Anatomy of testes Flashcards
Where do the testes originate?
Develop in abdomen on posterior abdominal wall behind the peritoneum, then descend. Pass through inguinal canal then interior abdominal wall and acquire 3 layers around them aka the spermatic cord.
When do the testes descend? What influences them?
B/w 28 and 32 weeks under influence of gonadotropins (maternal) and androgens (fetal)
Describe the descent of the testes
Guided by the gubernaculum down through inguinal canal into scrotum. Simultaneously, it takes an outpouching of peritoneum (processus vaginalis) which will form the coverings of the testes. The proximal end of the processus pinches off (obliterates) and the distal end forms the tunica vaginalis. Space around the testes is ironically called the vaginal cavity.
What happens if the processus vaginalis fails to obliterate?
You get congenital hydrocele, or congenital indirect inguinal, or inguino-scrotal hernia in adults (dx with bowel sounds in testes!)
What is hydrocele?
Water around the testes. The vaginal cavity fills with fluid.
Structures around the testes
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Pampiniform plexus of veins in the scrotum
Surround the testicular artery. Act as counter-current temp exchange to cool testes
What are the 3 layers around the testes that are acquired during testes descent?
External spermatic fascia, cremaster muscle + fascia, Internal spermatic fascia. Surround the testes and the blood vessels and the Vas deferens.
What is cryptorchidism?
Testes don’t descend or not completely. Get stuck in abdominal cavity, at the inguinal canal,
Scrotal septum
Layer b/w testes.
Tunica albuginea
“white tunic”. Capsule around the testes. Creates septa within testicle, making some 250 lobules of seminiferous tubules.
Testicular mediastinum
middle space in testes. Contains the rete - collection of blood vessels.
Tranverse cross section of testes
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Parasagittal cross section of testes
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How do sperm get to vas deferens?
15-20 Efferent ductules, into epididymis (head, body, tail), which leads into the vas deferens.
What is in the epithelia of the testes?
The spermatogonia: sperm production. B/w them is the interstitial cells of Leydig: testosterone. Sustentacular cells: inhibin (depress FSH)
Describe the path of the vas deferens
Up, through superficial inguinal ring, then inguinal canal, then deep inguinal ring. Then merges with seminal vesicle, then into the ejaculatory ducts which merge within the prostate, then into urethra.
Analogy for the spermatic cord
Person wearing shirt, sweater and oversized coat. The shoulder of the shirt is the deep inguinal ring, the lower hanging shoulder of the coat is the superficial ring, and the space b/w them is the inguinal canal. As an aside, a hernia is like another arm squeezing in down the sleeve of the shirt.
Where can the testes get stuck?
At the deep or superficial rings or above that.
Problems with cryptorchidism
Too warm so infertile, and higher risk of testicular cancer.
Erection and ejaculation nervous system control
Erection generated by parasympathetic control (hence morning wood). Ejaculation under sympathetic. Point and Shoot.
