Chapter 27 REPRODUCTION Asexual versus Sexual Reproduction Asexual

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Chapter 27 REPRODUCTION

Chapter 27 REPRODUCTION

Asexual versus Sexual Reproduction Asexual Reproduction: A single parent gives rise to two or

Asexual versus Sexual Reproduction Asexual Reproduction: A single parent gives rise to two or more offspring by: u Fission (Splitting): One individual splits into two or more of about equal size. F E. g. : Bacteria, sea anemone. u Budding: New individual(s) are generated from a portion of the parent and are smaller than parent. F E. g. : Many plants, budding yeast. u Fragmenting: Can regenerate body parts. F E. g. : Sea stars when cut into several pieces will regenerate into several new star fish. u Parthenogenesis: “Virgin development”. Unfertilized egg develops into an adult animal. Adaptation for stressful times. Whiptail lizard F Several insects F

Asexual versus Sexual Reproduction: u The most common type of animal reproduction. u Occurs

Asexual versus Sexual Reproduction: u The most common type of animal reproduction. u Occurs through the fusion of gametes (sperm and egg). Male: Produces sperm cells. Small and motile, propels itself by whiplike flagellum. F Female: Produces eggs (ova). Large and nonmotile. F u Zygote: Egg cell fertilized by a sperm cell. Fertilization: Creation of zygotes by fusion of ova and sperm cells. Two types: u Internal Fertilization: Gametes fuse inside the female’s body. Usually requires copulation (intercourse) in which male delivers sperm directly into body of female. F Practiced by most terrestrial animals, aquatic reptiles, birds, and mammals. F

Asexual versus Sexual Reproduction u External Fertilization: Gametes fuse outside the female’s body. Mating

Asexual versus Sexual Reproduction u External Fertilization: Gametes fuse outside the female’s body. Mating partners release eggs and sperm simultaneously into the water. F Practiced by most aquatic animals: fish, amphibians. F Many eggs are lost and eaten by predators. Therefore, many must be made and released for a few to survive. F Hermaphroditism: u A single individual produces both sperm and eggs. u Some such as the tapeworm are capable of self- fertilization. u Others (e. g. : earthworm) must mate with other animals. u In some species self-fertilization is prevented by development of testis and ovaries at different times. u Used by “solitary” animals.

Advantages of Sexual Reproduction: u Genetic diversity among offspring. u If environment changes drastically,

Advantages of Sexual Reproduction: u Genetic diversity among offspring. u If environment changes drastically, the population may survive if a few individuals have genetic traits that allow them to adapt to changes. Disadvantages of Sexual Reproduction: u Need to invest considerable time, resources, and energy searching for suitable mate. u Only pass on 50% of your genetic material to each offspring.

Advantages of Asexual Reproduction: u Don’t need to invest time and energy searching for

Advantages of Asexual Reproduction: u Don’t need to invest time and energy searching for suitable mate. u Replicates a given genotype rapidly and precisely. u Pass on 100% of your genetic makeup to each offspring. u Useful for organisms well adapted to a stable environment. Disadvantages of Asexual Reproduction: u No genetic diversity among offspring. u If environment changes drastically, the entire population may die out.

Reproductive System of Humans Reproductive Functions of Female: u Produces eggs (ova) u Receives

Reproductive System of Humans Reproductive Functions of Female: u Produces eggs (ova) u Receives sperm u Incubates and nourishes the embryo and fetus u Gives birth u Produces milk for young All of these processes are regulated and coordinated by hormones secreted by: u Hypothalamus u Pituitary gland (anterior portion) u Ovaries

Endocrine Glands Regulate Sexual Functions

Endocrine Glands Regulate Sexual Functions

Reproductive System of Humans Major Organs of Female Reproductive System: n Ovaries: Produce ova

