MA 5.4 NUMA SI GA RBHAVIKA S KRAM Completed Fetus in Prsava- Vastha Rasanufj*^SIK GARBHAVRUDHI
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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. -
4 Extraembryonic Membranes
Implantation, Extraembryonic Membranes, Placental Structure and Classification A t t a c h m e n t and Implantation Implantation is the first stage in development of the placenta. In most cases, implantation is preceded by a close interaction of embryonic trophoblast and endometrial epithelial cells that is known as adhesion or attachment. Implantation also is known as the stage where the blastocyst embeds itself in the endometrium, the inner membrane of the uterus. This usually occurs near the top of the uterus and on the posterior wall. Among other things, attachment involves a tight intertwining of microvilli on the maternal and embryonic cells. Following attachment, the blastocyst is no longer easily flushed from the lumen of the uterus. In species that carry multiple offspring, attachment is preceeded by a remarkably even spacing of embryos through the uterus. This process appears to result from uterine contractions and in some cases involves migration of embryos from one uterine horn to another (transuterine migration). The effect of implantation in all cases is to obtain very close apposition between embryonic and maternal tissues. There are, however, substantial differences among species in the process of implantation, particularly with regard to "invasiveness," or how much the embryo erodes into maternal tissue. In species like horses and pigs, attachment and implantation are essentially equivalent. In contrast, implantation in humans involves the embryo eroding deeply into the substance of the uterus. •Centric: the embryo expands to a large size before implantation, then remains in the center of the uterus. Examples include carnivores, ruminants, horses, and pigs. •Eccentric: The blastocyst is small and implants within the endometrium on the side of the uterus, usually opposite to the mesometrium. -
From Trophoblast to Human Placenta
From Trophoblast to Human Placenta (from The Encyclopedia of Reproduction) Harvey J. Kliman, M.D., Ph.D. Yale University School of Medicine I. Introduction II. Formation of the placenta III. Structure and function of the placenta IV. Complications of pregnancy related to trophoblasts and the placenta Glossary amnion the inner layer of the external membranes in direct contact with the amnionic fluid. chorion the outer layer of the external membranes composed of trophoblasts and extracellular matrix in direct contact with the uterus. chorionic plate the connective tissue that separates the amnionic fluid from the maternal blood on the fetal surface of the placenta. chorionic villous the final ramification of the fetal circulation within the placenta. cytotrophoblast a mononuclear cell which is the precursor cell of all other trophoblasts. decidua the transformed endometrium of pregnancy intervillous space the space in between the chorionic villi where the maternal blood circulates within the placenta invasive trophoblast the population of trophoblasts that leave the placenta, infiltrates the endo– and myometrium and penetrates the maternal spiral arteries, transforming them into low capacitance blood channels. Sunday, October 29, 2006 Page 1 of 19 From Trophoblasts to Human Placenta Harvey Kliman junctional trophoblast the specialized trophoblast that keep the placenta and external membranes attached to the uterus. spiral arteries the maternal arteries that travel through the myo– and endometrium which deliver blood to the placenta. syncytiotrophoblast the multinucleated trophoblast that forms the outer layer of the chorionic villi responsible for nutrient exchange and hormone production. I. Introduction The precursor cells of the human placenta—the trophoblasts—first appear four days after fertilization as the outer layer of cells of the blastocyst. -
Formation of Germ Layers (Second & Third Week of Development)
