ANSC 534 Exam 2 questions with verified answers
At what stage of the cell cycle does the first meiotic arrest take place?
What is happening with the oocyte at that point? Ans✓✓✓ -First
prophase
-Primary oocyte is receiving cGMP produced by cumulus cells through
gap junctions that blocks the hydrolysis of cAMP
-cAMP blocks MPF activation
-Maintained from birth until just before ovulation
At what stage of the cell cycle does the second meiotic arrest take
place? What is happening with the oocyte at that point? Ans✓✓✓ -
Metaphase II
-oocyte has completed meiosis I
-Sustained by high MPF activity, cyclin B destruction is inhibited due to
Cytostatic factor (CSF), CSF inhibits APC, thus maintains high MPF levels
Define angiogenesis and explain its role during luteinization. Ans✓✓✓ -
The generation of new blood vessels
-Degradation of the vascular basement membrane (VBM)
-Proliferation and migration of endothelial cells
-Formation of a new vascular basement membrane
-Formation of a new blood vessel
-Occurs rarely in the adult, exceptions: female reproductive system,
wound healing, cancer
,-Precise control of angiogenesis is critical for normal luteal function
Define germ cell "generations" within the seminiferous tubule. Ans✓✓✓
-Cells of the same type located at one site of the tubule
-Within any cross-section there are 4-5 concentric layers of germ cells
-Cells in each layer comprise a generation
-Cross sections along the length of the tubule will have a different
appearance, but cross sections of a given zone will appear similar
-Each generation will give rise to a succeeding, more advanced
generation
-There are only certain zones (stages) where spermatozoa are released
at a given time
Define puberty. What is the main factor that determines the onset of
puberty? (Explain the importance of GnRH) Ans✓✓✓ Puberty is the
process of acquiring reproductive competence. The onset of puberty
depends upon specific hypothalamic neurons to produce GnRH in
sufficient amounts to promote gametogenesis. GnRH secretion is
initially stimulated by kisspeptin production in the brain.
Define spermiation. Ans✓✓✓ -Release of mature spermatids from the
Sertoli cells into the lumen of seminiferous tubules
-Analogous to ovulation
-Continuous
,Define the meaning of a "stage" in the seminiferous tubule during
spermatogenesis. Ans✓✓✓ -Zones along the tubule contain different
cellular associations
-The arbitrarily defined cellular associations are called stages
-Each stage transit to the next at predictable intervals
-Stage duration: time required for completion of one stage
Define the spermatogenic wave. Ans✓✓✓ -The sequential ordering of
stages along the length of the seminiferous tubule
-Each stage transitions to a successively more advanced stage
-The site of spermiation is constantly changing, creating a wave of
sperm release
-Provides a constant supply of spermatozoa
-A wave is generated as retinoic acid pulses move along the tubules
driving the transition of spermatogonia
Describe and explain the "paradox" of follicular dynamics. Ans✓✓✓ -
How the dominant follicle continues to develop in the presence of low
FSH levels that are unable to maintain development of less mature
follicles
-As the follicle matures, it becomes less dependent on FSH
-It continues to mature in the presence of low FSH that is unable to
initiate the development of less mature follicles
-*Expression of LHR by granulosa cells as a result of FSH*
, -The maturing follicle reduces dependence on FSH by acquiring LH
receptors
-LH is able to substitute for FSH in supporting the growth of FSH-
stimulated follicles
-During preantral follicle development, LHRs are found exclusively on
theca cells and FSHRs on granulosa cells
Describe androgen insensitivity syndrome. Ans✓✓✓ -An intersex
condition caused by the inability of cells to respond to androgens
-Mutations in the androgen receptor gene can lead to complete AIS
-Androgens cannot cause defeminization and masculinization in genetic
males, resulting in female phenotype
Describe androgen receptors. Ans✓✓✓ -Nuclear receptor, located in
cytoplasm
-Acts as a DNA-binding transcription factor
-Activated by binding T or DHT
-Conformational change
-Dimerization
-Translocation to the nucleus
-Binding to hormone-response elements
-Regulation of gene transcription
At what stage of the cell cycle does the first meiotic arrest take place?
