Male Reproductive System

Clinical vs. Subclinical (Latent) Disease

-20% of men ages 50-59 have subclinical prostatic neoplastic disease -1/10 chance that a US man will develop signs of prostate cancer in his life -majority of prostate cancers: adenocarcinomas -subclinical disease: microscopic disease with no clinical signs/symptoms -subclinical disease occurs in more than 50% of men 80 and older; found with similar incidence around the world

Sources of Seminal Fluid: Seminal Vesicles

-5 cm long, formed from vas deferens -empties into ejaculatory duct and produces about 60% of semen volume -contains fibrinogen, prostaglandins, fructose, nutrients, high pH -large amounts of fructose nourishes sperm cells

Prostate Cancer Detection

-PSA: protease released by epithelial cells lining ducts of prostate in normal tissue and hyperplastic tissue/tumors -to identify disease progression must be 50% increase from baseline; 50-100% decrease for 3 serial months is proposed criteria for therapeutic response -PSA >0.4 ng/mL considered abnormal but can occur in many non-cancerous prostate disorders

Prostatic Cancer

-among most frequently diagnosed malignancy among men in US (increased awareness/testing) -second leading cause of cancer death in men -185,000 new cases expected to be diagnosed yearly; 40,000 annual deaths expected -rarely seen in individuals younger than 40; incidence increases with rising age -etiology unknown

Endocrine Regulation of Prostate Tissue Growth

-androgens are dominant stimulus for growth of both malignant and normal prostate epithelium -in absence of androgen, androgen-dependent prostate epithelial cells die -there are also hormone-resistant cells in both normal and resistant prostate whose growth and function are not affected by androgen withdrawal -both testosterone and dihydrotestosterone can cause the growth of prostate tissue

Penetration of the Zona Pellucida

-as acrosomal matrix disperses, releases proteolytic enzymes; helps sperm penetrate zona pellucida -following penetration, sperm binds to plasma membrane of ovum and fuses; binds to alpha-6-beta-1 integrin, resulting in membrane depolarization (Ca flux) -fusion process takes about 24 hours; fertilized ovum first cell of new organism

Final Stages of Spermatogenesis

-as daughter spermatids form, they fail to separate, so all remain in contact via cytoplasmic bridges (syncytia) -soon after their appearance spermatids become attached to luminal surface of Sertoli cells -bridges persist until development of spermatozoa is complete, then separate -may have survival value that half of spermatozoa contain X and half contain Y chromosomes; larger X may carry needed genes too big for Y -final stage of spermatogenesis involves maturation of spermatids into spermatozoa

Fertilization

-capable of fertilizing for up to 5 days -ovum can be fertilized for 10-15 hrs (degenerates after 24) -ovum enters uterine tube, travels to uterus (takes 3-5 days) -1/4 women become pregnant after one month of repeated intercourse without contraception -fertilization normally in uterine tube -single ovum released (rarely >1)

Prostatitis

-cause: inflammation of prostate; more likely to develop when young (even before age 40) -symptoms: fever, pain in genital area, increase in urinary frequency (night), burning urination -diagnosis: NIH nomenclature uses four classes -treatment: pain relievers, several weeks of antibiotics for categories 1 and 2; category 3 mainly involves relieving symptoms and is less clear; category 4 doesn't usually require treatment

Benign Prostatic Hyperplasia

-cause: over-growth of prostate -symptoms: enlarged prostate compresses urethra (difficulty urinating) -diagnosis: digital rectal examination and bladder distension; ultrasound scanning -complications: UTIs, bladder/kidney damage, bladder stones, incontinence -treatment: non-invasive surgery and removal of prostate; drugs that act by relaxing prostate/bladder neck smooth muscle -affects 15% of men over 60 and 50% of men over 80

Treatment: Watchful Waiting

-close follow-up in men with life expectancy <10 years who have low grade, low stage disease -should be biopsied every 6 months -rarely progress; only in 10-25% of patients do they progress within 10 years -immediate treatment not needed; good chance disease is stable -not offered to young men; more likely to have progressive disease because longer lifespan

Prostatic Urethra

-connected to bladder, passes through prostate -15-30 ducts from prostate empty into urethra