8.12.2014 Formation of Germ Layers (Second & Third week of Development) Dr. Archana Rani Associate Professor Department of Anatomy KGMU UP, Lucknow Day 8 • Blastocyst is partially embedded in the endometrial stroma. • Trophoblast differentiates into 2 layers: (i) Cytotrophoblast (ii) Syncytiotrophoblast • Cytotrophoblast shows mitotic division. Day 8 • Cells of inner cell mass (embryoblast) also differentiate into 2 layers: (i) Hypoblast layer (ii) Epiblast layer • Formation of amniotic cavity and embryonic disc. Day 9 • The blastocyst is more deeply embedded in the endometrium. • The penetration defect in the surface epithelium is closed by a fibrin coagulum. Day 9 • Large no. of vacuoles appear in syncytiotrophoblast which fuse to form lacunae which contains embryotroph. Day 9 • Hypoblast forms the roof of the exocoelomic cavity (primary yolk sac). • Heuser’s (exocoelomic membrane) • Extraembryonic mesoderm Day 11 & 12 • Formation of lacunar networks • Extraembryonic coelom (chorionic cavity) • Extraembryonic somatic mesoderm • Extraembryonic splanchnic mesoderm • Chorion Day 13 • Implantation bleeding • Villous structure of trophoblast. • Formation of Primary villi • Secondary (definitive) yolk sac • Chorionic plate (extraembronic mesoderm with cytotrophoblast) Third week of Development • Gastrulation (formation of all 3 germ layers) • Formation of primitive streak • Formation of notochord • Differentiation of 3 germ layers from Bilaminar to Trilaminar germ disc Formation of Primitive Streak (PS) • First sign of gastrulation • On 15th day • Primitive node • Primitive pit • Formation of mesenchyme on 16th day • Formation of embryonic endoderm • Intraembryonic mesoderm • Ectoderm • Epiblast is the source of all 3 germ layers Fate of Primitive Streak • Continues to form mesodermal cells upto early part of 4th week • Normally, the PS degenerates & diminishes in size. -
General Embryology-3-Placenta.Pdf
Derivatives of Germ Layers ECTODREM 1. Lining Epithelia of i. Skin ii. Lips, cheeks, gums, part of floor of mouth iii. Parts of palate, nasal cavities and paranasal sinuses iv. Lower part of anal canal v. Terminal part of male urethera vi. Labia majora and outer surface of labia minora vii. Epithelium of cornea, conjuctiva, ciliary body, iris viii. Outer layer of tympanic membrane and membranous labyrinth ECTODERM (contd.): 2. Glands – Exocrine – Sweet glands, sebaceous glands Parotid, Mammary and lacrimal 3. Other derivatives i. Hair ii. Nails iii. Enamel of teeth iv. Lens of eye; musculature of iris v. Nervous system MESODERM: • All connective tissue including loose areolar tissue, superficial and deep fascia, ligaments, tendons, aponeuroses and the dermis of the skin. • Specialised connective tissue like adipose tissue, reticular tissue, cartilage and bone • All muscles – smooth, striated and cardiac – except the musculature of iris. • Heart, all blood vessels and lymphatics, blood cells. • Kidneys, ureters, trigone of bladder, parts of male and female urethera, inner prostatic glands. • Ovary, uterus, uterine tubes, upper part of vagina. • Testis, epidydimis, ductus deferens, seminal vesicle ejaculatory duct. • Lining mesothelium of pleural, pericardial and peritoneal cavities; and of tunica vaginalis. • Living mesothelium of bursae and joints. • Substance of cornea, sclera, choroid, ciliary body and iris. ENDODERM: 1. Lining Epithelia of i. Part of mouth, palate, tongue, tonsil, pharynx. ii. Oesophagus, stomach, small and large intestines, anal canal (upper part) iii. Pharyngo – tympanic tube, middle ear, inner layer of tympanic membrane, mastoid antrum, air cells. iv. Respiratory tract v. Gall bladder, extrahepatic duct system, pancreatic ducts vi. -
Ultrasound Imaging of Early Extraembryonic Structures 1Sándor Nagy, 2Zoltán Papp
