Gastrulation PDF

Gastrulation Establishing of body axis: cell signaling and gene functioning in development CU: Introduction to Animal Organism CU: Introduction to Animal Life Joana Ropio, PhD Based on slides by Prof. Alexandra Sanfins INTRODUCTION TO...

Gastrulation Establishing of body axis: cell signaling and gene functioning in development CU: Introduction to Animal Organism CU: Introduction to Animal Life Joana Ropio, PhD Based on slides by Prof. Alexandra Sanfins INTRODUCTION TO ANIMAL ORGANISM – Alexandra Sanfins www.egasmoniz.com.pt www.egasmoniz.com/pt Gastrulation Reorganizing - the embryonic Master Degree in Veterinary Medicine cells INTRODUCTION INTRODUCTIONTO TOANIMAL ANIMAL ORGANISM ORGANISM –– Alexandra Alexandra Sanfins Sanfins  Master’s Degree in Veterinary Medicine & Degree in Biomedical Sciences Master’s Master Degree Medicine Veterinary Medicine inVeterinary Degreein - - www.egasmoniz.com/pt www.egasmoniz.com/pt www.egasmoniz.com.pt INTRODUCTION TO ANIMAL ORGANISM – Alexandra Sanfins  Gastrulation www.egasmoniz.com/pt www.egasmoniz.com/pt Master’s Degree in Veterinary Medicine & Degree in Biomedical Sciences Gastrulation is the process of germ layer formation. These changes occur through a series of orderly cell migrations from the surface of the blastula to its interior. www.egasmoniz.com.pt - A single-layered blastula is converted into a trilaminar - structure with three germ layers: Medicine Veterinary Medicine Ectoderm Mesoderme inVeterinary Endoderm Cells arising from each germ layer give rise to specific Degreein Master Degree organs and tissues. Master’s Patterns of gastrulation vary throughout the Animal Kingdom INTRODUCTION INTRODUCTIONTO TOANIMAL ANIMAL ORGANISM ORGANISM –– Alexandra Alexandra Sanfins Sanfins ©www.macmillanhighered.com  The three germ layers www.egasmoniz.com/pt www.egasmoniz.com/pt Master’s Degree in Veterinary Medicine & Degree in Biomedical Sciences Ectoderm gives rises to the epidermal layer of the skin and into neural tissue www.egasmoniz.com.pt Mesoderm originates de urogenital, circulatory and - - supportive muscular and skeletal system Medicine Endoderm forms the lining of the gastrointestinal and Veterinary Medicine respiratory tract Master Degree Master’s inVeterinary Degreein INTRODUCTION INTRODUCTIONTO TOANIMAL ANIMAL ORGANISM ORGANISM –– Alexandra Alexandra Sanfins Sanfins © www.macmillanhighered.com ©Moosmosis. Ectoderm vs Mesoderm  Master’s Degree in Veterinary Medicine & Degree in Biomedical Sciences Master’s Master Degree Medicine Veterinary Medicine inVeterinary Degreein - - www.egasmoniz.com/pt www.egasmoniz.com/pt www.egasmoniz.com.pt INTRODUCTION INTRODUCTIONTO TOANIMAL ANIMAL ORGANISM ORGANISM –– Alexandra Alexandra Sanfins Sanfins Gastrulation in Primitive Chordata  www.egasmoniz.com/pt www.egasmoniz.com/pt Gastrulation in Primitive Chordata Master’s Degree in Veterinary Medicine & Degree in Biomedical Sciences Gastrulation begins when the blastoderm at the vegetal pole flattens and invaginates. The embryo undergoes a series of morphological changes. www.egasmoniz.com.pt A cavity forms, the archenteron or primitive gut. The opening - - of the archenteron to the exterior is the blastopore Medicine Veterinary Medicine The outer layer of cells forms the ectoderm and the inner layer the endoderm. The mesoderm forms at the edges of the blastopore. inVeterinary Gastrula Later, mesodermal cells migrate to a position between the ectoderm and the endoderm. Degreein