Embryology/Pregnancy Flashcards
where does fertilization and cleavage occur?
occur in the fallopian tube/oviduct
how many eggs and sperm need to be fertilized to create fraternal twins
2 eggs and 2 sperm fertilized
how many eggs and sperm need to be fertilized to create identical twins
1 egg and 1 sperm
how many zygotes are formed after fertilization of a one egg and one sperm
2 zygotes
how are 2 zygotes created after fertilization of 1 egg and 1 sperm? Cā
indeterminate cleavage/regulative cleavage
what happens after 1st cleavage to both cells? what ability do they retain?
both cells that are separated retain the ability to develop into whole organisms
what is fertilization synonymous with
syngamy
what is syngamy
fusion of two gametes(sperm and egg) to form a zygote which marks the beginning of embryonic development
for fertilization to occur, what does sperm have to penetrate
sperm penetrates plasma of 2 oocyte
when sperm penetrates plasma of 2 oocyte what forms?
a zygote(spermatozoa)
where does implantation of the embryo occur
occurs in the endometrium of the uterus (uterine lining)
what is the cell called when implantation occurs in the endometrium of the uterus
blastocyst
what block is formed after sperm has made contact with egg
block to polyspermy
what are the blocks that prevent polyspermy
fast and slow block
how does fast block work
involves enzymes from the sperm= acrosomal reactionā> cause changes in the cell voltage
how does slow block work
cortical granules bind to membrane and create a physical barrier called vitelline layer to prevent sperm from entering
what are the key stages of embryonic development? from first to last?
fertilizationā> cleavageā> Morulaā>blastulaā> gastrulaā>organogenesis
what does cleavage do
mitotic divisions
how does cleavage affect number of cells and growth
increase in cell number but no growth
what cells result from cleavage
blastomeres
what is formed at the end of cleavage
morula
what is morula
solid ball of cells
what is blastula
hollow sphere of cells with fluid filled cavity
what is the fluid filled cavity in blastula called
blastocoel
what is trophoblast
outer layer of blastula
what is a precursor to placenta
outer layer of blastula
what implants into uterus
blastula implants into the uterine lining to begin pregnancy
what do cells do in gastrulation and what do they form
cells invaginate into gastrula and form 3 germ layered embryo
what three germ layer are created
ectoderm, mesoderm, endoderm
what germ layers are found in skin
ectoderm
what germ layer is found in eyes
ectoderm
what germ layer is found in muscles
mesoderm
what germ layer is found in lungs, digestive tract, respiratory, urinary tract
endoderm
what germ layer is found in hair, nails, teeth
ectoderm
what germ layer is found in bones
mesoderm
what germ layer is found in blood and lymphatic kidney
mesoderm
what germ layer is found in nervous system
ectoderm
what germ layer is found in epithelial lining
ectoderm
what is a blastopore
opening of archenteron
what describes where an archenteron develops
primitive gut (develops into the digestive tract)
when does blastopore become anus first
becomes anus 1st in deuterostomes
when does blastopore become mouth first
becomes mouth 1st in protostomes
what is cephalization
sensory structures and nerve cells mainly in head
what type of symmetry occurs in cephalization
bilateral symmetry
what is organogenesis? what does it do to cells
is the process where cells differentiate to form organs from the three germ layers(ectoderm, mesoderm, endoderm)
what chordates are affected by organogenesis
notochord, neural tube/plate, somites
what does notochord become once it goes through organogenesis? what specific germ layer does it differentiate from?
becomes vertebras from mesoderm
what does neural tube/plate become once it goes through organogenesis? what specific germ layer does it differentiate from?
the neural plate(from ectoderm) folds to become the brain/spinal cord which develops into central nervous system
what does somites become once it goes through organogenesis? what specific germ layer does it differentiate from?
becomes backbone, skull, ribs, and skeletal muscle (meso)
what are somites? and where do they form?
segmented blocks of tissue that form on the sides of the notochord
where is gray crescent located and what does it form? what type of symmetry does it help establish?
opposite the entry of sperm and it forms the body axis which helps establish bilateral symmetry
when does neural plate form
forms when ectodermal cells elongate and then it folds into the neural tube
what type of eggs have polarity
animal eggs have polarity
what type of fertilization do reptiles, birds, and monotremes do?
internal fertilization
where do embryo develop in reptiles, birds, and monotremes
develop externally within an egg after fertilization
what membranes support the embryo in reptiles, birds, and monotremes
chorion, allantois, yolk sac, amnion
what type of fertilization do fish and amphibians do?(E or I)
external fertilization
where does embryo develop in fish and amphibians
external development
what membranes do fish and amphibians lack
lack amnion and allantois
what is chorion
outer membrane implants into the endometrium
what is function of charion in reptiles and birds
moist membrane that connects to shell and permits gas exchange
what is allantois involved in
in respiration and excretion
what does allantois store?
stores nitrogenous waste in the form of an acid (O2, CO2, H2, salts )
what do blood vessels from the allantois become?
become the umbilical cord
what is function of yolk sac
source of food(provides nutrients)
what is function of amniotic fluid
cushion, shock absorber and protection
what is amniotic fluid vital during
vital during contractions
what is amniotic fluid enclosed by
enclosed by amnion
what are the two fertility methods
in vitro fertilization and micro injection technique
how does in vitro fertilization occur
fertilization between egg and sperm in a glass dish
how does micro injection technique occur
sperm is directly injected into the egg
why is micro injection technique done? what is it a treatment for?
done when sperm count is low and abnormal swimming sperm. treatment for make infertility
