Reproductive system

• Reproductive system


  System of sex organs within an organism which works together for the purpose of sexual reproduction
• Reproductive system


  • Unlike other systems, the sexes of differentiated species often have significant differences
  • These differences allow for a combination of genetic materials between two individuals, which allows for the possibility of greater genetic fitness of the offspring
• Components of the reproductive system


  • Gonads
  • Their products
  • Hormones
  • Gametes
  • Ducts that transport gametes
• Mammalian reproductive system

  Includes the external genitalia (Penis and Vulva) as well as a number of internal organs, including the gonads (testicles and ovaries) which produces the male and female gametes i.e Sperm and Ovum
• The key elements of the reproductive system are quite similar in all vertebrates. They all have gamete-producing organs or GONADS
• Rats

  • Easier to sex than many other small rodents
  • Testicles start to drop when they are around 2.5 weeks old, but it becomes visible when the male rat is about 3 weeks old
  • Sexual maturity occurs within three to four months, females can produce up to five litters a year
  • Gestation takes 21-24 days
  • Males have a greater anogenital distance than females, and larger genital papillae
• Until recently, scientists believed that women cease egg production forever at menopause. Intriguing new findings in mice, however, suggest that ovarian stem cells continue to produce eggs throughout the animals' lives. If the same is true in humans, it could have profound implications for infertility and aging in women
• Major reproductive organs of the male rat

  • Testes
  • Epididymis
  • Vas deferens
  • Urethra
  • Penis
• Inguinal canal

  More prominent and remains open throughout the animal's life in males
• Male rat penis possess penis bone (Baculum) or os penis
• Accessory sex glands in males

  • Ampulla
  • Seminal vesicle
  • Prostate
  • Bulbourethral glands
  • Coagulating glands
  • Preputial glands
• Major functions of the male reproductive system

  • Produce, maintain and transport sperm and protective fluid
  • Discharge sperm within the female reproductive tract during intercourse
  • Produce and secrete male sex hormones responsible for maintaining the male reproductive system
• Scrotum


  Loose pouchlike sac of skin that hangs behind and below the penis
• Functions of the scrotum


  • Thermal regulation
  • Temperature control necessary for sperm production
  • Sperm development cannot occur at body temperature, heat can cause infertility
• Spermatogenesis


  The process of sperm cell maturation which takes about 50 days in man
• Testes


  • Oval organs that lie in the scrotum, secured at either end by a structure called the spermatic cord
  • Within the testes are coiled masses of tubes called seminiferous tubules
  • Produce sperm
  • Responsible for producing primary male sex hormone - testosterone
• Epididymis


  • It takes 10-15 days for the sperm cells to pass through the epididymis
  • Functions include maturation of sperm cells, storage of sperm cells, and contains smooth muscles that help propel the sperm toward the penis by peristaltic contraction
  • Serves as a duct system for the passage of sperm from the testis to the ductus deferens
• Vas deferens

  Passageway for sperm cells
• Accessory glands in the male reproductive tract

  • Seminal vesicles
  • Prostate gland
  • Cowper's gland
• Seminal vesicles

  • Secrete water, fructose (energy source for sperm), prostaglandins and vitamin C
  • Provide 40-80% of ejaculate volume
  • Secretion provides an energy source for the motile sperm and also helps to neutralize the natural protective acidity of the vagina
• Prostate gland


  • Secretes water, enzymes, cholesterol, buffering salts and phospholipids
  • Provides 15-30% of ejaculate volume
• Cowper's gland

  • Cleanse and neutralize urethra
  • Keep sperm from dying
• Urethra

  • Passageway for semen
  • Carries semen to the end of the penis
• Retractor muscle


  • Retracts penis
  • Pulls the penis back within the sheath
• Penis


  • Carries urine through the urethra to the outside during urination
  • Transports semen through the urethra during ejaculation
• Primary hormones involved in the male reproductive system

  • Follicle stimulating hormone (necessary for sperm production)
  • Luteinizing hormone (stimulates the production of testosterone)
  • Testosterone (needed to make sperm and also responsible for the development of male sexual characteristics such as muscle mass, sex drive)
• Ovary


  • Primary organ of the female reproductive system
  • Produces eggs and secretes sex hormones
  • Immature eggs are called oocytes
• Oviducts


  Ducts for conducting oocytes from ovary to uterus, fertilization occurs in the oviduct
• Uterus


  Chamber in which new individuals develop
• Cervix


  Secretion of mucus that enhances sperm movement into uterus and reduces embryo risk of bacterial infection
• Vagina


  Organ of sexual intercourse, birth canal
• Female reproductive system in rats

  • Six pair of mammary glands - 3 thoracic, 1 abdominal, 2 inguinal
  • Uterus is bicornuate and duplex consisting of two uterine horns, two cervices, and one vagina
  • Hemochorial discoid placentation
  • A copulatory plug forms from semen coagulation following copulation, filling the reproductive tract from the vulva to the cervix and remaining for a few hours
• Internal sex organs of the female reproductive system

  • Uterus
  • Fallopian tubes
  • Ovaries
• Uterus

  • Accommodates the embryo which develops into a fetus
  • Produces vaginal and uterine secretions which helps to transit of sperm to the fallopian tubes
• Ovaries


  Produce the egg cells (ova)
• External sex organs


  Organs of the Vulva - labia, vaginal opening
• In rats, the female reproductive system is immature at birth and develops to maturity within three to five months to be able to produce gametes and to carry fetus to full term