Chapter 3 - Prenatal Development Flashcards
Define embryology
study of prenatal development
Duration of prenatal dev.
start of pregnancy - birth
3 distinct successive periods are
preimplantation, embryonic period, and fetal
The first trimester includes which 2 periods
preimplantation and embryonic
The last two trimesters include which period
fetal
what is primordium
earliest indication of a tissue type or an organ during prenatal development
define congenital malformations
birth defects that are evident at birth
which period and trimester do congenital malformations occur
first, implantation and embryonic
How common are malformations
3/100
What is the leading cause of infant death
congenital malformations
define amniocentesis (amniotic fluid test), and how is it done
prenatal diagnostic procedure to detect chromosomal abnormalities. amniotic fluid is removed and the fetal cells are grown for study of the chromosomes and sampled for determination of other complications
what cells are related to implantation period, and what occurs?
zygote turn into blastocyst. fertilization and implantation
preimplantation period consists of which week/s?
first
embryonic period consists of which week/s?
second - eighth
which cells and structure are related to the embryonic period, and what happens?
disk > embryo > folded embryo. induction, proliferation, differentiation, morphogenesis, and maturation
fetal period consists of which week/s?
third - ninth
what forms during fetal period, and what happens?
embryo > fetus, maturation
what causes malformation?
genetic factors (chromosome abnormalities), environmental agents and factors (infections, drugs, and radiation)
what are considered to be teratogens
infections, drugs, and radiation
zygote is
a fertilized egg
how many chromosomes results in the final stages of meiosis
46
XX chromosomes =
female
XY chromosomes =
male
What happens to the zygote after fertilization
mitosis
after initial cleavage during mitosis, what happens?
solid ball of cells from initial cleavage
a blastocyst forms from
a zygote that has fluid secreted by cells within the morula
what is mitosis
individual cell division
what is the difference between mitosis and meiosis
mitosis happens during tissue growth or regeneration, meiosis happens during fertilization
what happens during meiosis
ovum and sperm chromosomes join during fertilization
what is the self-duplication of the chromosomes of the parent cell and their equal distribution to daughter cells
mitosis
trophoblast layer is the
outside layer of the blastocyst
embryoblast layer is
the inner mass of embryonic cells in a blastocyst
What does the trophoblast layer do
gives rise to the embryo during the prenatal period
what chromosome is responsible for down syndrom
extra chromosome 21
define induction, and which period does it belong to
first process during embryonic period, one group of cells on another that leads to establishment of the developmental pathway in the responding tissue
what process follows induction, and what is it
proliferation during embryonic period, controls levels of cell growth present during prenatal dev.
what is appositional growth
tissue gets bigger by addition of layers on outside of structure
what happens during ectopic pregnancy
the zygote is implanted in the fallopian tube instead of uterus
what is interstitial growth
growth that’s deep within tissue type or organ
is hard tissue growth appositional?
yes
Is soft tissue growth is what kind of growth
intersitial
which tissue types use both growth methods
cartilage and immature bone tissue
what is differentiation during growth
dividing cells change their functional or phenotypical type; different rate of growth for different internal tissue types and organs
cytodifferentiation is
dev. of diff. cell types
histodifferentiation
dev. of dif. histologic tissue types within structur
morphodifferentiation
dev. of differing morphology
what is morphology
structure or shape of each organ or system
what is morphogenesis
process of dev. of specific tissue stru. or shape
why does morphogenesis occur
it occurs due to the migration or proliferation of embryonic cells, which is follwed by the inductive interaction of those cells
maturation of tissue types and organs begin during which period
embryologic
what week does embryonic period end on, and what is recogniable
eighth, embryo
what is the germ layer, and where is it
embryonic cell layer within blastocyst
what is bilaminar embryonic disk
flattened 3D circular plate of bilayered cells consisting of superior epiblast and inferior hypoblast
what cells make up epiblast layer
high columnar cells
what cells make up the hypoblast layer
small cuboidal cells
what layer does the amniotic cavity face
epiblast
what layer does the yolk sac face
hypoblast
what serves as initial nourishment for the disk
yolk sac
what connects momma and embryo
endometrial tissue of placenta and trophoblast layer of blastocyte
what flows through the umbilical cord
selective exchange of soluble bloodborne substances, o2, co2, nutritional and hormonal substances
what is the primitive streak
forms inside bilaminar disc, is furrowed, rod shaped thickening in the middle of the disk
what does the primitive streak do to the bilaminar embryonic disk
causes disc to have bilateral symmetry, left and right half
what is mesoderm and what creates it
embryonic connective tissue, made of epiblast and hypoblast cells
what makes up the trilaminar embryonic disc
mesoderm, embryonic endoderm, and epiblast layer (ectoderm)
what tissue does ectoderm give rise to
skin epidermis, CNS, plus more
What tissues do the mesoderm give rise to
connective tissues (skin dermis), cartilage, bone, blood, muscle, and other associated tissue.
