ANSC 333: Exam 3
What is implantation? - ANS-- intimate contact of the developing embryo with the
uterine mucosa
- interaction between embryo and dam
What is the immobilization? - ANS-initial sticky attachment between placenta and
embryo
What is hemotrophic nutrition? - ANS-stimulates nutritive materials to be provided by
dam to embryo
What is the difference between hemotrophic and histotrophic? - ANS-hemotrophic =
after attachment, once embryo forms a placenta
histotrophic = free floating embryo before attachment to the uterus
What are the functions of the placenta? - ANS-protection, nutrition, respiration, hormone
production
Explain the protection function of the placenta. - ANS-- fluid cushion (skeletal system
function)
- placental barrier (immune system function)
Explain the nutrition function of the placenta. - ANS-(digestive system function)
- supply of all energy, protein, CHO, FA precursors
- removal of waste products
Explain the respiration function of the placenta. - ANS-(respiratory system function)
- oxygenated blood to fetus/deoxygenated blood back to mother
Explain the hormone production function of the placenta. - ANS-(endocrine system
functions)
- chorionic gonadotropin (hormone detected by pregnancy tests)
- progesterone, estrogens
What are the four placental layers?
What are their primary functions? - ANS-yolk sac: birds = nutrition, mammals =
short-lived source of blood cells and primordial germ cells
chorion: outermost membrane, attachment to mother
, amnion: protective fluid cushion around fetus, closest membrane to fetus
allantois: blood vessels, waste collection
How is the yolk sac formed? - ANS-fusion of endoderm with trophectoderm
- hatched blastocyst is free floating in uterus
- lined with trophectoderm cells
- endoderm follows the line of trophectoderm cells
- endoderm forms and completes itself to form the yolk sac
How is the chorion formed? - ANS-fusion of mesoderm with trophectoderm
- extraembryonic coelom (fluid filled pockets) form in the mesoderm
- surrounded by trophectoderm cells
- trophectoderm fuse with the mesoderm to form the chorion
How is the amnion formed? - ANS-fusion of mesoderm with trophectoderm
- tips of chorion fold over the ectoderm to create a pocket around embryo = second sac
inside created
- chorion comes up and fuses together around the embryo and forms the amnion
How is the allantois formed? - ANS-fusion of mesoderm and endoderm
- allantois forms to collect the waste products from the fetus
What position is the ectoderm? - ANS-top/outside
What position is the endoderm? - ANS-bottom/inside
What position is the mesoderm? - ANS-middle
How do we start with four placental layers and end with two? - ANS-- yolk sac goes
away to next to nothing
- allantoic sac grows so big it fuses with the chorion
- so by the time we get to birth/late gestation we just have a chorioallantois and an
amnion
Function of the yolk sac in mammals vs birds? - ANS-Mammals:
- short-lived
What is implantation? - ANS-- intimate contact of the developing embryo with the
uterine mucosa
- interaction between embryo and dam
What is the immobilization? - ANS-initial sticky attachment between placenta and
embryo
What is hemotrophic nutrition? - ANS-stimulates nutritive materials to be provided by
dam to embryo
What is the difference between hemotrophic and histotrophic? - ANS-hemotrophic =
after attachment, once embryo forms a placenta
histotrophic = free floating embryo before attachment to the uterus
What are the functions of the placenta? - ANS-protection, nutrition, respiration, hormone
production
Explain the protection function of the placenta. - ANS-- fluid cushion (skeletal system
function)
- placental barrier (immune system function)
Explain the nutrition function of the placenta. - ANS-(digestive system function)
- supply of all energy, protein, CHO, FA precursors
- removal of waste products
Explain the respiration function of the placenta. - ANS-(respiratory system function)
- oxygenated blood to fetus/deoxygenated blood back to mother
Explain the hormone production function of the placenta. - ANS-(endocrine system
functions)
- chorionic gonadotropin (hormone detected by pregnancy tests)
- progesterone, estrogens
What are the four placental layers?
What are their primary functions? - ANS-yolk sac: birds = nutrition, mammals =
short-lived source of blood cells and primordial germ cells
chorion: outermost membrane, attachment to mother
, amnion: protective fluid cushion around fetus, closest membrane to fetus
allantois: blood vessels, waste collection
How is the yolk sac formed? - ANS-fusion of endoderm with trophectoderm
- hatched blastocyst is free floating in uterus
- lined with trophectoderm cells
- endoderm follows the line of trophectoderm cells
- endoderm forms and completes itself to form the yolk sac
How is the chorion formed? - ANS-fusion of mesoderm with trophectoderm
- extraembryonic coelom (fluid filled pockets) form in the mesoderm
- surrounded by trophectoderm cells
- trophectoderm fuse with the mesoderm to form the chorion
How is the amnion formed? - ANS-fusion of mesoderm with trophectoderm
- tips of chorion fold over the ectoderm to create a pocket around embryo = second sac
inside created
- chorion comes up and fuses together around the embryo and forms the amnion
How is the allantois formed? - ANS-fusion of mesoderm and endoderm
- allantois forms to collect the waste products from the fetus
What position is the ectoderm? - ANS-top/outside
What position is the endoderm? - ANS-bottom/inside
What position is the mesoderm? - ANS-middle
How do we start with four placental layers and end with two? - ANS-- yolk sac goes
away to next to nothing
- allantoic sac grows so big it fuses with the chorion
- so by the time we get to birth/late gestation we just have a chorioallantois and an
amnion
Function of the yolk sac in mammals vs birds? - ANS-Mammals:
- short-lived
