Human Development Summary
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3 Embryology and Development
BIOL 6505 − INTRODUCTION TO FETAL MEDICINE 3. EMBRYOLOGY AND DEVELOPMENT Arlet G. Kurkchubasche, M.D. INTRODUCTION Embryology – the field of study that pertains to the developing organism/human Basic embryology –usually taught in the chronologic sequence of events. These events are the basis for understanding the congenital anomalies that we encounter in the fetus, and help explain the relationships to other organ system concerns. Below is a synopsis of some of the critical steps in embryogenesis from the anatomic rather than molecular basis. These concepts will be more intuitive and evident in conjunction with diagrams and animated sequences. This text is a synopsis of material provided in Langman’s Medical Embryology, 9th ed. First week – ovulation to fertilization to implantation Fertilization restores 1) the diploid number of chromosomes, 2) determines the chromosomal sex and 3) initiates cleavage. Cleavage of the fertilized ovum results in mitotic divisions generating blastomeres that form a 16-cell morula. The dense morula develops a central cavity and now forms the blastocyst, which restructures into 2 components. The inner cell mass forms the embryoblast and outer cell mass the trophoblast. Consequences for fetal management: Variances in cleavage, i.e. splitting of the zygote at various stages/locations - leads to monozygotic twinning with various relationships of the fetal membranes. Cleavage at later weeks will lead to conjoined twinning. Second week: the week of twos – marked by bilaminar germ disc formation. Commences with blastocyst partially embedded in endometrial stroma Trophoblast forms – 1) cytotrophoblast – mitotic cells that coalesce to form 2) syncytiotrophoblast – erodes into maternal tissues, forms lacunae which are critical to development of the uteroplacental circulation. -
CCM2 and CCM3 Proteins Contribute to Vasculogenesis and Angiogenesis in Human Placenta
Histol Histopathol (2009) 24: 1287-1294 Histology and http://www.hh.um.es Histopathology Cellular and Molecular Biology CCM2 and CCM3 proteins contribute to vasculogenesis and angiogenesis in human placenta Gamze Tanriover1, Yasemin Seval1, Leyla Sati1, Murat Gunel2 and Necdet Demir1 1Department of Histology and Embryology, Akdeniz University, School of Medicine, Antalya, Turkey and 2 Department of Neurosurgery, Yale University, School of Medicine, New Haven, CT, USA Summary. Placenta as an ideal model to study Introduction angiogenic mechanisms have been established in previous studies. There are two processes, The placenta is a multifaceted organ that plays a vasculogenesis and angiogenesis, involved in blood critical role in maintaining and protecting the developing vessel formation during placental development. fetus. Normal development and function of the placenta Therefore, blood vessel formation is a crucial issue that requires extensive vasculogenesis and subsequent might cause vascular malformations. One of the vascular angiogenesis, in both maternal and fetal tissues. malformations is cerebral cavernous malformation Vasculogenesis is the formation of the primitive vascular (CCM) in the central nervous system, consisting of network de novo from progenitor cells, and angiogenesis endothelium-lined vascular channels without intervening is identified as the extension of blood vessels from normal brain parenchyma. Three CCM loci have been preexisting vascular structures (Demir et al., 1989, 2006; mapped as Ccm1, Ccm2, Ccm3 genes in CCM. In order Geva et al., 2002; Charnock-Jones et al., 2004). Many to investigate whether CCM proteins participate in blood factors, such as vascular endothelial growth factor vessel formation, we report here the expression patterns (VEGF), angiopoietins (Angpt-1 and -2) and their of CCM2 and CCM3 in developing and term human receptors are involved in the molecular regulation of placenta by means of immunohistochemistry and these diverse developmental steps. -
The Rotated Hypoblast of the Chicken Embryo Does Not Initiate an Ectopic Axis in the Epiblast
