Reproductive System

• Reproductive system


  The human species could not survive without functional male and female reproductive systems. The reproductive systems play essential roles in the development of the structural and functional differences between males and females, influence human behavior, and produce offspring.
• Functions of the reproductive system

  • Production of gametes
  • Fertilization
  • Development and nourishment of a new individual
  • Production of reproductive hormones
• Gametes


  Male: Sperm, Female: Eggs (Ova)
• Formation of gametes


  1. Meiosis

  2. 2 consecutive cell divisions halve the chromosome number from 46 to 23
• Male reproductive system


  • Serves to produce, transport and introduce mature sperm into the female reproductive tract for fertilization
• External portions of male reproductive system

  • Penis
  • Scrotum

  
• Scrotum


  • Sac containing testes
  • Dartos and cremaster muscles help regulate testes temperature
  • Median Septum divides the scrotum, isolating each testicle
  • Spermatic Cord contains the sperm duct, blood, lymphatic vessels and nerves
  • Cremaster Muscle surrounds the spermatic cord and testes

  
• Testes


  • Inside the scrotum
  • Divided into lobules containing the seminiferous tubules and interstitial cells
  • Organs that generate sperm and secrete the male sex hormone Testosterone
  • Tunica albuginea is a thick, dense connective tissue that surrounds each testis
  • Mediastinum testis is a thickening of the tunica albuginea at the posterior surface
  • Seminiferous tubules are the site of sperm development and contain germ cells and sustentacular cells (Sertoli cells)
  • Interstitial cells (Leydig cells) are found enmeshed with the seminiferous tubules and produce testosterone

  
• Spermatogenesis


  1. Sperm formation

  2. Begins at puberty and usually continues throughout life

  3. Thousands are produced each second

  4. 1-2 months maturation

  5. 1 germ cell = 4 sperm

  
• Sperm structure


  • Head: Contains the nucleus and acrosome
  • Middle piece: Contains numerous mitochondria
  • Tail: Flagellum propels the sperm forward

  
• Ductus epididymis


  • Single, highly coiled tube that forms the body and tail of the epididymis
  • Lined with pseudostratified columnar epithelium
  • Basal lamina has smooth muscle cells which help move sperm along the duct
  • Surface is covered with stereocilia

  
• Ductus (vas) deferens


  • Straight tube with a thick, muscular wall
  • Narrow mucosa with longitudinal folds
  • Covered by pseudostratified columnar epithelium with stereocilia

  
• Penis


  • Deposits sperm in the female vagina
  • Consists of erectile tissue
  • Three cylindrical masses of erectile tissue: Corpora cavernosa, Corpus spongiosum, Glans penis
  • Tunica albuginea is a layer of dense connective tissue that covers the corpora cavernosa

  
• Seminal vesicles


  • Located at the base of the bladder
  • Empty into the ejaculatory duct
  • Lined with cuboidal or pseudostratified columnar epithelium rich in secretory granules
• Prostate


  • Located below the bladder
  • Consists of glandular and muscular tissue and empties into the urethra

  
• Bulbourethral (Cowper's) glands


  • Empty into the urethra
  • Tubuloalveolar glands lined with mucus-secreting simple cuboidal epithelium
  • Secretes mucus which acts as a lubricant for sexual intercourse and neutralizes the acidity of residual urine in the urethra
• Secretions of the male reproductive system

  • Seminiferous tubules: Spermatogenesis
  • Epididymis: Sperm maturation
  • Ductus Deferens: Propel sperm to ejaculatory ducts
  • Seminal Vesicle: Provide nutrients for sperm and fluid
  • Prostate Gland: Provide enzymes and proteins for coagulation and liquefaction
  • Bulbourethral Glands: Add alkaline mucus to neutralize prostatic acid and vaginal acidity
• Semen


  Greyish white bodily fluid secreted by the gonads, containing sperm or spermatozoa, fructose and other enzymes
• Composition of semen


  • Spermatozoa: 5%
  • Seminal fluid: 60-70%
  • Prostate fluid: Enzymes, 20-30%
  • Bulbourethral glands: pH neutralizer, 5%

  
• Reference values for semen

  • Volume: 2-5 mL
  • Viscosity: Pours in droplets
  • pH: 6.0-6.5
  • Sperm Concentration: >20million/mL
  • Sperm Count: >40million/mL
  • Motility: >50% w/in 1 hour
  • Morphology: >14% normal forms (Strict Criteria), >30% normal forms (Routine Criteria)
  • Round Cells: <1.0million/mL
• Physiology of male reproduction

  • Hormonal control of: Development of reproductive structures, Development of secondary sexual characteristics, Spermatogenesis, Some aspects of sexual behavior
• Seminal Vesicle


  Provide nutrients for sperm and fluid
• Prostate Gland


  Provide enzymes and proteins for coagulation and liquefaction
• Bulbourethral Glands


  Add alkaline mucus to neutralize prostatic acid and vaginal acidity
• Semen


  Greyish white bodily fluid secreted by the gonads, contains sperm or spermatozoa, fructose and other enzymes
• Semen composition


  • 5% Spermatozoa
  • 60-70% Seminal Fluid
  • 20-30% Prostate Fluid
  • 5% Bulbourethral Glands

  
• Reference values for semen: Volume 2-5 mL, Viscosity pours in droplets, pH 6.0-6.5, Sperm Concentration >20million/mL, Sperm Count >40million/mL, Motility >50% w/in 1 hour, Morphology >14% normal forms (Strict Criteria) >30% normal forms (Routine Criteria), Round Cells <1.0million/mL
• Physiology of Male Reproduction

  • Hormonal control (development of reproductive structures, secondary sexual characteristics, spermatogenesis, sexual behavior)
  • Mature neural mechanisms (controlling the sexual act, expression of sexual behavior)
• Female Reproductive System


  • Produces gametes
  • Carrying, nourishing, and giving birth
  • Housed within the abdominal cavity
• Primary reproductive organs


  • Ovaries
• Accessory organs

  • Fallopian tubes
  • Uterus
  • Vagina
• Ovaries


  Almond shaped bodies: 3cm long, 1.5cm wide, and 1 cm thick, covered with germinal epithelium, with tunica albuginea, cortical region, and medullary region
• Oviducts

  • Uterine tubes, two muscular tubes of great motility, with fimbriae at the ovarian end, wall has 3 layers: mucosa, muscularis, serosa

  
• Uterus


  • Pear-shaped organ, composed of body, uterine cavity, cervix, and fundus, with serosa/adventitia, myometrium, and endometrium (basalis and functionalis zones)

  
• Vagina


  Connects the uterus (cervix) to the vestibule, consists of smooth muscle layer and moist stratified squamous epithelial lining, produces lubricating fluid, has hymen covering the vestibular opening in young females
• External Genitalia


  • Glands of Bartholin
  • Glandulae vestibulares minors
  • Clitoris
  • Labia minora
  • Labia majora

  
• Mammary Glands


  • 15-25 lobes of compound tubuloalveolar glands, each with their own excretory lactiferous duct that emerge independently in the nipple, organs for milk production, modified sweat glands with glandular lobes and adipose tissue, undergo development during puberty and adulthood