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Epididymis:
- shaped like a comma about 4 cm long on the posterior
- border of the testis
- long coiled tubule (23 ft)
- head: contains and receives sperm from the seminiferous tubules
- body: lies on the posterior-lateral border of the testis and contains the highly coiled duct of the epididymis
- tail: near the inferior border of the testis, coiling of the duct has diminished, reverses its direction and ascends into the ductus deferens, stores sperm
- lined with pseudostratified columnar epithelium with stereocilia that regulate the composition of tubular fluid
- wall also contains smooth muscle (peristaltic contraction move sperm through the duct)
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Ductus deferens (vas):
- approximately 45 cm long
- extends from the tail of the epididymis to the ejaculatory ducts
- ampulla:
- - expanded distal portion of the vas just before it reaches the prostate
- - joins the duct of the seminal vesicle to form the ejaculatory duct
- - the ejaculatory ducts penetrate the prostate and empty into the urethra (lined with simple columnar)
- lined with pseudostratified columnar epithelium with stereocilia
- thick layer of smooth muscle
- storage and transport of the sperm
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Urethra:
- 15 - 20 cm long
- prostatic
- membranous
- penile
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Accessory glands:
- seminal vesicles:
- prostate gland:
- bulbourethral glands:
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seminal vesicles:
- posterior surface of the bladder in front of the rectum
- large, coiled tubular glands
- pseudostratified, columnar or cuboidal epithelium depending on testosterone levels
- contributes 60% of the volume of semen
- secretion is a yellowish, viscous alkaline fluid that contains fructose, absorbic acid, coagulating enzymes called clotting proteins, prostaglandins
- ducts join with the vas to form the ejaculatory ducts
- sperm and seminal fluid are mixed in the ejaculatory ducts
- sperm start to become motile
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prostate gland:
- single gland
- consists of 30-50 tubular glands embedded in a mass of smooth muscle and connective tissue
- produces and secretes prostatic fluid which accounts for about 1/3 of the seminal fluid
- secretion is a milky, slightly acidic fluid
- contains seminalplasmin which is an antibiotic
- also contains citrate and helps the sperm to become active
- pseudostratified columnar epithelium
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bulbourethral glands:
- “Cowper’s glands”
- two pea-sized glands located immediately below the prostate at the base of the penis
- secretes a thick, clear alkaline mucus that drains into the penile urethra
- secretion is released before ejaculation to neutralize traces of acidic urine in the urethra and to lubricate the urethra and penis
- simple columnar epithelium
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Semen:
- mixture of sperm and accessory gland secretions
- provides for the transport, nutrition, activation and protection of the sperm
- ejaculate volume is 2-5 ml containing 20 -100 million sperm per ml:
- 60% from seminal vesicles, 30% from prostate, 5% from sustentacular cells, <5% from bulbourethral glands
- clotting protein function
- fibrinolysin functions to liquify the semen
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Penis:
- urinary and reproductive functions
- copulatory organ
- consists of three parts- root, body, glans
- root: fixed portion that attaches the penis to the
- ischium
- body: tubular moveable portion of the penis, consists of the erectile tissues, contains the urethra
- glans: expanded distal end, surrounds the urethral meatus
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corpora cavernosa:
- two erectile cylinders on the dorsal surface of the penis
- makes up most of the mass of the penis
- crura of the penis is the proximal portion of the corpora cavernosa and is attached to the bony pelvis via the ischiocavernosus muscle
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corpus spongiosum:
- surrounds the urethra
- distal end expands to form the glans
- proximal end is enlarged and called the bulb of the penis
- bulb is covered by the bulbospongiosus muscle which secures it to the urogenital diaphragm
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erectile tissue:
- 3-D maze of vascular channels separated by partitions of smooth muscle
- in the flaccid state the blood vessels are constricted and the smooth muscle partitions are tense which reduces blood flow into the erectile tissue by bypassing it
- under parasympathetic stimulation smooth muscle relaxes, vessels dilate and blood flows into the vascular channels, engorging the cylinders of erectile tissue causing the penis to become erect
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blood supply:
- deep and dorsal arteries of the penis
- deep dorsal vein
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