Proc. Natl. Acad. Sci. USA Vol. 92, pp. 10733-10737, November 1995 Developmental Biology The rotated hypoblast of the chicken embryo does not initiate an ectopic axis in the epiblast ODED KHANER Department of Cell and Animal Biology, The Hebrew University, Jerusalem, Israel 91904 Communicated by John Gerhart, University of California, Berkeley, CA, July 14, 1995 ABSTRACT In the amniotes, two unique layers of cells, of the hypoblast and that the orientation of the streak and axis the epiblast and the hypoblast, constitute the embryo at the can be predicted from the polarity of the stage XIII epiblast. blastula stage. All the tissues of the adult will derive from the Still it was thought that the polarity of the epiblast is sufficient epiblast, whereas hypoblast cells will form extraembryonic for axial development in experimental situations, although in yolk sac endoderm. During gastrulation, the endoderm and normal development the polarity of the hypoblast is dominant the mesoderm of the embryo arise from the primitive streak, (5, 6). These reports (1-3, 5, 6), taken together, would imply which is an epiblast structure through which cells enter the that cells of the hypoblast not only have the ability to change interior. Previous investigations by others have led to the the fate of competent cells in the epiblast to initiate an ectopic conclusion that the avian hypoblast, when rotated with regard axis, but also have the ability to repress the formation of the to the epiblast, has inductive properties that can change the original axis in committed cells of the epiblast. At the same fate of competent cells in the epiblast to form an ectopic time, the results showed that the epiblast is not wholly depen- embryonic axis. -
Fetal Blood Flow and Genetic Mutations in Conotruncal Congenital Heart Disease
Journal of Cardiovascular Development and Disease Review Fetal Blood Flow and Genetic Mutations in Conotruncal Congenital Heart Disease Laura A. Dyer 1 and Sandra Rugonyi 2,* 1 Department of Biology, University of Portland, Portland, OR 97203, USA; [email protected] 2 Department of Biomedical Engineering, Oregon Health & Science University, Portland, OR 97239, USA * Correspondence: [email protected] Abstract: In congenital heart disease, the presence of structural defects affects blood flow in the heart and circulation. However, because the fetal circulation bypasses the lungs, fetuses with cyanotic heart defects can survive in utero but need prompt intervention to survive after birth. Tetralogy of Fallot and persistent truncus arteriosus are two of the most significant conotruncal heart defects. In both defects, blood access to the lungs is restricted or non-existent, and babies with these critical conditions need intervention right after birth. While there are known genetic mutations that lead to these critical heart defects, early perturbations in blood flow can independently lead to critical heart defects. In this paper, we start by comparing the fetal circulation with the neonatal and adult circulation, and reviewing how altered fetal blood flow can be used as a diagnostic tool to plan interventions. We then look at known factors that lead to tetralogy of Fallot and persistent truncus arteriosus: namely early perturbations in blood flow and mutations within VEGF-related pathways. The interplay between physical and genetic factors means that any one alteration can cause significant disruptions during development and underscore our need to better understand the effects of both blood flow and flow-responsive genes. -
Genetic and Flow Anomalies in Congenital Heart Disease
Published online: 2021-05-10 AIMS Genetics, 3(3): 157-166. DOI: 10.3934/genet.2016.3.157 Received: 01 July 2016 Accepted: 16 August 2016 Published: 23 August 2016 http://www.aimspress.com/journal/Genetics Review Genetic and flow anomalies in congenital heart disease Sandra Rugonyi* Department of Biomedical Engineering, Oregon Health & Science University, 3303 SW Bond Ave. M/C CH13B, Portland, OR 97239, USA * Correspondence: Email: [email protected]; Tel: +1-503-418-9310; Fax: +1-503-418-9311. Abstract: Congenital heart defects are the most common malformations in humans, affecting approximately 1% of newborn babies. While genetic causes of congenital heart disease have been studied, only less than 20% of human cases are clearly linked to genetic anomalies. The cause for the majority of the cases remains unknown. Heart formation is a finely orchestrated developmental process and slight disruptions of it can lead to severe malformations. Dysregulation of developmental processes leading to heart malformations are caused by genetic