Showing papers on "Fetus published in 1973"

The Developing Human: Clinically Oriented Embryology

Abstract: 1. Introduction to The Developing Human 2. The Beginning of Human Development: First Week 3. Formation of Bilaminar Embryonic Disc: Second Week 4. Formation of Germ Layers and Early Tissue and Organ Differentiation: Third Week 5. Organogenetic Period: Fourth to Eighth Weeks 6. The Fetal Period: Ninth Week to Birth 7. Placenta and Fetal Membranes 8. Body Cavities, Mesenteries, and Diaphragm 9. The Pharyngeal Apparatus 10. The Respiratory System 11. The Digestive System 12. The Urogenital System 13. The Cardiovascular System 14. The Skeletal System 15. The Muscular System 16. The Limbs 17. The Nervous System 18. The Eye and Ear 19. The Integumentary System 20. Congenital Anatomical Anomalies or Human Birth Defects 21. Common Signaling Pathways Used During Development Appendix: Discussion of Clinically Oriented Problems

Care of the high-risk neonate

Abstract: 1. Antenatal and Intrapartum Care of the High-Risk Infant 2. Resuscitation of the Newborn Infant 3. Recognition, Stabilization and Transport of the High-Risk Newborn 4. Classification and Physical Examination of the Newborn Infant 5. The Physical Environment 6. Nutrition and Selected Disorders of the Gastrointestinal Tract Part I. Nutrition for the High-Risk Infant Part II. Selected Disorders of the Gastrointestinal Tract Part III. Necrotizing Enterocolitis 7. Care of the Parents 8. Nursing Practice in the Neonatal Intensive Care Unit 9. Respiratory Problems 10. Assisted Ventilation 11. Problems in Metabolic Adaptation: Glucose, Calcium and Magnesium 12. Neonatal Hyperbilirubinemia 13. Neonatal Infections 14. The Heart 15. The Kidney 16. Hematologic Problems 17. Brain Disorders of the Fetus and Neonate 18. The Outcome of Neonatal Intensive Care 19. Ethical Issues in the Perinatal Period Appendices: A-1 Drugs Used for Emergency and Cardiac Indications in Newborns A-2 Drug Dosing Table B-1 Drug Compatibility C-1 Blood Chemistry Values in Premature Infants During the First 7 Weeks of Life (Birth Weight 1500-1750 g) C-2 Other Serum Values C-3A Plasma-Serum Amino Acids in Premature and Term Newborns (mmol/L) C-3B Reference Serum Amino Acid Concentrations That Have Been Proposed as Standards for Neonates (mmol/L) C-4 Normal Hematologic Values C-5 Hematologic Values in the First Weeks of Life Related to Gestational Maturity C-6 White Cell and Differential Counts in Premature Infants C-7 Leukocyte Values and Neutrophil Counts in Term and Premature Infants D-1 Urine Amino Acids in Normal Newborns (mmol/day) E-1 Siggaard-Anderson Alignment Nomogram F-1 Cerebrospinal Fluid Findings in Term and Premature Infants F-2 Comparison of WBC Counts in Neonates With and Without Meningitis G-1 Fetal Growth Curves for Trimmed and Raw Data G-2 Fetal Growth by Selected References G-3 Smoothed Percentiles of Birth Weight (g) for Gestational Age: US 1991 Single Live Births to Resident Mothers G-4 Growth Record for Infants G-5 Head Circumference G-6 Intrauterine Growth Curves G-7 Low-Birth-Weight Infants Daily Growth-Weight G-8 Low-Birth-Weight Infants Weekly Growth-Head Circumference G-9 Low-Birth-Weight Infant Growth Curves, With and Without Major Morbidities G-10 The Time of First Void and Stool G-11 Mean Arterial Blood Pressure by Birth Weight G-12 Blood Pressure by Age and Gestational Age G-13 Blood Pressure by Age H-1 Percent Mortality and Major Morbidity by Birth Weight H-2 Mortality Risk by Birth Weight and Gestational Age I-1 Equipment Found on the Umbilical Catheterization Tray, University Hospitals, Cleveland, Ohio I-2 Umbilical Vessel Catheterization J-1 Conversion of Pounds and Ounces to Grams J-2 Conversion Table to Standard International (SI) Units J-3 Conversion Tables

