonpregnant sheep studied concomitantly and with data previously obtained from term fetal lambs. The results of our studies show: (1) resting heart rate declines spontaneously throughout the 8 weeks of neonatal life approaching that of adult sheep; (2) the progressive bradycardia is not related to changes in the parasympathetic or sympathetic tone; (3) resting systemic BP is under strong neurohumoral control during the first two to three weeks of neonatal life; the control decreases progressively, becoming similar to that of adult sheep; (4) resting pulmonary artery pressure of neonatal and adult sheep has no neurohumoral control; (5) the systemic BP response of the neonate to autonomic agonists is greater than that of the term fetus and is similar to that of the adult; (6) in neonatal and adult sheep, compared to the term fetus, the pressor response to norepinephrine is accompanied by a baroreceptor-mediated bradycardia, and acetylcholine-induced systemci hypotension is accompanied by a "paradoxical" tachycardia mediated through beta-adrenergic stimulation; (7) in contrast to our finding for the fetus, the pulmonary vascular pressure of neonatal and adult sheep is unresponsive to autonomic agonists.

B lymphocyte development in fetal liver. I. Development of reactivities to B cell mitogens "in vivo" and "in vitro"

Abstract: Single cell suspensions of fetal liver cells, prepared from embryos at day 13 of gestation until birth, develop mitogen bacterial lipopolysaccharide (LPS)-reactive B cells “in vitro” within the same time as they do “in vivo”. The development of these mitogen LPS-reactive B cells in vitro is dependent on unknown components of fetal calf serum, found in some but not all batches. It does not require the presence of the corresponding B cell mitogens, i.e. LPS, in culture. Fetal liver cells, put in culture at different times of gestation, all acquire LPS reactivity at the equivalent of birth in vitro. When the cells have become LPS-reactive, they are then stimulated by LPS to growth and maturation into clones of IgM-secreting, IgA-secreting and IgG-secreting plaque-forming cells (PFC). The development of these PFC responses is mitogen-dependent: in the absence of LPS only 2-5 % of the LPS-stimulated PFC responses develop. Only the magnitude, but not the development in time, of LPS reactivity of fetal liver cells is different in vivo and in vitro. This may indicate either that an early precursor cell to LPS-reactive B cells can only divide in vivo but not in vitro, or that early precursors continue to migrate with time of gestation into fetal liver. After birth B cells in liver are immediately reactive to LPS; however, they rapidly leave the liver. Few, if any, dextrans sulfate or lipoprotein-reactive B cells, yielding a PFC response, develop in fetal liver cells either in vivo or in vitro. Neonatal spleen contains immediately mitogen-reactive B cells. Comparable numbers of LPS, dextran sulfate and lipoprotein-reactive cells are found. Development of fetal liver cells to Ig-secreting PFC, occurs, therefore, in two stages. The first (pre-B B) is independent of externally added mitogen (such as LPS), the second (B PFC) requires the addition of mitogen. The majority of spleen cells have already passed this first stage of development.

A critical review of current methods for induction of parturition in the mare.

Abstract: The efficacy and safety of oxytocin, dexamethasone and prostaglandin, used alone or in combination as inducing agents, are discussed. It is contended that insufficient evidence exists to support the routine application of any of these methods in practice. Oxytocin has been the most widely used and it is claimed by some to be free from side effects. However, the synthetic prostaglandin analogue, fluprostenol, seems to pose the least risk to the foetus and dexamethasone appears to be either ineffective, or too dangerous to use at all. The main indications for induced foaling are managerial convenience or for research and teaching purposes. There are few clinical indications, although ventral rupture and cases of prolonged gestation have been mentioned by various workers. It is considered that foetal maturity is the pre-requisite before a decision to induce should be made in practice, and 3 criteria are essential: 1) a gestational length of greater than 320 days, 2) substantial mammary development, 3) the presence of colostrum in the mammae.

Quantitative structural study of pulmonary circulation in the newborn with pulmonary atresia.

Abstract: The lungs of eight newborn infants who had died from pulmonary atresia were studied by quantitative morphometric techniques. It was established for the first time that the abnormal pattern of blood flow through the heart and great vessels in a fetus with pulmonary atresia is associated with impaired lung development as shown by arteries that are too few, too small, and with an abnormally thin muscle coat, although the distribution of muscle along the arterial pathway is normal. Differences between the cases in the degree of impairment of lung development could be detected and related to the degree of reduction in pressure and flow before birth in the individual case. Although blood flow through the pulmonary circulation is small before birth lung development seems sensitive to any further reduction.

Fetal fuels. I. Utilization of ketones by isolated tissues at various stages of maturation and maternal nutrition during late gestation.

Abstract: The availability and utilization of B-hydroxybutyrate as an alternate oxidative fuel during fasting hypoglycemia has been examined in the rat conceptus at 18 and 20 days gestation. A 48-hr maternal fast between days 16 and 18 or 18 and 20 resulted in a 50% fall in fetal glucose levels and a marked rise in B-hydroxybutyrate, i.e., 30-fold at 18 and 60-fold at 20 days. Tissue concentrations of B-hydroxybutyrate or acetoacetate did not exceed extracellular levels. Placenta, fetal brain, carcass, and liver all oxidized 14C-labeled B-hydroxybutyrate to 14CO2 when incubated in vitro in the presence of B-hydroxybutyrate. Highest rates of oxidation were apparent in the placenta, followed by brain, liver, and carcass. The D isomer of B-hydroxybutyrate appeared to be oxidized preferentially by all tissues studied. Despite levels of 3-ketoacid CoA transferase and acetoacetyl CoA thiolase lower at 18 than at 20 days, rates of oxidation in individual tissues incubated under identical concentrations of substrate were similar at both times. In liver and brain, increasing rates of 14CO2 generation proportionate to graded concentrations of B-hydroxybutyrate in vitro indicated that such rates were probably determined by substrate availability. B-hydroxybutyrate oxidation in extrahepatic fetal tissues was unaffected by maternal fasting. By contrast, fetal liver derived from fasted mothers generated significantly less 14CO2 from B-hydroxybutyrate than livers from fed mothers. It has been suggested that capabilities for ketone utilization are widespread in tissues of the conceptus, and that such utilization may fulfill in part the oxidative demands for continued anabolic growth during fasting hypoglycemia in the mother.

Vitamin A and retinol-binding protein metabolism during fetal development in the rat.

Abstract: Studies were conducted on the metabolism and placental transport of vitamin A and plasma retinol-binding protein (RBP) during fetal development in the rat. Vitamin A accumulated in the conceptus in three phases: an early phase (days 7-9 of gestation) characterized by a high vitamin A concentration; a second phase (days 11-14) where vitamin A and RBP accumulated in parallel; and a third phase of continued vitamin A and RBP accumulation (days 16-20) in which vitamin A was stored in the fetal liver. The early phase of vitamin A accumulation may reflect a mechanism that exists to prepare the conceptus to meet the presumably higher vitamin A requirements of the critical period (days 10-14) of organ differentiation. Fetuses and placentas from retinol-deficient dams showed low levels of RBP through days 16-18 of gestation. A retinol-repletion study suggested, moreover, that the maternal retinol-RBP complex crossed the placenta. The various studies all suggest that vitamin A is transported from dam to fetus, from and after day 11, mainly by transplacental transport of maternal retinol-RBP. Finally, evidence was obtained indicating that the fetal liver begins to synthesize RBP around the 16th day of gestation and that by the 20th day, the fetal liver has a considerable capacity for RBP synthesis.