Spermatogenesis and Sperm Morphology Quiz

Spermatogenesis

• Produces haploid sperm (n) from diploid spermatogonia (2n) in 74 days
• Involves meiosis I (reduction division) where homologous pairs form a tetrad, resulting in haploid secondary spermatocytes

Sperm Morphology

• Adapted for reaching and penetrating a secondary oocyte
• Head contains DNA (23 chromosomes) and acrosome with enzymes hyaluronidase and proteinase
• Midpiece contains mitochondria for ATP production
• Produced at a rate of 300 million/day with a 48-hour life expectancy in the female reproductive tract

Accessory Sex Glands

Seminal Vesicles

• Produce 60% of semen volume as viscous alkaline fluid
• Contain fructose for ATP production and prostaglandins for sperm motility and viability

Prostate Gland

• Produce 25% of semen volume as milky, slightly acidic fluid
• Contain citric acid for ATP production and proteolytic enzymes like PSA and seminalplasmin

Paired Bulbourethral (Cowper's) Glands

• Produce alkaline fluid to protect sperm from acidic urine
• Secrete mucus to lubricate the end of the penis and urethra lining

Reproductive System Ducts in Males

Ducts of Testis

• Series of coiled efferent ducts that empty into the epididymis

Epididymis

• Site of sperm maturation and storage

Ductus (vas) Deferens

• Conveys sperm during sexual arousal through peristaltic contractions

Spermatic Cord

• Ductus deferens ascends out of the scrotum with arteries, veins, autonomic nerves, lymphatic vessels, and cremaster muscle

Ejaculatory Ducts

• Formed by the union of ducts from seminal vesicle and ductus deferens, terminating in the prostatic urethra

Urethra

• Shared terminal duct of reproductive and urinary systems
• Subdivided into prostatic, membranous, and spongy (penile) urethra

Penis

• Passageway for semen ejaculation
• Composed of three erectile tissue masses filled with blood sinuses

Erection

• Parasympathetic fibers release nitric oxide, dilating arterial smooth muscle
• Blood sinuses fill with blood, compressing veins draining the penis

Anatomy of the Male Reproductive System

• Gonads (testes) produce sperm and secrete hormones
• System of ducts transport and store sperm, assisting in maturation and conveying them to the exterior
• Accessory sex glands add secretions to semen
• Supporting structures include the scrotum and penis

Scrotum

• Cutaneous outpouching of the abdomen that supports the testes
• Maintains temperature 2-3°C below core body temperature for normal sperm production and survival

Testes or Testicles

• Paired oval glands that descend from the abdomen to the scrotum during fetal development
• Covered by tunica albuginea and contain lobules with seminiferous tubules

Cells of the Testes

• Leydig cells secrete testosterone in the spaces between seminiferous tubules

Sertoli Cells

• Form blood-testes barrier
• Nourish spermatocytes
• Mediate testosterone and FSH effects on spermatogenesis
• Phagocytose excess spermatids
• Secrete inhibin to regulate sperm production