Download Extra Embryonic Membranes

[Glossary]
Extra Embryonic Membranes,
Types & Physiology of Placenta
Subject:
Zoology
Course:
B.Sc. 3rd Year
Paper No. & Title:
Z-305B
Developmental
Biology
Topic No. & Title:
Topic – 5
Extra Embryonic
Membranes, Types &
Physiology of Placenta
Lecture Title:
Extra Embryonic
Membranes, Types &
Physiology of Placenta
Glossary
Allantoic stalk
The narrow connection between the intra embryonic portion
of the allantois and the extra embryonic allantoic vessel.
Allantois
It is the foetal membrane formed as an outgrowth of the
embryo’s gut. It lies below the chorion in many vertebrates.
In birds and reptiles, it grows to surround the embryo; in
eutherian mammals, it forms part of the placenta.
Amnion
The innermost extra embryonic membrane that encloses the
embryo of a mammal, bird or reptile.
Blastoderm
A blastula having the form of a disc on top of the yolk.
Chorion
The outermost extra embryonic membrane surrounding of a
reptile, bird, or mammal. In mammals, it contributes to the
formation of the placenta.
Desiccation
It is the state of extreme dryness, or the process of extreme
drying.
Insectivores
An
animal
that
feeds
on
insects,
worms,
and
other
invertebrates.
Parturition
The action of giving birth to young; childbirth.
Pathogenic organism
An organism usually bacteria or virus, that cause disease.
Pinocytosis
The ingestion of liquid into a cell by the budding of small
vesicles from the cell membrane.
Ruminants
An
even-toed
ungulate
mammal
that
chews
the
cud
regurgitated from its rumen. The ruminants comprise the
cattle, sheep, antelopes, deer, giraffes, and other relatives.
Sedative
A drug taken for its calming or sleep-inducing effect.
Semi-permeable membrane
It is a type of selectively permeable membrane that will allow
certain molecules or ions to pass through it by diffusion.
Somatopleure
A layer of tissue in a vertebrate embryo comprising the
ectoderm and the outer layer of mesoderm, and giving rise to
amnion, chorion, and part of the body wall.
Splanchnopleure
A layer of tissue in a vertebrate embryo comprising the
endoderm and the inner layer of mesoderm, and giving rise
to the gut, lungs and yolk sac.
Synctium
A single cell or cytoplasmic mass containing several nuclei,
formed by fusion of cells or by division of nuclei.
Trophoblast
A layer of tissue on the outside of a mammalian blastula,
supplying the embryo with nourishment and later forming the
major part of the placenta.
Yolk sac
A membranous sac containing yolk attached to the embryos
of reptiles and birds and the larva of some fishes. A sac
lacking yolk in the early embryo of a mammal.
Yolk stalk
In humans, it is a long narrow tube that joints the yolk sac to
the midgut lumen of the developing foetus. It appears at the
end of the fourth week, when the yolk sac presents the
appearance of a small-pear shaped vesicle.