Basic Anatomy

-consists of the testis, a series of ducts, accessory glands, and supporting structures -the ducts: epididymis, ductus deferens, ejaculatory duct, urethra -accessory glands: the seminal vesicles, prostate, and bulbourethral glands -supporting structures: include scrotum and penis

Interstitial Spaces of the Testes

-contain blood vessels, lymphatic vessels, nerve fibers, fibroblasts, macrophages, mast cells; nerve fibers and blood vessels leave testes via spermatic cord -the interstitial cells of Leydig (large polyhedral cells in compact groups); testosterone they produce acts on Sertoli cells; testosterone binding is a prerequisite for normal sustenacular function -connective tissue, extracellular fluid

Movement of Sperm

-cytoplasmic bridge between sperm closed and they move freely -average velocity is 4 mm/min -spermatids formed from single spermatogonium: 512-4000 -sperm enter lumen of seminiferous tubule, then epididymis

Varicocele

-dilation of testicular venous supply, resembles varicose vein -affects 10-15% of men -usually affects left side in men 15-25 -can cause sub-fertility because of increased heat -doesn't usually require treatment

Ejaculation of Semen

-during arousal, stimulation of sympathetic nerves results in smooth muscle contraction of the epididymis, vas deferens, prostate, and seminal vesicle -prostate has elaborate valve system; during ejaculation, valve opens and semen injected into urethra; simultaneously, sphincter in prostate contracts and seals off bladder, preventing flow of urine into urethra at time of ejaculation -normal semen volume 2-5 mL; concentration of sperm is 40-120 million/mL

Male Erection: Chemical

-during stimulation nerve fibers release acetylcholine and nitric oxide -NO: labile gas that diffuses across membranes into the vascular smooth muscle cells and activates guanylate cyclase (converts GTP to cGMP) -cGMP causes a decrease in cellular calcium, causing smooth muscle relaxation and blood vessels in erectile tissues to dilate -erection involves release of CO in corpus cavernosum during sexual stimulation

Lobuli Testis

-each lobule contains one to four highly convoluted seminiferous tubules embedded within a loose connective stroma containing vessels, nerves, and interstitial cells -material between the septa consists of: i) seminiferous (seed carrier) tubules in which sperm develop 2) loose connective stroma that surrounds the tubules and contains endocrine cells called interstitial or Leydig cells (secrete testosterone)

Sildenafil (Viagra)

-enhances effect of NO -inhibits PDE5 -no direct relaxant effect -introduced 1998 for treatment of ED -selective for PDE5 (4,000 fold over PDE3, important because PDE3 involved in cardiac contractility) -only 10fold stronger for PDE6 (found in retina; often observe abnormalities in color vision at high doses)

Sperm Movement: Epididymis

-epididymis lies along the back portion of each testes and is lined with smooth muscle -muscle contractions ultimately move sperm to the vas deferens -duct wall pseudostratified columnar epithelium with microvilli for fluid absorption -sperm entering: immature, non-motile, fertilization incapable -2 weeks to pass through (maturation) -90% of fluid reabsorbed as they pass so very concentrated sperm enters vas deferens -sperm can be stored in caudal epididymis for several months -sperm reduce cytoplasm amount, acrosome maturation, gain capacity to bind zona pellucida and increase motility (fertilization capable)

Meiosis II

-equatorial division: second nuclear division; no replication of DNA -chromosomes line up and the chromatids separate from each other at centromere -cells formed are called spermatids and are haploid (23)

Cervical Secretions: Midcycle

-estrogen high at mid-cycle (ovulation); stimulates cervix to secrete lots of clear, watery, non-viscous mucus -in response to estrogen, glycoproteins in cervical mucus assemble to form elongated fibers arranged in channels -channels allow sperm to penetrate mucus and pass into cervix

Causes of Male Infertility

-exposure to toxic drugs and radiation: chemotherapy affects germinal epithelium; marijuana, heroin, methadone associated with lower testosterone (germ cells sensitive to radiation; Leydig resistant) -mumps: 15-25% of men who contract mumps develop orchitis; testicular atrophy in months-years -chromosomal abnormalities -sertoli cell syndrome: germinal cell defect -bacterial infection: involve epididymis with subsequent scarring/obstruction (E coli) -varicocele: 40% of infertile men have one; possibly from increased testicular temp due to venous stasis, germinal epithelial hypoxia, buildup of blood toxins -anti-sperm antibodies: 3-7%; reduced sperm motility; leads to sperm agglutination (sperm washing) -25-40% of infertile men have idiopathic infertility

