Showing papers on "Fetus published in 1974"

Studies of insulin, growth hormone and prolactin binding: ontogenesis, effects of sex and pregnancy.

Abstract: The ontogenesis of specific binding of 125I-labeled insulin, hGH and oPRL was measured in tissues from rat, rabbit and guinea pig. Binding of 125I-oPRL and 125I-hGH was very low in liver membranes from fetal and immature rats. A 9- fold (oPRL) and 3.5-fold (hGH) increase in binding occurred between 20 and 40 days of age with a greater increase in binding in mid and late pregnancy. Binding to male liver membranes was significantly lower at all stages of development. There were no significant changes in the binding of 125I-hGH from fetal through 30 day rabbit liver membranes. Between 30 and 60 days of age, a 6-fold increase in binding occurred, with a further increase in binding during pregnancy. A similar overall pattern was observed with I25I-bGH. The increase in specific binding of 125I-oPRL was more gradual and occurred earlier than for 125I-GH. In the guinea pig, three patterns of 125I-insulin binding with respect to development were observed. Fetal placenta and kidney showed marked increase in specifi...

Before We Are Born: Essentials of Embryology and Birth Defects

Abstract: 1 - Introduction to Human Development Importance of and Advances in Embryology Descriptive Terms Clinically Oriented Questions 2 - Human Reproduction Reproductive Organs Female Reproductive Organs Male Reproductive Organs Gametogenesis Meiosis Spermatogenesis Oogenesis Comparison of Male and Female Gametes Female Reproductive Cycles Ovarian Cycle Menstrual Cycle Transportation of Gametes Oocyte Transport Sperm Transport Maturation of Sperms Viability of Oocytes and Sperms Clinically Oriented Questions 3 - First Week of Human Development Fertilization Phases of Fertilization Results of Fertilization Cleavage of Zygote Formation of Blastocyst Clinically Oriented Questions 4 - Second Week of Human Development Formation of Amniotic Cavity, Embryonic Disc, and Umbilical Vesicle Development of Chorionic Sac Implantation Sites of Blastocytes Clinically Oriented Questions 5 - Third Week of Human Development Gastrulation: Formation of Germ Layers Primitive Streak Notochordal Process and Notochord Neurulation: Formation of the Neural Tube Neural Plate and Neural Tube Neural Crest Formation Development of Somites Development of Intraembryonic Coelom Early Development of Cardiovascular System Vasculogenesis and Angiogenesis Development of Chorionic Villi Clinically Oriented Questions 6 - Fourth to Eighth Weeks of Human Development Folding of Embryo Head and Tail Folds Lateral Folds Germ Layer Derivatives Control of Embryonic Development Estimation of Embryonic Age Highlights of the Fourth to Eighth Weeks Fourth Week Fifth Week Sixth Week Seventh Week Eighth Week Clinically Oriented Questions 7 - Fetal Period: The Ninth Week to Birth Highlights of Fetal Period Nine to Twelve Weeks Thirteen to Sixteen Weeks Seventeen to Twenty Weeks Twenty-One to Twenty-Five Weeks Twenty-Six to Twenty-Nine Weeks Thirty to Thirty-Eight Weeks Expected Date of Delivery Factors Influencing Fetal Growth Procedures for Assessing Fetal Status Ultrasonography Diagnostic Amniocentesis Chorionic Villus Sampling Cell Cultures Percutaneous Umbilical Cord Blood Sampling Magnetic Resonance Imaging Fetal Monitoring Alpha-Fetoprotein Assay Noninvasive Prenatal Diagnosis Neonatal Period Clinically Oriented Questions 8 - Placenta and Fetal Membranes Placenta Decidua Development of Placenta Fetomaternal Junction Intervillous Space Amniochorionic Membrane Placental Circulation Parturition Stages of Labor Placenta and Fetal membranes after Birth Umbilical Cord Amnion and Amniotic Fluid Significance of Amniotic Fluid Umbilical Vesicle Significance of Umbilical Vesicle Allantois Multiple Pregnancies Twins and Fetal Membranes Other Types of Multiple Births Clinically Oriented Questions 9 - Body Cavities, Mesenteries, and Diaphragm Embryonic Body Cavity Mesenteries Division of Embryonic Body Cavity Development of Diaphragm Septum Transversum Pleuroperitoneal Membranes Dorsal Mesentery of Esophagus Muscular Ingrowth from Lateral Body Walls Positional Changes and Innervation of the Diaphragm Clinically Oriented Questions 10 - Pharyngeal Apparatus, Face, and Neck Pharyngeal Arches Pharyngeal Arch Components Pharyngeal Pouches Derivatives of Pharyngeal Pouches Pharyngeal Grooves Pharyngeal Membranes Development of Thyroid Gland Development of Tongue Lingual Papillae and Taste Buds Nerve Supply of Tongue Development of Salivary Glands Development of Face Development of Nasal Cavities Paranasal Sinuses Development of Palate Primary Palate Secondary Palate Clinically Oriented Questions 11 - Respiratory System Development of Larynx Development of Trachea Development of Bronchi and Lungs Maturation of Lungs Clinically Oriented Questions 12 - Alimentary System Foregut Development of Esophagus Development of Stomach Development of Duodenum Development of Liver and Biliary Apparatus Development of Pancreas Development of Spleen Midgut Rotation of Midgut Loop Cecum and