Therefore, mesodermal and endodermal structures relocate Master Degree from the surface of the embryo to its interior forming a The pattern of gastrulation in the Amphioxus represents trilaminar embryo referred to as gastrula. Master’s the major cellular events observed in more evolutionary advanced species. INTRODUCTION INTRODUCTIONTO TOANIMAL ANIMAL ORGANISM ORGANISM –– Alexandra Alexandra Sanfins Sanfins © Veterinary Embryology  Master’s Degree in Veterinary Medicine & Degree in Biomedical Sciences Master’s Master Degree Medicine Veterinary Medicine inVeterinary Degreein - - www.egasmoniz.com/pt www.egasmoniz.com/pt www.egasmoniz.com.pt INTRODUCTION INTRODUCTIONTO TOANIMAL ANIMAL ORGANISM ORGANISM –– Alexandra Alexandra Sanfins Sanfins Gastrulation in Amphibians  www.egasmoniz.com/pt www.egasmoniz.com/pt Gastrulation in Amphibians Master’s Degree in Veterinary Medicine & Degree in Biomedical Sciences At the junction of the animal and vegetal hemispheres, cells from the surface move to the interior forming a cleft or dorsal lip of the blastopore, the forerunner of the primitive gut. www.egasmoniz.com.pt This dorsal lip deepens because of the influx of cells to its - - interior forming the archenteron. Medicine Veterinary Medicine As the primitive gut deepens the yolk-cells move to the interior. inVeterinary A trilaminar embryo is formed, the gastrula. Degreein Master Degree Invagination cannot occur due to the presence of yolk-filled Master’s cells in the vegetal hemisphere of the amphibian blastula. INTRODUCTION INTRODUCTIONTO TOANIMAL ANIMAL ORGANISM ORGANISM –– Alexandra Alexandra Sanfins Sanfins Principles of development in biology-Gilbert  Master’s Degree in Veterinary Medicine & Degree in Biomedical Sciences Master’s Master Degree Medicine Veterinary Medicine inVeterinary Degreein - - www.egasmoniz.com/pt www.egasmoniz.com/pt www.egasmoniz.com.pt INTRODUCTION INTRODUCTIONTO TOANIMAL ANIMAL ORGANISM ORGANISM –– Alexandra Alexandra Sanfins Sanfins Embryo development in Amphibians https://www.youtube.com/watch?v=riSA1mo86Kg  Master’s Degree in Veterinary Medicine & Degree in Biomedical Sciences Master’s Master Degree Medicine Veterinary Medicine inVeterinary Degreein - - www.egasmoniz.com/pt www.egasmoniz.com/pt www.egasmoniz.com.pt INTRODUCTION INTRODUCTIONTO TOANIMAL ANIMAL ORGANISM ORGANISM –– Alexandra Alexandra Sanfins Sanfins Gastrulation in Avian species and Mammals  Formation of the primitive streak www.egasmoniz.com/pt www.egasmoniz.com/pt Sciences Sciences in Biomedical The major structural characteristic of avian, reptilian and mammalian Biomedical gastrulation in the primitive streak. & Degree&inDegree www.egasmoniz.com.pt The primitive streak consists of: - - Primitive groove MedicineMedicine Primitive node Medicine Medicine Primitive pit in Veterinary After primitive streak formation, the embryo has: Veterinary Master Degree in Veterinary Cranio-caudal axis Dorsal and Ventral surfaces Veterinary Right and Left sides Degree inDegree in www.egasmoniz.com.pt Degree Master’s Master’s Master’s INTRODUCTION INTRODUCTIONTO TOANIMAL ANIMAL ORGANISM ORGANISM –– Alexandra Alexandra Sanfins Sanfins  Veterinary Degree inDegree Master’s Master’s in Veterinary Biomedical & Degree&inDegree MedicineMedicine Sciences Sciences in Biomedical Master’s Degree in Veterinary Master Degree in Veterinary Medicine Medicine - - www.egasmoniz.com/pt www.egasmoniz.com/pt www.egasmoniz.com.pt www.egasmoniz.com.pt INTRODUCTION