Reproductive System of Humans Major Organs of Female Reproductive System: n Ovaries: Produce ova (oogenesis) and sex hormones. u Size and shape of large almonds. u Located close to lateral walls of pelvic cavity and held in place by connective tissue. u Mainly connective tissue containing scattered eggs (ova) in different stages of development. u Follicles: A single egg with surrounding cells that nourish and protect it. Women are born with all of their follicles (40, 000 to 400, 000). F Only a fraction of follicles release eggs during a woman’s reproductive life. F

Frontal View of Female Reproductive System

Frontal View of Female Reproductive System

Side View of Female Reproductive System

Side View of Female Reproductive System

Female Reproductive System: u Ovulation & Oogenesis: After puberty, each month one immature egg

Female Reproductive System: u Ovulation & Oogenesis: After puberty, each month one immature egg (oocyte), is released from ovary. F Each follicle contains a primary oocyte, arrested in prophase I of meiosis. F Pituitary hormones FSH (follicle stimulating hormone) and LH (luteinizing hormone) cause a follicle to enlarge and complete meiosis I. F One large cell (secondary oocyte) and a tiny cell (polar body) are produced. F LH (luteinizing hormone) causes the secondary oocyte to be released by the ovary during ovulation. F Oocyte will not finish meiotic division, until fertilized. F In the end, one large ovum (egg) and 3 small polar bodies are made from oogenesis.

Oogenesis and Ovary Structure

Oogenesis and Ovary Structure

Major Organs of Female Reproductive System: n Oviducts (Fallopian Tubes): Transport the egg from

Major Organs of Female Reproductive System: n Oviducts (Fallopian Tubes): Transport the egg from the ovary to the uterus. u Peristalsis of smooth muscle in oviduct and beating of cilia, help the egg move along. u Fertilization occurs in the first third of oviduct. u Scarring of oviducts is a common consequence of sexually transmitted diseases: chlamydia and gonorrhea. u Ectopic Pregnancy: Fertilized egg does not reach the uterus. Usually starts to develop in oviduct. Usually due to a blocked oviduct. F Occurs in 1% of all pregnancies in the U. S. F Must be surgically removed. F May cause death and severe hemorrhage. F

Fertilization Occurs in the Oviducts

Fertilization Occurs in the Oviducts

Ectopic Pregnancy of Twins Ectopic pregnancies occur in about 1% of pregnancies in U.

Ectopic Pregnancy of Twins Ectopic pregnancies occur in about 1% of pregnancies in U. S. and usually require surgical removal of embryos.

Reproductive System of Humans Major Organs of Female Reproductive System: n Uterus: Incubates the

Reproductive System of Humans Major Organs of Female Reproductive System: n Uterus: Incubates the embryo/fetus. u Size of a fist, in center of pelvic cavity. u Oviducts open into upper corners of uterus. u Has thick walls of smooth muscle (myometrium) responsible for uterine contractions and cramps. u Endometrium: Inner mucous lining, which thickens each month in preparation for pregnancy. u If fertilization does not occur, endometrium breaks down and is discharged during menstruation. u If fertilization occurs, the egg implants in the endometrium which supports its growth until the placenta develops.

The Uterus Incubates and Nourishes the Fetus

The Uterus Incubates and Nourishes the Fetus

Reproductive System of Humans Major Organs of Female Reproductive System: n Cervix: Lower portion

Reproductive System of Humans Major Organs of Female Reproductive System: n Cervix: Lower portion of the uterus, which projects into the vagina. u Pap smear: Examination of cervical tissue to detect abnormalities. Recommended yearly. u Cervical cancer: Most cases caused by a viral infection with human papillomavirus. u Women are infected through intercourse with asymptomatic male. u Takes about 20 to 30 years to develop. u Men don’t appear to be affected.

