testis chapter

Chapter Overview: Testis and Testicular Adnexa

• Overview of key topics to be covered.

  • Normal embryology and anatomy of the testis.

  • Cryptorchidism (undescended testis).

  • Atrophy and infertility issues related to the testis.

  • Various non-neoplastic lesions.

  • Tumors of the testis.

  • Anatomy of testicular adnexa including rete testis, epididymis, and spermatic cord.

Normal Embryology and Anatomy of the Testis

• Phases of Testicular Development:

  • Static Phase: Birth to age 4 years; tubules filled with undifferentiated cells.

  • Growth Phase: Ages 4 to 10 years; gradual growth of tubule and cell size.

  • Development Phase: Begins around age 10; onset of puberty marked by increase in gonadotropins and spermatozoa formation.

• Structure of Adult Testis:

  • Average weight: 15–19 g (right testis typically heavier).

  • Capsule consists of three layers:

    • Outer serosa (tunica vaginalis).

    • Tunica albuginea.

    • Tunica vasculosa.

  • The mediastinum contains blood vessels, nerves, and portions of the rete testis.

  • Parenchyma divided into about 250 lobules; each lobule contains seminiferous tubules.

  • Histologic Components:

    • Sertoli cells (supporting germ cells).

    • Leydig cells (produce testosterone).

    • Germ cells at various development stages (spermatogonia, spermatocytes, spermatids, spermatozoa).

• Spermatogenesis Timeline:

  • Process takes approximately 70 days, involves several maturation stages in an overlapping helical pattern.

  • Sertoli cells play crucial roles in nurturing germ cells and may express intermediate filaments (e.g., vimentin).

Cryptorchidism

• Definition: Condition of undescended testes; more common in abdominal retention.

• Incidence: Affects 1 in 10 males, with 1 in 100 remaining undescended permanently.

• Management: If not correct by age 2-3, surgical intervention (orchidopexy) recommended to prevent anatomical changes.

• Fertility Outcomes:

  • Unilateral cryptorchidism results in higher rates of fertility if corrected early.

  • Gross appearances in adulthood show atrophic changes in the tubules, often leading to infertility.

Atrophy and Infertility of the Testis

• Causes of Testicular Atrophy:

  • Examples Include:

    • Cryptorchidism.

    • Orchitis, particularly mumps post-puberty.

    • Liver cirrhosis affecting estrogen levels.

    • Radiation and chemotherapy exposure.

  • Impact of Atrophy:

    • Histologically, testes may show varying conditions ranging from complete absence of germ cells (Sertoli cell-only syndrome) to areas of fibrosis and spermatogenic arrest.

• Male Infertility Contributors:

  • Classified into three categories: pretesticular (hormonal issues), testicular (direct testicular disease), and post-testicular (obstruction).

• Evaluation of Infertility:

  • Comprehensive assessment includes semen analysis, hormonal levels, and possible biopsy (especially in cases of azoospermia).

Non-Neoplastic Lesions and Conditions

• Various histopathological issues affecting the testis:

  • Granulomatous Orchitis: Inflammation due to non-specific reactions, sometimes related to sperm degeneration.

  • Infarcts: Resulting from torsion or other vascular issues; can mimic neoplasms histologically.

  • Malakoplakia and Other Histiocytic Disorders: Various inflammatory conditions observed microscopically.

Tumors of the Testis

• Classification: Major categories include:

  • Germ cell tumors (90% of testicular tumors).

  • Sex cord-stromal tumors.

  • Primary non-specific testicular tumors.

  • Metastatic tumors.

• Epidemiology and Demographics:

  • Germ cell tumors are rare overall but predominant in young males (ages 25-29).

  • Increasing incidence, with factors such as cryptorchidism and genetic predispositions noted.

• Clinical Presentation:

  • Often presents as a painless enlargement of the testis; may metastasize to lungs or retroperitoneum.

  • Bilaterality is rare but increased in undescended cases.

• Molecular and Genetic Features:

  • Specific genetic abnormalities such as isochromosome 12p associated with invasive germ cell tumors.

  • Variability in genetic changes in different tumor types, influencing treatment and prognosis.