Appendix Hindgut Cloaca Anal Canal Clinically Oriented Questions 13 - Urogenital System Development of Urinary System Development of Kidneys and Ureters Positional Changes of Kidneys Changes in Blood Supply of Kidneys Development of Urinary Bladder Development of Urethra Development of Suprarenal Glands Development of Genital System Development of Gonads Development of Genital Ducts Development of External Genitalia Development of Inguinal Canals Relocation of Testes and Ovaries Descent of Testes Descent of Ovaries Clinically Oriented Questions 14 - Cardiovascular System Early Development of Heart and Blood Vessels Development of Veins Associated with Embryonic Heart Pharyngeal Arch Arteries and Other Branches of the Dorsal Aorta Fate of Vitelline and Umbilical Arteries Later Development of Heart Circulation through Primordial Heart Partitioning of Primordial Heart Changes in Sinus Venosus Primordial Pulmonary Vein and Formation of Left Atrium Partitioning of Primordial Ventricle Partitioning of Bulbus Cordis and Truncus Arteriosus Development of Cardiac Valves Conducting System of Heart Birth Defects of Heart and Great Vessels Derivatives of Pharyngeal Arch Arteries Derivatives of First Pair of Pharyngeal Arch Arteries Derivatives of Second Pair of Pharyngeal Arch Arteries Derivatives of Third Pair of Pharyngeal Arch Arteries Derivatives of Fourth Pair of Pharyngeal Arch Arteries Fate of Fifth Pair of Pharyngeal Arch Arteries Derivatives of Sixth Pair of Pharyngeal Arch Arteries Pharyngeal Arch Arterial Birth Defects Fetal and Neonatal Circulation Fetal Circulation Transitional Neonatal Circulation Derivatives of Fetal Vessels and Structures Development of the Lymphatic System Development of Lymph Nodes Development of Spleen and Tonsils Clinically Oriented Questions 15 - Musculoskeletal System Skeletal System Development of Cartilage and Bone Histogenesis of Cartilage Histogenesis of Bone Development of Joints Fibrous Joints Cartilaginous Joints Synovial Joints Development of Axial Skeleton Development of Vertebral Column Cartilaginous Stage of Vertebral Development Bony Stage of Vertebral Development Development of Ribs Development of Sternum Development of Cranium Development of Appendicular Skeleton Muscular System Development of Skeletal Muscle Development of Smooth Muscle Development of Cardiac Muscle Development of Limbs Early Stages of Limb Development Final Stages of Limb Development Cutaneous Innervation of Limbs Blood Supply of Limbs Clinically Oriented Questions 16 - Nervous System Development of Nervous System Development of Spinal Cord Development of Spinal Ganglia Development of Spinal Meninges Positional Changes of Spinal Cord Myelination of Nerve Fibers Birth Defects of Spinal Cord Development of Brain Brain Flexures Hindbrain Myelencephalon Metencephalon Choroid Plexuses and Cerebrospinal Fluid Midbrain Forebrain Congenital Anomalies of Brain Development of Peripheral Nervous System Spinal Nerves Cranial Nerves Development of Autonomic Nervous System Sympathetic Nervous System Parasympathetic Nervous System Clinically Oriented Questions 17 - Development of Eyes and Ears Development of Eyes and Related Structures Development of Retina Development of Choroid and Sclera Development of Ciliary Body Development of Iris Development of Lens Development of Aqueous Chambers Development of Cornea Development of Eyelids Development of Lacrimal Glands Development of Ears Development of Internal Ears Development of Middle Ears Development of External Ears Clinically Oriented Questions 18 - Integumentary System Development of Skin and Appendages Epidermis Dermis Development of Glands Development of Hairs Development of Nails Development of Mammary Glands Development of Teeth Bud Stage of Tooth Development Cap Stage of Tooth Development Bell Stage of Tooth Development Tooth Eruption Clinically Oriented Questions 19 - Human Birth Defects Teratology: Study of Abnormal Development Birth Defects Caused by Genetic Factors Numerical Chromosomal Abnormalities Structural Chromosomal Abnormalities Birth Defects Caused by Mutant Genes Birth Defects Caused by Environmental Factors Principles of Teratogenesis Human Teratogens Environmental Chemicals as Teratogens Infectious Agents as Teratogens Radiation as a Teratogen Maternal Factors as Teratogens Mechanical Factors as Teratogens Birth Defects Caused by Multifactorial Inheritance Clinically Oriented Questions 20 - The Cellular and Molecular Basis of Development Intercellular Communication Gap Junctions Cell Adhesion Molecules Morphogens Retinoic Acid Transforming Growth Factor-ss/Bone Morphogenetic Protein Sonic Hedgehog Wnt/ss-Catenin Pathway Receptor Tyrosine Kinases Common Features Regulation of Angiogenesis by Receptor Tyrosine Kinases Notch-Delta Pathway Transcription Factors Hox/Homeobox Proteins Pax Genes Basic Helix-Loop-Helix Transcription Factors Epigenetics DNA Methylation Histone Modifications Stem Cells: Differentiation versus Pluripotency Summary of Common Signaling Pathways Used during Development Bibliography and Suggested Reading Answers to Clinically Oriented Questions Index

