What is embryology? The study of developmental events that occur during the prenatal stage . The branch of biology and medicine concerned with the study of embryos and their development. 2. Embryonic period vs. Fetal period Embryonic - first 8 weeks Development of the three primary germ layers give rise to all structures and Basic body plan takes shape Fetal period - remaining 30 weeks. Instant PDF download; This book was prepared to present an integrated revi~w of selected topics in Human Embryology. • 13 FORMATION OF THE PLACENTA • • • 16 FETAL MEMBRANES AND UMBILICAL CORD • • 20 EARLY DEVELOPMENT OF THE CONCEPTUS • 23 DEVELOPMENT OF GENERAL BODY FORM · 28 NERVOUS SYSTEM • 31 In this article we describe the 2nd week of embryonic development. Following all the excitement associated with the first gestational week, the newly formed blastocyst is ready to settle into a supportive environment and continue the growth process. Week 2 is often referred to as the week of twos. It's the week when the embryoblast Within this framework, synthetic embryology has be-come a vivid research area in the last decade, and we refer the reader to a recent review on the subject [1]. Since the mouse has historically been the model of choice for mam-malian embryology, it is without surprise that mouse em-bryoids are currently significantly more advanced than human ones. Embryology is the study of the origin and prenatal development of an organism, comprising the germinal (first two weeks from conception), embryonic (third to eighth week from conception), and fetal period (ninth week from conception until birth). Gestation in embryology refers to conceptional age, i.e., the time period from conception to birth, and should be distinguished from gestational age conceptus, abortus Terms of reference — Cranial, rostral, caudal, dorsal, ventral, lateral, medial, median, He is referred to as the "Father of Modern Embryology" and the founder of comparative embryology. He described the development of many vertebrate types. Karl Ernst Von Baer (1792-1876) Title: ch4.pmd Download full-text PDF. Read full-text. Download citation. I n a process called "hatchin g, " the conceptus breaks. with emphasis on the common ground between cattle and human embryology. 5. Embryo Stage of human development occurring between the ovum and the fetal stages, or from 2-8 weeks after conception. 6. Foetus • Infant in utero after completion of the embryonic stage at 8 weeks of gestation; major development occur from this time until birth. embryology as ultrasound resolution is still relatively poor. Twenty-five years ago, the biometric assessment of the first-trimester conceptus was established23,24, and descrip-tions of embryonic features such as the midgut herniation and the rhombencephalic cavity using transabdominal ultrasound were published in the middle of the 1980s25,26. Reading time: 19 minutes The first week of embryonic development is filled with an eclectic arrangement of physical and biochemical changes. Each step is a part of a cascade of events that must be intricately coordinated in order to produce a healthy baby at the end of the thirty eight to forty week period. Fetogenesis entails the growth and differentiation, particularly functional differentiation, of the conceptus after embryogenesis is comple ted. It thus begins on day 57, following the Stage 23 embryo that already has its principal organs, Müller F. Human Embryology & Teratology. 3. rd. ed. New York: Wiley-Liss; 2001. 5. E1.0.1.0.0