REPRODUCTIVE SYSTEM

• Sexual reproduction


  The process by which organisms produce offspring by making germ cells called gametes
• Fertilization


  The male gamete or the sperm cell unites with the female gamete with the resulting cell containing one set of chromosomes from each parent
• Gynecology


  The specialized branch of medicine concerned with the diagnosis and treatment of diseases of the female reproductive system
• Urology


  The study of the urinary system
• Urologists


  Diagnose and treat diseases and disorders of the male reproductive system
• Andrology


  The branch of medicine that deals with male disorders, especially infertility and sexual dysfunction
• Testes


  Male gonads that produce sperm and secrete hormones
• Duct system


  Transports and stores sperm as well as assist in their maturation and convey them to the exterior
• Semen


  Contains sperm plus the secretions provided by the accessory sex glands
• Penis


  Delivers sperm into the female reproductive tract and the scrotum supports the testes
• Scrotum


  A sac-like structure containing the testes
• Dartus muscle


  Layer of loose connective tissue and a layer of smooth muscle causing the skin of the scrotum to become firm and wrinkled and reducing the overall size of the scrotum
• Cremaster muscles


  Extensions of abdominal muscles into the scrotum consequently, the testes are pulled nearer the body, and their temperature is elevated
• Raphe


  The scrotum has a raised medial thickening on the surface
• Testes


  • Produce both sperm and androgens, such as testosterone
• Tunica vaginalis


  A serous membrane that has both a parietal and a thin visceral layer
• Tunica albuginea


  A tough, white, dense connective tissue layer covering the testis itself
• Lobules


  Cover the outside of the testis and invaginates to form septa that divide the testis into 300 to 400 structures
• Seminiferous lobules


  Within the lobules, sperm develop in structures
• Descent of the testis


  In the seventh month of the developmental period of a male fetus, each testis moves through the abdominal musculature to descend into the scrotal cavity
• Cryptorchidism


  The clinical term used when one or both testis fail to descend into the scrotum prior to birth
• Spermatogenesis


  1. The development of sperm occurs in the seminiferous tubules that form the bulk of each testis; begins with mitosis of the diploid spermatogonia

  2. Spermatogonia (stem cells) undergo mitotic division to produce primary spermatocytes

  3. The primary spermatocytes then undergo meiotic division to produce secondary spermatocytes, each containing half the normal chromosome number (23 instead of 46)

  4. The secondary spermatocytes rapidly divide again through another meiotic division to form spermatids, each with a haploid chromosome number (23 chromosomes)

  5. The spermatids then undergo a process called spermiogenesis, where they transform into fully developed spermatozoa with a distinct head, midpiece, and tail
• The production cycle or the process of development from an immature spermatogonia through formed mature sperm takes approximately 64 days
• A new cycle starts approximately every 16 days although this timing is not synchronous across the seminiferous tubules
• Sperm counts or the total number of sperm a man produces slowly decline after age 35
• Meiosis

  1. The daughter cells of spermatogonia must undergo a second cellular division process

  2. Primary Spermatocyte DNA is replicated and the cell undergoes cell division to produce two cells with identical chromosomes

  3. Secondary Spermatocyte separating the chromosome pairs. This second meiotic division results in a total of four cells with only half of the number of chromosomes

  4. Spermitid new cells
• Spermiogenesis


  Transforms these early spermitids, reducing the cytoplasm and beginning the formation of the parts of a true sperm
• Spermatizoa


  The formed sperm is the end result of this process
• Epididymis


  A coiled tube attached to the testis where newly formed sperm continue to mature
• Though the epididymis does not take up much room in its tightly coiled state, it would be approximately 6m or 20 feet long if straightened
• The average transit time for sperm to move through the coils of the epididymis is 12 days, with the shortest recorded being 1 day
• Ejaculation


  The sperm exit the tail of the epididymis and are pushed by smooth muscle contractions to be in the ductus deferens or vas deferens
• Ductus deferens


  A thick, muscular tube that is bundled together inside the scrotum with connective tissue, blood vessels, and nerves into a structure called the spermatic cord
• Vasectomy


  A procedure where surgical sterilization to interrupt sperm delivery can be performed by cutting and sealing a small section of the ductus vas deferens
• Ampulla


  The ductus deferens continues posteriorly to the pelvic cavity ending
• Semen


  Sperm makes up only 5% of the final volume, the bulk is produced by the seminal vesicles, prostate glands, and bulbourethral glands
• Seminal vesicle fluid


  Contains large amounts of fructose, which is used by the sperm mitochondria to generate ATP to allow movement through the female reproductive tract
• Prostate gland


  The centrally located prostate gland sits anterior to the rectum at the base of the bladder surrounding the prostatic urethra or the portion of the urethra that runs within the prostate and formed of both muscular and glandular tissues
• The prostate normally doubles in size during puberty at age 25 it gradually begins to enlarge again
• Benign Prostatic Hyperplasia


  Abnormal growth of the prostate can then cause constriction of the urethra as it passes through the middle of the prostate gland, leading to a number of lower urinary tract symptoms