Human Embryogenesis

Question 1

when does oocyte get stalled

Answer 1

second meiotic division

Question 2

Capactiation

Answer 2

head of sperm can release enzymes

• occurs in uterus/uterine tube
• 6 hours of exposure

Question 3

acrosome reaction

Answer 3

allows sperm to petite corona radiate and zone pellucida

-degrades zona poluza to allow 1 sperm to fuse to PM of oocyte

Question 4

sperm fuse with oocyte

Answer 4

causes Ca concentration increase (diffuses into oocyte)

-causes corticol reaction

Question 5

Corticol reacion

Answer 5

vesicles in presynaptic membrane to fuse in

corticol granulas cause changes in zona pellucida preventing polymspermia-ensure no multiple sperm

Question 6

when does oocyte complete 2nd meiotic division

Answer 6

when sperm extrudes contents into oocyte (nuclei,s centrosome and mts)
-ALL OTEHR ORGANELLES ARE FROM MOM

Question 7

When does zygotic trx occur

Answer 7

3 weeks, all else occurs with maternal mRNA

Question 8

when does fist mitotic division occur

Answer 8

response to sperm fusing to oocyte

Question 9

what space do first several mitotic division occur+ how do they differ

Answer 9

inside zone pellucid-they are also identical

Question 10

Ectopic preganacy

Answer 10

implantation in any place other that uterun

Question 11

uterine tube terminates in

Answer 11

ampulla-most common place of ectopic reg

fimbrae-caress ovary
=open up into GI tract-peritoneal cavity

Question 12

Placenta forming on cervix

Answer 12

many problems-eventually gets torn

Question 13

What causes uterine lining changes

Answer 13

placenta formation

Question 14

where are two common sites of ectopic preg

Answer 14

ampulla of uterine tube

recouterine ch-most common peritoneal cavity place

Question 15

blastocyst strcutre

Answer 15

inner cell mass-embryoblast and trophoblast

• embryoblast becomes embryo
  
  • aka embryonic stem cells
• trophoblast becomes placenta

Question 16

how does trophoblast become placenta

Answer 16

becomes huge cell with many nuceli-syncitio
-produces and releases HCG (hormone)
0HCG levels rise at implantation
-hormione reg tests look for rise in HCG

Question 17

syncytiotrophoblast

Answer 17

produces HCG

invades uterine lining and induces vascular changes

Question 18

what happens when synctioblast invades

Answer 18

embroblast differentiates into epiblast and hypoblast

-epiblast is more dorsal (posterior)

Question 19

cytotrophoblast

Answer 19

no nutrients-get nutrients from maternal fluid

• primitive yolk sac
• eventually biomes primary villi

Question 20

Lacunae

Answer 20

formed from syncytiotrohphoblast

• hollow spaces
• fill with blood

Question 21

Epiblast vs hypoblast + wjere adjere

Answer 21

cell layers in developing embryo

epiblast-posterior/dorsal-aminiotic caivty is more dorsal than epiblast

hypobast-anterior+ventral

adjere at buccopharyngeal (cranial) and cloacal (caudal) membrane
-WHEN embryo TRX BEINGS

Question 22

Primitive yolk sac

Answer 22

from cytotrphoblast

dives in tear drop formation into secondary yolk sac (suspended from connecting yolk sac)

and cyst(which develop ointo microvilli_

Question 23

4th week

Answer 23

zygotic trx beings

gastrulation starts

primitive streak appears at caudal end of dorsal surface of epiblast

all sides defined

Now called an embryo

Question 24

Primitive node

Answer 24

appears at cranial end of primitive streak

Cells here have single, solitary, motile cilia

Fluid here has SHH-sets up assymetry

Question 25

Motile cilia in primitive node

Answer 25

move right to left

• move vesicles and release thier contents (shh)
• cuases gene expresión changues on left vs right

Question 26

Sidus inversus

Answer 26

everything reverses-cilia beat other way

Question 27

Defects in cilia at promitive node

Answer 27

no assymetry-many problems such as deafness, sids inverses, death, kidney diseases

Question 28

Fate of primitive streak cells

Answer 28

delaminate-migrate between epiblast and hypoblast-establish mesoderm

Some cells will invade hypblast and replace it to establish endoderm

All epiblast will become ectoderm
-wil not invdade buccopharyngeal or cloacal membrane

Question 29

Fate of epiblast cells in primitive node

Answer 29

delaminate and establish middling notochord between endoderm cranial to primitive streak