INTRODUCTIONTO TOANIMAL ANIMAL ORGANISM ORGANISM –– Alexandra Alexandra Sanfins Sanfins Formation of the primitive streak https://www.youtube.com/watch?v=-Oay7q_xw9U  Gastrulation in www.egasmoniz.com/pt www.egasmoniz.com/pt Master’s Degree in Veterinary Medicine & Degree in Biomedical Sciences Avian species Posterior epiblast cells start invaginating forming the primitive steak. www.egasmoniz.com.pt These cells give rise to two layers: - - Upper epiblast, that comprises prospective ectoderm and mesoderm Lower hypoblast destined to become the extra-embryonic Medicine Veterinary Medicine endoderm. As cells migrate, the primitive steak elongates forming at inVeterinary the cranial end, the primitive node (or Hensen’s node). These cells will form head structures and notochord. As cells from the epiblast migrate inwards to the primitive Degreein streak, cells from the adjoining areas divide and replace Master Degree the cells from the epiblast. Therefore, the primitive streak is a structure that persists throughout gastrulation. Master’s The avian blastoderm consists of two parts: Throughout the process of gastrulation, the epiblast is the The area pellucida (blastodisc) and area opaca (yolk) source of all the germ layers. INTRODUCTION INTRODUCTIONTO TOANIMAL ANIMAL ORGANISM ORGANISM –– Alexandra Alexandra Sanfins Sanfins ©2003 Pearson Education Inc. publishing as Benjamin Cummings  www.egasmoniz.com/pt www.egasmoniz.com/pt Gastrulation in Mammals Sciences Sciences in Biomedical In mammals, the blastocyst cavity is the equivalent to an Biomedical empty yolk sac cavity. & Degree&inDegree www.egasmoniz.com.pt The embryonic disc occupies a position comparable to that Amniotic cavity - of the blastoderm in avian species and gastrulation - proceeds in a manner remarkably similar to avian species. MedicineMedicine Medicine Medicine The primitive streak forms as with the avian embryos. in Veterinary The first process is the formation of a flat layer of cells, Veterinary Master Degree in Veterinary derived from the embryonic disc, occupying a position on Veterinary its lower surface (endoderm). This layer corresponds to the hypoblast of the chick blastoderm and extends along the Degree inDegree in www.egasmoniz.com.pt entire surface of the blastocyst forming a bilaminar yolk sac. Degree Master’s Master’s The remaining cells of the inner cell mass are equivalent to Master’s the epiblast of the chick blastoderm and give rise to the ectoderm. INTRODUCTION INTRODUCTIONTO TOANIMAL ANIMAL ORGANISM ORGANISM –– Alexandra Alexandra Sanfins Sanfins ©McGraw-Hill Companies, Inc.  Veterinary Degree inDegree Master’s Master’s in Veterinary Biomedical & Degree&inDegree MedicineMedicine Sciences Sciences in Biomedical Master’s Degree in Veterinary Master Degree in Veterinary Medicine Medicine - - www.egasmoniz.com/pt www.egasmoniz.com/pt www.egasmoniz.com.pt www.egasmoniz.com.pt INTRODUCTION INTRODUCTIONTO TOANIMAL ANIMAL ORGANISM ORGANISM –– Alexandra Alexandra Sanfins Sanfins Gastrulation in mammals https://www.youtube.com/watch?v=ADlYn0ImTNg  Master’s Degree in Veterinary Medicine & Degree in Biomedical Sciences Master’s Master Degree Medicine Veterinary Medicine inVeterinary Degreein - - www.egasmoniz.com/pt www.egasmoniz.com/pt www.egasmoniz.com.pt INTRODUCTION INTRODUCTIONTO TOANIMAL ANIMAL ORGANISM ORGANISM –– Alexandra Alexandra Sanfins Sanfins Establishment of body axis  www.egasmoniz.com/pt www.egasmoniz.com/pt Establishment of body axis Sciences