embryology Flashcards
name of weeks 0-3 of foetal development
conceptus
name of weeks 3-8 of foetal development
embryonic period
which period of time is most risk during foetal development
embryonic period
name of weeks 9-40 of foetal development
foetal period
what happens during the foetal period
mostly growth
what are the 6 main stages of embryogenesis
gametogenesis
fertilisation
cleavage
gastrulation
formation of a body plan
organogenesis
what is oogenesis
formation of female gametes
when does oogenesis occur
starts in development in the embryo and ends at menopause
what is spermatogenesis
formation of male gametes
when does spermatogenesis occur
occurs at puberty and continues throughout life
what is fertilisation
fusion of sperm and oocyte
what is formed during fertilisation
a zygote
what is cleavage
rapid mitotic cell division
what is a morula
16-cell embryo
describe the cells of the morula
totipotent
what develops from the morula
blastocyst
what are the 2 main parts of a blastocyst
embryoblast and trophoblast
what is gastrulation
the movement of epiblast cells through the primitive streak to form 3 germ layers
name the 3 germ layers
ectoderm
mesoderm
endoderm
what does the ectoderm form
epidermis of the skin and the nervous system
what are the 3 regions of mesoderm
paraxial
intermediate
lateral plate
what does the endoderm form
lining of the gut tube, resp tract, bladder and urethra
what does the intermediate mesoderm form
urogenital system
what causes body axes to be established
presence of the primitive streak
what happens during formation of a body plan
embryonic folding
what is epigenetics
the preferential expression of either the maternal or paternal copy of a gene
what causes angelman syndrome
deletion on maternal chromosome 15
what causes prader-willi syndrome
deletion on paternal chromosome 15
where does fertilisation occur
in the ampulla
when does implantation typically occur
by day 6
where does implantation occur
on the posterior or anterior uterine wall
what is an ectopic pregnancy
implantation in a location outside of the uterus
role of trophoblast
contacts with the endometrium and facilitates implantation and formation of the placenta
role of the embryoblast
responsible for formation of the embryo
role of the syncytio-trophoblast
produces hCG
division of the embryo into which 2 cell layers occurs on day 7.5
epiblast and hypoblast
what forms from the epiblast layer
amniotic cavity
what forms from the hypoblast layer
primitive yolk sack
when does the primitive streak appear in the midline
week 3
where does the primary heart field arise from
visceral mesoderm
what are the 5 dilatations of the heart tube
truncus arteriosus
bulbus cordis
ventricle
atrium
sinus venosus
direction of blood flow through the primitive heart
caudal to cranial
what does the truncus arteriosus form
aorta and pulmonary trunk
what does the bulbus cordis form
parts of the ventricles
when, during development, does the heart begin to loop and fold
day 23