Pulmonary arterial development during childhood: branching pattern and structure

Abstract: In lungs from 18 children aged between birth and 11 years the development of the branching pattern and structure of the pulmonary arteries, particularly the intralobular and intra-acinar, has been quantitatively analysed after injection with a radio-opaque medium. Up to 18 months of age as new alveolar ducts appear conventional arterial branches develop within the acinus: supernumerary arteries increase in number up to 8 years as new alveoli form. Both types increase in size with age. After birth there is an immediate drop in wall thickness of the vessels below 200 μm diameter while the larger vessels take up to 4 months to fall to adult thickness, suggesting two types of response—one dilatation, the other a growth rate change of the muscle cells. During childhood muscle cell formation in the intra-acinar arteries lags behind increase in artery size so that during childhood few muscular arteries are found within the acinus. The functional significance of these changes is discussed.

Effect of human chorionic somatomammotrophin and human chorionic gonadotrophin on phytohaemagglutinin-induced lymphocyte transformation.

Abstract: There is, as yet, no experimental evidence to explain why the foetus, a homograft, is not rejected by the mother1. Two of the many interesting features of the implanting blastocyst are that it is surrounded by maternal lymphocyte-like cells, and it has the ability to synthesize large quantities of the glycoprotein human chorionic gonadotrophin (HCG), which can be detected in both blood and urine almost immediately after implantation. The presence of HCG in urine forms the basis of a pregnancy test. At a later stage, the syncytiotrophobiastic cells which have differentiated from the blastocyst synthesize the polypeptide hormone human chorionic somatomammotrophin (HCS)2. It has been found in maternal blood during the fourth week after conception. Its concentration increases rapidly throughout pregnancy, reaching its peak in the last trimester3. It is possible that either or both of these polypeptide hormones, which are specific to the human placenta, may modify the immunological competence of maternal lymphocytes and could be factors in preventing rejection of the foetus. Using a standard technique, we have investigated the effect of the hormones on phytohaemagglutinin (PHA)-induced transformation of peripheral lymphocytes, which is a measure of cell-mediated immunity.

Radioimmunoassay of Testosterone During Fetal Development of the Rhesus Monkey

Abstract: A radioimmunoassay was developed for measuring testosterone (T) in the plasma of the rhesus monkey (Macaca mulatto). The method is sensitive and specific and can distinguish 20 pg of T when added to plasma from the adrenalectomized- ovariectomized monkey. When plasma obtained from cord blood at various times during gestation was analyzed by this method, the levels of T in plasma from the umbilical artery of males were significantly higher than those in females. Plasma from females did, however, contain small amounts of this hormone with little variation between animals. Large fluctuations in the concentrations of T in plasma from the fetal male were observed. Significantly higher amounts of T were found in the umbilical artery than in the vein in male but not in female fetuses. Castration of the fetus on day 100 of gestation abolished the sex difference in the amounts of T found on day ISO to 156 of gestation. These data indicate that the fetal testis of the monkey is the source of the elevated levels of ...

Mixed gonadal dysgenesis

Abstract: The syndrome of mixed gonadal dysgenesis (MGD) is characterized by a unilateral testis, usually intra-abdominal, a streak gonad on the contralateral side, and persistent Mullerian structures. The external genitalia are always masculinized to some extent, on occasion achieveing a normal male phenotype: the somatic signs of Turner9s syndrome are frequently present. These patients are always chromatin-negative, and appear to represent the commonest expression of the mosaicism of XO and XY cells, probably resulting from a cytogenetic era very early in embryogenesis. Patients with Turner9s syndrome who are slightly masculinized because of "hilus cells" in their streak gonads appear on the one hand to represent a clinical and cytogenetic stage intermediate between MGD and XO Turner9s syndrome; while on the other, certain male pseudohermaphrodites with bilateral dysgenetic testes are probably intermediate between MGD and the normal XY male. Testicular androgenic function appears to be quantitatively and qualitatively normal at puberty in MGD, despite complete lack of germ-cell proliferation. The discrepancy between normal Leydigcell function at puberty and the evidence of incomplete genital masculinization during fetal life may possibly be explained by delayed and asynchronous fetal testicular development. Although patients with unilateral gonadoblastoma and contralateral streak gonad were included in the original description of the syndrome of MGD, most such patients differ clinically and cytogenetically from patients with a testis and probably should be considered more akin to patients with the syndrome of pure gonadal dysgenesis, than to MGD.

