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82 Cards in this Set
- Front
- Back
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The bilaminary embryo consists of what layers?
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Outer circular formation of trophoblasts with an inner cell mass of epiblasts at one end.
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The inner cell mass becomes ???? and forms the ???
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flattened
embryonic disc |
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The embryonic disc is formed when?
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10 - 12 days post gestation.
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The ICM eventually only has ???? layers
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2 layers
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The ICM pushes out epiblasts and forms ??? within the ???.
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1 cell layer thick lining
trophoblast ring |
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Gastrulation is the process where the ?????? is converted to a ???????
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bilaminar embryonic disc
trilaminar embryonic disc. |
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What happens (generally) during gastrulation
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the epiblast cells from the surface of the bilaminar embryonic disc migrate into the interior to form primitive germ layers
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`The 3 primitive germ layers are the
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ectoderm, endoderm and mesoderm
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Ectoderm
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the most exterior germ layer
forms skin, brain, nervous system and other external tissues |
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Endoderm
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the most internal germ layer forming the lining of the gut and other intenral organs
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Besides forming 3 germ layers, gastrulation also forms the?
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primitive streak and notochord.
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The function of the primitive streak is?
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to establish the longitudinal or craniocaudal axis of the embryo.
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The epiblast cells that migrate through the cranial end of the primitive streak ____
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migrate cranially and stay on the midline of the embryonic disk, forming the notochordal process
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The ?? and ?? of the embryo form via ???? through the ?????
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mesoderm
endoderm gastrulation primitive streak |
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The notochord is _____
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a dense rod of cells and the notochord forms the midline axis of all chordates and is basis of axial skeleton
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Mesoderm can also be called
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intraembryonic mesoderm (inside body), or extraembryonic mesoderm (assoc with extraembryonic membranes)
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Intraembryonic mesoderm can be classified 2 ways:
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splanchnic
somatic |
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splanchnic mesoderm is ___
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associated with the viscera and developing GI tract
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Somatic mesoderm is _____-
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associated with the body wall of the developing embryo
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Endoderm cal also be classified as:
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intraembryonic endoderm (inside body
extraembryonic endoderm ( with extraembryonic membrane) |
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monotocous
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animals that usually have single births
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polytocous
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animals that usually have many births
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A freemartin is
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a sterile, intersex or pseudohermaphrodite femal born twin to a normal male
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The six principles of development
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Cell proliferation, induction, differentiation, migration, cell growth, cell death= programmed cell death or apoptosis
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Cell proliferation is ____
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cells undergoing mitosis in order to increase the number of cells
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Induction is ____
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the process by which one group of cells stimulates differentiation of an adjuacent group of cells. Signals between cells
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Inductive is the causal relationship that
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exists between 2 events such that the presence and action of one tissue is necessary for development of 2nd tissue
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Inductive interactions are usually not a
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single event, but is a series of events
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Differentiation
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process that gives a cell or group of cells a unique and stable phenotype
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Phenotype
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physical or biochemical characteristics of an organism based on genes and environment
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Migration
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process by which cells move from one area to fht embryonic body to a different area of the embryonic body
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Cell growth
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increase in cell number (proliferation) or cell size
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Cell death
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cells are removed in a precisely regulated manner and cell death is under genetic contro.
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Morphogenesis
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any change in the shape or location of a cell or tissue ie gastrulation
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Patterning
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establishment of programmed subsets of cells in proper relatioship to each other and surrounding cells and tissues
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Tissue interactions
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signaling that typically occur between adjacent tissues
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Epigenetics
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study of heritable changes in gene function that occur without a change in the sequence of the DNA ie methylation, and chromatin remodeling
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In embryonic development, epigenetics refers to
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X chromosome inactivation
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Epigenetically marked genes refer to genes that
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have one copy turned off and only one is functional.
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Euploid
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exact multiples of n
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Genomic imprinting can occur with
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DNA methylation (covalent), DNA protein and DNA/RNA interactions (non-covalent) and genomic localization in nuclear space
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Genomic imprinting is dependent on
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whether it resided in a male or female in the previous generation.
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Imprinted expression can vary
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between tissues, developmental stages, and species,.
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Genomic imprinting is a form of
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epigenic processing of genetic material
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The 4 extraembryonic membranes are:
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amnion
yolk sac allantois chorion |
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Amniotes
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any vertebrate of the group Amniota:reptiles, birds, mammals;have extra embryonic membrane called amnion
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Yolk sac
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first extraembryonic membrane to form
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The yolk sac forms from
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endoderm that is continous with the primitive embryonic gut
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As mesoderm becomes associated with endoderm of the yolk sac it is called
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splanchnic mesoderm
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splanchnopleure
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the complete wall of the yolk sac (mesoderm closely associated with endoderm)
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The yolk sac is considered to be an extension of the
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GI tract
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The yolk stalk is the
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connection that develps between the embryonic midgut and the yolk sac
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Amnion is a
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membrane that surround the embryo and separates the embyro from immediate contact with the enviroment
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The amnion is continuous with the
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ectoderm on the surface of the embryo
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The amnion eventually forms the
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outer layer of the umbilical cord
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The amnion is considered to be a ??? because it is formed from????
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somatopleure
ectoderm plus somatic mesoderm |
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Amniotic cavity is the ??? and contains ???
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space between the embryo and the amnion
amniotic fluid. |
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Amniotic fluid functions to
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keep the embryo moist
protect it from desiccation, protect and cushion the embryo from physical environmental forces |
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The amniotic fluid also prevents
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adhesion of the embryo/fetus to the embryonic membranes
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Chorion forms ???? and consists of
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Forms outside the amnion
consists of somatopleure (ectoderm + somatic mesoderm) |
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During early development the chorion is
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contiuous with the amnion at the chorioamniotic folds
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Extraembryonic coelom
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a space between the chorion and the amnion lined by mesoderm.
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The extraembryonic coelom may be continous with
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the body cavity or coelom of the embryonic body
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intraembryonic coelom
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The body cavity or coelom of the embryonic body
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Allantois
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extraembryonic membrane the begins as an extension of the hindgut
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The allantois is composed of
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endoderm with a closely applied layer of splanchnic mesoderm
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splachnopleure
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Endoderm with closely associated splanchnic mesoderm
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allantois is the ?? extraembryonic membrane to form
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last
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The allantois moves into the
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space between the amnion and the chorion.
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The allantoic stalk
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The portion of the allantois that remains attached to the embryonic hindgut
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The allantois is an important
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storage area for excretory substances that are produced during development
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The allantois has an extensive
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system of blood vessels
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In bird, the yolk sac consists of what 2 layers
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splanchnic mesoderm plus endoderm.
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The yolk stalk
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connects the yolk sac to the embyro/fetal gut
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Yolk is absorbed through
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the yolk sac endoderm and endothelial lining of blood vessels
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The yolk sac is drawn into ??? and is incorporated into the ???
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abdominal cavity
small intestine |
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The amnion and chorion body folds form ??/
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head fold
lateral fold tail fold |
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The fusion of the chorioamniotic folds produces what 2 layers?
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amnion (ectoderm +somatic mesoderm)
chorion (ectoderm + somatic mesoderm) both are somatopleures |
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In mammals the yolk sac contains
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no yolk.
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Marsupial yolk sac becomes
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quite large and makes contact with the chorion
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Most mammals develop a
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chorioallantoic placenta
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In mammals the chorion is an integral component of
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the placenta
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