Reproductive System of Humans Major Organs of Female Reproductive System: n Vagina: Thin walled,

Reproductive System of Humans Major Organs of Female Reproductive System: n Vagina: Thin walled, muscular chamber. u u u n Vulva: External structures. u u u n Receives the sperm and penis Acid p. H kills bacteria and sperm cells Part of birth canal Clitoris: Equivalent to male penis. Labia minora: Skin folds that border vaginal opening. Labia majora: Protect entire genital region. Hymen: Ring of tissue that forms a border around vaginal entrance. No known function. Bartholin’s gland: Secrete lubricating fluid during sexual arousal. Breasts: Lactation

Female Hormones Controlling Reproduction n Follicle Stimulating Hormone (FSH) u u n Luteinizing Hormone

Female Hormones Controlling Reproduction n Follicle Stimulating Hormone (FSH) u u n Luteinizing Hormone (LH) u u n Secreted by pituitary gland Stimulates growth of follicle and completion of meiosis I Induces ovulation Promotes development of corpus luteum and hormone secretion. Estrogen u u n Secreted by pituitary gland Stimulates growth of ovarian follicle Secreted by ovarian follicle Low levels inhibit FSH and LH secretion High levels stimulate FSH and LH secretion Promotes growth of endometrium Progesterone and Estrogen u u u Secreted by corpus luteum Maintain endometrium, sharp drop causes menstruation High levels inhibit FSH and LH secretion

Female Menstrual Cycle: Approximately 28 days. n Menstruation: Day 1 of cycle. u u

Female Menstrual Cycle: Approximately 28 days. n Menstruation: Day 1 of cycle. u u u n Pre-Ovulatory phase: Starts around day 5 of cycle. u n Rising estrogen levels cause the endometrium to start thickening. Ovulation: Occurs around day 14 of cycle. u u u n Walls of endometrium break down. Caused by falling levels of progesterone and estrogen. Lasts 3 to 7 days. FSH stimulates growth of ovarian follicle. LH causes follicle to finish meiosis I (secondary oocyte) and to be released by ovary. Corpus luteum: Starts to secrete estrogen and progesterone. Post-ovulatory Phase: Starts around day 15. u u u Endometrium continues to grow in response to rising estrogen and progesterone. If no fertilization occurs, corpus luteum degenerates and menstruation occurs. If fertilization occurs, embryo maintains corpus luteum.

Stages of Female Reproductive Cycle

Stages of Female Reproductive Cycle

Reproductive System of Humans Reproductive Functions of Male: u Produces sperm u Delivers sperm

Reproductive System of Humans Reproductive Functions of Male: u Produces sperm u Delivers sperm to female reproductive tract All of these processes are regulated and coordinated by hormones secreted by: u Hypothalamus u Pituitary gland (anterior portion) u Testes (Sing. Testis)

Side View of Male Reproductive System

Side View of Male Reproductive System

Front View of Male Reproductive System

Front View of Male Reproductive System

Major Organs of Male Reproductive System: n Testes: Paired male gonads. u Produce sperm

Major Organs of Male Reproductive System: n Testes: Paired male gonads. u Produce sperm through spermatogenesis, which produces four sperm cells of equal size. u Spermatogenesis occurs in a vast system of hollow tubes called seminiferous tubules. u Each mature sperm has a head, a midpiece, and a flagellum. u Sperm head has an acrosome, which produces enzymes that help it penetrate the egg. u Human sperm cannot develop at body temperature. u Testicles descend from abdominal cavity into scrotum, a skin covered sac, about two months before birth. u Undescended testicles (cryptorchidism) may cause infertility.

Spermatogenesis Occurs in Seminiferous Tubules of Testes

Spermatogenesis Occurs in Seminiferous Tubules of Testes

Sperm Cell Structure

Sperm Cell Structure

Reproductive System of Humans Major Organs of Male Reproductive System: n Epididymus: u Large

Reproductive System of Humans Major Organs of Male Reproductive System: n Epididymus: u Large coiled tube (23 ft long) that surrounds testes. u Stores sperm while they develop fertilizing ability and motility (about 20 days). u During ejaculation, sperm cells are propelled from epididymus. n Vas Deferens: u Long muscular ducts from scrotum to back of bladder. During ejaculation, the sperm pass from epididymus into these two ducts. u Vasectomy: Each vas deferens is cut to prevent sperm from entering urethra. u

Reproductive System of Humans Major Organs of Male Reproductive System: n Ejaculatory Duct: u

Reproductive System of Humans Major Organs of Male Reproductive System: n Ejaculatory Duct: u Short duct after two vas deferens ducts unite. n Urethra: u Deliver sperm to the exterior. u In males, urine and sperm pass through the urethra. u Females have a separate urethra from the reproductive system.

