ANSC 3040 EXAM QUESTIONS AND CORRECT ANSWERS
embryonic period of developmental biology - Answers - d0-42 in cattle
starts w/formation of zygote after fertilization
- morulation: morula formation by cleavage of zygote
- blastulation: formation of blastocyst, ICM forms embryonic disk, rest if trophectoderm,
conceptus elognates when trophectoderm proliferates
- gastrulation: formation of germ cell layers
ends w/formation of basic structure of organs
fetal period of developmental biology - Answers - d43-278 (birth) in cows
growth, maturation, remodeling, of organ systems
do we see elongation in the equine conceptus? - Answers - no
what does endoderm form into? - Answers - digestive system
lungs
endocrine system
what does mesoderm form into? - Answers - muscle
skeleton
cardiovascular
repro system
urinary system
what does ectoderm form into? - Answers - nervous system
skin
hair
external parts of RT
what causes variability in body weight at birth? - Answers - genetics of dam (contributes
to embryo genetics and uterine physiology) and embryo (influenced by genetics of
mother and father) ex.Brahman in Charolais increases fetus BW
type of embryo (IVF, cloning)
nutrition and health of dam
maternal maturity
infectious diseases
environmental temperature
gestation length
twins/litter size (compete for nutrients and space)
consequences of variability in body weight at birth - Answers - dystocia (too big)
health ex. babies that grow very quickly post-natally are more likely to have
cardiovascular problems in life
,performance ex. if too small could have trouble surviving post-partum
carcass traits
functions of placenta - Answers - fetal/maternal exchange of nutrients, gases, and
waste ex. glucose (main carb for fetus), acetate (for lipid synthesis)
endocrine organ - produces P4, E2, placental lactogen, glycoproteins, eCG, hCG
physical protection - shock, trauma, disturbance
biological protection - maternal immune system (paternal DNA may cause immune
reaction bc recognized as non-self cell), toxins
components of placenta - Answers - embryonic/fetal - extraembryonic membranes,
starts to form before implantation in domestic species
maternal - endometrium, forms by differentiation of endometrial cells during implantation
nutrition of conceptus - Answers - pre and peri-implantation: histotroph, becomes a
limitation w/the development of the conceptus bc no direct contact
post-implantation w/functional placenta: haemotroph, allows exchange of nutrients,
hormones, gases, and waste b/w fetal and maternal blood circulation
hemochorial placenta - Answers - primates, rodents
no layers on maternal side
3 layers
chorionic villi adhere to endometrium in disc, highly invasive trophoblast break down
endothelium of maternal vessels and maternal blood supply so surrounded by blood
endotheliochorial - Answers - degradation of epithelium
4-5 layers
bitch, queen
zonary - chorionic villi are concentrated in one section (transfer zone) and go around
whole unit of chorion
pigmented zone, some accumulation of blood, some researchers believe this is
important for iron transfer
synepitheliochorial - Answers - 5-6 layers bc maternal and fetal endothelium are mixed
cow, ewe, doe
cotyledonary
epitheliochorial - Answers - 6 layers, diffuse, in mare (microzones of chorionic
villi/microcotyledons) and sow (interconnected villi over entire chorion surface)
BNGC - Answers - binucleated giant cells
~20% of trophectoderm differentiates into BNGCs, migrates to maternal-fetal interface
and fuse w/maternal epithelium, leading to cotyledon formation
these cells are very active, and excrete PAGs and placental lactogen, which go into
maternal circulation and are associated w/pregnancy survival
, PAGs - Answers - can be detected using ELISA test to diagnose pregnancy in cows
eCG - Answers - secreted by endometrial cups
functions similarly to LH (stimulates CL/P4 secretion)
can induce ovulation of extra follicle during pregnancy, which will form a CL and secrete
more P4
hCG - Answers - secreted in primates
has luteotropic activity
secretion starts early in pregnancy, used in pregnancy tests
effects of P4 during pregnancy - Answers - stimulates histotroph secretion by uterine
glands
inhibit myometrial contractions (P4 block) by keeping oxytocin receptors low
- thought PG expression continues, could lead to pregnancy loss
species w/no secretion of P4 by placenta - Answers - queen
bitch
sow
species w/secretion of progesterone by the placenta - Answers - mare
ewe
woman
cow
how does sex of fetus influence milk production? - Answers - first calving has biggest
effect, if have daughter first produce most milk
could be bc males stay in uterus longer, so might not need as much nutrition once born,
testosterone or AMH could have effect
- ultimately don't really know why
how does the fetus trigger the onset of parturition? - Answers - fetus runs out of space,
gets stressed, and produces ACTH and cortisol
this increases expression and activity of enzymes that convert P4 to E2, inducing CL
regression, removing P4 block and stimulating myometrial contraction, which position
the fetus
also causes production of placental PGF2alpha
E2 loosens cervix, increases mucus secretion/lubrication
pressure of fetus in cervix causes brain to produce oxytocin and induces more
contractions (Ferguson reflex, positive feedback loop)
stage I parturition - Answers - myometrial contraction
cervical dilation
stage II parturtion - Answers - fetal expulsion
