Mosby items and derived items © 2007, 2003 by Mosby, Inc.Slide 1 Chapter 31 Male Reproductive System

Mosby items and derived items © 2007, 2003 by Mosby, Inc.Slide 2 Introduction  Proper functioning of the reproductive system ensures the survival of the species  Male reproductive system consists of organs whose functions are to produce, transfer, and introduce mature sperm into the female reproductive tract where fertilization can occur

Mosby items and derived items © 2007, 2003 by Mosby, Inc.Slide 3 Male Reproductive Organs  Classified as essential organs for production of gametes or accessory organs that support the reproductive process (Figure 31-1, A)  Essential organs—gonads of the male; testes  Accessory organs of reproduction Genital ducts convey sperm to outside of body; pair of epididymides, paired vasa deferentia, pair of ejaculatory ducts, and the urethra Genital ducts convey sperm to outside of body; pair of epididymides, paired vasa deferentia, pair of ejaculatory ducts, and the urethra Accessory glands produce secretions that nourish, transport, and mature sperm; pair of seminal vesicles, the prostate, and pair of bulbourethral glands Accessory glands produce secretions that nourish, transport, and mature sperm; pair of seminal vesicles, the prostate, and pair of bulbourethral glands Supporting structures—scrotum, penis, and pair of spermatic cords Supporting structures—scrotum, penis, and pair of spermatic cords

Mosby items and derived items © 2007, 2003 by Mosby, Inc.Slide 4 Male Reproductive Organs  Perineum—in males, roughly diamond-shaped area between thighs; extends anteriorly from symphysis pubis to coccyx posteriorly; lateral boundary is the ischial tuberosity on either side; divided into the urogenital triangle and the anal triangle (Figure 31-1, B)

Mosby items and derived items © 2007, 2003 by Mosby, Inc.Slide 5 Testes  Structure and location  Several lobules composed of seminiferous tubules and interstitial cells (of Leydig), separated by septa, encased in fibrous capsule called the tunica albuginea (Figure 31-2)  Seminiferous tubules in testis open into a plexus called rete testis, which is drained by a series of efferent ductules that emerge from top of organ and enter head of epididymis  Located in scrotum, one testis in each of two scrotal compartments  Microscopic anatomy

Mosby items and derived items © 2007, 2003 by Mosby, Inc.Slide 6 Testes  Functions  Spermatogenesis—formation of mature male gametes (spermatozoa) by seminiferous tubules  Secretion of hormone (testosterone) by interstitial cells  Structure of spermatozoa (Figure 31-7)—consists of a head (covered by acrosome), neck, midpiece, and tail; tail is divided into a principal piece and a short end-piece

Mosby items and derived items © 2007, 2003 by Mosby, Inc.Slide 7 Reproductive (Genital) Ducts  Epididymis  Structure and location Single tightly coiled tube enclosed in fibrous casing (Figure 31-8) Single tightly coiled tube enclosed in fibrous casing (Figure 31-8) Lies along top and side of each testis Lies along top and side of each testis Anatomical divisions include head, body, and tail Anatomical divisions include head, body, and tail  Functions Duct for seminal fluid Duct for seminal fluid Also secretes part of seminal fluid Also secretes part of seminal fluid Sperm become capable of motility while they are passing through epididymis Sperm become capable of motility while they are passing through epididymis

Mosby items and derived items © 2007, 2003 by Mosby, Inc.Slide 8 Reproductive (Genital) Ducts  Vas deferens (ductus deferens)  Structure and location Tube; extension of epididymis Tube; extension of epididymis Extends through inguinal canal, into abdominal cavity, and over top and down posterior surface of bladder Extends through inguinal canal, into abdominal cavity, and over top and down posterior surface of bladder Enlarged terminal portion called ampulla—joins duct of seminal vesicle Enlarged terminal portion called ampulla—joins duct of seminal vesicle  Function One of excretory ducts for seminal fluid One of excretory ducts for seminal fluid Connects epididymis with ejaculatory duct Connects epididymis with ejaculatory duct  Ejaculatory duct  Formed by union of vas deferens with duct from seminal vesicle  Passes through prostate gland, terminating in urethra  Urethra

Mosby items and derived items © 2007, 2003 by Mosby, Inc.Slide 9 Accessory Reproductive Glands  Seminal vesicles  Structure and location—convoluted pouches about 5 to 7 cm long on posterior surface of bladder  Function—secrete the viscous, nutrient-rich part of seminal fluid (60% of semen volume)  Prostate gland  Structure and location Doughnut-shaped Doughnut-shaped Encircles urethra just below bladder Encircles urethra just below bladder  Function—adds slightly acidic, watery, milky-looking secretion to seminal fluid (30% of semen volume)

Mosby items and derived items © 2007, 2003 by Mosby, Inc.Slide 10 Accessory Reproductive Glands  Bulbourethral gland  Structure and location Small, pea-shaped structures with ducts about 2.5 cm (1 inch) long leading into urethra Small, pea-shaped structures with ducts about 2.5 cm (1 inch) long leading into urethra Lie below prostate gland Lie below prostate gland  Function—secrete alkaline fluid that is part of semen (5% of semen volume)

Mosby items and derived items © 2007, 2003 by Mosby, Inc.Slide 11 Supporting Structures  Scrotum  Skin-covered pouch suspended from perineal region  Divided into two compartments  Contains testis, epididymis, and lower part of a spermatic cord  Dartos and cremaster muscles elevate the scrotal pouch

Mosby items and derived items © 2007, 2003 by Mosby, Inc.Slide 12 Supporting Structures  Penis (Figure 31-12)  Structure—composed of three cylindrical masses of erectile tissue, one of which contains urethra  Functions—penis contains the urethra, the terminal duct for both urinary and reproductive tracts; during sexual arousal, penis becomes erect, serving as a penetrating copulatory organ during sexual intercourse

Mosby items and derived items © 2007, 2003 by Mosby, Inc.Slide 13 Supporting Structures  Spermatic cords (internal)  Fibrous cylinders located in inguinal canals  Enclose seminal ducts, blood vessels, lymphatics, and nerves

Mosby items and derived items © 2007, 2003 by Mosby, Inc.Slide 14 Composition and Course of Seminal Fluid  Consists of secretions from testes, epididymides, seminal vesicles, prostate, and bulbourethral glands  Each milliliter contains millions of sperm  Passes from testes through epididymis, vas deferens, ejaculatory duct, and urethra

Mosby items and derived items © 2007, 2003 by Mosby, Inc.Slide 15 Male Fertility  Relates to many factors—number of sperm; size, shape, and motility  Infertility may be caused by antibodies some men make against their own sperm

Mosby items and derived items © 2007, 2003 by Mosby, Inc.Slide 16 Cycle of Life: Male Reproductive System  Reproductive functions begin at time of puberty  Development of organs begins before birth; immature testes descend into scrotum before or shortly after birth  Puberty—high levels of hormones stimulate final stages of development  System operates to permit reproduction until advanced old age  Late adulthood—gradual decline in hormone production may decrease sexual appetite and fertility