anomalies but also environmental factors including blood flow. Intra-cardiac blood flow dynamics plays a significant role regulating heart development and perturbations of blood flow lead to congenital heart defects in animal models. Defects that result from hemodynamic alterations recapitulate those observed in human babies, even those due to genetic anomalies and toxic teratogen exposure. Because important cardiac developmental events, such as valve formation and septation, occur under blood flow conditions while the heart is pumping, blood flow regulation of cardiac formation might be a critical factor determining cardiac phenotype. The contribution of flow to cardiac phenotype, however, is frequently ignored. -
The Effects of Alcohol in Newborns Efeitos Do Álcool No Recém-Nascido
REVIEW The effects of alcohol in newborns Efeitos do álcool no recém-nascido Maria dos Anjos Mesquita* ABSTRACT alcoólicas leva a prejuízos individuais, para a sua família e para The purpose of this article was to present a review of the effects toda a sociedade. Apesar disso, a dificuldade do seu diagnóstico e of alcohol consumption by pregnant mothers on their newborn. a inexperiência dos profissionais de saúde faz com que o espectro Definitions, prevalence, pathophysiology, clinical features, diagnostic dessas lesões seja pouco lembrado e até desconhecido. As lesões criteria, follow-up, treatment and prevention were discussed. A causadas pela ação do álcool no concepto são totalmente prevenidas search was performed in Medline, LILACS, and SciELO databases se a gestante não consumir bebidas alcoólicas durante a gestação. using the following terms: “fetus”, “newborn”, “pregnant woman”, Assim, é fundamental a detecção das mulheres consumidoras “alcohol”, “alcoholism”, “fetal alcohol syndrome”, and “alcohol- de álcool durante a gravidez e o desenvolvimento de programas related disorders”. Portuguese and English articles published from específicos de alerta sobre as consequências do álcool durante a 2000 to 2009 were reviewed. The effects of alcohol consumed by gestação e amamentação. pregnant women on newborns are extremely serious and occur frequently; it is a major issue in Public Health worldwide. Fetal alcohol Descritores: Bebidas alcoólicas/efeitos adversos; Feto; Recém-nascido; spectrum disorders cause harm to individuals, their families, and the Síndrome alcoólica fetal; Transtornos relacionados ao uso de álcool entire society. Nevertheless, diagnostic difficulties and inexperience of healthcare professionals result in such damage, being remembered rarely or even remaining uncovered. -
Gastrulation
Embryology of the spine and spinal cord Andrea Rossi, MD Neuroradiology Unit Istituto Giannina Gaslini Hospital Genoa, Italy [email protected] LEARNING OBJECTIVES: LEARNING OBJECTIVES: 1) To understand the basics of spinal 1) To understand the basics of spinal cord development cord development 2) To understand the general rules of the 2) To understand the general rules of the development of the spine development of the spine 3) To understand the peculiar variations 3) To understand the peculiar variations to the normal spine plan that occur at to the normal spine plan that occur at the CVJ the CVJ Summary of week 1 Week 2-3 GASTRULATION "It is not birth, marriage, or death, but gastrulation, which is truly the most important time in your life." Lewis Wolpert (1986) Gastrulation Conversion of the embryonic disk from a bilaminar to a trilaminar arrangement and establishment of the notochord The three primary germ layers are established The basic body plan is established, including the physical construction of the rudimentary primary body axes As a result of the movements of gastrulation, cells are brought into new positions, allowing them to interact with cells that were initially not near them. This paves the way for inductive interactions, which are the hallmark of neurulation and organogenesis Day 16 H E Day 15 Dorsal view of a 0.4 mm embryo BILAMINAR DISK CRANIAL Epiblast faces the amniotic sac node Hypoblast Primitive pit (primitive endoderm) faces the yolk sac Primitive streak CAUDAL Prospective notochordal cells Dias Dias During -
Human Blastocyst Morphological Quality Is Significantly Improved In
