Sexual Reproduction

Objectives

When you have completed this section, you should be able to

• define sexual reproduction;
• state the most fundamental biological distinction between male and female; and
• define primary sex organs, secondary sex organs, and secondary sex characteristics.

Key Point Review

1. Define gonad and gamete. Explain the relationship between the terms.

2. Define male, female, sperm, and egg.

Sex Determination and Development

Objectives

When you have completed this section, you should be able to

• explain the role of the sex chromosomes in determining sex;
• explain how the Y chromosome determines the response of the fetal gonad to prenatal hormones;
• describe which of the male and female external genitals are homologous to each other; and
• describe the descent of the testes and explain why it is important.

Think About It

In what way is androgen-insensitivity syndrome (see special topic 27.1) similar to noninsulin-dependent diabetes mellitus and Laron dwarfism (discussed in chapter 17)?

Key Point Review

3. What are mesonephric and paramesonephric ducts? What factors determine which one develops and which one regresses in the fetus?

4. What male structures develop from the phallus and labioscrotal folds?

5. Define the gubernaculum and describe its function.

Reproductive Anatomy

Objectives

When you have completed this section, you should be able to

• describe the anatomy of the testes, scrotum, and penis;
• describe the pathway taken by a sperm cell from its formation to its ejaculation; and
• describe the accessory glands and other secondary sex organs of the male, and state their functions.

Think About It

Would you expect to find blood capillaries in the walls of the seminiferous tubules? Why or why not?

Key Point Review

6. State the names and locations of two muscles that help regulate the temperature of the testes.

7. Name three types of cells in the testis, and describe their locations and functions.

8. Name all the ducts that the sperm follow, in order, from the time they leave the testis to the time of ejaculation.

9. Describe the locations and functions of the seminal vesicles, prostate, and bulbourethral glands.

10. Name the erectile tissues of the penis, and describe their locations relative to each other.

Puberty and Climacteric

Objectives

When you have completed this section, you should be able to

• describe the hormonal control of puberty;
• describe the resulting changes in the male body; and
• define and describe male climacteric and the effect of aging on male reproductive function.

Think About It

If a male animal is castrated, would you expect FSH and ICSH levels to rise, fall, or be unaffected. Why?

Key Point Review

11. State the source, target organ, and effect of GnRH.

12. Identify the target cells and effects of FSH and ICSH.

13. Explain how testicular hormones affect the secretion of FSH and ICSH.

14. Describe the major effects of androgens on the body.

15. Define climacteric and impotence.

Spermatogenesis, Spermatozoa, and Semen

Objectives

When you have completed this section, you should be able to

• describe the stages of meiosis and contrast meiosis with mitosis;
• describe the sequence of cell types in spermatogenesis, and relate these to the stages of meiosis;
• describe the role of the sustentacular cell in spermatogenesis;
• draw or describe a sperm cell; and
• describe the composition of semen and functions of its components.

Key Point Review

16. State how many chromosomes a cell has, and how many chromatids each chromosome has, at the conclusion of meiosis I and meiosis II.

17. Name the stages of spermatogenesis from spermatogonium to spermatozoon.

18. Describe the three major parts of a spermatozoon and state what organelles or cytoskeletal components are contained in each.

19. List the major contributions of the seminal vesicles and prostate gland to the semen, and state the functions of these components.

Sexual Intercourse

Objectives

When you have completed this section, you should be able to

• describe the blood and nerve supply to the penis; and
• explain how these govern erection and ejaculation.

Think About It

Why is it important that the corpus spongiosum not become as engorged and rigid as the corpora cavernosa?

Key Point Review

20. Explain how penile blood circulation changes during sexual arousal and why the penis becomes enlarged and stiffened.

21. State the roles of the sympathetic and parasympathetic nervous systems in male sexual response.

Copyright ©1998 The McGraw-Hill Companies. All rights reserved. Any use is subject to the Terms of Use and Privacy Policy.
McGraw-Hill Higher Education is one of the many fine businesses of The McGraw-Hill Companies.
For further information about this site contact mhhe_webmaster@mcgraw-hill.com.