Circulatory changes in the reproductive tissues of ewes during pregnancy.

Abstract: The blood flows to reproductive organs were measured by means of radionuclide-labeled microspheres in 24 pregnant ewes with gestational ages ranging from 38 to 141 days. The microspheres were injected

Cytoplasmic receptor for glucocorticoids in lung of the human fetus and neonate.

Abstract: In fetal animals, glucocorticoids accelerate development of the lung and cause precocious appearance of alveolar surfactant. To determine if the human lung also can respond to corticosteroids, we examined lungs of the human fetus and neonate for both cytoplasmic binding and nuclear uptake of glucocorticoids. In slices of fetal lung incubated with [3H]dexamethasone at 2 degrees C, specific macromolecular binding occurs primarily in the "cytoplasmic" fraction. After further incubation at 37 degrees C. nearly 75% of the radioactivity localizes in the "nuclear" fraction with a concentration of 0.3 pmol/mg DNA at apparent dexamethasone saturation (47 nM). The cytoplasmic receptor binds dexamethasone in vitro with high affinity (dissociation constant = 8.9 nM), and the affinity of various other steroids correlates with their glucocorticoid potency. Receptor was present in lungs of fetuses and neonates of gestational age 12-43 wk, with a mean concentration in hysterotomy specimens of 0.24 pmol sites/mg cytosol protein. Similar binding activity was present at lower concentration in fetal liver, gut, kidney, heart, muscle, and skin. Cytoplasmic receptor was not detected in lung and liver of premature infants with respiratory distress syndrome. This deficit appears to result from increased levels of endogenous steroids (mean cortisol 45.5 micrograms/100 ml cytosol) as well as inactivation of receptor secondary to the illness. Thus, the lung of the human fetus and neonate contains the receptor mechanism necessary for direct responsiveness to glucocorticoids. These findings support the potential usefulness of these hormones in prevention of respiratory distress syndrome in the premature infant.

