1. Sexual reproduction
  2. A. Involves gametes: Sperm swim to egg.

  3. Male reproductive system
  1. Sperm are produced in testes.
    1. Testes lie in the scrotum.
  1. The testes develop inside the abdominal cavity and descend into scrotal sacs during the last 2 months of fetal development.
    1. If the testes donít descend then you are sterile.
  1. Internal body temperature is too high for sperm.
    1. Scrotum is 34 degrees centigrade. Wearing tight clothing can reduce sperm production.
    2. When it is cold testes are held close to body.
  1. The walls of the testes are made of fibrous connective tissue.
    1. Divided into lobules.
    2. Each lobule has 1-3 seminiferous tubules that are 70 cm in length.
    3. Seminiferous tubules are packed with cells undergoing spermatogenesis.
    4. Spermatognia become spermatocytes that undergo meiosis. Primary spermatocytes give rise to secondary spermatocytes.
    5. Secondary spermatocytes divide to give 4 spermatids. Spermatids differentiate into sperm.
    6. Sperm have 23 chromosomes.
    7. This process takes 48 days.
  1. Sperm
  1. Sperm has 3 parts
    1. Tail is called flagellum.
    2. Middle piece has mitochondria.
    3. Head has 23 chromosomes in the nucleus.
  1. Adhering to the nucleus is a lysosome called the acrosome. The acrosome has enzymes that help digest the zona pellucida (mucoprotein.) on egg.
  2. Interstitial cells between the seminiferous tubules produce androgens (testosterone).
  3. Sperm stored in epididymis, a coiled tubule (5-6 meters longs) just outside of testis.
    1. Epididymis joins with vas deferns, ascends the inguinal canal. Enters abdomen, curves around urinary bladder and empties into urethra.
    2. Urethra located in penis.
  1. Ejaculation: Seminal fluid comes from seminal vesicles, prostate gland and Cowperís gland.
    1. Prostate gland is a doughnut shaped gland around the urethra below the bladder. Prostate gland can enlarge and squeeze off the urethra.
    2. Seminal fluid is pH 7.5, contains fructose as sugar source, and prostaglandin that cause the uterus to contract. Contractions propel sperm towards egg.
    3. 400-600 million sperm in 3.5 ml of sperm.
    4. Infertile men have less than 35-50 million sperm (many abnormal in appearance).
  1. Hormone levels
  1. Hypothalamus controls testis functions.
    1. Gonadotropic releasing hormone (GnRH) stimulates the anterior pituitary to release gonadotropic hormones.
    2. FSH and LH are found in both sexes.
    3. FSH promotes spermatogenesis in seminiferous tubules.
    4. LH promotes production of testosterone.
    5. LH is controlled by negative feedback, which keeps blood testosterone at constant levels.
    6. Seminiferous tubules produce a hormone (inhibin) that blocks FSH secretion.
  1. Testosterone
  1. Involved in the development and function of primary sex hormones.
  2. Production of sperm.
  3. FSH causes spermatogenic cells to take up testosterone, which promotes spermatogenesis.
  4. Increases at puberty, stimulates maturation of penis and testes
  5. Secondary sex characteristics include beard, underarm hair, pubic hair, larynx and vocal cord enlargement, voice change, greater muscular strength, oil and sweat glands secrete acne and body odor.
  6. Involved in baldness. Baldness is a sex-influenced trait.
  7. Involved in sex drive and aggressiveness.
  1. Female Reproductive System
  1. Ovaries
    1. Outer cortex, inner medulla, follicles in cortex.
    2. Immature eggs are called oocytes.
    3. 2 million follicles reduced to 300-400K at puberty, 400 mature.
    4. Oogenesis takes place in the follicle. Primary become secondary oocytes.
    5. Primary oocytes divides into 2 cell each having 23 duplicated chromosomes.
    6. The secondary oocyte gets all the cytoplasm. The other oocyte is a polar body, which disintegrates.
    7. In the Graafian follicle the pressure balloons the wall of the ovary and bursts releasing the secondary oocyte. Rupturing of follicle is called ovulation. A clear membrane called the zona pellucida surrounds the secondary oocyte.
