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Chapter 17
Male Reproductive System
Each testis contains about 250 meters of seminiferous tubule
• Testes: produce sperm (spermatogenesis)
– Production Site: seminiferous tubules
– About 250 meters of tubule/testis
– 100 – 300 million sperm/day produced
• Testes also produce male hormones
(testosterone)
Two Major Functions of Testes
Delivery of Sperm to the Egg
• The duct system stores and transports sperm
– Delivery through reproductive tubules: epididymis
vas deferens urethra penis
Delivery of Sperm to the Egg
• The seminal vesicles and prostate gland (accessory glands) produce most of the volume of semen
• The penis transfers
sperm to the female
The organ where sperm are
produced is
A. Testes
B. Prostate gland
C. Seminal vesicle
D. Penis
• Sperm development involves reduction in the
number of chromosomes and in the structure
of sperm cells
• Several cell divisions of mitosis and meiosis
–Purpose: produce a large number (> 100
million/day) of sperm with half the number of
chromosomes of somatic cells (haploid)
Sperm Production
(Leydig cells)
The organ where sperm are
produced is
A. Prostate gland
B. Testes
C. Seminal vesicle
D. Ovary
Mature sperm contain:
A. 46 chromosomes
B. The same number of chromosomes
as the father
C. 23 chromosomes
D. Half the number of chromosomes as
the father
• Hormones:– Testosterone• Source: Interstitial (Leydig) cells in testes
– LH: stimulates production of testosterone in interstitial (Leydig) cells
– FSH: enhances sperm formation by Sertoli cells
Male Reproductive Hormones
Testosterone secretion is regulated by a negative
feedback loop (see in class worksheet)
The Male Reproductive System
• The hypothalamus (neurosecretory cells)
releases gonadotropin-releasing hormone
(GnRH)
• GnRH stimulates the anterior pituitary
gland to secrete luteinizing hormone
(LH)
• LH stimulates the production of
testosterone by the testes
The rising testosterone level inhibits the
release of GnRH to complete the loop
Actions of Testosterone on Target
Tissues
• Actions of Testosterone
– Controls growth and function of male
reproductive tissues (e.g., prostate &
seminal vesicles)
– Secondary sexual characteristics: muscle,
auxiliary hair, larynx, balding pattern
– Stimulates aggression and sexual behavior
Testosterone has effects on:
A. Male secondary sexual
characteristics, e.g., muscle, beard
growth
B. Prostate gland
C. Sex drive
The function of the prostate gland is to:
A. Produce sperm
B. Produce testosterone
C. Produce secretions (semen) that
make sperm mobile
D. Store sperm