Reproduction 753- Which of the following statements regarding
spermatogenesis is false?
a. Testosterone stimulates spermatogenesis.
b. The chromatin becomes highly compacted as protamines
replace histone proteins.
c. Sertoli cells engulf spermatid cytoplasm by phagocytosis.
d. FSH is required for spermatogenesis to occur. - Which of the following statements about progesterone is false?
a. Progesterone is secreted by the corpus luteum
b. Progesterone is secreted by the placenta.
c. Progesterone decreases the basal body temperature.
d. Progesterone secretion drops towards the end of the
nonfertile luteal phase.Test Your Understanding
- Identify the conversion products of testosterone and describe
their functions in the brain, prostate, and seminiferous tubules. - Explain why a testis is said to be composed of two separate
compartments. Describe the interactions that may occur
between these compartments. - Describe the roles of the Sertoli cells in the testes.
- Describe the steps of spermatogenesis and explain its
hormonal control. - Explain the hormonal interactions that control ovulation and
cause it to occur at the proper time. - Compare menstrual bleeding and bleeding that occurs during
the estrous cycle of a dog in terms of hormonal control
mechanisms and the ovarian cycle. - “The [contraceptive] pill tricks the brain into thinking you’re
pregnant.” Interpret this popularized explanation in terms of
physiological mechanisms. - Why does menstruation normally occur? Under what
conditions does menstruation not occur? Explain. - Explain the proposed mechanisms whereby the act of
a mother nursing her baby results in lactation. By what
mechanisms might the sound of a baby crying elicit the
milk-ejection reflex? - Describe the steps of oogenesis when fertilization occurs and
when it does not occur. Why are polar bodies produced? - Identify the hormones secreted by the placenta. Why is the
placenta considered an incomplete endocrine gland? - Describe the endocrine changes that occur at menopause and
discuss the consequences of these changes. What are the benefits
and risks associated with hormone replacement therapy? - Explain the sequence of events by which the male
accessory sex organs and external genitalia are produced.
What occurs when a male embryo lacks receptor proteins
for testosterone? What occurs when a male embryo lacks the
enzyme 5 a -reductase?- Describe the mechanisms that have been proposed to time
the onset of parturition in sheep and humans.
Test Your Analytical Ability- According to your friend, there is a female birth control pill
and not a male birth control pill only because the medical
establishment is run by men. Do you agree with her conspiracy
theory? Provide physiological support for your answer. - Elderly men with benign prostatic hyperplasia are
sometimes given estrogen treatments. How would this help
the condition? What other types of drugs may be given, and
what would you predict their possible side effects to be? - Discuss the role of apoptosis and follicle atresia in ovarian
physiology. How might this process be regulated? - Is it true that estrogen is an exclusively female hormone and
that testosterone is an exclusively male hormone? Explain
your answer. - Surgical removal of a woman’s ovaries (ovariectomy) can
precipitate menstruation. Ovariectomy in a dog or cat,
however, does not cause the discharge of uterine blood. How
can you explain these different responses? - Endometrial tissue is maintained by estrogen, and yet
endometriosis is treated with a GnRH agonist drug. Explain
this seeming paradox. - If scientists developed a new drug to block the FSH receptor
in men, or to reduce a man’s FSH secretion, would that
lead to a male contraceptive pill? Explain, in terms of the
hormonal control of spermatogenesis. - Describe the locations and characteristics of adult stem
cells. How does their potential relate to normal embryonic
tissue development? What are the potential advantages and
disadvantages of using adult stem cells, compared to embryonic
stem cells, for regenerative medicine (stem cell therapies)?
Test Your Quantitative Ability
Refer to figure 20.32 to answer the following questions:- During which range of days are the secretions of both
estradiol and progesterone at their highest levels in the graph? - What is the percentage increase in LH secretion in the day
leading up to the LH peak? - In the 5 days leading up to the LH peak, what is the
percentage increase in estradiol secretion? - At 5 days after the LH peak, how many times greater is the
blood concentration of progesterone compared to estradiol?
(Hint: a picogram is 10^2 12 g, whereas a nanogram is 10^2 9 g.)
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