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Chapter 20 The Reproductive Systems http://new.wavlist.com/movies/101/kc-boysgirls.wav

COMMON STRUCTURAL AND FUNCTIONAL CHARACTERISTICS BETWEEN THE SEXES Common general structure and function can be identified between the systems in both sexes Systems adapted for development of sperm or ova followed by successful fertilization, development, and birth of offspring Sex hormones in both genders important in development of secondary sexual characteristics and normal reproductive system activity Slide 3

MALE REPRODUCTIVE SYSTEM Structural plan—organs classified as essential or accessory Essential organs of reproduction are the gonads (testes), which produce sex cells (sperm or spermatozoa) Accessory organs of reproduction Ducts—passageways that carry sperm from testes to exterior Sex glands—produce protective and nutrient solution for sperm External genitals Slide 4

MALE REPRODUCTIVE SYSTEM Testes—the gonads of men Structure and location (Figure 20-2) Testes in scrotum—lower temperature 10 C Covered by tunica albuginea, which divides testis into lobules containing seminiferous tubules Interstitial cells produce testosterone Slide 5

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MALE REPRODUCTIVE SYSTEM Testes (cont.) Functions Spermatogenesis is process of sperm production (Figure 20-4) Sperm precursor cells called spermatogonia Meiosis produces primary spermatocyte, which forms four spermatids with 23 chromosomes Spermatozoa—highly specialized cells Head contains genetic material Acrosome contains enzymes to assist sperm in penetration of ovum Mitochondria in midpiece provide energy for movement Production of testosterone by interstitial cells Testosterone “masculinizes” and promotes development of male accessory organs Promotes and maintains development of male accessory organs Stimulates protein anabolism and development of muscle strength Slide 7