Female Reproductive System and Pregnancy

Female Reproductive System

Objectives:
- What is the structure of the FRS?
- Reproductive cycles?
- Diseases of FRS?

- What is pregnancy?
- Major steps in pregnancy
- Changes in pregnancy

Ovary: 2 oval bodies in pelvic region. Outer cortex with follicles (connective tissue and blood vessels between follicles), inner medulla (connective tissue, blood vessels)
Functions:
1. Oogenesis - egg development
2. Production of steroid hormones (Estrogen, Progestins, Androgens)

Fallopian tube: 2 ducts connecting to uterus. Uterus - pear shaped region, endometrium (mucous membrane), myometrium (smooth muscle)

Vagina:
- canal of smooth muscle/mucous membrane connecting to exterior.
- External genitalia - vulva.
- Labia minus and Labia majus
- Clitoris

Female Reproductive Cycles

* Reproductive life of female: 2 cycles occuring simultaneously
* Menstrual - uterus
* Ovarian - ovaries
* Range = 24-35days
* Control: by Hypothalamus and Pituitary - GnRH, FSH, LH

Click diagram on the right to see fluctuations of hormones during one menstrual cycle.

1. Menstrual Cycle
* Period - 28 days.
* Growth of uterine endometrium for maintainance of fertilised egg.
* Shedding if fertilisation doesn't occur.
Follicular Phase: days 1-14
Luteal Phase: days 15-28

2. Ovulatory Cycle
* Development of mature eggs (oogenesis, primordial follicle to graafian)
* Graafian follicle (mature follicle)
* Ovulation (day 14, LH surge)
* Corpus luteum (yellow body, continues estrogen secretion if implantation of egg)
* Corpus albicans (degeneration of corpus luteum to white body, scar tissue, if no implantation of egg)

Oogenesis
- Formation of eggs in ovaries
- Embryo - oogonia; primary oocytes (1-2mill at birth)
- Primordial follicles (200,000-400,000 at puberty)
- Primary follicles; Secondary follicles; Tertiary follicles
- Graffian follicle has secondary oocyte - release 1/month; 400-500
- After fertilisation, meiosis complete - mature egg.

Menstrual and Ovulatory changes

 Hormones

- GnRH, Gonadotrophin Releasing Hormone. +ve anterior pituitary
- FSH, Follicle Stimulating hormone. +ve oestrogen from follicles, +ve development of Graafian follicle.
- LH, Luteinising Hormone. +ve ovulation, +ve devel of corpus luteum, +ve devel of follicles and oestrogens
- Oestrogens: repairs uterine wall, +ve LH
- Progesterone. +ve FSH production, +ve development of follicles, prepares endometrium and uterus for implantation
- Others: Inhibin, Relaxin, hCG

Hormonal Changes

Disorders

* Ovarian Cancer:
        - Risk factors: age>50yrs, ethnicity: caucasians, family history, exposure to asbestos
        - Very few symptoms, then gut, urinary, mentstrual
        - Ovarian cysts: fluid filled follicle or corpus luteum keeps growing
* Cervical Cancer
     - Causes: viruses (HPV), cigarettes, many sexual partners
* Endometriosis: growth of endometrial tissue outside uterus; eg. ovaries, abdominal wall, bladder.
* Pelvic inflammatory disease: bacterial infection of the pelvic organs; eg. uterus, fallopian tubes, ovaries
* Breast Cancer: age>30, genes (BRCA1,p53), post menopause, family history, excessive alcohol, cigarrete smoking, late pregnancy, high oestrogen
* STDs: Gonorrhea, Syphilis

* Menopause: gradual loss of cycles.
        - Age 45-55; Marked oestrogen, progesterone loss;
        - Changes - bone loss, vaginal atrophy and dryness, increased CVD risk, hot flushes;
        - Treatment: HRT
* PMS: discomfort - luteal phase
    - Symptoms: irritability, depression, bloating, weight gain, breast tenderness, headaches
* Dysmenorrhea: painful menstruation
    - ischaemia due to periodic contractions of uterus; Prostaglandins, ovulatory cycles
* Polycystic Ovarian Syndrome: large ovary, very few mature follicles, hirsutism, acne; High steroids, oestrogens, LH, low FSH;
              Cause: signal problem between ovary - (hypopituitary)?

Conclusions

1. FRS: ovaries, fallopian tubes, uterus and vagina

2. Menstrual cycle;28day,2phases: Follicular (growth of endometrium) and Luteal (shedding of endometrium)

3. Ovulatory Cycle: development of Graafian follicle (oogenesis), ovulation and Corpus Luteum formation.

4. Regulation: GnRH, FSH, LH.  

           - Oocyte development: FSH, FSH and LH stimulation, Oestrogen. Inhibin and Oestrogen inhibit FSH.     

           - Ovulation: day 14, high [FSH, LH, Oestrogen]

           - Corpus Luteum: follicle collapse, LH, Oestrogen and Progesterone secretion

5. Disorders: cancer of ovaries, breast, cervix; STDs

Pregnancy

What is Pregnancy?
Major steps in pregnancy?
Changes in Pregnancy?

Pregnancy is the period of approximately 9 months from fertilixation to parturition, during which a fertilised egg undergoes development to a foetus.

Transport:     Sperm: release into vagina -> uterus -> fallopian tube
                       Egg:  ovulation, down fallopian tubes (cilia, smooth muscle) to uterus

Fertilization

Fertilization in fallopian tube, formation of Blastocyst


Journey to Uterus
Zygote -> cleavage -> Morula -> Blastocyst

Blastocyst
- Outer layer: trophoblast - placenta
- Inner cell mass: embryo
- Central fluid cavity: amniotic cavity

Implantation of Blastocyst

Placenta
- Structure: flat, selective permeable barrier, 25mm thick, weight=500g, d=185mm, S.A=10m^2. Fetal part,  chorian, outer layer. Maternal part: decidua basalis (endometrium). Chorionic villi: capillaries linking foetal and maternal circulations.
- Functions: exchange, protection, production, metabolic, endocrine

Development

Development

Embryo:
 - 3rd week: 3 layered embryo. 2mm long -> Gastrulation -> organogenesis
- 8 weeks: 22mm long, 1g weight
- 9-40: foetus

Blood Supply

 Changes in Pregnancy

a. Hormonal changes during pregnancy

b. Effects of pregnancy on the mother

c. Pregnancy prevention

Hormonal changes

a. Hormonal changes
- Corpus luteum: Oestrogen and Progesterone
- Trophoblast tissue: human Chrorionic Gonadotropin (hCG)
- Placent: oestrogen, progesterone, hCG, HPL, others: Relaxin, ACTH, TSH





b. Effects of pregnancy on the mother
- Anterior Pituitary enlargment
- Larger breasts, uterus
- Increased size of placenta
- Ca2+ increase
- CVS: blood volume, H2O retention, BP, HR, C.O
- Respiratory: increased FVC, dyspnoea
- Others: nausea, vomiting, constipation, more urine, backaches, increased weight

c. Pregnancy Prevention
- Birth control pills
- Morning after pill
- Mifepristone
- Depoprova
- Norplant
- IUD
- Barrier
- Others: Vasectomy, Coitus Interruptus
- Newer: Inhibin, GnRH antagonist