Male Reproductive System

Testes Contained in scrotum Fibrous capsule surrounding a network of tubules ▫ Lined with epithelium  undergo meiosis ▫ Interstitial cells in-between  secrete hormones Tubules join into the epididymis which coils around the surface of the testis ▫ Epithelial w/ non-motile cilia

Testicular Cancer Cause is unknown Most common form of cancer in men ages Often have no symptoms ▫ Pain in lower back ▫ Discomfort ▫ Lump

Testosterone Released during fetal development ▫ Stops until puberty Primary roles ▫ Enlargement of testes ▫ Development of accessory organs ▫ Stimulate sexual activity

Testosterone Secondary roles ▫ Increase body hair ▫ Enlargement of larynx ▫ Thicken skin ▫ Increase muscle growth ▫ Broaden shoulders ▫ Thicken & strengthen bones

Spermatogenesis Embryonic development ▫ Epithelial cells undergo mitosis  Undifferentiated cell  Primary spermatocyte Process stalls until puberty Post-puberty ▫ Mitosis occurs continually ▫ Primary spermatocyte undergoes meiosis

Spermatogenesis Meiosis results in spermatids These gather in the epididymis and mature ▫ Secrete glycogen to promote maturation ▫ Developing sperm move through via peristalsis  Don’t “swim” until post-ejaculation

Hormone Control Spermatogenesis is controlled by FSH and testosterone ▫ FSH is released from anterior pituitary ▫ Testosterone is produced in testes by interstitial cells  LH develops interstitial cells to release testosterone  LH is released from anterior pituitary Release of FSH & LH triggered by gonadotropin releasing hormone ▫ From hypothalamus

Seminal Vesicle Secretes ▫ Alkaline fluid: regulate pH ▫ Fructose: energy source for sperm ▫ Prostaglandins: trigger muscle contractions in female reproductive organs to help sperm along

Vas deferens Aka ductus deferens Epididymis converges into here Joins with seminal vesicle forming the ejaculatory duct ▫ Passes through prostate ▫ Empties into urethra

Vasectomy

Prostate Connective tissue supporting branched tubular glands ▫ Open into urethra ▫ Secrete thin, milky fluid  Neutralize acidity  Metabolic waste build-up  Secretions of vagina

Prostate Cancer Rarely found in men <40; 3 rd most common death from cancer in men Risks: agent orange exposure, farming, alcoholics, tire plant workers, painters, high-meat diet Symptoms similar to BPH PSA test – now a standard blood test given to men of age

Bulbourethral Glands Secrete mucus-like fluid ▫ In response to sexual stimulation ▫ Lubrication Released prior to semen ▫ Average # of sperm in ejaculate is 120 million/mL ▫ Can survive for several weeks in male system ▫ Up to 5 days in female

Scrotum Skin & smooth muscle ▫ Contracts when cold to pull testes closer to body for warmth (and v.v.) Septum ▫ Keeps testes separate Serous-lined ▫ Smooth movement

Penis Excrete urine & Release sperm 3 tissue columns comprise shaft ▫ Top 2: corpus cavernosum ▫ Bottom 1: corpus spongiosum  Contains urethra Shaft enlarges into glans penis ▫ Contains sensory cells for sexual stimulation

Prepuce Begins just posterior to the glans & covers it

Erection Stimulation  parasympathetic from sacral spinal cord  nitric oxide  arterial dilation  compression of veins  blood comes in quicker, but leaves slower  blood pools in corpa cavernosa

Erectile Dysfunction Impotence Repeated inability to get or keep an erection firm enough for sexual intercourse ▫ Disease (nerve & muscle damage) ▫ Injury/surgery ▫ Smoking ▫ Overweight/lack of exercise ▫ Drug side-effect ▫ Psychological (stress, depression)

Nocturnal Emission Happen w/ or w/o erection Correlated with frequency of masturbation ▫ Both ends of spectrum argued  More stimulation during dreams do to high frequency  Need release due to lack of ejaculation

Emission ≠ Ejaculation Sympathetic Impulse from spinal cord  smooth muscle contraction  urethra fills with semen Sensory receptors in urethra  sacral spinal cord  motor impulse  muscle contraction at base of erectile columns  ejaculation