Urethra

-extends from urinary bladder to distal end of penis -passageway for urine/male reproductive fluids -three parts: prostatic, membranous, spongy/penile

Membranous Urethra

-extends through perineum (muscular floor of pelvis)

Prostate Cancer Diagnosis

-false positives for PSA high as 65%, false negatives 20% -recommended men 50+ undergo annual PSA measurement and digital rectal examination (DRE); men at high risk should begin at 40 -diagnosis is confirmed via biopsy -chest X-ray and transrectal ultrasound (TRUS); bone scan; lab tests, CBC, chemistry panel, liver/renal function tests, baseline PSA, lymph node involvement

Sertoli Cells Synthesize:

-fluid: most of the fluid in the lumen of the seminiferous tubules. fluid contains: proteins, enzymes, nutrients, androgens (which stimulate and nourish developing sperm) and flushes the sperm out of the tubules into the epididymis -androgen binding protein (APB): binds testosterone and increases the concentration of testosterone within the seminiferous tubules -inhibin: secreted into the blood and transported to the pituitary where it inhibits FSH

Testicular Cancer

-malignant tumor is rare -most frequent in young to middle aged men -risk is higher in men with history of undescended testis -most common: seminomas and teratomas -symptoms: painless swelling of one testis -diagnosis: CT scanning, MRI, ultrasound, orchidectomy, histology -treatment: orchidectomy, chemotherapy, radiation -early cure rate: 95-100% -advanced cure rate: 80-90% -if other testis is healthy, treatment with radiation/anti-cancer drugs does not cause infertility

Structurally Abnormal Sperm

-many not able to penetrate mucus at midcycle -not known whether due to motility or immunological factors

Germ Cells

-generate spermatozoa -smaller cells scattered amongst sustenacular cells -germ cells arise from yolk sac endoderm and enter the testes in early development -germ cells comprise a stratified layer of epithelium 4-8 cells deep -most peripheral cells (adjacent to basement membrane) are spermatogonia (divide by mitosis) -spermatogonia (diploid 2n) undergo mitosis; some daughter cells don't differentiate and act as reservoir of stem cells and remain near basement membrane; rest of daughter cells lost contact w/ basement membrane of seminiferous tubule and differentiate into primary spermatocytes (2n) -arranged so most immature cells at periphery and most mature near lumen -during differentiation spermatids attach to the Sertoli cells which are a source of nutrients -proliferation pushes cells toward lumen and closest ones turn into spermatozoa and detach

GnRH

-gonadotropin releasing hormone -hypothalamus -triggers LH and FSH secretion -secretion fairly constant day to day but must be released in pulses to function on pituitary -constancy due to feedback loop, with hypothalamus sensitive to changes in levels of sex hormones

Spermatozoa Anatomy

-head, midpiece, tail/flagellum -head contains chromosomes and leading end has an acrosome cap which contains hydrolytic enzymes needed for penetrating egg (hyanuronidase, acid phosphatases, acrosin, proteinases) -acrosome develops from golgi zone, tail from centriole (excess cytoplasm shed as residual body) -flagellum is cilium-like and movement of microtubules past each other causes tail to move and propel sperm -mid-piece has large numbers of mitochondria which produce ATP necessary for microtubule movement

Seminiferous Tubules

-highly convoluted, 0.2 mm in diameter and 30-70 cm long (in both testis 700 ft) which have either blind ends or join other tubules -lined by complex germinal epithelium: epithelial cells lie on a thin basal lamina, and are covered by a fibrous layer of fibroblasts and smooth muscle (myoid cells which by rhythmic contractions aid the movement of spermatozoa along the length of the tubule) -epithelium contains: sustenacular or sertoli cells (nurse cells) and spermatogenic germ cells