Factors Affecting the Secretion of Insulin and Glucagon by the Rat Fetus

Abstract: Insulin (IRI) and glucagon (IRG) increased in the plasma of the rat fetus from 18½ to 20½ days of gestation and decreased on day 21½. The demonstrated failure of insulin and glucagon to cross the placenta of the rat allowed the conclusion that fetal rat pancreas secreted IRI and IRG in the plasma of the fetus at the end of gestation. Fetal hyperglycemia induced by perfusing pregnant rats with glucose for one hour produced a marked increase in fetal plasma IRI but did not modify plasma IRG. Fetal hypoglycemia induced by perfusing pregnant rats with insulin for one hour produced a fall in fetal plasma IRI but no rise in fetal plasma IRG. Chronic fetal hypoglycemia produced by fasting pregnant rats for ninety-six hours or by intrauterine growth retardation of fetuses increased fetal plasma IRG and decreased fetal plasma IRI. Norepinephrine injection in term rat fetus increased plasma IRG and decreased plasma IRI. Acetylcholine injection increased both plasma IRI and IRG, whereas serotonin remained without effect. These data suggest that IRI and IRG secretion by the fetal rat pancreas is controlled by both the blood glucose level and autonomic nervous system activity. Lower blood glucose levels and higher plasma IRI and IRG levels in pregnant than nonpregnant rats are also reported.

Effect of stage of gestation and uterine space on prenatal survival in the pig.

Abstract: Summary The influence of uterine space on prenatal survival was examined in 251 gilts at three stages of gestation: days 25 to 30, days 31 to 40 and days 41 to term. Uterine space was varied so that either twice normal, half normal or the normal amount of uterine space was available per embryo. When the uterus was unchanged but the number of embryos entering the uterus was reduced the proportion of embryos surviving at any stage of gestation was not different from normal. Decreasing the uterine space to half that of normal did not affect embryo survival to day 30 but the proportion of embryos surviving after day 30 was reduced. These results demonstrate that uterine space is not associated with the embryonic mortality normally observed before day 30 but after day 30 it may be a factor in fetal death when large numbers of fetuses are present or when uterine space is restricted.

Oestrone, oestradiol-17beta and oestriol levels in human foetal plasma during gestation and at term.

Abstract: PIP: Marked rises in both unconjugated and sulphoconjugated estrone, estradiol-17-beta and estriol were observed in human fetal plasma between midgestation and term. Significant arterio-venous differences were found in the umbilical cord plasma. No consistent arterio-venous differences were found in the umbilical cord plasma. This indicates that all 3 estrogens are secreted from the placenta into the fetal circulation in the unconjugated form. Mean unconjugated estrogen (estrone + estradiol-17-beta + estriol) levels rose from 22.7 ng/ml at 17-20 weeks of gestation to 108.9 ng/ml at term in umbilical venous plasma and from 4.3 ng/ml to 23.3 ng/ml in umbilical arterial plasma. This represents a secretion rate of approximately 30 mg estrogen/day into the umbilical vein at term. Mean estrogen sulphate levels rose from 128 ng/ml to 313 ng/ml in the cord plasma during the same period. Of the 3 estrogens measured, estriol was quantitatively the major estrogen in fetal plasma. It consistently represented about 78% of the unconjugated fraction and 95% of the sulphate fraction at all stages of gestation. The method of delivery did not have a significant effect on the estrogen levels in uncomplicated pregnancies. Similar estrogen levels were found in fetal heart blood after either hysterotomy at spontaneous abortion at 16-20 weeks of gestation, and no significant differences were found for estrogen levels in cord plasma after elective Caesarean section at 38-39 weeks when compared with estrogen levels after normal delivery at term. A significant rise in fetal unconjugated estrogens at a time when fetal corticosteroids are increasing may be of physiological importance for fetal maturation in women.

Variations in the levels of cytoplasmic glucocorticoid receptors in lungs of various species at different developmental stages.

