ch.3 embryology week 1 Flashcards
embryology and its importance
study of the origin and development of an individual.
-importance: for understanding the normal relationship of adult structures.
prenatal period
time between conception and birth
what are the portions of the prenatal period
-embryonic: first 8 weeks, crucial for development
-fetal period: remaining 30 weeks; body size increases
what does the adult body basic plan include?
-skin
-outer body wall: trunk musculatore
-body cavities and inner tube
what are the key events of week 1:
-fertilization and zygote formation
-cleavage and blastocyst formation
-beginning of implantation
week 2 key events
-completion of implantation
-formation of embryonic disc
-amniotic sac and yolk sac
week 3 key events:
- gastrulation
-neural tube formation
-mesoderm differentiation
week 4 key events:
-folding embryo into normal shape
-derivates of germ layer
week 5 key events:
all development processes occur by week 5
week 1: fertilization
-how does it start?
-release of an immature egg
what is the term for an immature egg?
oocyte
where does fertilization occur?
in the lateral 1/3 of the uterine tube.
egg needs to be cast off and meet sperm
how long does healthy sperm last?
up to five days
what does semen contain
enzymes, nutrients and other compounds that promote healthy sperm and aid in movement
female infertility and causes
-accounts 30%
-hormonal imbalances causing ovulation issues
-blockages in uterine tubes
-infections in the lining of the uterus
-endometriosis and uterine fibroids.
where does the sperm bind to the oocyte during fertilization?
bind to receptors on the zona pellucida (external membrane), around the oocyte
once one sperm binds
all other sperm are rejected
the sperm head contains
paternal genetic info
what is the outcome of fertilzation?
production of a zygote (fertilized egg)
week 1: cleavage and blast
-once the zygote divides, it makes
two daughter cells called blastomeres
cleavage
the process of creating blastomeres.
-creates large number of cells that become the building blocks of the embryo.
week 1: cleavage and blast
-what is a morula
a solid ball of cells
-made by day 3
week 1: cleavage and blast
-compaction?
the tight alignment of morula cells, allows greater cell to cell interaction; a pre-req for embryonic formation
week 1: cleavage and blast
-what happens on day 4?
the morula reaches the uterus and undergoes a series of changes:
-fluid from the uterus enters the morula and collects between the blastomeres= generates a central cavity
* makes a blastocyst
week 1: cleavage and blast
-what is a blastocyst?
new fluid filled structure (day 4)
almost ready for implantation
week 1: cleavage and blast
what happens on days 4-7 to the blastocyst’s structure?
-trophoblast and embryoblast forms
week 1: cleavage and blast
-describe trophoblast and embryoblast
-trophoblast: an outer cell layer surrounding the blastocyst cavity. helps form the placenta
-embryoblast: inner cell mass. helps form the embryo.
week 1: cleavage and blast
-how long does the blastocyst stage last? and where does it go?
-around three days. days 4-7.
-during that time the blastocyst is free. but around day 6 it starts to burrow into the uterine wall
week 1: beginning of implantation
-when does implantation start and how long does it take?
-starts on day 6 and takes about a week to complete
week 1: beginning of implantation
-what is overall what happens during implantation
the trophoblast erodes the uterine lining until the entire blastocyst becomes embedded within the structure
-the projections of the trophoblast tat erode the maternal lining allow the blastocyst to penetrate itself inside .
ectopic pregancy:
implantation occurs somewhere else, no good epithelium.
