ANSC 3040 Final Exam and All Correct
Answers 2026/2027 Updated.
What characterizes an Ootid to go to a Zygote and what is this process called - Answer fusion
of the two nuclei to one.
called Syngamy
What characterizes the change from a Zygote to a 2 cell embryo - Answer the one cell embryo
will undergo cleavage and become a 2 cell
What are 7 stages of early embryonic development - Answer 1. Ootid
2. Zygote
3. 2-cell embryo
4. Morula
5. Early blastocyst
6. Hatching Blastocyst
7. Hatched blastocyst
What characterizes a morula - Answer when you can no longer count the amount of cells in
the embryo
What stage of embryonic development is when the inner cell mess and the trophectoderm form
- Answer early blastocyst
What are the 3 steps in the hatching process - Answer 1. blastocyst growth and fluid
accumulation
2. production of enzymes by the trophoblast
3. contraction of the blastocyst
What is the only stage of embryonic development that occurs in the uterus/uterine horn -
Answer the blastocyst
Accumulation of maternal RNA and proteins accumulated in the ooplasm during.. and where -
Answer during= oogenesis
in the ovary
,embryo genome activation and replacement of maternal-derived with embryo-derived
transcripts starts to occur where - Answer in the oviduct
Embryo takes ownership of gene expression and cell biology of what embryonic stage? where is
this located? - Answer in the blastomeres
in the uterine horn
What happened during the fist round of cell differentiation in morulas to an early blastocoele
(3) - Answer 1. compactions of the morula and cells that are in the outer layer of the embryo
will form tight junctions and form a layer of trophectoderm cells (creates the ICM in the
blastocyst)
2. outer layers of of the compacted morula cells start to secrete a lot of Na and send it to the
middle part
3. this Na will attract fluid and will create the blastocoele - fill it with mostly water
Where will fertilization occur - Answer in the ampulla
What occurs after hatching in the embryo - Answer conceptus development - differs among
species though
When does attachment and implantation occur in the primates and rodents - Answer shortly
after hatching of the blastocyst
What type of implantation occurs in primates and rodents? how invasive is this - Answer
hemochorial placentation
Highly invasive
What are the 5 phases of implantation in primates and rodents - Answer 1. shedding of ZP
2. pre-contact blastocyst orientation
3. apposition cellular contacts
4. adhesion
5. penetration of endometrium
What happens to hatched blastocysts in bovine and howdoes that affect implantation - Answer
hatched blastocysts are free floating in the uterine lumen - may take days to weeks before
implantation
What type of implantation occurs in bovine - Answer shallow - strong adhesion of cells rather
than actually physically going into the endometrial layer
, What are the 4 phases of implantation in bovines - Answer 1. shed ZP
2. elongation of conceptus
3. apposition
4. adhesion
What is elongating during conceptus elongation in bovnies - Answer the trophectoderm cells
are elongating while the inner cell mass stays in the middle
What gets secreted by the elongated conceptus in ruminants only that tells the mother she's
pregnant? where will it act - Answer IFNT
Will act in the endometrium - luminal epithelium
What does IFNT do to the uterus in bovines - Answer blocks expression of oxytocin receptors
so there are no pulses of PGF2alpha and progesterone will remain high
What is the cause of maternal recognition of pregnancy in ruminants - Answer production of
IFNT
What does oxytocin do in a non-pregnant cow - Answer oxytocin receptors are increased in
the endometrium of the uterus at late diestrus. this induced pulsatile secretion of PGF2alpha
which will cause luteolysis and regression of CL
How is progesterone maintained constant in a pregnant ruminant - Answer IFNT blocks
oxytocin, so there is no PGF2Alpha pulsing to the CL, which means no regression of the CL
Why is it important for the conceptus in the the bovine so secrete prostaglandins as well as IFNT
(2) - Answer PG's lead to increased innate immune responses but decreases cellular immune
response (Tcells) which is important for pregnancy recognition and progression
Also leads to endometrial remodelling for cell adhesion
What is histotroph - Answer uterine milk
What influenced the secretion of the histotroph? Around what day does this start - Answer
progesterone being secreted by the CL around day 7 of the estrous cycle
What are 3 steps in the elongation of preimplantation conceptus in bovine - Answer 1. ovoid
Answers 2026/2027 Updated.