Teratogenic effects of cadmium in rats

Abstract: The teratogenic effects of subcutaneous injections of cadmium in CD rats were investigated. Injections of 4–12 mg/kg CdCl2 on 4 consecutive days beginning on days 13–16 of gestation resulted in a dose-related rise in the fetal death rate, decrease in fetal weight, arid increase in the rate of anomalies. The anomalies included micrognathia, cleft palate, clubfoot, and small lungs. The lung/body weight ratios were significantly reduced in fetuses of animals injected with 8 mg/kg CdCl2 on days 14–17 of gestation. The data indicate that this was a specific retardation and not merely a reflection of differential organ growth rates and overall fetal growth retardation.

Growth and development of twins dissimilar in size at birth.

Abstract: Serial observations on nine pairs of monozygous twins who differed in birth weight on the average of 36 per cent indicated that the undersized members continue to be inferior in both growth and intelligence into adult life. Some equalization occurs in school performance, as opposed to test scores, suggesting that the smaller twin has made a compensatory effort. The twin who was smaller at birth remained the smaller in height, weight and head circumference. In the eight pairs who have reached maturity, mean differences continue to have the same order of magnitude as in previous comparisons, but head circumference is less affected than height and weight. Although monozygotic pairs are a useful model for study of the effect of fetal undergrowth on later development, interpretation must be done cautiously in view of the complex interaction of placental and environmental factors. (N Engl J Med 289:937–940, 1973)

Prenatal Diagnosis of GM1-Gangliosidosis

Abstract: Amniocentesis at 14 weeks' gestation on a mother who had previously had an affected child demonstrated Type 1 GM1-gangliosidosis. β-galactosidase activity was absent in cell-free amniotic fluid (normal, 33.2 ± 16 nmoles methylumbelliferyl β-D-galactoside hydrolysed per milliliter per hour). The enzyme activity in extracts of cultured amniocytes was 1 per cent of that in normal cells. The pregnancy was terminated by hysterotomy at 17 weeks' gestation. Vacuolation and abnormal inclusions were seen by light and electron microscopy in epon-embedded sections from brain, liver, kidney and other organs. Typical zebra bodies werefound in cells of the dorsal-rootganglions. β-galactosidase activity was present but decreased in liver and brain from the affected fetus, whereas sphingomyelinase activity was increased two to six times that in controls.

Placental Secretion of Unconjugated Estrone, Estradiol and Estriol into the Maternal and the Fetal Circulation

Abstract: The plasma concentrations of unconjugated estrone (E1), estradiol (E2) and estriol (E3) were measured by radioimmunoassay in plasma samples of umbilical artery (U.A.), umbilical vein (U.V.), retroplacental space (R.P.S.) and maternal peripheral vein (M.P.V.) of 5 patients at 10–20 weeks of pregnancy and 5 patients at term. The plasma concentrations of the 3 classical unconjugated estrogens were 4–7- fold higher in R.P.S. than in M.P.V. and 2-fold higher in U.V. than in U.A. (P < 0.05), indicating placental secretion of these estrogens into the maternal and fetal circulation. On the basis of the differences between U.V. and U.A. plasma concentrations and reported umbilical blood flow, it was estimated that the secretion rate of unconjugated Ea into the fetal circulation of 2.7 ± 1.7 (SK) mg/day was 1–8 times higher than that of E1, and E2 combined (1.0 ± 0.5 mg/day). Secretion into the fetal circulation of unconjugated E1, E2 and E3, was estimated, however, to be about 10-fold lower than that into the mate...

Teratogenic effects of methylmercury in the cat: note on the use of this species as a model for teratogenicity studies.