Reproductive System of Humans Major Organs of Male Reproductive System: Accessory Glands: Produce semen.

Reproductive System of Humans Major Organs of Male Reproductive System: Accessory Glands: Produce semen. u Functions of semen: F Activate sperm cells F Provide nutrients for motility F Counteract acidity of vagina and male urethra F Stimulate contractions of female reproductive tract F Antimicrobial action u Ejaculation volume 4 to 5 ml. F One ejaculation has 50 -500 million sperm cells F Sperm cells account for less than 5% of semen volume. F Secretions from 3 different accessory glands make up the rest of the volume: Seminal vesicles (2), prostate, and bulbourethral glands (2).

Major Organs of Male Reproductive System: Accessory Glands: A. Seminal vesicles (2): Secrete fluid

Major Organs of Male Reproductive System: Accessory Glands: A. Seminal vesicles (2): Secrete fluid that nourishes sperm. u Contribute about 60% of semen volume. u Thick, clear, alkaline fluid. u Contains: Fructose: Provides energy for sperm motility. F Prostaglandins: Stimulate smooth muscle contractions of female and male reproductive tracts. F Fibrinogen: Forms temporary clot in vagina. F u Sperm cells become highly motile when mixed with this fluid.

Accessory Glands: B. Prostate gland: Produces a thin milky secretion. u Largest of semen

Accessory Glands: B. Prostate gland: Produces a thin milky secretion. u Largest of semen secreting glands. u Contributes 30% of semen volume. u Produces an antibiotic that may prevent urinary tract infections in men. u Benign (noncancerous) prostate enlargement is common among older men. 50% of men over 40. F Almost all men over 70. F u Prostate cancer is the second leading cause of cancer and cancer deaths in men. Over 330, 000 new cases/year and 40, 000 deaths. F Average at diagnosis: 72 F Detected by blood test or digital rectal exam. F Treated surgically or with drugs to reduce prostate size or activity. F

Benign Prostate Enlargement Usually Procedes Prostate Cancer Normal prostate is 2 to 3 cm

Benign Prostate Enlargement Usually Procedes Prostate Cancer Normal prostate is 2 to 3 cm in diameter

Major Organs of Male Reproductive System: Accesory Glands: C. Bulbourethral glands (2): Release a

Major Organs of Male Reproductive System: Accesory Glands: C. Bulbourethral glands (2): Release a mucous secretion that lubricates penis and facilitates its entry into vagina. u Pair of small glands below the prostate. u Contribute 5 -10% of semen volume. u Before ejaculation secrete a clear mucus that neutralizes acid from remaining urine in urethra. u Bulbourethral fluid also carries some sperm that is released before ejaculation. One cause of high failure rate of withdrawal method.

Major Organs of Male Reproductive System: n Penis: Copulatory organ that delivers sperm to

Major Organs of Male Reproductive System: n Penis: Copulatory organ that delivers sperm to female body. u Composed of three cylinders of erectile tissue. u During sexual arousal, the penis fills with blood from the arteries. u Erection is essential for penetration. u Impotence is the inability to maintain an erection. May be caused by alcohol, drugs, illness, and/or emotional problems. F Viagra acts by relaxing smooth muscle of penis blood vessels, allowing blood to enter erectile tissue. F u Penis structure: Shaft: Long cylinder with thick skin. F Glans: Enlarged tip of penis. Thin skin, covered by prepuce or foreskin. F