DSJUOG Ultrasound Imaging10.5005/jp-journals-10009-1500 of Early Extraembryonic Structures REVIEW ARTICLE Ultrasound Imaging of Early Extraembryonic Structures 1Sándor Nagy, 2Zoltán Papp ABSTRACT to arrive at an accurate diagnosis and appropriate dis- Transvaginal sonography is the most useful diagnostic method position, thus providing efficient care that benefits both to visualize the early pregnancy, to determine whether it is intra- patients and doctors. The specific sonographic appear- uterine or extrauterine (ectopic), viable or not. Detailed examina- ance of normal pregnancy depends upon the gestational tion of extraembryonic structures allows us to differentiate the age. As the gestational age increases, the ability to assess types of early pregnancy failures and highlights the backgrounds the location and normal development of the pregnancy of vaginal bleeding, as the most frequent symptom of the first trimester of gestation. The reliable ultrasonographic sign of an becomes better. intrauterine pregnancy is visualization of double decidual ring, Spontaneous abortion is one of the most common which represents the trophoblast’s layer. The abnormality in the complications of pregnancy; every 12 to 15 out of 100 sonographic appearance of a gestational sac, a yolk sac, and conceptus are miscarried in the first half of gestation. a chorionic plate can predict subsequent embryonic damage and death. Vaginal bleeding is one of the most serious symptoms of the spontaneous abortion, which the pregnant are afraid Keywords: Blighted ovum, Chorionic plate, Extraembryonic structures, Gestational sac, Missed abortion, Subchorionic of, especially when extrachorial bleeding is detected by hemorrhage, Yolk sac. ultrasound. Transvaginal sonography is the optimal way to image How to cite this article: Nagy S, Papp Z. -
17. Formation and Role of Placenta
17. FORMATION AND ROLE OF PLACENTA Joan W. Witkin, PhD Dept. Anatomy & Cell Biology, P&S 12-432 Tel: 305-1613 e-mail: [email protected] READING: Larsen, 3rd ed. pp. 20-22, 37-44 (fig. 2-7, p. 45), pp. 481-490 SUMMARY: As the developing blastocyst hatches from the zona pellucida (day 5-6 post fertilization) it has increasing nutritional needs. These are met by the development of an association with the uterine wall into which it implants. A series of synchronized morphological and biochemical changes occur in the embryo and the endometrium. The final product of this is the placenta, a temporary organ that affords physiological exchange, but no direct connection between the maternal circulation and that of the embryo. Initially cells in the outer layer of the blastocyst, the trophoblast, differentiate producing an overlying syncytial layer that adheres to the endometrium. The embryo then commences its interstitial implantation as cells of the syncytiotrophoblast pass between the endometrial epithelial cells and penetrate the decidualized endometrium. The invading embryo is first nourished by secretions of the endometrial glands. Subsequently the enlarging syncytiotrophoblast develops spaces that anastomose with maternal vascular sinusoids, forming the first (lacunar) uteroplacental circulation. The villous placental circulation then develops as fingers of cytotrophoblast with its overlying syncytiotrophoblast (primary villi) extend from the chorion into the maternal blood space. The primary villi become secondary villi as they are invaded by extraembryonic mesoderm and finally tertiary villi as embryonic blood vessels develop within them. During the first trimester of pregnancy cytotrophoblasts partially occlude the uterine vessels such that only plasma circulates in the intervillous space. -
The Placenta Learning Module
The placenta Learning module Developed by Carolyn Hammer Edited by Fabien Giroux Diagrams by Dr Yockell –Lelievre where indicated The placenta – Learning module Table of content 1) Introduction…………………………………………………………………………...…3 2) Anatomy and Physiology…………………………………………………….………...6 3) Roles and Functions…………………………………………………………..………23 4) Development and formation…………………………………………………………..35 5) What happens after birth…………………………………………………………...…44 6) What happens when things go wrong……………………………………………....46 7) Interesting facts about pregnancy…………………………………..……………….57 8) Testing what you know………………………………………..