embryology Flashcards
when is the pre-embryonic phase
0-3 weeks
when is the embryonic phase
4-8 weeks
when is the foetal phase
9-40 weeks
what haapens in week one of pre-embronic phase
zygote is forned, divides to blastocyst
Moves through uterine tube, to reach uterine cavity.
what does zygote form?
morula
what does morulas form
blastocyst
what happens in week 2 pre-embryonic phase
Implantation occurs in the uterine endometrial layer and placenta begins to develop (this may start by day 6 of 1st week)
Cells that later form the embryo form a bilaminar disc
Sacs, membranes and cord to nourish the human conceptus (baby) start to form
whats the uterine wall callled
endometrium
whats implantation
the blastocyst begins to burrow into the uterine wall
Cells that form the outer cell mass is initially called the
trophoblast
what does the trohpoblast form?
the chorion
whats the function of chorions
Implantation process (chorionic villi) Forms part of the placenta in due course Secretes human Chorionic gonadotropin (HCG) (used to detect pregnancy)
what hapens to the inner cell mass?
The cells of the inner cell mass form a 2–layered flat disc called the BILAMINAR DISC
what are the 2 cavities thta begin to form?
amniotic cavity and yolk sac
what are the main functions of placenta?
Foetal nutrition
Transport of waste and gases
Immune etc
Fertilisation zygote-> morula -> blastocyst with inner cell mass -> bilaminar disc with amniotic cavity above and yolk sac below
some key info init
Morula reaches uterine cavity -> blastocyst implants-> outer cells form chorionic villi which help implantation -> decidua basalis formed -> placental formation begins
where it all happens
what is GASTRULATION
Formation of germ layers
what is NEURULATION
Formation of neural tube
what happens in week 3
–GASTRULATION
NEURULATION
Development of somites
Early development of cardiovascular system
where does epiblast cells migrate into?
space between epiblast and hypoblast
what are the 3 germ layers?
Ectoderm
Mesoderm
Endoderm
Inner cell mass of blastocyst -> bilaminar disc -> primitive streak -> cells from primitive streak invaginate, displace hypoblast -> endoderm, mesoderm, ectoderm
yeet
when does heart beat start?
day 24
whats Teratology
Study of when things go wrong during development
what are Teratogens
environmental factors that cause abnormal development.
what is Congenital rubella syndrome caused by
contraction of german measles when pregnant
what are Malformed limbs due to
maternal use of Thalidomide
how many sperm penetrates the egg
one
what will a blastocyst reach if it moves through the uterine tube?
uterine cavity
which parent does mitochondria and cell organelles come from?
mother
If a father had an effected mitrochondria disease and the mother was uneffected, how will the children turn out?
What would happen if it was vise versa?
unaffected
the children would be affected
What is a morula
a solid ball of cells divded from a zygote
how does a morula become a blaszstocyst?
enlarges and divides further
what are the outer cells surrounding the blastocyst?
trohpoblast