Male Infertility 1

Question 1

What is the epidemiology for male infertility?

Answer 1

• Approximately 15% of couples trying to achieve a pregnancy by natural means will be unable to do so within one year
• For couples with infertility, approximately 50% have a male factor involved
• A wide array of conditions can lead to decreased male reproductive health; the only way to appropriately evaluate the male partner is with a proper history, physical examination, and indicated laboratory testing
• Numerous behavioral, medical, and surgical treatments are available to optimize male fertility
• By optimizing the male partner’s reproductive potential, very often the burden of invasive treatments for the female partner can be lessened
• Finally, male infertility is sometimes “the tip of the iceberg,” as infertility might be the only clinically apparent sign of a more important, underlying condition

Question 2

What is the endocrinology involved in male fertility?

Answer 2

• Integrated process involving the hypothalamus, pituitary, and testicle
• Characterized by the actions of peptide hormones (GnRH, FSH, LH) and steroid hormones (testosterone, estradiol) on target tissue (testicle).
• Feedback loops minimize perturbations and also help to maintain hemostasis

Question 3

Describe the cycle of spermatogenesis.

Answer 3

• Cycle of sperm production takes approximately 90 days
• Wave of production arranged in a spiral configuration in the tubule.
• Each primary spermatocyte yields 4 spermatids
• One Primary spermatocyte(2n) → One Primary spermatocyte(4n) →Two Secondary spermatocytes(2n) → Four Spermatids(n)

Question 4

Describe the process of spermiogenesis.

Answer 4

• The process by which spermatids develop into mature spermatozoa
  
  • Acrosome is formed from the Golgi apparatus
  • Flagellum is formed from the centriole
  • Mitochondria migrate around the midpiece
  • Nucleus compacts (~10% of former size)
  • Cytoplasm extruded (cytoplasmic droplet)

Question 5

Describe the process of sperm maturation?

Answer 5

• Sperm maturation occurs in the epididymis.
• Changes in surface proteins, surface charge, membrane composition.
• Sperm acquire motility and the ability to fertilize the oocyte in the epididymis.
• Duration of travel through the epididymis is 15 days.

Question 6

Describe the process of fertilization from the sperm’s perspective.

Answer 6

• Fertilization occurs in the ampullary portion of the vas deferens
• Sperm entry into uterus facilitated by cervical mucus changes (more watery, more abundant.)
• Sperm undergo capacitation and hyperactivation.
• Acrosome reaction: Lytic enzymes released
• Fertilization (sperm penetration of oocyte)
• Zona reaction: In zona pellucida; prevents polyspermy