What characterizes an Ootid to go to a Zygote and what is this process called - Answer fusion
of the two nuclei to one.
called Syngamy
What characterizes the change from a Zygote to a 2 cell embryo - Answer the one cell embryo
will undergo cleavage and become a 2 cell
What are 7 stages of early embryonic development - Answer 1. Ootid
2. Zygote
3. 2-cell embryo
4. Morula
5. Early blastocyst
6. Hatching Blastocyst
7. Hatched blastocyst
What characterizes a morula - Answer when you can no longer count the amount of cells in
the embryo
What stage of embryonic development is when the inner cell mess and the trophectoderm form
- Answer early blastocyst
What are the 3 steps in the hatching process - Answer 1. blastocyst growth and fluid
accumulation
2. production of enzymes by the trophoblast
3. contraction of the blastocyst
What is the only stage of embryonic development that occurs in the uterus/uterine horn -
Answer the blastocyst
Accumulation of maternal RNA and proteins accumulated in the ooplasm during.. and where -
Answer during= oogenesis
in the ovary
,embryo genome activation and replacement of maternal-derived with embryo-derived
transcripts starts to occur where - Answer in the oviduct
Embryo takes ownership of gene expression and cell biology of what embryonic stage? where is
this located? - Answer in the blastomeres
in the uterine horn
What happened during the fist round of cell differentiation in morulas to an early blastocoele
(3) - Answer 1. compactions of the morula and cells that are in the outer layer of the embryo
will form tight junctions and form a layer of trophectoderm cells (creates the ICM in the
blastocyst)
2. outer layers of of the compacted morula cells start to secrete a lot of Na and send it to the
middle part
3. this Na will attract fluid and will create the blastocoele - fill it with mostly water
Where will fertilization occur - Answer in the ampulla
What occurs after hatching in the embryo - Answer conceptus development - differs among
species though
When does attachment and implantation occur in the primates and rodents - Answer shortly
after hatching of the blastocyst
What type of implantation occurs in primates and rodents? how invasive is this - Answer
hemochorial placentation
Highly invasive
What are the 5 phases of implantation in primates and rodents - Answer 1. shedding of ZP
2. pre-contact blastocyst orientation
3. apposition cellular contacts
4. adhesion
5. penetration of endometrium
What happens to hatched blastocysts in bovine and howdoes that affect implantation - Answer
hatched blastocysts are free floating in the uterine lumen - may take days to weeks before
implantation
What type of implantation occurs in bovine - Answer shallow - strong adhesion of cells rather
than actually physically going into the endometrial layer
, What are the 4 phases of implantation in bovines - Answer 1. shed ZP
2. elongation of conceptus
3. apposition
4. adhesion
What is elongating during conceptus elongation in bovnies - Answer the trophectoderm cells
are elongating while the inner cell mass stays in the middle
What gets secreted by the elongated conceptus in ruminants only that tells the mother she's
pregnant? where will it act - Answer IFNT
Will act in the endometrium - luminal epithelium
What does IFNT do to the uterus in bovines - Answer blocks expression of oxytocin receptors
so there are no pulses of PGF2alpha and progesterone will remain high
What is the cause of maternal recognition of pregnancy in ruminants - Answer production of
IFNT
What does oxytocin do in a non-pregnant cow - Answer oxytocin receptors are increased in
the endometrium of the uterus at late diestrus. this induced pulsatile secretion of PGF2alpha
which will cause luteolysis and regression of CL
How is progesterone maintained constant in a pregnant ruminant - Answer IFNT blocks
oxytocin, so there is no PGF2Alpha pulsing to the CL, which means no regression of the CL
Why is it important for the conceptus in the the bovine so secrete prostaglandins as well as IFNT
(2) - Answer PG's lead to increased innate immune responses but decreases cellular immune
response (Tcells) which is important for pregnancy recognition and progression
Also leads to endometrial remodelling for cell adhesion
What is histotroph - Answer uterine milk
What influenced the secretion of the histotroph? Around what day does this start - Answer
progesterone being secreted by the CL around day 7 of the estrous cycle
What are 3 steps in the elongation of preimplantation conceptus in bovine - Answer 1. ovoid
