Ch 111 - Testes, epididymides and scrotum Flashcards
What are the three layers of the scrotum?
- Skin
- Tunica dartos
- Scrotal fascia
What are the three different cell types which make up the seminiferous tubules within the testes?
Spermatogenic cells
Sertoli (sustentacular) cells
- Support development and maturation of spermatozoa
- Controls release of spermatazoa into tubules
- Form the blood-testis barrier
- Stimulated by FSH, negative feedback via inhibin
Leydig cells
- Lie within spaces between seminiferous tubules
- Produce testosterone
- Negative feedback with LH
What is the function of the epididymis?
Stores spermatazoa until they are released with ejaculation
What are the secondary sex glands of the dog and cat?
- Dog: prostate
- Cat: prostate and bulbourethral glands
Produce seminal fluid
What structure is responsible for the migration of the testis into the scrotum?
The gubernaculum
List the factors involved in thermoregulation of the scrotum
- Skin is thin and lightly haired, little SQ fat and abundant sweat glands
- Cremaster muscle and tunica dartos to move testes farther away or closer to the body as needed
- Countercurrent thermoregulation in the pampiniform plexus
Seminiferous tubule temp needs to be 2-3 degrees cooler that the body for viable production of spermatazoa
What tests can help to differentiate anorchism from bilat cryptorchidism?
- After administration of hCG, testesterone should rapidly rise if a testicle is present
- Cats have testerone-dependant penile spines which should dissappear within 6wk of castration
What cause cryptorchidism?
How old should animals be before a final diagnosis is made?
What breeds are overrepresented?
- Abnormalities of the gubernaculum
- 6 months old
- Chihuahua, Min Schnauzer, Pom, Poodles, Shelties, Huskies, Yorkies and Persian cats
What secondary complications are seen with cryptorchidism?
Dogs:
- Neoplastic transformation 9.2-13.6%
- Hip dysplasia
- Patellar luxation
- Defects of penis and prepuce
- umbilical hernia
Cats:
- Patellar luxation
- Shortened or kinked tail
- Tetralogy of Fallot
- Tarsal deformities
- Microphthalmia
- Upper eyelid agenesis
List the most common forms of testicular neoplasia
- Interstitial (Leydig) tumour
- Sertoli (sustentacular) tumour
- Seminomas
What syndrome is commonly seen with Sertoli cell tumours?
- Feminisation syndrome in 9.2-13.6% (significant increase in oestradiol/testosterone ratio)
- Myelotoxicosis can be irreversible and fatal
What concurrent abnormalities can be seen with Leydig tumours?
Assoc with increase testosterone production
- Perineal hernias - 15%
- Perianal adenomas - 37.3%
- Perianal gland adenocarcinoma - 9%
What is the metastatic rate of each testicular tumour?
- Sertoli 6.38-11%
- Leydig - very rare
- Seminoma - ?
Prognosis excellent with bilateral orchiectomy if no mets and no myelosuppression
List causes of epididymal occlusion
- Aplasia (developmental failure fo the mesonephric (Wolffian) duct)
- Acquired duct occlusion
- Abnormal position of the epididymis in relation to the testis
Bileratel orchiectomy!
List DDx for scrotal enlargement
- Orchitis
- Epididymitis
- Sperm granuloma
- Testicular torsion
- Scrotal hernia
- Scrotal neoplasia (MCT, melanoma, hamartoma, HSA etc)
- Testicular neoplasia
MCT - Staffys, Boxers, Beagles, Boston Terriers, viszlas
Melanomas - Schnauzers, Golder Ret
Histiocytoma - Beagle, Boxer
HSA - Goldern Ret, Boxer
