EMBRYOLOGY Flashcards
define embryology
study of embryo
another term for embryology
study of prenatal development
prenatal is divided into
embryology state and fetal stage
1st week from week 2-8 after fertilization is called?
embryo
after week 8 which is week 9 we call it?
fetus
from week 0-8 its called?
embryology
define ontogeny
state of development , healthy and normal individual
define teratology
due to malformation , abnormal development
meiosis is for
gamet cell division
mitosis is for
somatic cell division
in meiosis its 1 diploid cell undergoes how many rounds of division and produces how many cells
undergoes 2 rounds to produce 4 haploid cells.
in meiosis is the 4 haploid cells similar to the mother cell
no due to the cross over that happens in prophase I
in mitosis its 1 diploid cell undergoes how many rounds of division and produces how many cells
undergoes 1 round to produce 2 diploid cells
in mitosis is the 2 diploid cells similar to the mother cell
yes but smaller in size
define gametogenesis
formation and development of the sperm and ovum and reduction in number of chromosomes from diploid 46 to haploid 23
define primary germ cell
early precursor undifferentiated cells that eventually migrate to the gonads and differentiate into gametes (sperm or eggs) through meiosis
zygote which is now 46 chromosomes will divide rapidly by which process
mitosis to form a mass of 2,4,8,16,32 to infinity until it gives us tissue and organs
when primary cell become haploid 23 they are known as
mature germ cells which is also called gamets
in gametogenesis we have change in shape of primary germ cells what change takes in sperm and ovum
Sperm: Develops from a round cell into a streamlined, motile cell with a head, midpiece, and tail, designed for mobility and fertilization.
ovum: Remains large and round, optimizing for nutrient storage and support of the early embryo, with no structures for movement.
define phenotype
traits, which result from interaction of genotype with environment
where does the sperm contact the ovum to form a zygote
uterine tube
zygote is also known as
fertilized ovum
how can the sperm enter the ovum
the sperm head contains acrosomes which is basically lysosomes which will penetrate the ovum membrane.
define induction
one group of cells influences the development of another group of cells
define genotype
specific set of genes an individual carries
define competence
the ability of cell to respond to signals
what happens if the cell is not responding to the signals which means it isnβt competent
differentiation wont occur in order for it to occur we need induction and competence
define morula
solid ball of cells resulting from early divisions of zygote
define blastocyst
morula develops into blastocyst which has a fluid filled cavity and begins to implant to uterine wall due to trophoblast cuz it got enzymes
blastocyst has two main structures
Embryoblast: Becomes the embryo and eventually forms all the tissues and organs of the body.
Trophoblast: Contributes to the formation of the placenta, which supports and nourishes the developing embryo.
there is cavity filled with fluid in blastula from does the fluid comes from
this fluid seeps inside from the uterine wall
why is the morula known as undifferentiated totipotent cells
cells of the morula are considered undifferentiated because they have not yet begun to specialize, and they are totipotent because each cell has the potential to develop into a complete organism
whys is blastocyst differentiated and pluripotent
cells started to differentiate resulting in two distinct cell types: the inner cell mass (pluripotent, forms the embryo) and the trophoblast (specialized, forms the placenta) and inner cell mass cells are pluripotent because they can form almost any cell type in the body but are no longer capable of forming an entire organism, including the placenta.
1st week of development ends with
the implantation of blastocyst into the endometrium of uterus and this process involves the blastocyst embedding itself into the uterine lining, causing localized damage to the endometrium
what happens in the 2nd week
the bilaminar embryo forms which is characterized by the presence of two distinct layers derived from the inner cell mass (embryoblast) of the blastocyst the layers are called epiblast and hypoblast
epiblast is
columnar cells and will give us ectoderm
hypoblast is
squamous cells and will give us endoderm
what makes mesoderm
in week 3 the epiblast will migrate towards the primitive streak and gives us mesoderm
what happens when you got the 2 layers which is epiblast and hypoblast
when you have these two layers we will divide the yolk sac into two sacs called AMNIOTIC AND SECONDARY YOLK SAC and this is in week 2
define gastrulation
the formation of the 3 germ layers
beginning of morphogenesis
why is primitive streak important
it divides the embryo into right and left
what is the name of the gene which is important in gastrulation
BMP imp for morphogenesis of embryo
formation of neural crest cells
group of cells that arise from ectoderm and migrate to various parts of embryo to form diff tissues EXCEPT ENAMEL
what induces the formation of the neural plate
notochord (a structure derived from mesoderm) induces the overlying ectoderm to thicken and form the neural plate.
define notochord
its a primitive spinal cord that will disappear and be replaced by the vertebrate also it gives support to the trilaminar disc
define neurulation
is the transformation of neural plate into neural tube
steps of neurulation
1- neural plate will fold to form neural groove
2- neural groove will fuse to form neural tube
3- neural tube give rise to brain and spinal cord
what are the temporary openings at the ends of the neural tube
cranial neuropore and caudal neuropore
neural crest gives rise to
cranial cells and sensory ganglia and nerves
sympathetic neurons
Schwan cells
pigment cells
meninges
cartilages of branchial arches
most of CT of face βectomesenchymeβ EXCEPT ENAMEL
why is neural crest imp
for development of face, neck and oral tissues
neural crest defects
treacher collins syndrome ( mandibulofacial dysostosis) which underdevelopment of zygomatic bones, small mandible, malformed ears.
what is caudal neuropore
end of embryo
how many somites as humans we have
44 as humans
when does somites disappear
week 4
what is cranial neuropore
develop brain
when do somites appear
week 3
what will give us somiteβs
through segmentation of paraxial mesoderm
what forms paraxial mesoderm
forms through the thickening of the mesoderm on each side of the midline. This thickened mesoderm first organizes into somitomeres, which are precursor structures that later develop into somites.
somiteβs has 3 compartments
sclerotome : 2 adjacent vertebrae and their disks
myotome: segmented mass of muscle
dermatome: CT of skin overlying somite
