List of definitions of terms and concepts commonly used in the study of developmental biology
This glossary of developmental biology is a list of definitions of terms and concepts commonly used in the study of
developmental biology and related disciplines in
biology, including
embryology and
reproductive biology, primarily as they pertain to
vertebrate animals and particularly to humans and other mammals. The developmental biology of invertebrates, plants, fungi, and other organisms is treated in other articles; e.g terms relating to the reproduction and development of insects are listed in
Glossary of entomology, and those relating to plants are listed in
Glossary of botany.
One of four extraembryonic membranes formed during the development of
amniotes, arising as a sac-like extension of the
hindgut and having the dual function of
excretion and
respiration.[1] In mammals, the allantois arises as a
diverticulum made of
splanchnopleure almost as soon as the hindgut is established, and quickly builds a dense network of circulatory vessels which eventually assumes responsibility for all metabolic interchange between the
fetus and mother.[2]
One of four extraembryonic membranes formed during the development of animals belonging to the clade
Amniota, all of which are terrestrial vertebrates. Arising from
somatopleure very early in development, the amnion grows to surround and define the
amniotic cavity, which contains
amniotic fluid that cushions and protects the developing embryo from injury.[2]
The central internal cavity of the
gastrula in most animal embryos, fated to develop into the lumen of the
digestive tube; the primitive
gut. The archenteron initially has only one open end, known as the
blastopore.
Also blastocoele, blastocele, cleavage cavity, and segmentation cavity.
The fluid-filled or
yolk-filled cavity that forms in the developing
blastula or
blastocyst in virtually all animal species. The blastocoel appears to serve two functions: it permits cell migration during
gastrulation, and it prevents cells beneath it from interacting prematurely with cells above it by physically separating them.[2]
An early form of the animal
embryo generally consisting of a hollow sphere of cells (
blastomeres) in a single layer (the
blastoderm) surrounding a fluid-filled cavity (the
blastocoel).[2] Mammalian embryos develop into a specialized blastula known as a
blastocyst, containing a differentiated
inner cell mass and
trophectoderm.
A stage in the embryonic development of all animals defined by the formation of the
blastula, following
morulation and preceding
gastrulation. During blastulation, the early embryo develops from a solid ball of cells called a
morula into a hollow sphere consisting of an
internal cavity surrounded by a single layer of
blastomeres; a significant amount of embryonic activity is also dedicated to establishing
cell polarity and the basic axes of the
body plan, determining the fates of specific cells,
activating the embryonic genome, and ultimately
transferring full control of
gene expression from the mother to the embryo. In mammals, blastulation results in a
blastocyst, a specialized blastula marked by very early
differentiation of cell populations.
1. One of four extraembryonic membranes formed during the development of
amniotes, arising from
trophoblast and
somatopleure as a corollary of the
amnion and enclosing both the amnion and the
allantois. The chorion provides the fetal contribution to the formation of the
placenta.[1][2]
2. A tough coat surrounding the eggs of some insects and fish.[2]
Another name for the
inner cell mass, i.e. that portion of the
blastocyst that actually gives rise to
embryonic tissues, as opposed to extraembryonic tissues.[2]
The growth and formation of the
embryo; the course of development that occurs during the time period beginning with the
fertilization of the
ovum and ending when the developing animal can no longer be considered an embryo, the criteria for which may vary widely and arbitrarily depending on species. In humans, the embryonic period ends nine weeks after conception, after which time the term
fetus is used instead of embryo. In many other animals, embryogenesis is considered complete only after hatching or birth.