Testosterone During Puberty

-human chorionic gonadotropin (produced by placenta) stimulates testosterone production in fetal testis -before puberty, hypothalamic gonadal system relatively dormant (low testosterone) -puberty begins with increased secretion of GnRH from hypothalamus, leads to increases in LH + FSH -FSH enlarges testes; LH stimulates testosterone -increase in testosterone results in: enlargement of penis, scrotum, and testes; stimulates development of secondary sex characteristics; mainly responsible for growth spurt at puberty

Testosterone Feedback Regulation

-if level of testosterone high: hypothalamus decreases GnRH release, which drops LH and FSH release, which results in reduced Leydig testosterone production/secretion -testosterone can also act directly on the anterior pituitary to inhibit release of LH

Cryptorchidism

-incomplete or improper descent of testes -direct relationship with testicular cancer -10 fold increased risk if uncorrected -treatment: surgery, orchidectomy

Use of Androgens-->Infertility

-increased testosterone inhibits secretion of LH/FSH by inhibiting secretion of GnRH -testosterone also inhibits secretion of FSH

Radiation Therapy

-indicated for prostate cancer that has not yet spread to distant areas of body -external: given daily for several weeks; X-rays targeted at tumor -interstitial: placing radioactive seeds (iodine/palladium) directly into tumor -can combine both therapies

Epididymitis

-inflammation of epididymis -pain, chills, fever, malaise, scrotal swelling -occurs when bacteria reach epididymis -treatment: bed rest, antibiotics, scrotal elevation

Orchitis

-inflammation of testes -most commonly a complication of mumps -can be result of trauma or infection -treatment: antibiotics, cold compresses, genital support

Hormonal Regulation of Male Reproductive System

-involves hypothalamus, anterior pituitary, testes

LH and FSH

-leutinizing hormone, follicle stimulating hormone -anterior pituitary -secreted in response to GnRH -LH binds to interstitial cells (Leydig) in testes and causes testosterone secretion -FSH binds primarily to Sertoli cells and promotes sperm development; also increases secretion of inhibin by Sertoli cells

Hormone Therapy

-main goal: decrease symptoms/tumor size -androgen deprivation therapy (ADT): majority of prostate cancers are androgen-dependent; need to ablate both testicular and adrenal androgens -orchiectomy: standard form of androgen ablation; only effective, non-controversial form of systemic therapy for prostate cancer -bilateral orchiectomy reduces testosterone levels 90% within 24 hours and remains permanently suppressed; side effects include loss of libido, impotence, hot flushes -drugs: GnRH agonists: initially stimulate pituitary to release LH for 4-5 days, then suppress because of down regulation from LHRH receptors; Initially get an increase in serum testosterone, followed by a decrease over 2-3 weeks to serum level in castrates. Some patients develop hormone refractory disease, median survival is 6 months. -anti-androgens: give estrogen, rapidly decreases production of testosterone by testes; used to use DES (diethylstilbestral) but has significant CV risk

Thermoregulation of the Testes

-male reproductive organs are external in order to maintain the temperature needed for spermatogenesis (2 C below body temp) -in the cold: the dartos muscle contracts, reducing the overall scrotum size; the cremaster muscle (extension of abdominal muscle into scrotum) contracts and lifts testes closer to body -in the heat: the dartos muscle relaxes and the scrotum skin becomes loose and thin; the cremaster muscle relaxes and the testes descend away from the body

Prostatic Cancer: Risk Factors

-males who have a relative who has/had disease (doubles for men whose fathers/brothers had it) -low among Asians, high among Scandinavians; American whites 30% less likely to develop clinical cancer than African Americans -men who have had vasectomies have a 1.5-2.0x increased risk -high dietary fat intake can cause changes in sex hormone levels, may cause risk -incidence is low in castrates but increased testosterone levels are not consistently observed in prostatic cancer patients

Hydrocele

-most common cause of scrotal enlargement -caused by by fluid accumulation around a testis -common in newborn males, usually goes away in first year of life -when sac closes (process vaginalis) and fluid remains, it's called a noncommunicating hydrocele (often found in newborns and usually self-resolves) -if scrotal sac compressed and fluid slowly goes up to abdomen or if hydrocele changes size, called communicating hydrocele (appears smaller in morning when child wakes and larger in evening) -also occurs during inflammation of epididymis and testis, injury, neoplasm

