male

• Male sex hormones


  Physiology and functional role of male sex hormones
• Male sexual development


  1. Programmed in the genome

  2. Bipotential stage

  3. Differentiation into male and female characteristics
• Sexual development is programmed in the genome
• Pseudohermaphroditism is the dual-sex offspring of Hermes and Aphrodite
• Male sexual development stages

  1. Gonad (cortex) forms ovary

  2. Gonad (medulla) forms testis

  3. Development of male reproductive organs
• Testosterone converts Wolffian duct into seminal vesicle, vas deferens, and epididymis
• Dihydrotestosterone controls prostate development
• Testosterone


  • Stimulates enlargement of testes and male accessory organs
  • Stimulates development of male secondary sex characteristics
• Actions of Testosterone
• Testosterone levels throughout life
• Hormonal control of male reproductive functions

  1. Secretion by hypothalamus, anterior pituitary gland, and testes

  2. Development of sperm cells and secondary sex characteristics
• Hormonal control of reproduction

  Brain control through GnRH and pituitary gonadotropins (FSH and LH)
• Reproduction control in both sexes

  • The brain controls reproduction through GnRH and pituitary gonadotropins (FSH and LH)
• Effects of hormone levels

  • Low estrogen or androgen
  • Moderate estrogen or androgen
  • High androgen
  • Sustained high estrogen
  • Absence of negative feedback
  • Negative feedback
  • Positive feedback
• Feedback effects of sex steroids on gonadotropin release

  1. Long-loop feedback may be negative or positive

  2. Short-loop negative feedback
• Gametogenesis


  Germ cells first duplicate themselves through mitosis. Then, through meiosis, they form gametes with one chromosome from each pair
• Gametogenesis in Females


  Primary oocyte divides into two secondary gametes
• Gametogenesis in Males


  Primary spermatocyte divides into two secondary spermatocytes
• Leydig cells secrete testosterone
• Sertoli cells secrete proteins to support sperm production
• Luminal fluid composition is high in K+ and steroid hormones
• What can go wrong in the reproductive system:
• Primary testicular failure: Infertility + associated hypogonadism and lack of 2nd sexual characteristics. Testosterone treatment can stimulate 2nd sexual characteristics but the patient remains infertile
• Hypogonadotropic hypogonadism: Infertility + associated hypogonadism and lack of 2nd sexual characteristics. Pituitary hormones treatment can improve 2nd sexual characteristics and fertility. Testosterone can sometimes improve fertility
• Hypogonadism