……………………...62 2 The placenta – Learning module Introduction 3 The placenta – Learning module What is the placenta? •The placenta is a: “vascular (supplied with blood vessels) organ in most mammals that unites the fetus to the uterus of the mother. It mediates the metabolic exchanges of the developing individual through an intimate association of embryonic tissues and of certain uterine tissues, serving the functions of nutrition, respiration, and excretion.” (Online Britannica Encyclopaedia) •The placenta is also known as a hemochorical villous organ meaning that the maternal blood comes in contact with the chorion and that villi protrude out of this same structure. As the fetus is growing and developing, it requires a certain amount of gases and nutrients to help support its needs throughout pregnancy. Because the fetus is unable to do so on its own, it is the placenta that carries out this function. http://health.allrefer.com/health/plac enta-abruptio-placenta.html 4 The placenta – Learning module What are the main roles of the placenta? •The placenta provides the connection between fetus and mother in order to help carry out many different functions that it is incapable to do alone. -
The Duplication Op Male and Female
THE DUPLICATION OP MALE AND FEMALE EXTERNAL GENITALIA: With Records of Two Cases, by THOMAS GILCHRIST, M.A., M,B«, Ch.B. THESIS for the Degree of M;D; September, 1932. ProQuest Number: 13905404 All rights reserved INFORMATION TO ALL USERS The quality of this reproduction is dependent upon the quality of the copy submitted. In the unlikely event that the author did not send a com plete manuscript and there are missing pages, these will be noted. Also, if material had to be removed, a note will indicate the deletion. uest ProQuest 13905404 Published by ProQuest LLC(2019). Copyright of the Dissertation is held by the Author. All rights reserved. This work is protected against unauthorized copying under Title 17, United States C ode Microform Edition © ProQuest LLC. ProQuest LLC. 789 East Eisenhower Parkway P.O. Box 1346 Ann Arbor, Ml 48106- 1346 CONTENTS. Page Introduction ... ... 1. A. Duplication of Male External Genitalia 6. Historical Notes ... ... • • • 7. Summary of Recorded Cases ... 24. Description of Author1s Case ... 29. Post-Mortem Examination ... 33. Family History ••• ••• 37. B. Duplication of Female External Genitalia 41. Historical Notes ... ... ... 42. Summary of Recorded Cases ... 53. Description of Author's Case ... 56. Po81-Mortem Examination ... 60. Family History ... ... 68. II. Page G. DISCUSSION «*« •. * ••• i»* ••• 70. EMBRYOLOGY .............. 71. Early Differentiation of the Embryonic Area .♦• 71. The Development of the Posterior Aspect of the Yolk Sac *• i»* ... 77. The Development of the Urogenital Organs •., 85. EXPLANATION of the ABNORMALITIES 89. SUMMARY * 11 * * * • * * .«. 117. BIBLIOGRAPHY 121. III. I ILLUSTRATIONS. Figure Page 1. Photograph of Author* s Male Case of Duplicated External Genitalia 30. -
A Novel in Vitro Model of Trophoblast-Mediated Decidual
0023-6837/03/8312-1821$03.00/0 LABORATORY INVESTIGATION Vol. 83, No. 12, p. 1821, 2003 Copyright © 2003 by The United States and Canadian Academy of Pathology, Inc. Printed in U.S.A. A Novel In Vitro Model of Trophoblast-Mediated Decidual Blood Vessel Remodeling Caroline Dunk, Ljiljana Petkovic, Dora Baczyk, Janet Rossant, Elke Winterhager, and Stephen Lye Departments of Physiology and Fetal and Maternal Health (CD, LP, DB, JR, SL), Samuel Lunenfeld Research Institute, Mount Sinai Hospital, Toronto, Ontario, Canada; and Institute of Anatomy (EW), University of Essen, Essen, Germany SUMMARY: In vivo the extravillous trophoblasts (EVTs) penetrate the decidua and the first third of the myometrium to remodel the uterine spiral arteries and achieve the high-flow, low-resistance circulation characteristic of the intervillous space of the term placenta. Much of our understanding of these processes comes from histologic analysis of placental bed biopsies, a limited tissue source and one that can provide only a snapshot of a dynamic process. To better characterize these cellular interactions, we have developed an in vitro co-culture system in which first trimester villous explants are cultured at low oxygen tension in contact with 2-mm2 sections of decidua parietalis from the same patient. Hematoxylin eosin counterstaining of paraffin sections shows that EVT columns form at the tips of the placental villi and adhere and penetrate the decidual surface. The decidual blood vessels in the path of the EVT show morphologic disruption. Immunohistochemical analysis of the co-cultures using both an endothelial specific anti-CD31 and an anti–smooth muscle actin antibody show a disruption of the integrity of the vessel lining together with a complete loss of organized smooth muscle actin surrounding the blood vessels. -
