1. The Female Reproductive System Chapter 48

2. The Ovaries Produce both the egg cells and sex hormones Made primarily of connective tissue and held in place by ligaments Found internally, on either side of the uterus Released eggs travel from ovary, through oviduct (Fallopian tube) If egg is fertilized (in the oviduct), it implants in the endometrium of the uterine wall If egg is not fertilized, the egg and endometrium are shed through the cervix and vagina during menstrual ‘bleeding’

3. Oogenesis Oogonia – produced before birth Some oogonia increase in size and become primary oocytes At birth, these are in prophase of meiosis I This lasts through childhood and into adult life Each oocyte is surrounded by a barrier of granulosa cells that make up a follicle At puberty, a few follicles each month begin to mature in response to follicle-stimulating hormone (FSH) from the pituitary gland As the follicle matures, the oocyte completes meiosis I and produces 2 haploid cells – one polar body and one secondary oocyte The secondary oocyte goes into meiosis II but remains in metaphase II until fertilization

4. Ovulation – the release of the egg from the ovary The maturing follicle cells secrete fluids and estrogen These cells move closer to the surface of the ovary At ovulation the mature egg cell (called the ovum) is ejected from the ovary wall and into the pelvic cavity Cilia in the oviduct sweep the ovum into the tube and move it toward the uterus Sperm present in the oviduct when the ovum is present can result in fertilization and pregnancy

5. The menstrual cycle Designed to prepare the uterus for a pregnancy Days 1-5: menstrual bleeding – when the endometrium is being shed through the vagina Days 6-14: pre-ovulatory phase – development of follicle and build up of uterine lining Day 14: ovulation Day 15-28: (without fertilization) post-ovulatory phase – degeneration of egg, follicle, and endometrium This cycle is controlled by several hormones: – Estrogen, FSH, and progesterone

6. Fertilization Sperm survive within the female reproductive tract for 2 – 3 days The ovum remains viable for around 24 hours Pregnancy is most likely to occur during days 12-16 of the menstrual cycle – during the time of ovulation HOWEVER – most women do NOT have ‘regular’ menstrual cycles that always follow this pattern Unlike other mammals in which the females go into ‘heat’ when they are most likely to become pregnant, humans have no overt signs of ovulation Only one sperm is able to fertilize the ovum – the plasma membrane changes immediately The nucleus of the sperm and the ovum join to form one diploid cell

7. Pregnancy After fertilization, the zygote moves from the oviduct to the uterus and implants on in the endometrium The follicle remaining in the ovary continues to secrete hormones The placenta and the embryo develop together – the placenta is the connection between the mother and the infant A normal human pregnancy is considered 40 weeks from the first day of the last menstrual period Labor begins when the uterus contracts and the cervix dilates The placenta should be delivered after the baby Milk production begins shortly after birth

8. Birth Control Abstinence Chance Rhythm method Barrier methods – prevent sperm from reaching egg – Condom – Diaphragm – IUD (?) – Vasectomies and tubal ligations Chemical methods – Spermicidal creams and jellies Hormone methods – The ‘pill’ – Injectable contraceptive, patch, ring