1. Under the influence of androgens, the embryonic _______________ duct develops into the male reproductive tract.

2. Spermatozoa obtain energy for locomotion from _______________ in the semen.

3. The _______________ , a network of veins in the spermatic cord, helps keep the testes cooler than core body temperature.

4. All germ cells beginning with the _______________ are genetically different from the rest of the body and therefore must be protected by the blood-testis barrier.

5. The corpora cavernosa as well as the testes have a fibrous capsule called the _______________ .

6. Over half the semen consists of secretions from a pair of glands called the _______________ .

7. The blood-testis barrier is formed by tight junctions between the _______________ cells.

8. The earliest haploid stage of spermatogenesis is the _______________ .

9. Erection of the penis results when nitric oxide causes dilation of the _______________ arteries of the penis.

10. The _______________ of a sperm contains enzymes used to penetrate the egg.

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