Talk:2010 Foundations Lecture - Introduction to Human Development

From Embryology

--Mark Hill 10:05, 28 January 2010 (EST) New page construction begins. Key features are to simplify concepts into a timed sequence and select special features and terms.

Introduction to Embryology Dr Mark Hill Department of Anatomy School of Medical Sciences Introduction to Embryology Lecture Overview Aim Purpose of learning embryology Basic facts early human development Differences between conceptus embryo fetus Concepts Fertilization, early conceptus, embryo, fetus, placenta, Timetable/stages of human development germ layers, tissue origins Critical periods of development UNSW Embryology Online 2010 Foundations Lecture – Introduction to Human Development Textbooks Human Embryology (4th ed) Schoenwolf, Gary C; Larsen, William J. Philadelphia, PA : Elsevier/Churchill Livingstone, c2009. The Developing Human: Clinically Oriented Embryology (8th ed) Moore, Keith L; Persaud, T V N; Torchia, Mark G Philadelphia, PA : Saunders/Elsevier, c2008. Four Basic Tissue Types Epithelial Connective Muscular Nervous Menstrual Cycle Oogenesis- Antral Follicle Oogenesis- Ovulation Menstrual Cycle Seminiferous Tubule Fertilization Fertilization Stage 1 Embryo - Zygote Stage 2 Embryo Movie: Embryo Mitosis First week of human development Stage 3 Embryo - Blastocyst Blastocyst “hatching” Allows uterine attachment Week 2 Implantation Conceptus Entire product of fertilization event Ovary and Uterus Week 2 - Implantation Movie: Fetal Cavities/Membranes Blastocyst - Implant Gestation Begins? Gestation Calculation Primiparas 274 days just over 39 weeks Multiparas 269 days 38.4 weeks Median duration of gestation assumed from ovulation to delivery Historic - Franz Carl Naegele (1777-1851) first rule for estimating pregnancy length Current - Ultrasound the most accurate staging method Gestation Abnormal Implantation Ectopic Sites external surface of uterus, ovary, bowel, gastrointestinal tract, mesentery, peritoneal wall If not spontaneous then, embryo has to be removed surgically Uterine Placental Abnormalities placenta accreta abnormal adherence, absence of decidua basalis placenta percreta villi penetrate myometrium placenta previa placenta overlies internal os of uterus Implantation Embryonic Period - Week 1 to 8 Trilaminar Embryo Embryonic Origins Germ Layers 3 simple layers form all body structures 2 epithelia and 1 embryonic connective tissue Ectoderm Mesoderm Endoderm Embryonic Layers Early Placenta - Fetal Membranes Decidua (uterus) forms 3 distinct regions At approx 3 weeks Decidua Basalis implantation site Decidua Capsularis enclosing the conceptus Decidua Parietalis remainder of uterus Decidua Capsularis and Parietalis fuse uterine cavity is lost by 12 weeks Placenta Materno/fetal organ No exchange of blood Many different roles

Embryo Stages Movie Embryonic Period - Week 1 to 8 Stage 7 Embryo Trilaminar Embryo Stage 9 Embryo Stage 10 Embryo Carnegie stage 23 Embryonic Period - Week 1 to 8 Organogenic Period First Trimester Week 1 to 8 From fertilization Neuralation Neural tube Brain and spinal cord Gastrulation Gastrointestinal Tract Body Organs Heart first to form

Fetal Period - Week 9 - 38 Continuing growth and differentiation Of organs formed in embryonic period Human Fetal Resources Fetal Period - 2nd and 3rd Trimesters Fetal Period - 2nd Trimester Continued organ/tissue differentiation Fetal length growth Fetal Period- Growth Changing relative proportions Head growth slower than body 9-16 weeks most rapid Large body weight gain in final weeks Fetal Membranes Placenta - Fetal Parturition (Birth) Stage 1- Dilatation Stage 2- Expulsion Stage 3- Placental Stage 4- Recovery Newborn Homoeostasis Lung function Fluid drainage, Gas exchange, muscular activity Circulatory changes Closure of 3 shunts Thermoregulation Metabolic rate, fat metabolism Nutrition gastrointestinal tract function peristalsis Waste kidney function Endocrine function Loss of placenta, maternal hormones Critical Periods of Development Additional Slides The following slides are provided for background information purposes only IVF history Australian birth data Maternal Age effects Paternal Age effects Teenage Pregnancy Embryology 1887 collection of human embryos Carnegie Collection 1978 Louise Brown first “test tube baby” Mar 1997 Sheep cloning Feb 2004 Human cloning blastocysts Mar 2009 Obama allows USA human stem cell research Australian Birth Statistics Maternal Age Australian Birth Statistics Multiple births IVF Statistics Louise Brown was born in the UK 3 million births (2006) worldwide Australia 2005 - Mothers 267,793 women gave birth to 272,419 babies 15,214 more births (5.9%) than in 2004 Mothers mean age was 29.8 years continuing the upward trend in maternal age 9,867 Aboriginal or Torres Strait Islander origin 3.7% of all mothers 17.4% reported smoking at all during pregnancy 58.5% had a spontaneous vaginal birth 30.3% gave birth by caesarean section 19.5% in 1996 1.7% had a multiple pregnancy median length hospital stay 3.0 days caesarean section 5.0 days Australia 2005 - Babies 8.1% preterm (less than 37 weeks gestation) 6.4% babies of low birthweight (< 2,500 grams) sex ratio 105.5 male / 100 female live births 15.5% of liveborn babies were admitted to a special care nursery or neonatal intensive care unit 6,044 admitted to neonatal intensive care units 78.0% were preterm fetal death rate 7.3 per 1,000 births neonatal death rate was 3.2 per 1,000 live births perinatal death rate was 10.5 per 1,000 births Birth Issues - Teenage Pregnancy Carnegie stage 9 Blastocyst