Dr. Anderson
GCIT

• Many organisms clone themselves to produce more offspring (progeny) and therefore have no need for the exchange of gametes (sex cells)
• However, many organisms (including humans) have evolved to reproduce sexually
• What are the advantages of each form of reproduction?

• Only system that is broadly different between genders
• Also the only system whose anatomy is meant to compliment that of the opposite gender
• Male – largely external
• Female – largely internal

• To produce, maintain and deliver gametes to the uterus where they can combine for fertilization

Tissue Type
Gametes
Male
Sperm
Gonads Testes
Copulatory
Organ
Accessory
Organs
Penis
Egg
Female
Ovaries
Vagina
Mammary
Glands

• Much of the male anatomy, including the gamete-producing organs are outside of the body
– Why?

• Testes –
– produce sperm via meiosis
– Also secrete the hormone testosterone
• Protected by the scrotum
– Cremaster muscle regulates the tension and therefore temperature of scrotum
– Why is this important?

• Consist of spermatogenic cells
(sperm producing cells) in tubules called the seminiferous tubules
• Once-produced, sperm migrate to the epididymis, where they are stored until ejaculation

Spermatic Cord – contains nerve, blood vessels, and efferent ducts that serve the cells of the testes

• During ejaculation, sperm are released from the epididymis via the vas deferens
– Vas deferens is cut during a vasectomy
• The vas deferens empties into the urethra to give passage to sperm

• Gland in which the vas deferens and urethra combine
• Add alkaline fluid to semen prior to ejaculation
– Why?
• One of the most common cancers in older men

• Seminal Vesicles – paired exocrine glands that empty into each vas deferens
• Add a variety of compounds to semen
– Vitamin C
– Fructose
– Proteins
– Why?

• Copulatory organ in males
• Composed mainly of spongy tissue that fills with blood to produce an erection during sex

• Parasympathetic nerves relax during sexual stimulation, allowing blood to expand arterioles and erectile tissue
– Corpora cavernosa

• A mixture of
– Sperm
– Accessory gland secretions
• Stimulates reverse peristalsis of the uterus
• Slightly alkaline
• Immunosupressive
– Adaptive?

• Spinal reflex
• Bladder sphincter contracts
• Accessory glands, ducts and the penile muscles contract, propelling semen out

• End product of meiosis!
Sperm (or egg) cells
Body (somatic) cells

• Spermatocyte cells go through meiosis to produce immature 4 sperm cells (spermatids)
– Initiated by Follicle stimulating hormone (FSH)
• Flagella are produced and much of the cytoplasm is lost
• Sperm are “streamlined” for their trip to meet the egg
• Up to 200 million sperm produced daily!

• The female reproductive system is more complex than the male system because:
– Used for copulation
– Must support the growth and development of the baby for 9 months!

• Ovaries
– paired organs that flank either side of the uterus
– produce one (usually) egg per month (~28 days)
• Ovaries also regulate the menstrual cycle via hormone release
– Progesterone
– Estrogen
– Leutenizing hormone – triggers ovulation by stimulating estrogen production
– Follicle stimulating hormone – stimulates maturation of follicles to produce mature oocytes (eggs)

• Egg cells (oocytes) are formed in the ovarian cortex
• The follicles mature (eggs “ripen”) in each follicle over time
• Eventually one follicle ejects its oocyte, leaving behind a “corpus luteum”, which produces hormones (progesterone and estrogen)

• Eggs are released into the peritoneal (abdominal) cavity
• The ampullae of the fallopian tubes collect the newly released egg
– Where fertilization most often occurs
• The brush-like fimbriae bear cilia which sweep the egg into the fallopian tube (most times)

• The white tissue left in the ovary after the egg is released (ovulation)
• This tissue will produce hormones (progesterone) depending on whether a fertilized egg is present

• If egg is not fertilized:
– Corpus luteum degrades and progesterone stops being produced after about 10 days, uterine lining degrades and sloughs off
• If egg is fertilized:
– The egg will produce human chorionic gonadotropin
(hCG) which will stimulate the corpus luteum to keep producing progesterone, keeping the uterine wall thick and perfused

• Transport egg from the ovary to the uterus
– Ciliated cells
– Smooth muscle contractions (peristalsis)

• Sometimes, a fertilized egg will implant in the wall of the fallopian tube and an embryo will start to grow
– Generally results in loss of pregnancy
(either naturally or with surgery)

• Fallopian tubes are open superiorly
• Therefore, bacteria
(Gonorrhea) may get swept into the peritoneal cavity
– Scarring of fallopian tubes
– Major cause of female sterility

• Anterior to rectum and posterior to bladder, about the size of a pear
• From where it connects with the vagina, it flexes anteriorly
(anteverted)

• Rounded superior region (fundus)
• Cervix – joins the uterus with the vagina

• Three layers
– Perimetrium – outermost layer
– Myometrium – Muscular layer (smooth muscle)
– Endometrium – internal, epithelial layer
• Sloughed off during menstruation
• Tissue that accepts the fertilized egg (zygote)

• The inferior opening to the uterus
• Secretes viscous mucus which serves as a barrier to pathogens and sperm
– Viscosity greatly decreases peri-ovulation

• Human Papilloma virus – 60 subtypes
• At least four (probably more) of these are known to be associated with cervical cancer

• How women can protect themselves
– Gardasil
– Regular visits to gynecologist if sexually active to check for abnormal cervical cells
• Pap smear

• 3-4 inches long, very thin, flexible tissue
• Also three layers
– Elastic outer layer
– Smooth muscle (muscularis)
– Inner mucosal layer
• Acidic due to glycogen release

• Hymen – forms incomplete partition over vaginal orifice (in virgins)
• Labia – skin folds that flank and protect the vaginal opening
• Clitoris – nerve-filled, erectile structure; primary organ of sexual sensation

• Milk producing glands that develop at puberty
• 15-25 exocrine lobes produce milk soon after birth of a child (prolactin is secreted)
• Negative feedback loop limits milk production
– Disuse halts production

• Cancer cells can move into lymphatic ducts and produce
“lumps”
• Why such an extensive lymphatic system in breast tissue?

• Risks
– Early menstruation (menarche)
– No or late pregnancies
– No or reduced breast feeding
– Family history
• Possessing the BRCA1 or BRCA2 genes (10% of American women)

• Self-examination – palpating the breast tissue for tumors
(lumps)
• Mammogram – x-ray of breast tissue
• Genetic screening – testing for BRCA1 or
BRCA2 genes