A diagram that shows what will become of each region of the
embryo during the course of normal development. Fate maps are created by selectively marking populations of cells in distinct regions of the early embryo with distinct visual
reporters (by any of a variety of methods designed to permit easy visualization of the marked cells, e.g. vital stains, fluorescent compounds, or retroviral transfection) and then allowing the embryo to proceed normally through the subsequent stages of development, after which each specific reporter can again be visualized, thereby revealing the new positions and morphologies of the marked cells and/or their daughter cells. Visualizing the reporters at two or more different developmental stages shows how the different parts of the embryo have moved and changed over time.[2]
A stage in the embryonic development of most animals defined by the formation of the
gastrula, following
blastulation and preceding
neurulation. During gastrulation, the
blastula or
blastocyst undergoes a major reorganization from a single, continuous layer of cells surrounding a single cavity into the complex, multilayered, multicavity gastrula, in which all of the primordial
germ layers are present. Though the precise pattern of morphogenetic changes constituting gastrulation varies considerably between species, all types of gastrulation are unified by five basic classes of cell movements: the
invagination of one side of the blastula into the
blastocoel; the
involution of the inner layer of cells over the basal surface of the outer layer; the
ingression of individual cells into the embryo; the
delamination of one layer into two layers via splitting or migration; and the
epiboly or expansion of one layer over other cells or layers.[3] By the end of gastrulation, the cells of the embryo have begun
differentiation into distinct lineages, the basic axes of the
body plan have been established (e.g. dorsal-ventral, anterior-posterior, etc.), and one or more layers of cells have been internalized, including the
prospective gut.
The process by which the definite cells and tissues that make up the body of an organism arise from embryonic cells; or, more generally, the generation of new tissues at any stage of life.[2]
A very early form of the animal
embryo consisting of a solid ball of 16 to 32
blastomeres. By the morula stage, these cells have become flattened and have begun to develop stronger cell-to-cell adhesion, as well as to pump fluid into an internal cavity that will eventually become the
blastocoel.
Either of the haploid
gametic nuclei, i.e. that of the
ovum or
sperm, as they exist prior to
syngamy. The female pronucleus is formed during
oogenesis at the time of the
second meiotic division, which occurs before
fertilization; in contrast, the nucleus of a spermatozoon is generally only considered a pronucleus after fertilization, once it is inside the cytoplasm of the egg and has begun to decondense.[2]
List of definitions of terms and concepts commonly used in the study of developmental biology
This glossary of developmental biology is a list of definitions of terms and concepts commonly used in the study of
developmental biology and related disciplines in
biology, including
embryology and
reproductive biology, primarily as they pertain to
vertebrate animals and particularly to humans and other mammals. The developmental biology of invertebrates, plants, fungi, and other organisms is treated in other articles; e.g terms relating to the reproduction and development of insects are listed in
Glossary of entomology, and those relating to plants are listed in
Glossary of botany.
One of four extraembryonic membranes formed during the development of
amniotes, arising as a sac-like extension of the
hindgut and having the dual function of
excretion and
respiration.[1] In mammals, the allantois arises as a
diverticulum made of
splanchnopleure almost as soon as the hindgut is established, and quickly builds a dense network of circulatory vessels which eventually assumes responsibility for all metabolic interchange between the
fetus and mother.[2]
One of four extraembryonic membranes formed during the development of animals belonging to the clade
Amniota, all of which are terrestrial vertebrates. Arising from
somatopleure very early in development, the amnion grows to surround and define the
amniotic cavity, which contains
amniotic fluid that cushions and protects the developing embryo from injury.[2]
The central internal cavity of the
gastrula in most animal embryos, fated to develop into the lumen of the
digestive tube; the primitive
gut. The archenteron initially has only one open end, known as the
blastopore.
Also blastocoele, blastocele, cleavage cavity, and segmentation cavity.
The fluid-filled or
yolk-filled cavity that forms in the developing
blastula or
blastocyst in virtually all animal species. The blastocoel appears to serve two functions: it permits cell migration during
gastrulation, and it prevents cells beneath it from interacting prematurely with cells above it by physically separating them.[2]
An early form of the animal
embryo generally consisting of a hollow sphere of cells (
blastomeres) in a single layer (the
blastoderm) surrounding a fluid-filled cavity (the
blastocoel).[2] Mammalian embryos develop into a specialized blastula known as a
blastocyst, containing a differentiated
inner cell mass and
trophectoderm.
