Reproductive System

• Male External Structures

  • Penis
  • Scrotum
  • Testes

  
• Scrotum


  • Rugated skin covered muscular pouch suspended from the perineum
  • Functions to support the testes and help regulate temperature of sperm
  • Composed of Dartos muscle and cremaster muscle
  • In cold weather, scrotal muscle contracts, brings testes closer to the body
  • Regulates temperature, promote the production and viability of sperm
• Testes


  • Two ovoid glands, 2 to 3 cm wide that lie in the scrotum
  • First form in utero in the pelvic cavity
  • Descend into the scrotal sac late in uterine life (34th to 38th week)
  • Many preterm born infants have undescended testes (cryptorchidism)
  • In most males one testis is slightly larger than the other and is suspended slightly lower in the scrotum that the other (usually the left one)
  • Spermatozoa do not survive at a temperature as high as that of the body
  • Location of the testes outside the body, where the temperature is approximately 1oF than the body temperature, provides protection for sperm survival
  • Testicular self-examination is encouraged in adolescence so they can detect tenderness or any abnormal growth
  • Normal testes feel firm, smooth and egg-shaped
• Penis


  • Composed of three cylindrical masses of erectile tissue in the penis shaft: two termed the corpus cavernosa, and a third termed the corpus spongiosum
  • The urethra passes through these layers of erectile tissue, making the penis serve as the outlet for both the urinary and the reproductive tracts in men

  
• Penile erection


  1. With sexual excitement, nitric oxide is released from the endothelium of blood vessels

  2. This results in dilation of blood vessels and an increase in blood flow to the arteries of the penis (engorgement)

  3. Ischiocavernosus muscle at the base of the penis then contracts, trapping both venous and arterial blood on the three sections of erectile tissue and leading to distention and erection of the penis

  4. Penile erection is stimulated by the parasympathetic nerve innervation
• Glans


  The distal part of the penis and is homologous to the female's clitoris
• Prepuce


  The skin covering the glans
• Male Internal Structures

  • Epididymis
  • Vas deferens
  • Seminal vesicles
  • Ejaculatory ducts
  • Prostate gland
  • Urethra
  • Bulbourethral glands

  
• Epididymis


  • The tube that carries sperm away from the testes
  • Encased by a protective white fibrous capsule and is composed of a number of lobules
  • Each lobule containing interstitial cells (leydig's cells) and seminiferous tubule
  • Seminiferous tubules produce spermatozoa
  • Leydig's cells are responsible for production of male hormones
  • The seminiferous tubules of the testes leads to tightly coiled tube
  • Approximately 20 ft. long
  • Responsible for conducting sperm from the testis to the vas deferens
  • Stores sperm
  • It takes 12-20 days for the sperm to travel the length of the epididymis, and a total of 64 days for them to reach maturity
  • Aspermia - absence of sperm
  • Oligospermia - fewer than 20 million sperm per milliliter
• Semen


  • Male ejaculate is composed of spermatozoa (2% to 5%) and seminal fluid (95% to 98%)
  • Alkaline pH: 7.2 to 7.4
  • Average volume of ejaculate: 2.5 to 5 mL; may vary from 1-10 mL
  • Repeated ejaculation may lead to decreased volume
  • Normal sperm count: 100 million per mL
  • Once expelled, sperm can live up to 24-48 hours
• Vas deferens (Ductus deferens)


  • Hollow tube surrounded by arteries and veins and protected by a thick fibrous coating
  • Carries sperm from the epididymis through the inguinal canal into the abdominal cavity where it ends at the seminal vesicles and the ejaculatory ducts
  • Sperm mature as they pass through the vas deferens
  • Blood vessels and vas deferens are referred as the spermatic cord
• Seminal vesicles


  • Two convoluted pouches that lie along the lower portion of the posterior surface of the bladder and empty into the urethra by way of the ejaculatory ducts
  • Secrete viscous portion of the semen, which has a high content of a basic sugar, protein, and prostaglandins and is alkaline
  • Sperm becomes motile
• Ejaculatory ducts


  Pass through the prostate gland and join the seminal vesicles to the urethra
• Prostate gland


  • Chestnut-sized gland that lies just below the bladder
  • The urethra passes through the center of it, like the hole in a doughnut
  • Secretes a thin, alkaline fluid
• Bulbourethral glands (Cowper's gland)


  • Lie beside the prostate gland and empty by short ducts into the urethra
  • Secrete an alkaline fluid that helps counteract the acid secretion of the urethra and ensure safe passage of spermatozoa
  • Semen is derived from prostate (60%), seminal vesicles (30%), epididymis (5%), bulbourethral (5%)
• Urethra


  • A hollow tube leading from the base of the bladder, which after passing through the prostate gland, continues to the outside through the shaft and glans of the penis
  • Approximately 8 inches long
• Female Reproductive Organs

  • Vulva
  • Mons veneris
  • Labia minora and majora
  • Vestibule
  • Clitoris
  • Fourchette
  • Perineal body
  • Hymen
  • Skene's and Bartholin's glands

