1. Explain why testosterone may be considered both an endocrine and paracrine secretion of the testes. Review paracrines in chapter 17 if necessary.

2. Suppose you were a physician who had a midadolescent patient who looked and felt completely feminine but who was concerned that she had not started her menstrual periods and had grown no pubic hair. Tests revealed that she was an XY individual with androgen-insensitivity syndrome. Would you consider the patient to be a boy or a girl? What would you tell your patient? Discuss your rationale.

3. Considering the temperature in the scrotum, would you expect hemoglobin to unload more oxygen to the testes, or less, than it unloads to the warmer internal organs? (Hint: see fig. 22.25). Why? How would you expect this to influence sperm development?

4. Why is it possible for spermatogonia to be outside the blood-testis barrier but essential for primary spermatocytes and later stages to be within the barrier (isolated from the blood)? Explain this contrast.

5. A 68-year-old man taking medication for hypertension complains to his physician that it has made him impotent. Explain why this could be an effect of antihypertensive drugs.

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