(13.1) Reproductive System of the Dog - The Male Genital Organs in Dogs ( Finals ) Flashcards
The external male genital organs are:
– Testis
– Epididymis
– Ductus deferens
– Extra-pelvic urethra
– Penis
The internal or accessory genital organs are:
– Prostate
– Ampulla of the ductus deferens
• Oval, lies obliquely within the scrotum (with its long axis running dorsocaudally)
Testes
a stout, white fibrous capsule that surrounds the surface of the testis
Tunica albuginea
• The peritoneal layer that permits testicular mobility within the scrotum
• Develops from the vaginal process, an outpocketing of the abdominal peritoneum that exits the abdomen through the inguinal canal
Parietal and visceral vaginal tunics of the testis
• Develops within the abdominal cavity, just caudal to the kidneys (retroperitoneal)
• Descend from their abdominal position to take up residence within the scrotum
Testes
As the testis continues distally into the scrotum, it passes alongside (but not into) the?
vaginal process
The vaginal process envelops testis forming two layers:
the visceral (directly against the testis) and parietal (directly against the internal wall of the scrotum) vaginal tunic
• A pouch of skin carried high between the thighs in the caudal inguinal region
• Houses/covers the testes
• Controls testicular temperature
Scrotum
covers the external scrotal surface, variably pigmented, thin (facilitating heat loss), slightly oily, sparsely covered by fine hairs, and little subcutaneous fat is present
Skin
a thin layer of smooth muscle, elastic and collagenous fibers; contracts the scrotal skin when the cremaster muscle draws the testes near the body (during cold temp. and sympathetic drive)
Muscle (tunica dartos)
the parietal layer of the vaginal tunic forms the inner lining of the scrotum
Peritoneum
divides the internal cavity of the scrotum in half
Median septum
a line (external) extending the full length of the scrotum along the midline
Scrotal raphe
• The convoluted tubular structure that stores maturing and mature sperm following their production by the testis and prior to their ejaculation
Epididymis
Epididymis Position:
slightly applied to the dorsolateral surface of the testis
Part of the epididymis that lies at the cranial head of the testis; continuous with the internal duct system of the testis
Head
Part of the epididymis that passes along the dorsolateral region of the testis
Body
the caudal extremity of the epididymis, continuous with the ductus (vas) deferens
Tail
This ligament attaches the epididymal tail to the vaginal tunic and the internal spermatic fascia
Ligament of the tail of the epididymis
This ligament attaches the tail of the epididymis to the caudal pole of the testis
Proper ligament of the testis
• The tubular organ that conduct sperm from the tail of the epididymis to the prostatic region of the urethra
Ductus Deferens
Ductus Deferens Course:
– Testis
– Spermatic cord
– Abdominal cavity
– Prostate gland
– Prostatic urethra
Ductus deferens passes from the lateral to medial surface of the caudal testicular pole; straightens and pass cranially along the dorsomedial border of the testis towards the cranial testicular pole
Testis
It pass as one of the components of the spermatic cord through the inguinal canal and enters the interior of the abdominal cavity
Spermatic cord
courses slightly more cranially to make a wide arc across the lateral surface of the bladder cranial to the ureter
Abdominal cavity
turns caudally and courses towards the prostate gland; pierces and enters the lobe of the prostate gland
Prostate gland
passes through the substance of the gland before opening into the lumen of the prostatic urethra
Prostatic urethra
• A collection of structures passing to and from the testis
• Extends from the deep inguinal ring to the testis
Spermatic Cord
What structure contains the testicular artery and vein, efferent testicular lymphatic vessels, testicular nerve, and the ductus deferens with its associated artery and vein?
Spermatic cord
– The components of the spermatic cord are invested by the visceral layer of the original vaginal process
Mesenteries
What surrounds the deferent duct, artery and vein?
Mesoductus deferens
surrounds the testicular artery, vein, nerves and efferent lymphatics
Mesorchium
This muscle originates from the caudal edge of the internal abdominal oblique; elevates the testis in response to cold or to sympathetic drive
Cremaster muscle
specialization of testicular vein; convoluted veins that cools the arterial blood to testes by countercurrent exchange
Pampiniform plexus
This animal have a musculocavernous penis characterized by predominance of cavernous tissue (tissue containing a myriad of small spaces that fills with arterial blood to achieve erection of the penis)
Dogs
the most proximal portion of penis, located in the region of ischial arch
Root
two paired regions ( root of the penis )
Crura
median region ( root of the penis )
Bulb
the intermediate portion of the penis extending from the root to the beginning of the glans; the narrowest region of the penis
Body
the most distal free portion of the penis; slightly larger than the body in the non-erect state
Glans
globular in shape; entirely surrounds the proximal end of the glans; the most distensible part, increases dramatically in size owing to its role in forming the “tie” or “lock” characteristic of canine copulation
Bulbus glandis
the elongate distal portion of the glans
Pars longa glandis
surrounds the urethra
Corpus spongiosum
contributes in the formation of the root, body and glans
Corpus spongiosum penis
forms a portion of penile root and contributes to the formation of body and glans; surrounds the urethra in the region of ischial arch
Bulb of the penis
comprise the two parts of the penile glans (bulbus glandis and pars longa glandis)
Corpus spongiosum glandis
positioned dorsal to the urethra
Corpus cavernosum
originates as the paired crura of the penis; blends with the base of the os penis
Tunica albuginea
extends through the full length of the penile glans
Os penis
contraction obstructs venous outflow from the penis, necessary from the beginning of penile erection throughout copulation ( muscle )
Ischiourethralis muscle
This muscle withdraw the penis into the prepuce following erection
Retractor penis muscle
The sheath of skin that houses the penile glans when the penis is not erect
Prepuce
ring at the cranial end that opens into the preputial cavity
Preputial orifice
forms a blind “gutter” the preputial fornix
Internal lamina
• Prevents the prepuce from dangling from the end of the glans when the penis is flaccid
• During erection, relaxes and allows the glans to protrude from the prepuce
• After erection, contracts and draw the prepuce back over the penile glans
Preputial muscle
• Accessory Genital Organ
• A bilobed organ surrounding the neck of the urinary bladder and the urethra
• Secretion of the gland contribute to the seminal fluid
The Prostate Gland