Overview of the Development of the Human Brain and Spinal Cord
Chapter 1 Overview of the Development of the Human Brain and Spinal Cord Hans J.ten Donkelaar and Ton van der Vliet 1.1 Introduction tant contributions to the description of human em- bryos were also made by Nishimura et al. (1977) and The development of the human brain and spinal cord Jirásek (1983, 2001, 2004). Examples of human em- may be divided into several phases, each of which is bryos are shown in Figs. 1.1 and 1.2. In the embryon- characterized by particular developmental disorders ic period, postfertilization or postconceptional age (Volpe 1987; van der Knaap and Valk 1988; Aicardi is estimated by assigning an embryo to a develop- 1992; Table 1.3). After implantation, formation and mental stage using a table of norms,going back to the separation of the germ layers occur, followed by dor- first Normentafeln by Keibel and Elze (1908). The sal and ventral induction phases, and phases of neu- term gestational age is commonly used in clinical rogenesis, migration, organization and myelination. practice, beginning with the first day of the last men- With the transvaginal ultrasound technique a de- strual period. Usually, the number of menstrual or tailed description of the living embryo has become gestational weeks exceeds the number of postfertil- possible. Fetal development of the brain can now be ization weeks by 2. During week 1 (stages 2–4) the studied in detail from about the beginning of the sec- blastocyst is formed, during week 2 (stages 5 and 6) ond half of pregnancy (Garel 2004). In recent years, implantation occurs and the primitive streak is much progress has been made in elucidating the formed,followed by the formation of the notochordal mechanisms by which the CNS develops, and also in process and the beginning of neurulation (stages 7– our understanding of its major developmental disor- 10). -
Electron and Scanning Microscopic Observations on The
isord D ers od & lo T r B f a n o s l f a u n s r Journal of i o u n o Selim et al., J Blood Disorders Transf 2013, 4:1 J ISSN: 2155-9864 Blood Disorders & Transfusion DOI: 10.4172/2155-9864.1000137 Research Article OpOpenen Access Access Electron and Scanning Microscopic Observations on the Syncytiotrophoblast Microvillous Membrane Contribution to Preeclampsia in Early Placental Rats Manar E Selim1,2*, Nouf G Elshmry3 and El Hamidi A Rashed1 1Department of Zoology, College of Science, King Saud University, Saudi Arabia, Riyadh-11451, KSA 2Department of Zoology, Ain Shams University, Cairo, Egypt 3Department of Zoology, College of Science, Hail University, Saudi Arabia Abstract Pre-eclampsia is a pregnancy-specific syndrome characterized by new-onset hypertension and proteinuria, occurring usually after 20 weeks’ gestation. The current study was carried out on 60 female Wistar rats. Group I: included virgin non-pregnant rats. Group II: included pregnant rats that were received saline solution (0.5 ml/100 g body weight) subcutaneously daily starting from day 7 to day 14 of gestation and served as control group. Group III: included pregnant rats that were treated with bestatin dissolved in saline in a dose of (40.0 μg/ml)/100 g body weight subcutaneously and daily starting from the same day of gestation and for the same duration as mentioned for group II, to make an animal model of preeclampsia. Hence several possible mechanisms of the activation in pre-eclampsia can be considered, all dependent on the syncytiotrophoblast microvillous surface membrane which is the placental surface in contact with maternal blood.