Fertilization: Sperm Cell Penetrates Egg with Acrosomal Enzymes

Fertilization: Sperm Cell Penetrates Egg with Acrosomal Enzymes

Fertilization and Early Embryonic Development

Fertilization and Early Embryonic Development

Developing Embryo is Nourished by Placenta

Developing Embryo is Nourished by Placenta

Pregnancy and Human Development u Gestation: In humans starts at conception and lasts approximately

Pregnancy and Human Development u Gestation: In humans starts at conception and lasts approximately 38 weeks (266 days). u Due date typically 40 weeks after last menstruation. u First Trimester: By the end of week 13 F Sex distinguished externally F Fetus weighs about 150 grams u Second Trimester: F F By the end of week 26 Fetus weighs about 1000 g May survive if born at this point. u Third Trimester: F Fetus By the end of week 38 weighs about 3500 g (7 ½ lb. ) F Testes have descended in males.

Critical Stages of Embryonic and Fetal Development

Critical Stages of Embryonic and Fetal Development

Childbirth (Labor) and its Three Stages Hormonal triggers: u Rising estrogen levels causes the

Childbirth (Labor) and its Three Stages Hormonal triggers: u Rising estrogen levels causes the formation of oxytocin receptors on smooth muscle of uterus. u Oxytocin is secreted by fetal cells and mother’s pituitary. u Prostaglandins are released by placenta. Stages of Childbirth u First Stage: Dilation Cervix opens from 1 cm to 10 cm. F Lasts several hours or days. F u Second Stage: Expulsion Strong uterine contractions every 2 to 3 min push baby through birth canal. F Lasts 20 min to a couple of hours. F u Third Stage: F Delivery of placenta (afterbirth) Usually within 15 minutes of delivery

Labor Contractions Are Induced by Several Hormones

Labor Contractions Are Induced by Several Hormones

Birth of Human Child Requires Dilation of Cervix

Birth of Human Child Requires Dilation of Cervix

Different Contraceptive Methods 1. Prevent Release of Gametes: u Birth control pill (combination): Prevents

Different Contraceptive Methods 1. Prevent Release of Gametes: u Birth control pill (combination): Prevents ovulation 2. Prevent Fertilization u u u u u Vasectomy: Male sterilization Tubal ligation: Female sterilization Minipill: Progestin only, blocks cervical opening Norplant implant: Releases progestin for 5 years Rhythm (calendar): Avoid intercourse around ovulation Withdrawal: Remove penis before ejaculation Condom: Latex or sheepskin barrier Diaphragm, cervical cap: Block cervical opening Spermicide: Kill sperm cells 3. Prevent Implantion u u Intrauterine device (IUD) Morning after pills

Effectiveness of Methods of Contraception

Effectiveness of Methods of Contraception

Effectiveness of Methods of Contraception

Effectiveness of Methods of Contraception

Incidence (New Cases) of Sexually Transmitted Diseases in the U. S. (1996)

Incidence (New Cases) of Sexually Transmitted Diseases in the U. S. (1996)

Reproductive System Diseases 1. Gonorrhea u Characteristics: Acute infection of urethra, anus, vagina, cervix,

Reproductive System Diseases 1. Gonorrhea u Characteristics: Acute infection of urethra, anus, vagina, cervix, and fallopian tubes. Yellow foul discharge (more common in men). Causes pelvic inflammatory disease (PID) in women. Major cause of infertility in both men and women. May also result in throat and eye infections. In a large percentage of cases, symptoms are mild or absent. u Pathogens: Neisseria gonnorrhoea (bacterium). u Transmission: Direct sexual or mucous membrane contact. Mother to infant transmission during childbirth. u Incubation period: 2 to 7 days.

