Embryology Flashcards
What is the time period for a human to be considered a embryo?
fertilization to 8 weeks
What is the time period for a human to be considered a fetus?
Week 8 to birth
What is a fertilized egg called?
zygote
When a cell undergoes mitosis and is 8 to 16 cells what is it called? 1. Are these cell differentiated? 2. Where is this usually located? 3
- morula
- no
- stage usually entering uterus
What is it called when the embryo stays in the fallopian tube?
tubal pregnancy
What is it called when the embryo is not in the uterus?
Ectopic pregnancy
What is it called when the morula begins to cavitate when in the uterus?
blastocyst
What does the blastocyst differentiate into:
- covers entire outside of blastocyst
- at one pole of embryo
- trophoblast
2. inner cell mass
Is contact with the endometrium and the blastocyst at the pole or away from the pole?
at the pole
What does the trophoblast differentiate into? and which of them moves into the uterine wall>
- cytotrophoblast
- syncytiotrophoblast
- syncytiotrophoblast
What does the embryo start to secrete around day 9?
Human Chorionic Gonadotropin (hCG)
Without conception, what does the corpus luteum involute into?
corpus albicans
What hormone causes dozens of follicles to develop?
FSH
What do follicular cells secrete that has a negative feedback on FSH?
estrogen
What does luteinizing hormone (LH) do?
- Turns follicular cells yellow
2. triggers ovulation
What does the corpus luteum secrete that initiates secretory phase?
progesterone
When estrogen and progesterone decrease what section of the uterus becomes ischemic and sloughs off?
zona functionalis
What does Human Chorionic Gonadotropin (hCG) do?
- maintain uterus in gravid state (missed period)
2. allows embryonic implantation
Syncytio and cytotrophoblast continue to develop to form what?
placenta
After how many months does the placenta release progesterone and what does this progesterone do?
2 months and it eliminates the corpus luteum
Embryoblast cells differentiate into:
- monolayer ventral layer near blastocyst cavity
- Remaining cells
- endoderm
2. epiblast
What is the second fluid filled area formed dorsal to the embryo?
Amniotic cavity
At the end of week two, a group of endoderm cells at one pole of embryo further differentiate to form: 1. Which end of the embryo is this? 2
- prochordal plate
2. cranial
What is it called when the trophoblast is maintained during pregnancy but inner cell mass fails to develop embryoblast? 1. Why are there no signs and symptoms of this? 2. What is it caused by? 3. What are the options for the mother? 4
- Blighted ovum
- hCG is maintained so seems like pregnancy still
- chromosomal abnormalities
- miscarry or D&C
What is the formation of a trilaminar embryo called?
gastrulation
What is the formation of the central nervous system called?
neurolation
What are the two parallel rows of epiblast cells at the caudal axial pole with a trench between them called? 1. What is the morphology of these cells? 2
- primitive streak cells
2. columnar
Once the formation of primitive streak cells takes place what are all other cells now called?
ectoderm
What is the layer that forms when the primitive streak cells mitose and touch at midline then migrate ventrally making a layer in between two other layers?
mesoderm
The primitive knot is located at the 1 end of the 2. It is a circular mass which cells move 3 through its center. Once these cells reach the mesoderm they migrate in an axial pattern towards 4. What structure do these cells from? 5
- cranial
- primitive streak
- radially inward
- prechordal plate
- notochord
What layer of tissue is most dorsal in a trilaminar embryo?
ectoderm
What releases growth factor that causes ectoderm cells to have gene activation and differentiation? 1. What are these differentiated cells called? 2. What are all other cells that did not differentiate now called?
- notochord
- neuroectoderm
- surface ectoderm
Neuroectoderm cells form a groove which eventually form into a 1. This is then covered over dorsally by 2
- neural tube
2. surface ectoderm
What ate the openings at the end of the neural tube called? 1-2. Which end closes quicker? 3
- anterior neuropore
- posterior neuropore
- cranial closure (anterior neuropore)
When do neural crest cells form? 1. What type of cells give rise to the crest cells? 2
- during formation of the neural tube
2. neuroectoderm
What forms the placenta?
syncytio and cytotrophoblast
While the neural groove and tube formation is occuring, the lateral aspects of the embryo move ventrally make the embryo into:
a tube
What does the neural tube ultimately differentiate into?
CNS (brain and spinal cord)
What does the neural crest ultimately differentiate into?
PNS (ganglia)
What does the notochord ultimately differentiate into?
part of nucleus pulposus of intervertebral disc
What is linked to neural tube deformity?
low folic acid levels in mother
What is it called when the neural tube does not fuse fully?
Spina bifida
What type of spina bifida is it if you cannot tell when looking at the person (ephoria)?
Occulta
What type of spina bifida is it if you can tell when looking at the person (strabismus)? 1. What are the two types of these? 2-3
- manifesta
- meningocele
- meningomyelocele (most severe)
What is the condition of the embryo forming a brain stem but usually not a cerebrum and hemisphere?
Anencephaly
What protein is tested for in embryo, increases with paternal age, and if elevated increases the chance for a neural defect?
Alpha fetal protein
What does the mesoderm differentiate into?
- paraxial plate
- intermediate plate
- lateral plate
What does the intermediate plate of the mesoderm ultimately give rise to?
urogenital system including gonads, ducts and accessory glands
What does the lateral plate of the mesoderm ultimately give rise to?
- CT and muscle of viscera
- Serous membranes of pleura, pericardium, and peritoneum
- Blood and lymph cells
- cardio and lymph systems
- spleen
- adrenal cortex
What does the paraxial mesoderm form?
Somites
How old is an embryo that has 10 somites? 1. 19 somites? 2. 26-28 somites? 3
- 23 days
- 25 days
- 4 weeks
How many somite pairs ultimately develop?
32