    8. When egg leaves the follicle becomes the corpus luteum, and secretes hormones.
    9. If no pregnancy the corpus luteum disintegrates in 10 days.
    10. If pregnancy the corpus luteum persists for 3-6 months and secretes estrogen and progesterone.
  1. Oviducts
    1. Called fallopian tubes.
    2. Fimbriae are finger like projections that sweep over the ovary.
    3. Cilia in oviducts sweep egg along.
    4. Egg can get lost and enter the abdominal cavity, and get fertilized.
    5. Egg moves along fallopian tube because of cilia and contraction.
    6. Fertilization and zygote formation occur in oviduct.
    7. Embryo arrives at uterus, and implants in uterine lining.
  1. Uterus
    1. Thick walled muscular, size of pear. Pound for pound the strongest muscle in the human body.
    2. Placed above bladder.
    3. The uterus is 5-cm side but can stretch to 30 cm.
    4. Lined with endometrium. Endometrium has two layers, the basal layer and the functional layer. The functional layer varies in thickness according to uterine cycle.
    5. Pap smears test for cancer of the cervix.
  1. Female hormone levels
  1. Hypothalamus secretes GnRH.
  2. Anterior pituitary secretes FSH and LH.
  3. Ovaries secrete estrogen and progesterone.
  4. Estrogen is responsible for sexual maturation at puberty and for secondary sex characteristics in females.
  5. Secondary sex characteristics include uterine cycle, body hair, fat distribution, enlarged pelvic girdle and breast development (progesterone too).
  1. Ovarian cycle
  1. Average of 28 days
  2. FSH secreted by anterior pituitary promotes the development of follicle in ovary. Follicle in ovary secretes estrogen, which exerts negative feedback control over anterior pituitary and FSH. FSH secretion ends, marked by ovulation on day 14 of 28 day cycle.
  3. High levels of estrogen cause GnRH to be released, leading to surge of LH on day 14.
  4. During 2nd half of cycle LH promotes development of corpus luteum, which secretes progesterone.
  5. Uterine lining builds up.
  6. Increased progesterone exerts feedback control over LH secretion, and degradation of corpus luteum.
  1. Estrogen and Progesterone
  1. Uterine cycle
  2. Days 1-5 low level of sex hormones, uterine lining disintegrates, flow of blood, menses, menstruation.
  3. If painful, endometriosis
  4. Days 6-13 increased production of estrogen thickens endometrium, ovulation on day 14.
  5. Days 15-28 progesterone causes endometrium to double in thickness, and there is a thick mucoid secretion. This is called the secretory phase.
  1. Pregnancy
  1. After implantation the placenta produces human chorionic gonadotropin (HCG) which maintains the corpus luteum until placenta makes progesterone and estrogen.
  2. Progesterone and estrogen shut down anterior pituitary and prepare breasts for breastfeeding.
  1. Breastfeeding
  1. Today 60 % of women try. Only 20 % continue past 6 months.
  2. Our parentís generation: 20 % of women tried.
  3. Historically princes have breastfed for 15 years.
  4. Worldwide 5 years is the average length of time.
  5. In Egypt the number of child mortality increases at 3 years, about the time of weaning.
  6. Breast milk contains antibodies, all the immunities that the mother has which protect the baby.
  7. Formula. Costs 1500 a year, and is bad for the environment, and not as good for human babies. Packaging, water use for cows is a burden on the environment.
  8. Breast milk is free and contains nutrients not found elsewhere. Staves of allergic reactions, allergies, and asthma.
  9. Formula fed babies see doctor 2 x as often as breastfed babies.
  10. Formula fed babies are hospitalized for bacterial infections, SIDS, cancer, dermatitis, ear infections, diarrhea, diabetes, and liver disease 4 x more often as breastfed babies.