Chemotherapy

-no agent has been shown to consistently improve survival; largely used to treat symptoms in very progressed disease -androgen-independent cancer: taxotere can prolong lives of men who no longer respond to hormone therapy -Her-2/neu receptor tyrosine kinase is overexpressed in a subset of androgen-independent cancers; activates androgen receptor and converts androgen dependent prostate cells to androgen independent cells; tyrosine kinase inhibitors with specificity for Her-2/neu may be good drugs

Factors Affecting Sperm Success

-of sperm deposited in vagina (100-500 million), few thousand reach uterine tubes and few hundred reach vicinity of ovum -up to 50% may be incapable of fertilization due to abnormalities -some are destroyed by acidic vaginal secretions -sperm entry may be blocked by cervical mucus -1/2 enter the wrong uterine tube

Spongy/Penile Urethra

-passes through penis -several minute mucus-secreting urethral glands empty into spongy urethra

Male Erection: Physical

-penis contains 3 columns of erectile tissue (cavernosum and spongiosum) -engorgement of erectile tissue with blood causes erection/enlargement of penis -expanded erectile tissue compresses and partially occludes the veins -the increase in blood pressure in the sinusoids causes inflation

PDE 5

-phosphodiesterase type 5 -reverses action of cGMP related to smooth muscle relaxation allowing blood inflow -11 types of PDE discovered -expressed in corpus cavernosum smooth muscle and in lower levels in platelets and vascular/visceral smooth muscle and skeletal muscle

Tadalafil (Cialis)

-potent competitor for PDE 5 -without sexual stimulation and activation of NO/cGMP system, should not cause erection

Viagra Contraindications and Warnings

-potentiates hypotensive effects of nitrates -rare: non-arteritic anterior ischemic optic neuropathy (NAION) (2.8/100,000 patients) -systemic vasodilatory properties, results in transient decreases in supine blood pressure; affects patients with underlying cardiovascular disease; possible use in treatment of pulmonary hypertension -shouldn't be prescribed for patients who have suffered a stroke/MI within last 6 months or patients with resting hypotension -shouldn't use in patients with retinitis pigmentosa (minority of patients have genetic disorders of retinal PDE) -priapism (extended erection)

Testosterone

-produced by testes -steroid formed from cholesterol -Leydig cells don't store testosterone; store cholesterol precursor as lipid droplets -following synthesis, testosterone is secreted into extracellular fluid surrounding seminiferous tubules -also transported from extracellular fluid into blood vessels of the testis and then goes into general circulation where it has variety of effects -has some biological effect on almost every tissue of the body

Cervical Secretions: Post-Ovulation

-progesterone increases and stimulates cervix to secrete thick, viscous, sticky mucus with no glycoprotein channels -mucus plugs the cervix and acts as a barrier to impede sperm migration into uterus

Prostatectomy

-radical prostatectomy (RP) surgery -remove all/part of prostate -useful in early stage disease confined to prostate -to cure with surgery, tumor must be only in prostate and all of tumor must be removed -because detection is better and can diagnose sooner, surgery commonly chosen -until early 1990s, RP usually resulted in impotence/incontinence; new techniques pioneered at John Hopkin's now spare many of nerve bundles that control erection

Hypothalamic Control of Reproductive System

-receives input from variety of brain areas -amount of GnRH released controlled by excitatory and inhibitory signals -visual, olfactory, and tactile stimulation alter GnRH release (thoughts and moods can affect secretion of sex hormones) -stress (protracted aerobic exercise) can inhibit gonadotropin release in both males and females (results in transient inhibition of sperm production and disrupts the menstrual cycle)

Meiosis I

-reduction division: primary spermatocytes enlarge, DNA replicates and 46 chromosomes form (2 identical chromatids each) -the 4 chromatids of each homologous pair associate and form a tetrad; portions may be exchanged (recombination) -homologous chromosomes move to opposite sides of the cell; thus the spermatozoa produced are genetically unique -cells formed by first nuclear division: secondary spermatocytes -each chromosome in a secondary spermatocyte is still two chromatids attached to a centromere

Problems with Proteins as Drugs (like inhibin)

