implantation and early placentation Flashcards
what is gestational age
used clinically, from LMP to present. Expressed in terms of completed weeks plus days
when does implantation begin
day 6/7 after ovulation
what are the 3 stages of implantation
apposition, attachment, penetration
during apposition and adhesion of embryo what hormones are being released locally and what signalling occurs?
egf and lif signalling between embryo and endometrium
cox 2 surface epithelium
growth factors and cytokines from embryo and endometrium
estrogens and progesterones
complex interaction of all hormones allowing apposition and adhesion
with regards to menstrual cycle what phase can endometrium become receptive
secretory phase
outline the window in which the endometrium is receptive
on average day 7-10 of secretory phase
outline how endometrium can discriminate against embryos to prevent poor birth outcomes
if embryo is low quality likely to have defects, won’t allow implantation, high quality and it will allow implantation, generally.
what are the two layers of the primitive placenta (trophoblast)
Inner layer is composed of mononuclear cells and is
known as the cytotrophoblastic layer.
• Outer layer consists of multinucleated cells and is
known as the syncytiotrophoblast.
what two changes chracterise haemochorial placentation
differentiation of endometrium into decidua
transformation and opening of uterine spiral ateries
when do chorionic villi appear
at the end of the second week in placenta development
where do the central core of cells in primary villious stems come from
derived by the proliferation of the cytotrophoblast.
how do primary villi develop to secondary villi
they get mesoderm cores
how do secondary villi become tertiary
tertiary villus are characterized by villous capillaries developing
how do you get chorion leavae
As the growth continues, the villi on the decidua
capsularis (abembryonic) pole degenerate
how do you form chorion frondosum
Villi adjacent to the decidual plate rapidly grow and
expand
what impact does a spiral atery narrowed in a segment cause
placental villious tree has fewer branches because of blood flow chracteristics resulting in reduced fetal growth and pre eclampsia
by what month has the placenta achieved it’s defined form and undergoes no anatomical modifications
4 month of pregnancy
what forms the maternal portion of placenta
decidual plate
what forms the fetal portion of placenta
the chorion frondosum.
what is chorionicity
numbver of gestation sacs
what is gastrulation
Formation of 3 germ layers
ectoderm mesoderm endoderm
what does endoderm give rise to
epithelial lining GI & respiratory tracts & bladder.
liver, pancreas, thyroid, tonsils, auditory epithelium
what does mesoderm give rise to
connective tissue, musculoskeletal system,
gonads, kidneys, spleen, cardiovascular system,
lymphatics
what does ectoderm give rise to
epidermis, hair, nails, nervous system
mammary glands, enamel of teeth,
neural crest cells: melanocytes, branchial arches,
meninges, adrenal glands, autonomic NS
when does neurulation occur
early on 4 embryonic week
state neural tube defects
spina bifida, ancephaly,
what is holoprosencephaly, and what are its effects
Failure of forebrain to divide & develop
• Associated with other midline & facial defects, Tri 13
• Severity varies from not being compatible with life to more
mild mental retardation
when does cardiogenesis occur
d18-d22
in cardiogenesis how are heart tubes formed
Canalization of cardiogenic
clusters in the mesoderm
results in the formation of the
paired heart tubes
