Cryptorchidism on scrotal ultrasound
Scrotal ultrasonography of undescended testis: (a) Normal testis in the scrotum (b) Atrophic and decreased echogenicity of the contralateral testis of the same patient seen in the inguinal region
Inguinal cryptorchidism in a Chihuahua
A retained testicle with cancer removed during necropsy of a dog
Genitals of a 42-year-old man with cryptorchidism. The empty scrotum is clearly visible. The two bumps, that are above penis in pubic zone can be seen too, these are the testicles in the inguinal canal

Absence of one or both testes from the scrotum.

- Cryptorchidism

156 related topics



Common variation in fetal development of the penis in which the urethra does not open from its usual location in the head of the penis.

Different types of hypospadias
Example of penis with hypospadias
Penis with hypospadias (1) and two fistulae (2)

The most common associated difference is an undescended testicle, which has been reported in around 3% of infants with distal hypospadias and 10% with proximal hypospadias.


Anatomical male reproductive structure located at the base of the penis that consists of a suspended dual-chambered sac of skin and smooth muscle.

Diagram of the scrotum. On the left side the cavity of the tunica vaginalis has been opened; on the right side only the layers superficial to the Cremaster muscle have been removed.
Image showing musculature and inner workings of the scrotum.
Stages in the development of the male external genitalia.
Human scrotum in a relaxed state (left) and a tense state (right)

undescended testes


Male reproductive gland or gonad in all bilaterians, including humans.

Diagram of inner structures of testicles
Animation of the migration of spermatozoa from their origin as germ cells to their exit from the vas deferens. A) Blood vessels; B) Head of epididymis; C) Efferent ductules; D) Seminiferous tubules; E) Parietal lamina of tunica vaginalis; F) Visceral lamina of tunica vaginalis; G) Cavity of tunica vaginalis; H) Tunica albuginea; I) Lobule of testis; J) Tail of epididymis; K) Body of epididymis; L) Mediastinum; M) Vas deferens.
Male gonad (testes, left) and female gonad (ovaries, right)
Transverse section through the left side of the scrotum and the left testis
Cross section of rabbit testis, photographed in bright-field microscopy at 40× magnification
Testicle hanging on cremaster muscle. These are two healthy testicles. Heat causes them to descend, allowing cooling.
A healthy scrotum containing normal size testes. The scrotum is in tight condition. The image also shows the texture.
Testicle of a cat: 1: Extremitas capitata, 2: Extremitas caudata, 3: Margo epididymalis, 4: Margo liber, 5: Mesorchium, 6: Epididymis, 7: testicular artery and vene, 8: Ductus deferens
Testis surface
Testis cross section
The right testis, exposed by laying open the tunica vaginalis.
Microscopic view of Rabbit testis 100×

This is called cryptorchidism.

Testicular cancer

Cancer that develops in the testicles, a part of the male reproductive system.

7.4 × 5.5-cm seminoma in a radical orchiectomy specimen.
Image showing the first sign of testicular cancer
Micrograph (high magnification) of a seminoma. H&E stain.
Mixed germ cell tumor containing embryonal carcinoma, seminoma, and yolk sac tumor. The embryonal carcinoma component (upper left, upper right, and lower left) shows pseudoglandular growth with high-grade features of large, epithelioid, anaplastic cells with prominent nucleoli, indistinct cell borders with nuclear overlapping, pleomorphism, and frequent mitoses. The seminoma component (upper center) shows large, round-polyhedral cells with distinct cell membranes, abundant clear/watery cytoplasm, large central nuclei and prominent nucleoli. The yolk sac component (lower right, hugging the embryonal component) exhibits microcystic/reticular growth pattern.
Relative incidences of testicular tumors.

Risk factors include an undescended testis, family history of the disease, and previous history of testicular cancer.

Semen quality

Measure of male fertility, a measure of the ability of sperm in semen to accomplish fertilization.

Countries by fertility rate as of 2020

Cryptorchidism, hypospadias, testicular cancer and poor semen quality make up the syndrome known as testicular dysgenesis syndrome.


State of having only one testicle within the scrotum.

Diagram of inner structures of testicles

One testicle not descending into the scrotum during normal embryonic or fetal development (3–4% of 'normal' live births), also known as undescended testis or cryptorchidism. In this case the testis is within the abdominal cavity, somewhere along the normal route of descent – most commonly, within the inguinal canal. Such a testis has an increased risk of malignancy.


Medication used to treat fever and mild to moderate pain.

Important pathways of paracetamol metabolism.
Classical methods for the production of paracetamol.
Paracetamol crystals (crystallized from an aqueous solution) under a microscope.
Julius Axelrod (pictured) and Bernard Brodie demonstrated that acetanilide and phenacetin are both metabolized to paracetamol, which is a better-tolerated analgesic.

In animal experiments, paracetamol disrupts fetal testosterone production, and several epidemiological studies linked cryptorchidism with mother's paracetamol use for more than two weeks in the second trimester.

Pediatric surgery

Subspecialty of surgery involving the surgery of fetuses, infants, children, adolescents, and young adults.

congenital malformations: lymphangioma, cleft lip and palate, esophageal atresia and tracheoesophageal fistula, hypertrophic pyloric stenosis, intestinal atresia, necrotizing enterocolitis, meconium plugs, Hirschsprung's disease, imperforate anus, undescended testes, intestinal malrotation


Branch of medicine that focuses on surgical and medical diseases of the urinary-tract system and the reproductive organs.

Urologist performing a TURP

Such disorders include cryptorchidism (undescended testes), congenital abnormalities of the genitourinary tract, enuresis, underdeveloped genitalia (due to delayed growth or delayed puberty, often an endocrinological problem), and vesicoureteral reflux.


Castrated male horse or other equine, such as a pony, donkey or a mule.

A 3-year-old gelding
Gelding a male horse can reduce potential conflicts within domestic horse herds.
An open castration being performed on a horse under ketamine anaesthesia
Recumbent castration, including use of emasculators

For reasons not always clear, about 30% of all geldings may still display a stallion-like manner, some because of a cryptorchid testicle retained in the horse, some due to previously learned behavior, but some for no clear reason.