A stage in the embryonic development of all animals defined by the formation of the
blastula, following
morulation and preceding
gastrulation. During blastulation, the early embryo develops from a solid ball of cells called a
morula into a hollow sphere consisting of an
internal cavity surrounded by a single layer of
blastomeres; a significant amount of embryonic activity is also dedicated to establishing
cell polarity and the basic axes of the
body plan, determining the fates of specific cells,
activating the embryonic genome, and ultimately
transferring full control of
gene expression from the mother to the embryo. In mammals, blastulation results in a
blastocyst, a specialized blastula marked by very early
differentiation of cell populations.
1. One of four extraembryonic membranes formed during the development of
amniotes, arising from
trophoblast and
somatopleure as a corollary of the
amnion and enclosing both the amnion and the
allantois. The chorion provides the fetal contribution to the formation of the
placenta.[1][2]
2. A tough coat surrounding the eggs of some insects and fish.[2]
Another name for the
inner cell mass, i.e. that portion of the
blastocyst that actually gives rise to
embryonic tissues, as opposed to extraembryonic tissues.[2]
The growth and formation of the
embryo; the course of development that occurs during the time period beginning with the
fertilization of the
ovum and ending when the developing animal can no longer be considered an embryo, the criteria for which may vary widely and arbitrarily depending on species. In humans, the embryonic period ends nine weeks after conception, after which time the term
fetus is used instead of embryo. In many other animals, embryogenesis is considered complete only after hatching or birth.
A diagram that shows what will become of each region of the
embryo during the course of normal development. Fate maps are created by selectively marking populations of cells in distinct regions of the early embryo with distinct visual
reporters (by any of a variety of methods designed to permit easy visualization of the marked cells, e.g. vital stains, fluorescent compounds, or retroviral transfection) and then allowing the embryo to proceed normally through the subsequent stages of development, after which each specific reporter can again be visualized, thereby revealing the new positions and morphologies of the marked cells and/or their daughter cells. Visualizing the reporters at two or more different developmental stages shows how the different parts of the embryo have moved and changed over time.[2]
A stage in the embryonic development of most animals defined by the formation of the
gastrula, following
blastulation and preceding
neurulation. During gastrulation, the
blastula or
blastocyst undergoes a major reorganization from a single, continuous layer of cells surrounding a single cavity into the complex, multilayered, multicavity gastrula, in which all of the primordial
germ layers are present. Though the precise pattern of morphogenetic changes constituting gastrulation varies considerably between species, all types of gastrulation are unified by five basic classes of cell movements: the
invagination of one side of the blastula into the
blastocoel; the
involution of the inner layer of cells over the basal surface of the outer layer; the
ingression of individual cells into the embryo; the
delamination of one layer into two layers via splitting or migration; and the
epiboly or expansion of one layer over other cells or layers.[3] By the end of gastrulation, the cells of the embryo have begun
differentiation into distinct lineages, the basic axes of the
body plan have been established (e.g. dorsal-ventral, anterior-posterior, etc.), and one or more layers of cells have been internalized, including the
prospective gut.
The process by which the definite cells and tissues that make up the body of an organism arise from embryonic cells; or, more generally, the generation of new tissues at any stage of life.[2]
A very early form of the animal
embryo consisting of a solid ball of 16 to 32
blastomeres. By the morula stage, these cells have become flattened and have begun to develop stronger cell-to-cell adhesion, as well as to pump fluid into an internal cavity that will eventually become the
blastocoel.
Either of the haploid
gametic nuclei, i.e. that of the
ovum or
sperm, as they exist prior to
syngamy. The female pronucleus is formed during
oogenesis at the time of the
second meiotic division, which occurs before
fertilization; in contrast, the nucleus of a spermatozoon is generally only considered a pronucleus after fertilization, once it is inside the cytoplasm of the egg and has begun to decondense.[2]