What is happening with the oocyte at that point? Ans✓✓✓ -First
prophase
-Primary oocyte is receiving cGMP produced by cumulus cells through
gap junctions that blocks the hydrolysis of cAMP
-cAMP blocks MPF activation
-Maintained from birth until just before ovulation
At what stage of the cell cycle does the second meiotic arrest take
place? What is happening with the oocyte at that point? Ans✓✓✓ -
Metaphase II
-oocyte has completed meiosis I
-Sustained by high MPF activity, cyclin B destruction is inhibited due to
Cytostatic factor (CSF), CSF inhibits APC, thus maintains high MPF levels
Define angiogenesis and explain its role during luteinization. Ans✓✓✓ -
The generation of new blood vessels
-Degradation of the vascular basement membrane (VBM)
-Proliferation and migration of endothelial cells
-Formation of a new vascular basement membrane
-Formation of a new blood vessel
-Occurs rarely in the adult, exceptions: female reproductive system,
wound healing, cancer
,-Precise control of angiogenesis is critical for normal luteal function
Define germ cell "generations" within the seminiferous tubule. Ans✓✓✓
-Cells of the same type located at one site of the tubule
-Within any cross-section there are 4-5 concentric layers of germ cells
-Cells in each layer comprise a generation
-Cross sections along the length of the tubule will have a different
appearance, but cross sections of a given zone will appear similar
-Each generation will give rise to a succeeding, more advanced
generation
-There are only certain zones (stages) where spermatozoa are released
at a given time
Define puberty. What is the main factor that determines the onset of
puberty? (Explain the importance of GnRH) Ans✓✓✓ Puberty is the
process of acquiring reproductive competence. The onset of puberty
depends upon specific hypothalamic neurons to produce GnRH in
sufficient amounts to promote gametogenesis. GnRH secretion is
initially stimulated by kisspeptin production in the brain.
Define spermiation. Ans✓✓✓ -Release of mature spermatids from the
Sertoli cells into the lumen of seminiferous tubules
-Analogous to ovulation
-Continuous
,Define the meaning of a "stage" in the seminiferous tubule during
spermatogenesis. Ans✓✓✓ -Zones along the tubule contain different
cellular associations
-The arbitrarily defined cellular associations are called stages
-Each stage transit to the next at predictable intervals
-Stage duration: time required for completion of one stage
Define the spermatogenic wave. Ans✓✓✓ -The sequential ordering of
stages along the length of the seminiferous tubule
-Each stage transitions to a successively more advanced stage
-The site of spermiation is constantly changing, creating a wave of
sperm release
-Provides a constant supply of spermatozoa
-A wave is generated as retinoic acid pulses move along the tubules
driving the transition of spermatogonia
Describe and explain the "paradox" of follicular dynamics. Ans✓✓✓ -
How the dominant follicle continues to develop in the presence of low
FSH levels that are unable to maintain development of less mature
follicles
-As the follicle matures, it becomes less dependent on FSH
-It continues to mature in the presence of low FSH that is unable to
initiate the development of less mature follicles
-*Expression of LHR by granulosa cells as a result of FSH*
, -The maturing follicle reduces dependence on FSH by acquiring LH
receptors
-LH is able to substitute for FSH in supporting the growth of FSH-
stimulated follicles
-During preantral follicle development, LHRs are found exclusively on
theca cells and FSHRs on granulosa cells
Describe androgen insensitivity syndrome. Ans✓✓✓ -An intersex
condition caused by the inability of cells to respond to androgens
-Mutations in the androgen receptor gene can lead to complete AIS
-Androgens cannot cause defeminization and masculinization in genetic
males, resulting in female phenotype
Describe androgen receptors. Ans✓✓✓ -Nuclear receptor, located in
cytoplasm
-Acts as a DNA-binding transcription factor
-Activated by binding T or DHT
-Conformational change
-Dimerization
-Translocation to the nucleus
-Binding to hormone-response elements
-Regulation of gene transcription