-relatively unstable -oral administration inactivates proteins -do not cross membranes to move into blood readily (skin patch/implant ineffective)

Testosterone Levels in Old Age

-rise after puberty and stabilize at a maximum around 20 -remains fairly steady until 4th decade of life and then starts to decrease -as testosterone levels drop, gonadotropin levels increase, since brains of older men able to release GnRH and pituitary as able to release LH/FSH -thought that testes themselves affected by age -target tissues up-regulate testosterone receptors as testosterone levels drop -despite drop, in middle age levels adequate to support spermatogenesis and maintain function of accessory structures

Inhibin (type B)

-secreted by testes (Sertoli cells) -peptide hormone -directly inhibits FSH release -is a TGF-beta family member -at one time was a prime target for male contraception (inhibin levels reflect sperm production; elevating inhibin reduces sperm production without interfering with testosterone production, but it's a protein)

Sperm Movement: Urethra

-seminal vesicle fluid washes sperm out of ejaculatory duct -secretions added from bulbourethral glands (Cowper's gland) -semen forced through urethra through shaft of penis to outside of the body

Acrosome Reaction

-series of fusions between outer membranes of acrosome -results in formation of channels which expand to allow macromolecules to pass through and the release of enzymes (hyaluronidase and acrosin) -at the end of the reaction only the former inner membrane of the acrosome remains, revealing receptors important for fusion

Testis Function

-serve to produce sperm and as endocrine glands (testosterone)

Polyspermy Prevention

-several sperm may attach to ovum but usually only one penetrates -sperm penetrates the zona pellucida and attaches to ovum surface and membrane potential of ovum changes (Ca) -fusion of 1st sperm results in exocytosis of cortical granules from ovum into space between plasma membrane and zona pellucida -prevents other sperm from fusing (granules alter surface of ovum membrane and make penetration difficult)

Sources of Seminal Fluid: Prostate Gland

-size of a walnut; surrounds urethra -produces about 30% of semen -thin, milky secretion, high pH; contains clotting factors, fibrinolysin, citric acid, various enzymes, prostaglandins -clotting factors provide for coagulation of semen

Testis Anatomy

-small ovoid organs 4-5 cm long -testis is surrounded by a testicular capsule containing three layers (tunicas vaginalis, albuginea, and vasculosa) -thin partitions radiate from the mediastinum dividing the interior of the testis into 300-400 pyramidal compartments (lobuli testis)

Sertoli Cells

-spaced along seminiferous tubules at regular intervals -tall pillar-like cells resting in the basal lamina -nourish the germ cells and produce hormones (androgens, estrogens, inhibins) -cell membrane is highly irregular since the heads of maturing spermatozoa lie within deep recesses of the cytoplasm -tight junctions between cells form a blood-testis barrier and isolate the sperm cells from the immune system (essential because as sperm develop they express surface antigens that could activate an immune response)

Sperm Movement: Rete Testes

-sperm move from tubules into rete testes and then into epididymis because of pressure created by fluid in tubules -rete testes: seminiferous tubules meet at the top of testes in a network of ducts

Capacitation

-sperm need to have been in female tract for about 10 hours before they can fertilize an ovum -during capacitation: sperm's plasma membrane is altered; sperm loses its acrosomal cap; increases its motility -as sperm "zero in" on ovum they become hyperactive (consequence of increased Ca flux into tail through Ca channel Casper 1); helps them break through corona cells and zona pellucida

Sperm Movement: Time

-sperm reach uterine tube in a few hours, some sperm reach tube in minutes -this is shorter than can be accounted for by tail movement -propelled through female reproductive tract by wavelike movements of tail

Descent of the Testes

-testis develop as retroperitoneal organs in the abdominopelvic cavity (5 weeks) -each testis is connected to the scrotum by a gubernaculum (fibromuscular cord) -testis move from abdominal cavity through the inguinal canal to the scrotum (14-28 wks) -inguinal canals are bilateral passageways in the anterior abdominal wall; in females they develop but are much smaller than in males and the ovaries don't descend through them -as they move into the scrotum each testis is preceded by an outpocketing of the peritoneum called the process vaginalis -the superior part of each process vaginalis is lost and the inferior part remains a small closed sac, the tunica vaginalis

