Early developmental stages Flashcards
Fertilization is…
The joining of sperm and ovum
Fertilization usually occurs in the ____ of the Fallopian tube
Ampulla
How does the sperm penetrate the corona radiate and zone pelluicida?
By the use of acrosomal enzymes
Once the sperm contacts the located plasma membrane … The sperm establishes the ___ and injects its nucleus
Acrosomal apparatus
When the first sperm penetrates, it causes the release of what?
Calcium ions
The release of calcium ions, when the sperm penetrates, prevents what?
Prevents additional sperm from fertilizing the egg and increases the metabolic rate of the resulting zygote - this is called cortical reaction
A secondary locate is ovulated from the follicle on approximately what day of the cycle ?
Day 14
after fertilization, the zygote travels to the..
uterus for implantation
cleavage
when the zygote undergoes rapid mitotic cell divisions
one of the zygotes defining characteristics is:
unicellularity
by the zygote dividing into smaller cells, the cells increase two ratios:
nuclear to cytoplasmic ratio
surface area - to - volume ratio
two types of cleavage:
indeterminate cleavage
determinate cleavage
indeterminate cleavage
results in cells that can still develop into complete organisms
determinate cleavage
results in cells with fates that are already determined
these cells are committed to differentiating into a certain type of cell
morula
the embryo becoming a solid mass of cells
once the moral is formed, it undergoes _______
blastulation
blastulation forms the ______
blastula
blastula
a hollow ball of cells with fluid filled inner cavity known as blastocoel
blastocyst
the mammalian blastula that consists of two noteworthy cell groups - the trophoblast and inner cell mass
trophoblast cells
surround the blastocoel and give rise to the chorion and later the placenta
specialized to create an interface between the maternal blood supply and the developing embryo
inner cell mass
protrudes into the blastocoel and gives rise to the organism itself
trophoblast cells give rise to the ______
chorion
chorion
and extra embryonic membrane that develops in the placenta
chorionic villi
formed by trophoblasts
they are microscopic fingerlike projections that penetrate the endometrium
develop in the placenta
support maternal - fetal gas exchange
embryo is connected to the placenta by the …
unbilical cord
unbilical cord consist of
2 arteries and 1 vein encased in a gelatinous substance
unbilical arteries carry
deoxygenated blood and waste to the placenta for exchange
until the placenta is functional, the embryo is supported by the
yolk sac
early blood cell development :
yolk sac
2 extra embryonic membranes :
allantois
amnion
allantois
involved in early fluid exchange between the embryo and the yolk sac
surrounded by the amnion
amnion
thin, though membrane filled with amniotic fluid that serves as a shock absorber during pregnancy
Gastrulation
developmental process that begins once the cell mass implants
During Gastrulation, the _________ is formed with a ________ at the end
archentreron ; blastopore
As the archenteron grows through the blastocoel, it contacts the opposite side, establishing..
the 3 primary germ layers
the 3 primary germ layers
ectoderm
mesoderm
endoderm
ectoderm
becomes epidermis, hair, nails and the epithelia of the nose, mouth, and anal canal as well as the nervous system (including the adrenal medulla) and the lends of the eye
mesoderm
becomes much of the muscoskeletal, circulatory, and excretatory systems
gives rise to the gonads and the muscular and connective tissue layers of the digestive and respiratory systems as well as the adrenal cortex
endoderm
becomes much of the epithelial linings of the respiratory and digestive tracts and parts of the pancreas, thyroid, bladder, and distal urinary tracts
neurulation
development of the nervous system, begins after the formation of the 3 germ layers
notochord
introduced a group of overlying ectoderm cells to form neural folds surrounding a neural groos
the neural folds fuse to form the
neural tube; which becomes the CNS
Neural crest cells
found on the tip of the neural fold
becomes the PNS as well as specific cell types in other tissues
Teratogens
substances that interfere with development, causing defects of even death of the developing embryo.
Include alcohol, certain prescription drugs, viruses, bacteria, and environmental chemicals