embryonic period of developmental biology - Answers - d0-42 in cattle
starts w/formation of zygote after fertilization
- morulation: morula formation by cleavage of zygote
- blastulation: formation of blastocyst, ICM forms embryonic disk, rest if trophectoderm,
conceptus elognates when trophectoderm proliferates
- gastrulation: formation of germ cell layers
ends w/formation of basic structure of organs
fetal period of developmental biology - Answers - d43-278 (birth) in cows
growth, maturation, remodeling, of organ systems
do we see elongation in the equine conceptus? - Answers - no
what does endoderm form into? - Answers - digestive system
lungs
endocrine system
what does mesoderm form into? - Answers - muscle
skeleton
cardiovascular
repro system
urinary system
what does ectoderm form into? - Answers - nervous system
skin
hair
external parts of RT
what causes variability in body weight at birth? - Answers - genetics of dam (contributes
to embryo genetics and uterine physiology) and embryo (influenced by genetics of
mother and father) ex.Brahman in Charolais increases fetus BW
type of embryo (IVF, cloning)
nutrition and health of dam
maternal maturity
infectious diseases
environmental temperature
gestation length
twins/litter size (compete for nutrients and space)
consequences of variability in body weight at birth - Answers - dystocia (too big)
health ex. babies that grow very quickly post-natally are more likely to have
cardiovascular problems in life
,performance ex. if too small could have trouble surviving post-partum
carcass traits
functions of placenta - Answers - fetal/maternal exchange of nutrients, gases, and
waste ex. glucose (main carb for fetus), acetate (for lipid synthesis)
endocrine organ - produces P4, E2, placental lactogen, glycoproteins, eCG, hCG
physical protection - shock, trauma, disturbance
biological protection - maternal immune system (paternal DNA may cause immune
reaction bc recognized as non-self cell), toxins
components of placenta - Answers - embryonic/fetal - extraembryonic membranes,
starts to form before implantation in domestic species
maternal - endometrium, forms by differentiation of endometrial cells during implantation
nutrition of conceptus - Answers - pre and peri-implantation: histotroph, becomes a
limitation w/the development of the conceptus bc no direct contact
post-implantation w/functional placenta: haemotroph, allows exchange of nutrients,
hormones, gases, and waste b/w fetal and maternal blood circulation
hemochorial placenta - Answers - primates, rodents
no layers on maternal side
3 layers
chorionic villi adhere to endometrium in disc, highly invasive trophoblast break down
endothelium of maternal vessels and maternal blood supply so surrounded by blood
endotheliochorial - Answers - degradation of epithelium
4-5 layers
bitch, queen
zonary - chorionic villi are concentrated in one section (transfer zone) and go around
whole unit of chorion
pigmented zone, some accumulation of blood, some researchers believe this is
important for iron transfer
synepitheliochorial - Answers - 5-6 layers bc maternal and fetal endothelium are mixed
cow, ewe, doe
cotyledonary
epitheliochorial - Answers - 6 layers, diffuse, in mare (microzones of chorionic
villi/microcotyledons) and sow (interconnected villi over entire chorion surface)
BNGC - Answers - binucleated giant cells
~20% of trophectoderm differentiates into BNGCs, migrates to maternal-fetal interface
and fuse w/maternal epithelium, leading to cotyledon formation
these cells are very active, and excrete PAGs and placental lactogen, which go into
maternal circulation and are associated w/pregnancy survival
, PAGs - Answers - can be detected using ELISA test to diagnose pregnancy in cows
eCG - Answers - secreted by endometrial cups
functions similarly to LH (stimulates CL/P4 secretion)
can induce ovulation of extra follicle during pregnancy, which will form a CL and secrete
more P4
hCG - Answers - secreted in primates
has luteotropic activity
secretion starts early in pregnancy, used in pregnancy tests
effects of P4 during pregnancy - Answers - stimulates histotroph secretion by uterine
glands
inhibit myometrial contractions (P4 block) by keeping oxytocin receptors low
- thought PG expression continues, could lead to pregnancy loss
species w/no secretion of P4 by placenta - Answers - queen
bitch
sow
species w/secretion of progesterone by the placenta - Answers - mare
ewe
woman
cow
how does sex of fetus influence milk production? - Answers - first calving has biggest
effect, if have daughter first produce most milk
could be bc males stay in uterus longer, so might not need as much nutrition once born,
testosterone or AMH could have effect
- ultimately don't really know why
how does the fetus trigger the onset of parturition? - Answers - fetus runs out of space,
gets stressed, and produces ACTH and cortisol
this increases expression and activity of enzymes that convert P4 to E2, inducing CL
regression, removing P4 block and stimulating myometrial contraction, which position
the fetus
also causes production of placental PGF2alpha
E2 loosens cervix, increases mucus secretion/lubrication
pressure of fetus in cervix causes brain to produce oxytocin and induces more
contractions (Ferguson reflex, positive feedback loop)
stage I parturition - Answers - myometrial contraction
cervical dilation
stage II parturtion - Answers - fetal expulsion
