seminiferous tubule

Examples of seminiferous tubule in the following topics:

• Testes Ducts

  • Testes ducts, which include the seminiferous tubules and vas deferens, are involved in the creation or transportation of sperm.
  • Seminiferous tubules are located in the testes, and is where meiosis occurs and the gametes (spermatozoa) are created.
  • The seminiferous tubules are formed from primitive sex cords from the gonadal ridge.
  • There are two types of seminiferous tubules: 1) convoluted, located toward the lateral side, and 2) straight, as the tubule comes medially to form ducts that will exit the testis.
  • Diagram of cross-section of testes: 1: Testicular septa 2: Convoluted seminiferous tubules 3: Testicular lobules 4: Straight seminiferous tubules 5: Efferent ductules 6: Rete testis.

• Spermatogenesis

  • 1) Spermatocytogenesis: Mitotic division of a diploid spermatogonium that resides in the basal compartment of the seminiferous tubules resulting in two diploid intermediate cells called primary spermatocytes.
  • *Each primary spermatocyte then moves into the adluminal compartment of the seminiferous tubules, duplicates its DNA, and subsequently undergoes meiosis I to produce two haploid secondary spermatocytes
  • The mature spermatozoa are released from the protective Sertoli cells into the lumen of the seminiferous tubule in a process called spermiation.
  • Seminiferous epithelium is sensitive to elevated temperature in humans and will be adversely affected by temperatures as high as normal body temperature.

• Testes

  • Under a tough membranous shell, the tunica albuginea contains very fine coiled tubes called seminiferous tubules.
  • The tubules are lined with a layer of cells (germ cells) that develop into sperm cells (also known as spermatozoa or male gametes) from puberty into old age.
  • The developing sperm travels through the seminiferous tubules to the rete testis located in the mediastinum testis, to the efferent ducts, and then to the epididymis where newly-created sperm cells mature.
  • Leydig cells, localized between seminiferous tubules, produce and secrete testosterone and other androgens important for sexual development and puberty, including secondary sexual characteristics such as facial hair and sexual behavior.

• Male Reproductive Anatomy

  • Coiled in each testis are seminiferous tubules that produce sperm.
  • Sperm develop in the seminiferous tubules that are coiled inside the testes .
  • The walls of the seminiferous tubules are composed of the developing sperm cells, with the least-developed sperm at the periphery of the tubule and the fully-developed sperm in the lumen.
  • Other cells mixed in the wall of the tubules are the interstitial cells of Leydig; these cells produce high levels of testosterone once the male reaches adolescence.
  • Sperm are produced in the seminiferous tubules, mature in the epididymis, and then are forced out into the vas deferens and out of the body through the urethra during ejaculation.

• Anatomy of the Male Reproductive System

  • The coiled collection of tubes within the testes are the seminiferous tubules.
  • It is within these tubules that spermatogenesis takes place. 

• Testicular Cancer

  • Testicular seminoma originates in the germinal epithelium of the seminiferous tubules.

• Semen

  • Sertoli cells, which nurture and support developing spermatocytes, secrete a fluid into seminiferous tubules that helps transport sperm to the genital ducts.

• Male and Female Gonads

  • Testosterone is secreted by Leydig cells which are located between the seminiferous tubules.

• Embryological and Fetal Events

  • A large part of the head end of the mesonephros atrophies and disappears; of the remainder the anterior tubules form the efferent ducts of the testis; while the posterior tubules are represented by the ductuli aberrantes, and by the paradidymis, which is sometimes found in front of the spermatic cord above the head of the epididymis.
  • Cords of the central mass run together and form a network that becomes the rete testis, and another network, that develops the seminiferous tubules.

• Gametogenesis (Spermatogenesis and Oogenesis)

  • Spermatogenesis occurs in the wall of the seminiferous tubules , with stem cells at the periphery of the tube and the spermatozoa at the lumen of the tube.
  • Immediately under the capsule of the tubule are diploid, undifferentiated cells.
  • When it reaches the lumen of the tubule and grows a flagellum (or "tail"), it is called a sperm cell.