Gonorrhea: Acute Urethral Infection Typical discharge in male with gonorrhea. Source: Tropical Medicine and

Gonorrhea: Acute Urethral Infection Typical discharge in male with gonorrhea. Source: Tropical Medicine and Parasitology, 1995

Gonorrhea: Eye Infection in Newborn Ophtalmia neonatorum caused by Neisseria gonorrheae Source: Microbiology Perspectives,

Gonorrhea: Eye Infection in Newborn Ophtalmia neonatorum caused by Neisseria gonorrheae Source: Microbiology Perspectives, 1999

1. Gonorrhea (Continued) u Epidemiology : Up to 500, 000 new cases/year in U.

1. Gonorrhea (Continued) u Epidemiology : Up to 500, 000 new cases/year in U. S. u Control: Use of condoms, avoid sexual contact with infected individuals. Vaginal and cervical cultures of pregnant women. u Treatment: women. Antibiotics. Erythromycin for pregnant

2. Syphilis Characteristics: Disease occurs in three stages: 1. Primary stage: Painless lesion (chancre),

2. Syphilis Characteristics: Disease occurs in three stages: 1. Primary stage: Painless lesion (chancre), which disappears after several days. 2. Secondary stage: Skin rash with fever and mucous membrane lesions. Typically followed by a long latent period. 3. Tertiary stage: Extensive damage to central nervous system, cardiovascular system, bones, sense organs, visceral organs, and other sites. u Pathogens: Treponema pallidum (bacterium).

Syphilis: Primary and Secondary Stage Lesions Primary syphilitic chancre and secondary rash. Source: Tropical

Syphilis: Primary and Secondary Stage Lesions Primary syphilitic chancre and secondary rash. Source: Tropical Medicine and Parasitology, 1997

Syphilis: Secondary Stage Rash Secondary syphilitic rash. Source: Tropical Medicine and Parasitology, 1997

Syphilis: Secondary Stage Rash Secondary syphilitic rash. Source: Tropical Medicine and Parasitology, 1997

Syphilis: Tertiary Stage Lesions Syphilis, Gumma: Large rubbery ulceration of anterior tongue in a

Syphilis: Tertiary Stage Lesions Syphilis, Gumma: Large rubbery ulceration of anterior tongue in a patient with tertiary syphilis. Source: A textbook of oral pathology, 1983.

Syphilis: Advanced Tertiary Stage Lesions Severe gumma lesions in tertiary syphilis. Source: Tropical Medicine

Syphilis: Advanced Tertiary Stage Lesions Severe gumma lesions in tertiary syphilis. Source: Tropical Medicine and Parasitology, 1997

2. Syphilis (Continued) u Transmission: Direct contact with lesions, body secretions, blood, semen, saliva,

2. Syphilis (Continued) u Transmission: Direct contact with lesions, body secretions, blood, semen, saliva, vaginal discharges; usually during sexual contact. Mother to infant transplacental transmission (congenital syphilis). Blood transfusions. u Incubation period: 10 days to several weeks. u Epidemiology : Over 80, 000 new cases/year in U. S. u Control: Use of condoms, avoid sexual contact with infected individuals. Blood tests (VDRL) for high risk individuals. u Treatment: Antibiotics, long acting penicillin G, tetracycline, etc.

Congenital Syphilis Causes Teeth and Bone Defects Congenital Syphilis with Hutchinson incisors. Source: Physical

Congenital Syphilis Causes Teeth and Bone Defects Congenital Syphilis with Hutchinson incisors. Source: Physical evaluation of the dental patient, 1982.

3. Chlamydia u Characteristics: Painful urination, watery discharge, salpingitis, and pelvic inflammation in women.

3. Chlamydia u Characteristics: Painful urination, watery discharge, salpingitis, and pelvic inflammation in women. Symptoms may be mild or absent, especially in women. Common cause of sterility in both men and women. Newborns may develop eye infections and pneumonia. u Pathogens: Chlamydia trachomatis. u Reservoir: Humans. u Transmission: Direct sexual contact or mother to infant transmission during childbirth. u Incubation period: 2 to 3 weeks. May be asymptomatic. u Epidemiology : Up to 1 million new cases/year in U. S. Most common sexually transmitted disease in U. S. u Control: Use of condoms, avoid sexual contact with infected individuals. Prophylactic treatment of contacts and pregnant women. u Treatment: Antibiotics.

