DEV (Highison): Embryonic period week 3 thru 8 Flashcards
Embryonic period spans through what weeks?
three to eight
embryonic period develops what two early systems
nervous system
and cardiovascular system
by end of embryonic period, have ALL major organ systems begun to develop?
Yeah, but only MINIMALLY.
^^except the cardiovascular system which has developed extensively
What appearance does the fetus have by the end of the eighth week?
it starts looking distinctly human
What are the three phases of embryonic development?
- growth
- morphogenesis (development of form AND mass cell movements)
- differentiation which is the maturation of physiological processes
What are the TWO MAJOR subdivisions of ectoderm derivatives?
- neuroectoderm
2. epidermal covering of the body
What is the process of neurulation?
early neural tube formation
What does the blocking of BMP4 do for neurulation?
It allows for the induction of neural plate by the NOTOCHORD and the PRECHORDAL PLATE
Neural plate invaginates to form ____?
the neural tube!
The CNS comes from?
The NEURAL TUBE
In what direction does the fusion of the neural tube proceed?
Cranially to caudally
What are the two nucleopores and when do they close?
Cranial nucleopore and caudal nucleopore; they close at day 25 and 27 respectively
What’s a nucleopore?
An opening on the side of the neural tube; we got two, one on the cranial side and one on the caudal side
a. Where do neural crests cells come from?
b. Where do they go?
c. And what do they do?
a. neural folds.
b. from neural folds, they migrate into mesenchyme
c. they make up the PERIPHERAL NERVOUS SYSTEM and MORE
What do neural crest derivatives differentiate to? JUST THROW AS MANY AS YOU CAN OUT THERE
**connective tissue and bone of THE FACE AND THE SKULL.
**CN nerves
C cells of thyroid
Conotruncal septum
Odontoblast
**DERMIS of FACE AND NECK
**Spinal (dorsal root) ganglia
**Sympathetic chain and preaortic ganglia
**Parasympathetic ganglia of GI
Adrenal medulla
***Schwann + glial cells
Ariachnoid and pia mater
melanocytes
Ectoderm has two divisions–neuroectoderm and epidermal covering of body. T/F?
TRUE
The epidermal tissue of the body includes
The skin!!!!! contains epidermis sweat glands, sebaceous gland mammary glands anterior pituitary gland hair, nails, enamel internal ear lens of eye and corneal
What are the FIVE mesoderm derivatives?
Axial mesoderm paraxial mesoderm intermediate mesoderm lateral plate mesoderm mesodermal contribution to the chorion
Axial mesoderm has what three early developmental structures?
- prechordal plate (i think it eventually forms the vertebra)
- notochord, just helps folding and morphogeneisis
- caudal eminence, thing that sticks out of caudal region of early embryo (i think once the caudal neuropore closes)
______ fodling happens in the axial mesoderm
cephalocaudal folding
in cephalocaudal folding, the primitive streak and notochord establish what?
- cephalocaudal side
- R/L side
- dorsal and ventral surface
in cephalocaudal folding, rapid head and tail growth cause the embryo to move in what direction?
curl toward ventral surface
Paraxial mesoderm has two sets of somitomeres. where are they located?
somitomeres in the head
AND in the body
How many somitomeres do we have in the head? what do we call them?
we got 1-7 + neural plate.
they’re called neuromeres
they do wonderful things
What are body somitomeres called?
how do they move?
somites.
occipitally to caudally
How can you approximate embryo age?
with the position of the somites
What forms the sclerotome?
and what does the sclerotome make
somites form sclerotome.
it makes vertabrae, ribs, and some of the base of skull
What forms the dermatomyolome? and what are the two dermatomyolome parts and what do these two parts make?
somites form the dermatomyolome.
dermatome —-> makes dermis of skin
myolome —> makes skeletal muscles of body and limbs
Why are dermatomyolomes still clincally relevant in adulthood?
each one of them RETAINS own segmental innvervation from origin
Intermediate mesoderm forms most organs in _______ systems
genitoruinal
Intermediate mesoderm forms what three organ cell layers in genitourinal systems?
- connective tissue
- smooth muscle
- epithelial linings
In the UG organs, what provides the remaining epithelial lining that the intermediate mesoderm can’t provide?
The ENDODERM
The lateral plate mesoderm helps form the ______ cavity
interaembryonic
Does the lateral plate mesoderm split in the head?
Nope
What two arms splits up into what two segments (arms in his PPT)?
- somatic
2. splanchnic
The somatic arm of the lateral plate mesoderm makes up the connective tissue and smooth muscle of what three structures?
- body wall
- bones.
- cartilage of limbs and limb girdle
The splanchnic arm of the lateral plate mesoderm makes up the connective tissue and smooth muscle of what two regions?
ALL of the ENDOderm line organs
and ALL of the tissues of cardiovascular system
Regarding the mesodermal contribution to the chorion:
DURING THE FOLDING PROCESS, ENDOderm is formed into _______?
epithelial tube– which runs along body length!
Regarding the mesodermal contribution to the chorion:
the ENDOderm tube forms_______?
the epithelial lining of the GI tract
Regarding the mesodermal contribution to the chorion:
the mesoderm and ENDOderm collaborate to form ________?
SPECIFIC GI organs
mesodermal contribution to the chorion forms epithelial components of what organs?
pharyngeal buds, lung buds, liver, pancrease, and gall bladder
so we talked about cephalocaudal folding previously, what is the other kind of embryonic folding?
lateral folding!!!
How does lateral folding occur?
and what structure does it make?
ENDOderm folds in embryo.
forms a NARROW TUBE structure
in lateral folding, the mesoderm continues to separate out what two things?
ectoderm from endoderm
at this point, what encircles embryo completely?
the ectoderm forms outer covering of embryo
and then the amniotic cavity is around that
