B4-103 Intro to Development Flashcards
fertilization occurs in the
ampulla
steps of fertilization
5
- capacitation
- penetration of zona pellucida
- fusion of plasma membrane of oocyte and sperm
- completion of second meiotic division, formation of zygote
- cleavage at 24 hrs
what enzyme facillitates the passage of sperm through the corona radiata?
hyaluronidase
glycoprotein coat and seminal plasma proteins are removed from the plasma membrane of the sperm
capacitation
step 1 of fertilization
what enzymes facillitate the penetration of the zona pellucida?
3
esterases, acrosin, neuraminidase
what is the purpose of the zona reaction?
prevents polyspermy
granules cause zona to become stiff so no other sperm can enter
what parts of the sperm enter the oocyte?
head and tail
no mitochondria
what day does morula development occur
day 4
what day[s] is the blastocyst stage?
5-7
events of cleavage
- 2 cell stage
- 4 cell stage
- 8 cell stage
- morula
increase in cell number, decrease in cell size
embryo size remains unchanged
differentiate between the trophoblast and the inner cell blast
embryonic stem cells are derived from the
inner cell mass
are pluripotent
embryonic stem cells
the trophoblast is formed at week
1
the trophoblast gives rise to
2
cytotrophoblast
syncytiotrophoblast
the syncytiotrophoblast is responsible for implantation and intitial signs of pregnancy. What mechanisms does it have to aid in this?
2
- proteolytic enzymes
- chorionic gonadotropin
implantation occurs on day
6
- abnormal trophoblastic proliferation
- excessive amounts of hCG produced
clinical correlation
hydatidiform mole
lack of the zona reaction can result in
complete hydatidiform mole
if a hyatidiform mole isn’t found, it can mutate into
choriocarcinomas
very malignant
- vaginal bleeding
- pelvic pressure
- enlarged uterus
- HG
clinical correlation
hydatidiform mole
during week […] the inner cell mass forms a bilaminar disk
2
- organizes the head and mouth
- forms the oropharyngeal membrane
prechordal plate
the inner cell mass divides into two parts
- epiblast
- hypoblast
forms the ectoderm, amnion, and amniotic cavity
epiblast
forms the endoderm, prechordal plate, yolk sacs and extraembryonic mesoderm
hypoblast
gives rise to the placenta
extra embryonic mesoderm
hypoblast
- formed from extra embryonic somatic mesoderm
- forms at embryonic pole
- position changes during development
connecting stalk
umbilical chord
- forms the placental membrane
- consists of extra embryonic somatic mesoderm
- cytotrophoblast
- syncytiotrophoblast
chorion
vaginal bleeding beyond 20 weeks is a sign of
placenta previa
in placenta previa, palpation of the placenta can cause
severe hemorrahage
gastrulation occurs at week […]
3
aka trilaminar disk
forms skin, teeth, hair, CNS
ectoderm
forms connective tissue
mesoderm
forms lungs, GI, GU tracts
endoderm
why is there no mesoderm at the oropharyngeal and cloacal membranes?
no blood supply, causes the membrane to disintegrate leaving openings
caused by abnormal migration of germ cells or remnants of the primitive streak
teratoma
significance of primitive streak
axis is forming
the paraxial mesoderm gives rise to
3
- muscle
- vertebral skeleton
- dermis
the intermediate mesoderm gives rise to
urogenital
kidneys/gonads
the lateral plate of the mesoderm gives rise to
connective tissue
extends from the primitive node anterior to the prechordal plate
notochord
template for vertebral column
notochord
induces neural plate, and with SHH, neuralation
notochord
- rare slow growing aggressive neoplasms of bone
- arise from remnants of notochord
- cause headaches and vision loss
chordomas
neural crest derivatives: neurons
spinal ganglia
autonomic ganglia
neural crest derivatives: pigment cells
melanocytes of skin and internal organs
neural crest derivatives: endocrine
chromaffin cells of suprarenal medulla
neural crest derivatives: ectomesenchyme
- bone and cartilage of skull
- aorticopulmonary septation
major neurocristopathies
5
- aorticopulmonary septation defects
- cleft palate/lip
- DiGeorge
- pheochromocytoma
- albinism
gives rise to epidermis, hair, nails, enamel of teeth and lens of eye
surface ectoderm
gives rise to epithelial parts of trachea, lungs and GI organs
endoderm
gives rise to kidneys and gonads
intermediate mesoderm
give rise to cartilage and connective tissue of limbs
somatic mesoderm
gives rise to heart, spleen, and smooth muscle of GI tracts
splanchic mesoderm
give rise to pigment cells, cranial and sensory ganglia and nerves, the medulla of the suprarenal gland, head mesenchyme, and connective tissue
neural crest cells
secretes hCG
syncytiotrophoblast
- mitotically active
- stem cell layer of the embryonic portion of the placenta
- gives rise to synctioblast
cytotrophoblasts
- occurs at week 2
- cells that will form the primitive streak
- will become the embryo proper
epiblast
- occurs in week 2
- gives rise to extra embryonic endoderm and extra embryonic mesoderm
hypoblast
- occurs in week 1
- will give rise to embryo proper
embryoblast/inner cell mast
esterase, acrosin, and neuraminidase are needed for the
in acrosome of sperm
zona reaction
makes zona impermeable to other sperm
zona reaction
results from lysosomal enzymes released by cortical granules near the plasma membrane of the oocyte
zona reaction
glycoprotein coat and seminal proteins are removed from the surface of the acrosome during
capacitation
increase in cell number, but decrease in cell size
cleavage
- end of week 1
- syncytiotrophoblast invade the endometrial lining of the uterus
implantation
fertilization normally occurs in the
ampulla
most common location of ectopic tubal pregancy
isthmus
- mitotically active
- stem cells for the embryonic portion of placenta
cytotrophoblast cells
- displace endometrial cells at the implantation site
- release hCG
syncytiotrophoblast cells
cells that will form the primitive streak and become the embryo proper
epiblast
gives rise to extra embryonic endoderm and mesoderm
hypoblast
derived from epiblast and give rise to amnion and amniotic cavity
amnion cells
displaces endothelial cells at implantation site via apoptosis
syncytiotrophoblast
mitotically active and stem cell layer of embryonic placenta
cytotrophoblast
gives rise to synctiotrophoblast
cytotrophoblast
will form primitive streak and become embryo proper
epiblast
- abdominal pain
- vaginal bleeding
- high hCG
- empty uterus
ectopic pregnancy
most likely location of etopic pregnancy is the
isthmus or ampulla of uterine tube
- vaginal bleeding like prune juice
- pelvic pressure
- lack of fetal heartbeat
hydatidiform mole
rare slow growing neoplasm of bone thought to arise from the notochord
chordoma
tumor occuring in the coccyx region thought to arise from remnants of primitive streak or abnormal migration of germ cells
sacrococcygeal teratoma
the inner cell mass develops into
embryo proper
outer cell mass forms the
trophoblast
gastrulation starts with
creation of primitive streak on epiblast
ectoderm that forms the neural tube
neural plate
induces the neural plate to form
notochord
- located at cranial/cephalic end of primitive streak
- orchestrates gastrulation
primitive node
as the primitive streak extends cranially, the cells at the cranial end form the
primitive node