  11. Breast milk is sterile and always the right temperature.
  12. Breastfed babies have less diaper rash and diarrhea.
  13. Breastfed babies have less colic, gas, and spit up.
    1. Breast milk contains lipase, an enzyme that breaks down fats.
    2. 300 components in breast milk.
  1. Breast milk has lower sodium and protein than formula, so there is less kidney stress.
  2. Ca and iron in breast milk is in a form that is easily absorbed.
  3. Breast milk helps to avoid childhood weight problems.
    1. The composition of breast milk changes in the am vs. PM.
    2. The composition of breast milk changes between the 1st month and the 7th. Goes from whole milk to lowfat.
    3. The fat composition changes during a feeding. 1st milk is lowfat, the longer the infant nurses the more fat is added to the milk.
    4. Increasing the number of feeding increases the fat content of the milk.
  1. Breast milk increases IQ scores 5-10 pts.
    1. Breast milk contains essential fats that are parts of the myelin sheath (insulation on nerve cells). If the mom does not eat the correct fats, the breast will make these fats.
    2. There is a lot of cholesterol in human milk, little in cows milk and none in formula. Cholesterol is needed in brain development.
    3. Human milk has more lactose than any other mammalian milk. The more lactose in the milk the larger the mammals brain is.
  1. Breastfed babies are 40 % less likely to have misaligned teeth.
  2. Breastfed babies have better eyesight.
  3. ADD may be related to the overabundance of magnesium in formula.
  4. Breastfeeding decreases the risk of breast cancer in the mom and infant.
  1. Menopause
  1. Occurs between ages 45-55
  2. Ovaries not sensitive to gonadotropic hormones and donít produce estrogen or progesterone.
  3. Hot flashes, dizziness, headaches, insomnia, sleepiness, and depression.
  1. Animal development
  1. Development is from fertilization to birth.
  2. Fertilization
    1. Fusion of nuclei of egg and sperm.
    2. The new cell is a zygote.
    3. Studied in sea urchins.
  1. Cleavage
    1. Rapid series of mitotic cell divisions.
    2. Produces smaller cells of various sizes, shapes and activities.
  1. Gastrulation is the migration of cells to form germ layer.
    1. Ectoderm forms all nervous tissue, epidermis of skin, parts of eyes and ears, hair, feather, pituitary gland, adrenal medulla, skin, sense organs, parts of head, neck and nervous system.
    2. Endoderm forms most epithelium of digestive system, or respiratory system, ducts of reproductive system, urethra and urinary bladder, thyroid, parathyroid, thymus, glands in liver, pancreas, breathing and digestion.
    3. Mesoderm forms muscle, cartilage, bone, blood, kidneys, and gonads. Support, movement, transport, reproduction, excretion, muscles.
  1. Notochord
    1. Soon after gastrulation the mesoderm forms the notochord.
    2. The influences the ectoderm to form the neural plate, which becomes the neural fold, around the neural groove.
    3. The fold grows towards each other to make a hollow tube.
    4. This is the future spinal cord.
  1. Differentiation
    1. Some cells never have their fate sealed. Stem tip of plants stays embryonic.
    2. Flatworms can regenerate themselves if cut in half. Salamanders can regenerate a lost limb. Seastars can grow whole from one piece. Sponge cells that have been separated can re-aggregate into a sponge.
    3. In humans, young children under 11 can regenerate lost fingers.
    4. A lot of cells have their fate sealed. This is called differentiation.
    5. Skin cells are skin cells, and muscle cells are muscle cells. The cells are reading the same book, but reading different chapters.
    6. How is regulation achieved? Development requires a sequence of events. All control of these events comes from the chromosomes.
    7. All cells have the same DNA.
    8. Some DNA is on and some is off. How?
    9. Some cells grow at certain time, some slow and die. Some cells tell other cells what to do.
    1. The notochord is the inducer of the spinal cord. You can transplant the notochord to other areas of the embryo and if it is done before differentiation of the ectoderm a spinal cord will form elsewhere.
  1. Stages
  2. Human Development