Female Reproductive System

Reproduction and Development

Outcomes5. Identify the structures in the human female reproductive system and describe their functions. Ovaries, Fallopian tubes, Uterus, Endometrium, Cervix, Vagina

● Fetal Development: ovaries develop in abdomen - descend but remain in pelvic region

● At Birth: all oocytes (immature ova) are present in ovary

Female Development

● Puberty: hormonal stimulation - maturation of reproductive organs - stimulates reproductive cycle where one ovum matures every month - development of secondary sex characteristics

Anatomy● Ovaries: site of oogenesis (production of ovum)

- suspended by ligaments in abdominal cavity - contain follicles: specialized cells where ova develop

● Fallopian Tube (oviduct): connect ovaries to uterus - 2 tubes, at ends are fimbria (finger-like projections)

● Uterus (womb): largest organ - muscular, hollow - site of embryo/fetal development- outer lining and inner glandular lining (endometrium) - in humans: single hollow structure (simplex) - other mammals: duplex (separate uteri), bicornate (2 extenstions), bipartite (separate uteri, but share cervix)

1 Ovary: #2 Uterine Horn: #3 Uterine Body: #4 Cervix: #5 Uterine artery !Not a human image.

Not a human image

● Cervix: muscular ring, separates vagina from uterus - dilates during birth

● Vagina: connects uterus to outer environment- muscular, acidic (protects against microbes) - birth canal- site of sexual intercourse

Cervical Cancer● Abnormal cell division: cancer ● Main risk factor: infection of cervix by human papillomavirus

(HPV)- HPV: group of more than 100 viruses - some common, fought off by immune system - some sexually transmitted, cause changes to cervical cells -person may not have any symptoms or may get genital warts -Some HPV infections take up to 2 years to clear up !

● over 70% of people will have at least one genital HPV infection in their lifetime. Certain types of HPV infection cause almost all cases of cervical cancer. Recent data from Alberta shows that almost 100% of oropharyngeal head and neck cancers in men under 40 are HPV-related. The vaccine for boys is the same one that protects girls from the cause of 70% of cervical cancers.

● http://www.health.alberta.ca/health-info/imm-HPV.html

Cervical Cancer● Some factors increasing risk:

- smoking- sexually active at young age- multiple partners or sexual partner who has had many partners - on birth control for a long time

● Detection: Pap test ● Cells of cervix collected, analyzed for

abnormalities ● Test done every 2 years ● If abnormal cells detected, a colposcopy may

be required for further analysis ● If abnormalities are High-grade, the cervix will

be scraped of the lesions Treatment of High Grade

CervicalIntraepithelial Neoplasia

Oogenesis● Formation of an ovum ● Ovum (mature): ~ 100 000 times larger than sperm cell

- packed with nutrients for fast division upon fertilization - one released at a time

● Oocytes (immature): divides, halves chromosome number - 46 to 23 chromosomes

● Oogenesis occurs in specialized follicles in ovaries ● Follicles: 2 types of cells

- primary oocyte- granulosa: provides nutrients

Oogenesis● Begins when granulosa cells divide,

develops ● Primary oocyte divides, cytoplasm and

nutrients move to one end pole - secondary oocyte formed, 23 chromosomes - other cell: first polar body, has little cytoplasm and dies

● Follicle ruptures, secondary oocyte released into oviduct- pushes on ovarian wall, enzymes from inside weaken follicle wall

● OVULATION!!

Ovarian wall of pig ovary during ovulation

Secondary oocyte and polar body

Oogenesis● Surrounding cells of follicle remain in ovary ● Transformed into corpus luteum

- secretes hormones essential for pregnancy ● No pregnancy? Secondary oocyte swept into fallopian tube

(oviduct) by fimbria- moved along tube by cilia- healthy sperm present, fertilization occurs

● Cell division of secondary oocyte: unequal division of cytoplasm - develops into fertilized ovum and second polar body

● Secondary oocyte not fertilized? (No pregnancy) Deteriorate within 24 hrs and die- second cell division does not occur-Corpus luteum degenerates 10 days after ovulation

- woman will menstruate Ovarian Cycle

Corpus luteum in cat ovaries

Use Your Knowledge1. Sketch and label a diagram of the female reproductive system.