The endoderm gives rise to what?
the respiratory epithelium and cells of glands
cephalic end
head end
what membrane forms at the cephalic end, and what embryonic disc layer does it consist of?
oropharyngeal, ectoderm externally and endoderm internally. No mesoderm
where is the oropharyngeal membrane located and why is it significant
future primitive mouth (stomodeum) of the embryo, it’s the start of the digestive tract
what is the caudal end
the tail end
what membrane form at caudal end, what what will grow there in the future
caudal membrane, anus/terminal end of the digestive tract
which layer of the embryonic disc creates the neuroectoderm, which is the start of the spinal cord and brain
ectoderm
where are neuroectoderm cells
neural plate of embryo
what are the stages of spine creation
neuroectoderm at neural plate, this extends length of embryo from cephalic to caudal end, with growth it will deepen and invaginate inward creating neural groove, the groove deepens and is surrounded by neural folds, more growth results a neural tube
what forms the future spinal chord
neural tube and other neural tissue of CNS
what creation developes face and neck structures
mesenchyme
what is the neural crest cells
deriving from neuroectoderm, they migrate from neural folds to join with mesoderm which forms mesenchyme. also considered as 4th embryonic cell layer
three major regions of the digestive tube
foregut (anterior), midgut, and hindgut (both posterior)
what period do all essential external and internal structures form, thus most critical
embryonic
ectodermal dysplasia is what and which period screws it up if disturbed
weird teeth, hair, skin, nails, eyes, face structure, and glands since they derive from ectoderm during embryonic period
anodontia
absence of some or all teeth in
somites are
when mesoderm differentiates and divides on each side of neural tube into 38 paired cuboidal segments of mesoderm
What is Treacher collins synd. (mandibulofacial dysostosis)
failure of ncc’s migration to facial region. specific areas of orofacial development fails (downward slanting eyes), underdeveloped xzygomatic bone, drooping lateral lower eyelids, and conductive hearling loss, with malformed or absent ears, dental dev. disturbances (anodontia, enamel dysplasia, micrognathia (small lower jaw).
rubella is caused by, and can result in
cuased by teratogens, cataracts, heart defects, deafness
syphilis is caused by and can result in
teratogen, defects in the incisors and molars, blindness, deafness, and possibly paralysis
fetal alcohol syndrom
mental disabilities, small head circum., low nose bridge, short nose, small midface, wide spaced eyes, epicanthic folds and eyelid fissures, unclear philtrum, and thin upper lip. Also, oral changes, like croding, mouth breathing, open bite, and gum disease bc of finger sucking habit
what does radiation potentially do during prenatal growth
injure embryonic cells = cell death, chromosome injury, delay mental and physical growth
what is spina bifida
failure of fusion of the neural tube defects the vertebral arches and various degrees of disability.
which period do embryo’s begin breathing
third week of prenat. dev.
which period do fetases heart beat and move
end of fourth month