Sciences in Biomedical Before and during gastrulation body axes are created. Biomedical The establishment of anteroposterior (AP), dorsoventral & Degree&inDegree www.egasmoniz.com.pt (DV) and left-right (LR) body axes is regulated by molecular signaling pathways. - - MedicineMedicine Medicine Medicine in Veterinary Veterinary Master Degree in Veterinary Veterinary Degree inDegree in www.egasmoniz.com.pt The expression of specific sets of genes regulate which cells Degree Gastrulation and Body Axes Formation: A Molecular Concept and Its Clinical Correlates will develop into specific structures. Master’s Master’s Master’s Anomalies in gastrulation process are caused by aberrations of certain molecular pathways. INTRODUCTION TO ANIMAL ORGANISM – Alexandra Sanfins  Establishment of anteroposterior (AP) www.egasmoniz.com/pt www.egasmoniz.com/pt Sciences Sciences and dorsoventral (DV) body axis in Biomedical Biomedical The establishment of the DV and AP axes is controlled by & Degree&inDegree www.egasmoniz.com.pt interconnected regulatory mechanisms. - - The DV axis is determined by BMP signalling, which induces MedicineMedicine ventral destiny. Medicine Medicine The fibroblast growth factor (FGF) and WNT3 signalling in Veterinary pathways control AP patterning. Veterinary Master Degree in Veterinary Veterinary WNT3 stimulation, on the other hand, also promotes BMP signalling. Degree inDegree in www.egasmoniz.com.pt Degree Master’s Master’s Master’s INTRODUCTION TO ANIMAL ORGANISM – Alexandra Sanfins  Establishment of left-right symmetry in www.egasmoniz.com/pt www.egasmoniz.com/pt Sciences Sciences vertebrates in Biomedical Organs of vertebrates are positioned asymmetrically in the Biomedical thoracic and abdominal cavities. internal organs such as the & Degree&inDegree heart, stomach, and intestines have both asymmetric Ciliary movements of www.egasmoniz.com.pt structure and asymmetric positions within the body cavity. the cells in the primitive - node to the left cause - The left-right pattern of development is dependent on activation of a product of MedicineMedicine regulation by molecular processes. the Inv gene. This Medicine Medicine product activates Lefty2 The gene situs inversus viscerum (Iv) is one of the genes and Nodal proteins. responsible for establishing the left-right asymmetry. in Veterinary Diffusion of these Veterinary Mutation in this gene cause randomly positioning of each Master Degree in Veterinary proteins to the right is organ and is lethal. inhibited by the Lefty1 Veterinary gene product. Other gene involved is inversion of embryonic turning (Inv). Degree inDegree Nodal activates Pitx2 in www.egasmoniz.com.pt Mutations in this gene cause all organs to be reversed and has which induces formation Degree fewer deleterious consequences than mutations in the Iv of left-sided Master’s Master’s gene. development. Master’s Ciliary movements of the cells in the primitive node to the left are responsible for the development of left-sided structures. INTRODUCTION INTRODUCTIONTO TOANIMAL ANIMAL ORGANISM ORGANISM –– Alexandra Alexandra Sanfins Sanfins ©Genetic pathway for the determination of the left-right assymetry. Nature Reviews  Gastrulation Establishing of body axis: cell signaling and gene functioning in development CU: Introduction to Animal Organism CU: Introduction to Animal Life Joana Ropio, PhD Based on slides by Prof. Alexandra Sanfins INTRODUCTION TO ANIMAL ORGANISM – Alexandra Sanfins www.egasmoniz.com.pt