Human blastocyst morphological quality is significantly improved in embryos classified as fast on day 3 (R10 cells), bringing into question current embryological dogma Martha Luna, M.D.,a,b Alan B. Copperman, M.D.,a,b Marlena Duke, M.Sc.,a,b Diego Ezcurra, D.V.M.,c Benjamin Sandler, M.D.,a,b and Jason Barritt, Ph.D.a,b a Mount Sinai School of Medicine, Department of Obstetrics and Gynecology, Department of Reproductive Endocrinology and Infertility, and b Reproductive Medicine Associates of New York, New York, New York; and c EMD Serono, Rockland, Massachusetts Objective: To evaluate developmental potential of fast cleaving day 3 embryos. Design: Retrospective analysis. Setting: Academic reproductive center. Patient(s): Three thousand five hundred twenty-nine embryos. Intervention(s): Day 3 embryos were classified according to cell number: slow cleaving: %6 cells, intermediate cleaving: 7–9 cells, and fast cleaving: R10 cells, and further evaluated on day 5. The preimplantation genetic diagnosis (PGD) results of 43 fast cleaving embryos were correlated to blastocyst formation. Clinical outcomes of transfers involving only fast cleaving embryos (n ¼ 4) were evaluated. Main Outcome Measure(s): Blastocyst morphology correlated to day 3 blastomere number. Relationship between euploidy and blastocyst formation of fast cleaving embryos. Implantation, pregnancy (PR), and birth rates resulting from fast embryo transfers. Result(s): Blastocyst formation rate was significantly greater in the intermediate cleaving (72.7%) and fast cleav- ing (54.2%) groups when compared to the slow cleaving group (38%). Highest quality blastocysts were formed significantly more often in the fast cleaving group. Twenty fast cleaving embryos that underwent PGD, formed blastocysts, of which 45% (9/20) were diagnosed as euploid. -
Animal Form & Function
Animals Animal Form & Function By far, most diversity of bauplane (body forms). And most variations within bauplane. Animals are Animated “ANIMAL” ≠ MAMMAL — Fascinating Behaviors Animal Cells • Eukaryotic • No cell wall No plastids No central vacuole • Multicellular: – extensive specialization & differentiation – unique cell-cell junctions Heyer 1 Animals Animals Blastulation & Gastrulation • Motile • Early embryonic development in animals 3 In most animals, cleavage results in the formation of a multicellular stage called a 1 The zygote of an animal • Highly differentiated blastula. The blastula of many animals is a undergoes a succession of mitotic tissues cell divisions called cleavage. hollow ball of cells. Blastocoel • Intercellular junctions Cleavage Cleavage – tissue-specific cadherins 6 The endoderm of the archenteron develops into Eight-cell stage Blastula Cross section Zygote • Extracellular protein the the animal’s of blastula fibers digestive tract. Blastocoel Endoderm – collagen 5 The blind pouch formed by gastrulation, called Ectoderm • Diploid life cycle the archenteron, opens to the outside Gastrula Gastrulation via the blastopore. Blastopore 4 Most animals also undergo gastrulation, a • Blastula/gastrula rearrangement of the embryo in which one end of the embryo folds inward, expands, and eventually fills the embryo blastocoel, producing layers of embryonic tissues: the Figure 32.2 ectoderm (outer layer) and the endoderm (inner layer). Primary embryonic germ layers Primary embryonic germ layers • Diploblastic: two germ -
Messages from the Placentae Across Multiple Species a 50 Years
Placenta 84 (2019) 14–27 Contents lists available at ScienceDirect Placenta journal homepage: www.elsevier.com/locate/placenta Messages from the placentae across multiple species: A 50 years exploration T Hiroaki Soma Saitama Medical University, Japan ARTICLE INFO ABSTRACT Keywords: This review explores eight aspects of placentation in multiple mammalian. Gestational trophoblastic disease 1) Specialities of gestational trophoblastic disease. SUA(Single umbilical artery) 2) Clinical significance of single umbilical artery (SUA) syndrome. DIC(Disseminated intravascular coagulation) in 3) Pulmonary trophoblast embolism in pregnant chinchillas and DIC in pregnant giant panda. giant panda 4) Genetics status and placental behaviors during Japanese serow and related antelopes. Placentation in Japanese serow 5) Specific living style and placentation of the Sloth and Proboscis monkey. Hydatidiform mole in chimpanzee Placentation in different living elephant 6) Similarities of placental structures between human and great apes. Manatee and hyrax 7) Similarities of placental forms in elephants, manatees and rock hyrax with different living styles. Specific placental findings of Himalayan people 8) Specialities of placental pathology in Himalayan mountain people. Conclusions: It was taught that every mammalian species held on placental forms applied to different environ- mental life for their infants, even though their gestational lengths were different. 