Abstract: Cytoplasmic fractions obtained from lungs of several animal species at different stages of development were examined for dexamethasone receptors. Specific dexamethasone binding was measured by a charcoal assay and by sucrose density gradient centrifugation. Dexamethasone receptors were demonstrated in the lungs of rabbit fetuses between the 21st day of gestation and birth, rat fetuses during the last 3 days of pregnancy, guinea pig fetuses at 35–45 days of gestation and human fetuses at the 9th to 17th gestational weeks. The dexamethasone receptors present in all the species examined sediment near 7S on linear 10–30% sucrose gradients. In human fetal lung cytosol the concentration of binding sites increased about 3-fold between the 9th and the 17th week of gestation. Lower but significant levels of the dexamethasone binding component were found in lungs of mature rabbits but it could not be detected in lungs of adult rats, mice, hamsters or guinea pigs. More detailed studies in the rat showed that the rec...

Hormone Synthesis and Release from Human Fetal Adenohypophyses in Vitro

Abstract: The hormone synthesis and release in vitro from the adenohypophysis of 40 normal human fetuses was studied by radioimmunoassay and protein incorporation of C14-l-leucine. Within the first 20 days in vitro, the release of GH, prolactin (PRL), LH, FSH, TSH, ACTH and MSH decreased to low or undetectable levels. The production of PRL and MSH, after the initial fall, spontaneously increased with time in culture to sustained and elevated levels. For all the hormones the quantity released was related to the gestational age of the donor fetus. In the cases of LH and FSH the hormonal release was not only related to the age of the fetus but also to the sex. The duration of FSH release in vitro was significantly longer (p > 0.005) for female pituitary cultures than for males. The release of pituitary hormones was detected as early as 5 weeks fetal life. In some fetuses, abnormal release of certain hormones in vitro could be relatd to demonstrable fetal abnormalities. These results indicate that the fetal pi...

Growth and development of the thyroidectomized ovine fetus.

Abstract: Extract: Thyroidectomies were performed through a flank incision and uterotomy on five fetuses of 1–4-year-old Columbia and Columbia Suffolk date-bred ewes of 90–110 days gestation. The fetuses were killed 19–43 days post-thyroidectomy. Body and organ weights, limb roentgenograms, DNA, RNA, and protein concentrations of selected tissues, cerebral and cerebellar lipid concentrations, and cerebellar cerebroside fatty acid composition were measured and compared with similar measurements in control animals. In the thyroidectomized fetuses mean carcass and lung weights were significantly reduced and wool development was consistently delayed. Extremity x-rays showed a delay in the time of appearance and a decrease in the size of epiphyseal centers. The mean DNA concentration was low in muscle tissue; mean protein concentrations were reduced in cerebellum, heart, lung, thymus, and muscle tissues, while mean total lipid concentration was low in cerebral tissue; the percentage of 18-carbon fatty acids was significantly increased in cerebellar cerebrosides. These results indicate that thyroid hormone deficiency, present during the last trimester of gestation in the ovine fetus, impairs carcass and lung growth, delays bone and skin maturation, inhibits growth in cell size in heart, lung, thymus, and cerebral tissues, and delays myelination in the central nervous system (CNS). Speculation: The present results, considered with results of other investigations of the effects of thyroid hormone deficiency in fetal and newborn mammals, indicate that hypothyroidism impairs somatic growth, delays bone growth and maturation, delays cell growth and replication in the CNS, and inhibits CNS myelination. The critical period for these effects varies in different species. In the rat this period is postnatal, whereas in the sheep it extends into the third trimester of pregnancy. During pregnancy, carcass growth, bone maturation, and lung maturation are most affected in the sheep; CNS changes are minimal. In man fetal hypothyroidism may produce some delay in bone maturation but somatic growth retardation and signs and symptoms of hypothyroidism are not usually present at birth. Moreover, as in the sheep, any delay in CNS maturation probably is minimal in utero, since very early postnatal treatment minimizes mental retardation. Thus early diagnosis and treatment of hypothyroidism is necessary and consideration of the possibility of newborn screening would seem appropriate.

Ontogeny of rat hepatic glucocorticoid receptors.