2. What is a pap smear? !!3. Tubal ligation ties the Fallopian tubes as a method of female sterilization. a) Why would a woman who has undergone this

procedure be unable to get pregnant? !!

b) Would a woman who undergoes a tubal ligation still menstruate?

4. What is the role of follicles in ovulation? !!!5. Describe how the corpus luteum forms in the ovary.

Criterion Sperm Cell Egg Cell

Size

Energy Reserves

Mitochondria

Numbers Produced

Motility

Outer structures

Outcomes6. Identify the principal reproductive hormones in the female and explain their interactions in the maintenance of the mensrual cycle Estrogen, Progesterone, FSH, LH !7. Describe the role of hormones in the regulation of primary and secondary sex characteristics in females GnRH, FSH, LH, Estrogen, Progesterone

Menstrual Cycle● Puberty: initiates menstrual cycle

includes oogenesis, ovulation and thickening/shedding of endometrial layer of uterus

● Menstrual cycle Lasts approx 28 days, repeated over reproductive lifetime

● Regulated by hormones

4 phases: ● Flow phase: ● beginning of cycle, shedding of endometrium, (5 – 6 days)

● Follicular phase: ● development of follicles in ovary (days 6 – 13)

● Ovulatory phase: ● secondary oocyte bursts from ovary (day 14)

● Luteal phase: ● development of corpus luteum (days 15 – 28) !

● Endometrial thickness increases as cycle progresses (blood vessels & glandular tissues)

Estrogen & Progesterone

● Estrogen: development of secondary sex characteristics, promotes thickening of endometrium

● Progesterone: prepares for embryo, inhibits further ovulation, prevents uterine contractions, firms cervix

!● Developing follicles: stimulates estrogen release from ovaries ● Secondary oocyte bursts: estrogen levels decline ● Corpus luteum: secretes both estrogen and progesterone

Estrogen & Progesterone● Fertilization DOES NOT occur??

- concentrations of estrogen and progesterone decrease, uterine contractions begin - endometrium pulls away from uterine wall (menstruation) - marks beginning of next flow phase

Menopause● Each ovary contains approx. 400 000

follicles at puberty ● Many develop during each cycle, but

one dominant and reaches maturity ● Remaining deteriorate and reabsorbed ● Approx ages 12 – 50 yrs: ~ 400 eggs

mature ● Menopause: ovulation ceases,

hormonal levels drop ● Potential genetic defects: older follicles

(older women) ● Menopause marks end of reproductive

life

Feedback Control of Menstrual Cycle

● Hypothalamus-pituitary regulates production of estrogen and progesterone

● Gonadotropins FSH and LH regulate control of estrogen and progesterone, which then control gonadotropins by negative feedback

● Puberty: release GnRH from hypothalamus ● GnRH activates pituitary gland, releases FSH and LH ● Follicular phase: blood carries FSH to ovary, follicle

development stimulated - follicles secrete estrogen, initiates development of endometrium - rise in estrogen, negative feedback message sent to pituitary, FSH turned off

● Rise in estrogen stimulates LH-producing cells of pituitary - LH rises and ovulation occurs

● Luteal phase: remaining follicular cells, under influence of LH, transform into corpus luteum - secrete both estrogen and progesterone, build-up further increases development of endometrium - buildup triggers second negative feedback mechanism - inhibit release of both FSH and LH

● Without gonadotropins, corpus luteum deteriorates - estrogen and progesterone levels decrease, menstruation begins

● Both sexes produce testosterone and estrogen - males produce more testosterone than estrogen - estrogen excreted at accelerated rate in males (stallions)

USE YOUR KNOWLEDGEFemale Menstrual Cycle

Phase Description of Events Hormone Produced Days

--- 1-5

Estrogen (by follicle cells)

--- 14

Estrogen and Progesterone (by corpus luteum)

Female Reproductive Hormones

Hormone Location Function

Follicle cells (ovary)

Progesterone

Anterior Pituitary

Luteinizing Hormone (LH)

1. Describe the process of ovulation. Differentiate between primary oocytes, secondary oocytes, polar bodies, and ova. !!!!

2. Predict how low secretions of gonadotropin-releasing hormone from the hypothalamus would affect the female menstrual cycle.

3. Explain why female birth control pills often contain high concentrations of progesterone and estrogen. !!!!4. Explain why only one corpus luteum may be found in the ovaries of a woman who has given birth to triplets.