Both Chlamydia and Neisseria gonorrhea Cause Salpingitis

Both Chlamydia and Neisseria gonorrhea Cause Salpingitis

Chlamydia Infections: Inflammation of eyelid Source: Microbiology Perspectives, 1999

Chlamydia Infections: Inflammation of eyelid Source: Microbiology Perspectives, 1999

4. Candidiasis (Yeast Infection) u Characteristics: Painful irritation and inflammation of vagina and vulva

4. Candidiasis (Yeast Infection) u Characteristics: Painful irritation and inflammation of vagina and vulva in women. Redness and intense itching. White vaginal discharge. May cause infections of mouth, throat, and rectum in immunocompromised patients. u Pathogen: Candida albicans (yeast), part of normal flora of mucous membranes. u Reservoir: Humans. u Transmission: Opportunistic pathogen. F Antibiotic treatment F Weakened host: stress, diet, or illness. u Incubation period: u Epidemiology : u Treatment: 2 to 3 weeks. May be asymptomatic. Millions cases/year in U. S. Antifungal medication.

Oral candidiasis in an AIDS patient Source: Atlas of Clinical Oral Pathology, 1999

Oral candidiasis in an AIDS patient Source: Atlas of Clinical Oral Pathology, 1999

5. Herpes Simplex 1 & 2 Characteristics: u Herpes Simplex 1 (Oral Herpes): Recurring

5. Herpes Simplex 1 & 2 Characteristics: u Herpes Simplex 1 (Oral Herpes): Recurring painful blister lesions that form mainly on lips, but may be found in other areas of body. In immunocompromised patients may have extensive lesions on tongue and inside mouth. u Herpes Simplex 2 (Genital Herpes): Recurring painful blister lesions in genital and/or rectal areas. u Pathogens: F Human Herpes Virus 1: Oral Herpes. F Human Herpes Virus 2: Genital Herpes. u Reservoir: Humans. u Transmission: Kissing, touching lesions, sexual contact.

Oral Herpes: Recurrent Herpes Labialis Less than 1 day with erythema and burning Same

Oral Herpes: Recurrent Herpes Labialis Less than 1 day with erythema and burning Same patient 24 h later with multiple fluid filled vesicles and erythema Source: Atlas of Clinical Oral Pathology, 1999.

Oral Herpes: Recurrent Herpes Labialis: Bilateral vesicles on upper and lower lips. Source: Atlas

Oral Herpes: Recurrent Herpes Labialis: Bilateral vesicles on upper and lower lips. Source: Atlas of Clinical Oral Pathology, 1999.

Oral Herpes: Chronic Atypical Lesions Chronic Herpes Simplex infection with lesions on tongue and

Oral Herpes: Chronic Atypical Lesions Chronic Herpes Simplex infection with lesions on tongue and lips Source: Atlas of Clinical Oral Pathology, 1999.

Genital Herpes simplex 2 infection with fluid filled vesicles on penis. Source: Mike Remington,

Genital Herpes simplex 2 infection with fluid filled vesicles on penis. Source: Mike Remington, University of Washington Viral Disease Clinic

Genital Herpes Acyclovir resistant peri-rectal HSV 2 infection in HIV infected male. Source: AIDS,

Genital Herpes Acyclovir resistant peri-rectal HSV 2 infection in HIV infected male. Source: AIDS, 1997

5. Herpes Simplex 1 & 2 u Incubation period: Several days to weeks. May

5. Herpes Simplex 1 & 2 u Incubation period: Several days to weeks. May be asymptomatic. u Epidemiology : Millions cases/year in U. S. F Oral Herpes: Up to 70% of population is infected. Many have no symptoms. F Genital Herpes: Up to 20% of population is infected. Many have no symptoms. Others have recurring lesions several times a year. u Treatment and Prevention: No cure. Infection is for life. Antiviral medications (acyclovir) decrease frequency and severity of outbreaks. Women with genital herpes should deliver by cesarean section to avoid infecting newborn. Neonatal herpes is very serious and can be deadly.