Abstract: Some glucocorticoid-inducible hepatic enzymes fail to respond to hormone administration prenatally but do respond soon after birth. One possible mechanism for this lack of responsivity is incomplete development of the glucocorticoid receptor system in the fetus. To evaluate this hypothesis, 3H-dexamethasone binding was studied in vitro in liver cytosol from fetuses (days 19–20) and young rats (days 1–29). Glucocorticoid receptors are present as early as days 19–20 of gestation and resemble adult receptors in affinity for 3H-dexamethasone and specificity for other steroid hormones. By Scatchard analysis the concentration of receptors is lower in the fetus (0.11 pmoles/mg cytosol protein) than at any postpartum date studied (0.26–0.55). However, since only unoccupied receptors are detected by the assay, this apparent difference in receptor concentration is felt to be the result of elevated levels of endogenous corticosterone in the fetus (37.8 μg/100 ml) compared to young rats (1.3–6.4 μg/100 ml). The fetal...

The renin-angiotensin system in the fetal lamb.

Abstract: Extract: This study was designed to investigate the renin-angiotensin system in the fetal lamb Simultaneous measurements of plasma renin activity (PRA) were carried out in seven acute fetal-maternal sheep preparations at 91, 100, 104, 112, 124, 142, and 145 days of gestational age, respectively (term 145 days) The mean fetal PRA in this group was 487 mμ/ml as compared with 158 mμ/ml for the maternal plasma PRA was also measured simultaneously in three intrauterine nonstressed fetuses Six days after insertion of catheters, the fetal PRA was 90, 92, and 875 mμ/ml, respectively, and the maternal PRA was 04, 45, and 375 mμ/ml, respectively The fetal response to aortic constriction was studied in three fetuses and the PRA increased from control values of 48, 55, and 222 mμ/ml to 80, 115, and 345 mμ/ml, respectively, within 15 min after initiation of the aortic constriction and continued to rise to maximum levels of 118, 255, and 380 mμ/ml, respectively PRA then decreased after release to near control levels The maternal PRA did not change significantly during the study period PRA was also measured in the in utero fetus after decreasing the blood volume 8–10% by acute controlled bleeding, and the PRA rose from control values of 60 and 42 mμ/ml to 400 and 544 mμ/ml within 15 min after blood loss, followed by a return towards control values over the subsequent 30 min Morphologic studies in five fetuses, 91–141 days of gestational age, indicate that the juxtaglomerular apparatus contains Bowie-positive smooth muscle granular cells and appears well developed in the fetal kidney by light and electronmicroscopy These studies, therefore, indicate that the renin-angiotensin system is present during fetal development in the sheep and also demonstrate that the fetus does respond to stimuli which, in the adult, result in renin release However, further studies will be necessary in order to establish a definitive physiologic role for renin in the fetus Speculation: The renin-angiotensin system appears to be well developed during fetal development These observations suggest that the enhanced activity of the renin-angiotensin system may play a role in the control of renal hemodynamics and fluid and electrolyte homeostases in the developing fetus

Sources and Disposition of Pituitary Prolactin in Maternal Circulation, AmnioticFluid, Fetus and Placenta in the Pregnant Rhesus Monkey

Abstract: Experiments performed at 130 days gestation in 11 rhesus monkeys revealed a positive correlation between pituitary prolactin concentrations in maternal plasma, but not fetal plasma, and those in amniotic fluid. Minute amounts of radioactively-labeled prolactin passed between maternal and fetal circulation. Small amounts of labeled hormone also passed from the mother, but not from the fetus, to the amniotic cavity. Fetal plasma prolactin was elevated by fetalinjection of thyrotropin-releasing factor (TRF), but not to an extent comparable to maternal plasma rises seen after the hypothalamic hormone was injected into the mother. Fetal tissues andthe placenta acquired protein-bound radioactivity when l25I-labeled prolactin was injected intothe amniotic fluid, the 125I in the former organ being displaced by incubation with nonlabeled prolactin. It was concluded that the maternal circulation may be a major source of amniotic fluid prolactin, while fetal and maternal circulations show mutually, essentially indep...