  
• Mons veneris


  • Pad of adipose tissue located over the symphysis pubis, the pubis bone joint
  • Covered by a triangle of coarse, curly hairs
  • Protect the junction of the pubic bone from trauma
• Labia minora


  • Posterior to mons veneris spread two hairless folds of connective tissue
  • Pink, covered with mucous membrane, and external surface with skin
  • Abundant with sebaceous glands
  • Before menarche they are fairly small
  • By childbearing age they are firm and full
  • After menopause they atrophy and again become smaller
• Labia majora


  • Positioned lateral to the labia minora
  • Covered by pubic hair
  • Serve as protection for the external genitalia and the distal urethra and vagina
  • Two folds of adipose tissue covered by loose connective tissue and epithelium
• Vestibule


  • Flattened smooth surface inside the labia
  • The openings to the bladder (the urethra) and the uterus (the vagina) both arise from the vestibule
• Clitoris


  • 1 to 2 cm small rounded organ of erectile tissue at the forward junction of labia minora
  • Sensitive to touch and temperature, and is the center of arousal sexual arousal and orgasm in a woman
• Skene's glands (Paraurethral glands)


  • Located just lateral to the vaginal opening on both sides
  • Secretions help lubricate the external genitalia during coitus
  • Alkaline secretion helps improve sperm survival in the vagina
• Fourchette


  • Ridge of tissue formed by the posterior joining of the two labia minora and labia majora
  • This is the structure that is sometimes cut (episiotomy) during childbirth to enlarge vaginal opening
• Perineum


  • Muscular area easily stretched during childbirth to allow enlargement of the vagina and passage of the fetal head
  • Kegel's exercise aimed at making perineal muscle more flexible to allow easier expansion during birth without tearing the tissue
• Hymen


  • Tough but elastic semicircle of tissue that covers the opening at the vagina in childhood
  • Often torn during time of first sexual intercourse
• Vulvar blood supply


  • Blood supply of external genitalis is through the pudendal artery and inferior retus artery
  • Venous return is through the pudendal vein
  • Pressure on the pudendal vein by fetal head can cause extensive back-pressure and development of varicosities (distended vein) in the labia majora
• Vulvar nerve supply


  • Anterior portion of the vulva derives its nerve supply from the ilio-inguinal and genitofemoral nerves
  • Posterior portion of the vulva and vagina are supplied by the pudendal nerve
• Female Internal Organs of Reproduction

  • Ovaries
  • Fallopian tubes

  
• Perineum


  Muscular area easily stretched during childbirth to allow enlargement of the vagina and passage of the fetal head
• Kegel's exercise


  Aimed at making perineal muscle more flexible to allow easier expansion during birth without tearing the tissue
• Hymen


  Tough but elastic semicircle of tissue that covers the opening at the vagina in childhood, often torn during first sexual intercourse
• Vulvar blood supply


  • Blood supply through pudendal artery and inferior rectal artery
  • Venous return through pudendal vein
  • Pressure on pudendal vein by fetal head can cause varicosities in labia majora
• Vulvar nerve supply


  • Anterior portion supplied by ilio-inguinal and genitofemoral nerves
  • Posterior portion and vagina supplied by pudendal nerve
• Female internal organs of reproduction

  • Ovaries
  • Fallopian tubes
  • Uterus
  • Vagina

  
• Ovaries


  • 4cm long, 2cm diameter, 1.5cm thick
  • Size and shape of almonds
  • Located close to and on both sides of the uterus
  • Held suspended and in close contact with fallopian tubes by ligaments
  • Produce mature and discharge ova
  • Produce estrogen and progesterone
  • Initiate and regulate menstrual cycle
  • Necessary for maturation and maintenance of secondary sex characteristics
  • Estrogen secreted prevents osteoporosis
• Fallopian tubes


  • Arise from uterine corners and extend outward and backward to ovaries
  • Approximately 10cm in length
  • Lining composed of mucous membrane with mucous secreting and ciliated cells
  • Also composed of connective tissue and circular muscle layer
  • Muscle layer produces peristaltic motions to help conduct ovum
  • Mucus provides nourishment for fertilized egg
  • Convey ovum from ovaries to uterus and provide place for fertilization
  • Divided into interstitial, isthmus and infundibulum sections
• Uterus


  • Hollow, muscular, pear-shaped organ in lower pelvis
  • Posterior to bladder, anterior to rectum
  • Size of olive in childhood, increases from age 8 to adult size by 17
  • Adult size 5-7cm long, 5cm wide
  • Weighs approximately 60g in non-pregnant state
  • Functions to receive ovum, provide implantation and nourishment, protect growing fetus
  • After pregnancy 9cm long, 6cm wide, 3cm thick, 80g in weight
  • Consists of body/corpus, isthmus, and cervix
• Body of uterus


  • Uppermost part forming bulk of organ
  • Lining continuous with fallopian tubes
  • Expands to contain growing fetus
  • Fundus portion between fallopian tube attachments expands to contain fetus, can be palpated
• Isthmus


  • Short 1-2mm segment between body and cervix
  • Enlarges greatly to accommodate growing fetus
  • Most commonly cut during cesarean birth