Abstract: Pregnancy was induced in cats by coordinating gonadotropin-induced behavioral estrus and ovulation with natural matings. Reproductive indices were comparable with those already known for pregnancies in normally cycling estrous cats. Cats were orally administered 0, 0.03, 0.83, 0.25, or 0.75 mg/kg Hg (as CH3HgCl) from day 10–58 of induced pregnancy and at near term fetuses were delivered by Cesarean section. 0.75 mg/kg caused vomiting, ataxia, and death within 32 days of commencement of treatment. At 0.25 mg/kg there was an increased incidence of abortion and fetal anomalies; in surviving fetuses a reduced neuronal population in the external granular layer of the cerebellum was noticed. Minimal or no embryopathic effects were noted at lower doses. Mercury concentrations were determined and were in the following decreasing order: fetal blood > maternal blood > fetal brain. The blood and the brain of the test dams had similar concentrations. The literature on congenital anomalies in cats is briefly reviewed.

Alpha fetoprotein: Physiology and pathology during pregnancy and application to antenatal diagnosis.

Abstract: Results on the alpha fetoprotein (AFP) concentrations in normal and pathological pregnancies are reported and the clinical significance of the serum AFP levels in the antenatal diagnosis of high risk pregnancies is evaluated. Sera from 204 pregnant women between the 8th and the 42nd week of gestation were studied for the normal range. The following types of high risk pregnancies were investigated: 67 sera from 20 diabetic women; 116 specimens from 74 pregnant women with toxemia or hypertension and 48 samples from 27 pregnant women with a liver disorder. Intrauterine fetal death occurred in 22 patients. Amniotic fluid specimens were collected from 55 normal pregnancies. Sera from 10 normal and 10 toxemic pregnancies were collected 4-19 weeks after delivery for the study of AFP antibodies. AFP was measured by a highly sensitive radioimmunoassay in tissue homogenate of an early human conceptus maternal serum and amniotic fluid in normal and high risk pregnancies. Human products of conception contained more AFP than maternal serum at the 4th week of gestation indicating that AFP is synthesized by the human conceptus at this early stage of development. The AFP concentrations in maternal serum increased with advancing gestation. Circulating maternal AFP concentrations increased in cases with severe fetoplacental dysfunction. It is assumed that the major part of the circulating maternal AFP originates from the fetus and that the increase above the normal pregnancy range of maternal serum AFP concentration can result from an increased fetal serum AFP level increased transplacental passage of fetal blood or transmission of fetal elements from the amniotic fluid to the mother. In normal amniotic fluid the AFP concentrations decreased during gestation. In high risk pregnancies increased AFP concentrations in amniotic fluid were associated with fetal distress. On the basis of these preliminary results it appears that the AFP concentrations of both maternal serum and amniotic fluid can be useful in the assessment of fetal state in high risk pregnancies.

Unconjugated estrogens in the perinatal period.

Abstract: Extract: High levels of unconjugated estrone ((E1) 3-hydroxyestra-1,3,5(10)-triene-17-one) and estradiol ((E2) estra-1,3,5(10)-triene-3,17β-diol) were found at term in maternal venous, umbilical vein, and umbilical artery plasma. For estrone the respective values in nanograms per milliliter ±SD were 12.8 ± 5.9, 25.1 ± 6.5, and 13.2 ± 7.7. For estradiol the respective values were 17.3 ± 9.2, 8.1 ± 4.0, and 5.1 ± 3.2. For estrone, levels for umbilical vein were higher than those in the paired maternal and umbilical artery; estradiol was higher in maternal vein than in the paired umbilical vessels. Absence of the fetal adrenals was associated with low levels of estrone and estradiol for maternal and umbilical vessels, whereas, in anencephaly, only the maternal levels were markedly diminished. An initially rapid, and then a slower decline in both estrogens was found in normal infants during the first 72 hr of life.

Relationships between fetal weight, placental weight and maternal placental circulation in the rabbit at different stages of gestation

Abstract: Fetal weights, placental weights, myometrial, vaginal and maternal placental blood flows (estimated with radioactive micro\x=req-\ spheres) were measured in forty-one rabbits at 16, 20, 24 or 28 days of gestation; term occurs around Day 31. Multiple linear regression analysis indicated that fetal weight and placental weight were positively related at all stages of gestation examined. Fetal weight and placental blood flow were negatively related at Day 16, but positively related at Days 20, 24 and 28. The conceptus adjacent to the ovary had greater placental weight and flow values than the means from all conceptuses in the horn by Day 20 but fetal weight was only greater by Day 28. The relevance of these findings to the determination of fetal weight is discussed.

