31.3
Testicules : Histologie
Une membrane fibreuse et résistante, la tunique albuginée, recouvre les testicules et s'étend vers l'intérieur pour former des cloisons fibreuses ou s…
La tunique albuginée de chaque testicule s’étend vers l’intérieur pour former des cloisons fibreuses, ou septa testis, le divisant en compartiments internes appelés lobules.
Chaque lobule a 1 à 3 tubes séminifères étroitement enroulés, qui sont le site de production de spermatozoïdes.
Ces tubules fusionnent en un réseau tubulaire à l’arrière du testicule, connu sous le nom de rete testis. Il se connecte à 15 à 20 ductules efférents, menant à l’épididyme.
Dans les tubules séminifères, les cellules spermatogènes sont intégrées dans l’épithélium séminifère, entrecoupées de cellules sustentaculaires, également appelées cellules de Sertoli.
Les cellules spermatogènes, soutenues et nourries par les cellules de Sertoli, se différencient en spermatozoïdes matures à mesure qu’elles progressent vers l’extrémité luminale.
Entre les tubes séminifères adjacents se trouvent des cellules interstitielles, également appelées cellules de Leydig.
Ces cellules produisent des androgènes, dont la testostérone.
Les longues artères testiculaires, qui délivrent le sang oxygéné, sont entourées d’un réseau de veines interconnectées, le plexus pampiniforme.
Le plexus pampiniforme draine le sang désoxygéné et absorbe la chaleur du sang oxygéné, assurant une alimentation optimale et une régulation de la température du tissu testiculaire.
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Q1: How are the testes divided into internal compartments?
The tunica albuginea, a tough fibrous membrane covering each testis, extends inward to form fibrous partitions called septa testis. These septa divide the testis into internal compartments called lobules. Each lobule contains one to three tightly coiled seminiferous tubules, which are the primary sites for sperm production.
Q2: What is the role of Sertoli cells in the seminiferous tubules?
Sertoli cells, also called sustentacular cells, support and nourish spermatogenic cells within the seminiferous epithelium. These cells are interspersed among the developing sperm cells and provide essential nutrients and structural support as spermatogenic cells differentiate into mature spermatozoa progressing toward the tubule's lumen.
Q3: Where do Leydig cells produce testosterone in the testis?
Leydig cells, also known as interstitial cells, are located between adjacent seminiferous tubules. These cells produce androgens, including testosterone, the primary male sex hormone. Their strategic positioning allows them to deliver hormones directly into the surrounding tissue and bloodstream for systemic effects.
Q4: How do seminiferous tubules connect to the epididymis?
Seminiferous tubules merge into a tubular network at the back of the testis called the rete testis. The rete testis connects to 15 to 20 efferent ductules, which lead directly to the accessory ducts of the male reproductive system. This pathway allows newly produced sperm to travel from the seminiferous tubules toward storage and maturation sites.
Q5: What is the function of the pampiniform plexus in testicular temperature regulation?
The pampiniform plexus is a network of interconnected veins surrounding the testicular arteries. It drains deoxygenated blood from the testis while simultaneously absorbing heat from the incoming oxygenated arterial blood. This heat exchange mechanism ensures optimal temperature maintenance, which is critical for healthy sperm production.
Q6: Why is temperature control important for testicular function?
The testis requires precise temperature regulation to maintain normal sperm production. Deviation from the optimal temperature range disrupts the delicate process of spermatogenesis, leading to decreased fertility. The pampiniform plexus and testicular arteries work together to ensure the testicular tissue receives adequate nourishment and remains at the correct temperature.
Q7: What are the main structural components of a testicular lobule?
Each testicular lobule contains one to three tightly coiled seminiferous tubules where sperm production occurs. Within these tubules, spermatogenic cells are arranged in layers along the walls, supported by Sertoli cells. Between adjacent seminiferous tubules lie interstitial cells that produce testosterone and other androgens essential for male reproduction.