1. Introduction of effective chemotherapeutic agents. In 1959, I was fortunate tore- ceive an invitation from Prof. Kurt Benirschke at the Boston Lying-in Last October, Scientific American published a special issue about a Hospital. Before that, I had written to Prof. Arthur T. Hertig, Chairman baby's first organ, the placenta [1]. It is full of surprises and amazing of Pathology, Harvard Medical School, asking to study human tropho- science. -
FASD Effects of Alcohol on a Fetus
EFFECTS OF ALCOHOL ON A FETUS “Of all the substances of abuse (including cocaine, heroin, and marijuana), alcohol produces by far the most serious neurobehavioral effects in the fetus.” —Institute of Medicine Report to Congress, 19961 Prenatal exposure to alcohol can damage a fetus at any time, causing problems that persist throughout the individual’s life. There is no known safe level of alcohol use in pregnancy. WHAT IS THE SCOPE OF THE PROBLEM? identified in virtually every part of the body, including the brain, face, eyes, ears, heart, kidneys, and bones. No Alcohol is one of the most dangerous teratogens, which single mechanism can account for all the problems that are substances that can damage a developing fetus.1 Every alcohol causes. Rather, alcohol sets in motion many time a pregnant woman has a drink, her unborn child processes at different sites in the developing fetus: has one, too. Alcohol, like carbon monoxide from cigarettes, passes easily through the placenta from the • Alcohol can trigger cell death in a number of ways, mother's bloodstream into her baby's blood (See Figure causing different parts of the fetus to develop abnormally. 1)—and puts her fetus at risk of having a fetal alcohol • Alcohol can disrupt the way nerve cells develop, travel spectrum disorder (FASD). The blood alcohol level to form different parts of the brain, and function. (BAC) of the fetus becomes equal to or greater than the blood alcohol level of the mother. Because the fetus • By constricting the blood vessels, alcohol interferes with cannot break down alcohol the way an adult can, its BAC blood flow in the placenta, which hinders the delivery 2 remains high for a longer period of time. -
Segmentation and Specification of the Drosophila Mesoderm
Downloaded from genesdev.cshlp.org on September 25, 2021 - Published by Cold Spring Harbor Laboratory Press Segmentation and specification of the Drosophila mesoderm Natalia Azpiazu, 1,3 Peter A. Lawrence, 2 Jean-Paul Vincent, 2 and Manfred Frasch 1'4 1Brookdale Center for Molecular Biology, Mount Sinai School of Medicine, New York, New York 10029 USA; 2Medical Research Council Laboratory of Molecular Biology, Cambridge CB2 2QH, UK Patterning of the developing mesoderm establishes primordia of the visceral, somatic, and cardiac tissues at defined anteroposterior and dorsoventral positions in each segment. Here we examine the mechanisms that locate and determine these primordia. We focus on the regulation of two mesodermal genes: bagpipe (hap), which defines the anlagen of the visceral musculature of the midgut, and serpent (srp), which marks the anlagen of the fat body. These two genes are activated in specific groups of mesodermal cells in the anterior portions of each parasegment. Other genes mark the anlagen of the cardiac and somatic mesoderm and these are expressed mainly in cells derived from posterior portions of each parasegment. Thus the parasegments appear to be subdivided, at least with respect to these genes, a subdivision that depends on pair-rule genes such as even-skipped (eve). We show with genetic mosaics that eve acts autonomously within the mesoderm. We also show that hedgehog (hh) and wingless (wg) mediate pair-rule gene functions in the mesoderm, probably partly by acting within the mesoderm and partly by inductive signaling from the ectoderm, hh is required for the normal activation of hap and srp in anterior portions of each parasegment, whereas wg is required to suppress bap and srp expression in posterior portions.