Phenylalanine Hydoxylase in Human Liver during Development

Abstract: Extract: Phenylalanine hydroxylase activity is present in the liver of human fetuses after the 8th week of gestation, and activities similar to those found in liver from adult control subjects are reached at around the 13th fetal week. The mean enzyme activity in fetal liver after the 13th week of gestation was 107 μmoles tyrosine formed per g protein per hr, and 130 μumoles in livers from adult control subjects. In premature infants soon after birth the mean enzyme activity was 67 μmoles tyrosine formed. This difference from the level of activity in fetuses could be due to loss of activity during the 1–3-hr delay in obtaining liver samples after death. When the pteridine cofactor was omitted from the enzyme assay system only very low activity was found in the livers of fetuses which were studied. Tyrosine was formed when isolated fetal livers were perfused with phenylalanine. The Km for phenylalanine hydroxylase from the liver of human fetuses was 9 × 10-4 m and for liver from adults was 1 × 10-3 m. Thus, the human fetus and immature newborn infant do not lack phenylalanine hydroxylase in the liver. Speculation: The human fetus and immature newborn infant have considerable phenylalanine hydroxylase activity in the liver. The hyperphenylalaninemia or reduced tolerance for phenylalanine found in some infants with low birth weight should thus, not be paralleled with a transient form of phenylketonuria, but could rather be caused by a reduced efficiency of some other component of the phenylalanine-hydroxylating system.

Serum and thyroid gland triiodothyronine in the human fetus

Abstract: Serum T3 concentrations are low (<15 ng/100 ml) before 24 weeks and increase progressively thereafter to term, but both T3 and free T3 (FT3) levels are lower than paired maternal concentrations. Moreover, throughout gestation T4/T3 and FT4/FT3 ratios consistently exceed paired maternal ratios. The mean T4/T3 content ratio of fetal thyroid glands (14.3) is similar to that (19.5) of adult glands. These data indicate that a state of relative fetal T3 deficiency exists in the human as in the sheep. This deficiency probably is not due to decreased T3 secretion.

Maternal and fetal distribution of drugs in pregnancy.

Abstract: The disposition of drugs in the maternal-placento-fetal unit is influenced by several inter-reacting processes. Placental transfer of pharmacologically active molecules is modulated by characteristics of the drugs (e.g., lipid solubility, degree of ionization at physiologic pH, molecular weight) and properties of the placenta (e.g., maternal and fetal blood flow, drug metabolism, placental age). The distribution of drugs in the fetus may be determined by differences in permeability of specialized membranes (blood-brain barrier, renal tubule), binding to specific cellular constituents (binding proteins), selective distribution of the fetal circulation, and active secretion of drugs by the yolk sac. In a general sense the pattern of drug distribution in the fetus frequently resembles that of the mother; however unique differences in absolute tissue concentrations of drugs may occur as a result of increased drug transfer rates into specific tissues. Many compounds crossing the placenta initially concentrate in the fetal liver so that levels in systemic fetal blood may be Significantly different from umbilical venous concentrations. Consequently, the detection of unusual patterns of drug distribution in the fetus that may prove useful in assessing the potential hazards of maternal drug therapy will require more comprehensive data than can be provided by umbilical vessel blood concentrations alone.

Hemoglobin A synthesis in the developing fetus.

Abstract: To determine when synthesis of hemoglobin A (composed of 2 α and 2 β chains and the hemoglobin predominant in the human adult) begins in the fetus, hemoglobin synthesis was measured in fetuses of various gestational ages. Synthesis of hemoglobin A by reticulocytes obtained from 42 embryos and fetuses 3.5 to 20.0 cm in crown-to-rump length accounted for 4.3 to 13.0 per cent of total hemoglobin synthesis, and varied directly with fetal crown-to-rump length. Since the smallest embryo was estimated to be 55 days old, β-chain synthesis has begun by that gestational age. Furthermore, since β thalassemia is characterized by decreased β-chain synthesis, the accurate diagnosis of this condition in fetuses depends on knowledge of the values for hemoglobin A synthesis in normal fetuses of variousgestational ages. (N Engl J Med 289:58–62, 1973)