Tunica Vasculosa

-the inner layer -consists of a network of blood vessels embedded within a delicate connective tissue

Tunica Albuginea

-the middle layer -thick white capsule of fibroelastic connective tissue containing smooth muscle cells

Tunica Vaginalis

-the outer layer -a single layer of mesothelial cells

Spermatogenesis

-the process by which the seminiferous tubules of the testis produce haploid spermatozoa -in humans, takes about 74 days -primordial germ cells arising from the yolk sac endoderm enter the testis early in development and remain dormant until they begin mitotic proliferation at puberty, at which point the germ cells differentiate into spermatogonia (primitive germ cells) -once it begins it continues for the life of the male -spermatozoa mature at a rate of 300 million per day and have a life expectancy of 48 hours (up to 5 days) once ejaculated in the female reproductive tract

Sources of Seminal Fluid: Bulbourethral Glands

-the size of a pea; connects to urethra -forms pre-ejaculate -contributes about 5% of semen -clear viscous mucous secretion; added just before ejaculation -lubricates and neutralizes pH of male urethra and the vagina

Sperm Movement: the Ductus Deferens

-vas deferens: two ducts which extend from scrotum up into abdominal cavity and behind the bladder; empty into ejaculatory duct -thick wall is composed of smooth muscle and innervated by sympathetic nerves -ductus, testicular artery and venous plexus, lymphatic vessels, nerves, fibrous remains of process vaginalis (peritoneum) form the spermatic cord (supplies testes)

Sperm and the Zona Pellucida

-when sperm reaches ovum, glycoproteins in zona pellucida (gelatinous layer) induce sperm to undergo the acrosome reaction necessary to fertilize -typically 50-100 sperm reach zona pellucida -sperm bind to receptor called ZP3 in zona pellucida and this is followed by the acrosome reaction

Sperm Movement: the Ejaculatory Duct

-where vas deferens and seminal vesicle join -runs through center of prostate gland -fluid from prostate adds to volume of semen -empties into urethra

Classes of Prostatitis

1) acute prostatitis (bacterial); typically caused by intestinal bacteria 2) chronic bacterial prostatitis; cause unclear; sometimes develops after episode of type 1 3) chronic prostatitis/chronic pelvic pain syndrome; variety of causes (lifting heavy objects when bladder is full can cause urine to back up into prostate, jogging, cycling) 4) asymptomatic inflammatory prostatitis

Sperm Movement Through Female Tract: Influences

1) contraction of uterus and uterine tubes because of: release of oxytocin during intercourse as a result of vaginal/cervical stimulation; seminal fluid contains prostaglandins (prostate seminal fluid) 2) ability of sperm to migrate through cervix into the uterus is partially determined by secretions of the cervix: glycoproteins, salts, water; volume and consistency change during ovulation cycle, mucus becoming thin during ovulation

Sperm Movement: Summary

1) epididymis (site of sperm maturation; minimum of 1-2 days; stereocilia increase surface area to increase absorption of fluid from lumen of duct) 2) ductus deferens (epididymis-->abdominal cavity; distal ends enlarged as ampulla; peristalsis via smooth muscle; forms spermatic cord) 3) ejaculatory duct (joining of ductus deferens and seminal vesicle; ends at urethra within prostate gland) 4) urethra

Testes Functions

1) produce sperm (spermatogenesis) 2) production of male sex hormones

Spermatogenesis Stages

1) spermatogonia: self-renewing, undifferentiated stem cell; mitosis occurs; 16 days 2) primary spermatocyte: 46 pairs of chromosomes; meiosis 1 occurs; 24 days 3) secondary spermatocyte: 23 chromosomes; meiosis 2 occurs; some hours 4) spermatid: 23 chromosomes; differentiation occurs 5) sperm

Prostatic Cancer: Treatment

a) watchful waiting b) prostatectomy c) radiation therapy d) hormone therapy e) chemotherapy

Testes Components

each testes contains a large number of seminiferous tubules, tightly coiled tubules which contain: -spermatogenic cells (germ cells, sperm-producing cells) -sertoli cells: joined to one another by tight junctions surrounded by spermatogenic cells -leydig cells: produce testosterone and are located in the interstitial areas between seminiferous tubules