This preview shows pages 1–3. Sign up to view the full content.
This preview has intentionally blurred sections. Sign up to view the full version.View Full Document
Unformatted text preview: ANTEPARTUM- THE FAMILY BEFORE BIRTH 2007 2008 CONCEPTION Union of egg (ovum) and sperm Ovum burst from follicle at ovulation- Ovulation is 14 Days before the next period would begin.- The Egg bursts through weak spots of the follicle. Collapsed Follicle is transformed to corpus latum which is used to make final preparation of uterine lining for fertilized ovum. Fertile for 24 hours after ovulation Ejaculation releases 200 to 500 million sperm- Most sperm survive < 24 Hours in Female reproductive Tract , But few can remain for up to 5 days. Average transit time to site of fertilization is 4 to 6 hours Viable for 2 to 3 days Capacitation- is when the sperm changes to be able to penetrate the ovum FERTILIZATION Takes place in ampulla (outer third) of the fallopian tube Zygote formed and travels to uterus (3 to 4 days) Zygote forms morula the morula is a bundle of 12-16 cells secretes fluid and becomes blastocyst Morula becomes blastocyst Blastocyst develops into embryo and the embryonic membranes PAGE 92 PICTURE- the inner cell of the blastocyst develops in to the fetus - The outer cell of the blastocyst develops into the placenta and fetal membranes PROCESS OF FERTILIZATION- Sperm enters the ovum- 23 Chromosomes from sperm mingle with the 23 Chromosomes from the ovum = 46 (diploid)- Fertilized ovum (egg) is then called a zygote- and is then ready for the first mitotic cell division. IMPLANTATION Occurs between 6 and 10 days after conception Trophoblast burrows into the endometrium (lining of the uterus) until blastocyst completely covered. 1 Chorionic villi develop out of trophoblast & become fetal side of placenta- Chorionic Villi- used sometimes for genetic testing. Chorion secretes hCG- FIGURE 6-4- Upper uterus is the best area for implantation Because: o Rich blood supply (good for fetal gas exchange and placental development) o Thick uterine lining (easy expulsion of placenta after birth) o Limits blood loss after birth. o IMPLANTATION PROCESS- PG 92- Blastocyst- consists of nearly 100 cells- at this point it enters the uterus.- Blastocyst lingers in the uterus 2-3 days before beginning implantation--endomitrium is now called deciduas. Zygote secretes hCG- which signals that pregnancy has begun. EMBRYONIC DEVELOPMENT- PAGE 93 Embryonic stage lasts from day 15 until 8 weeks after conception Critical stage due to organ development Embryo vulnerable to teratogens End of 8 weeks all organ systems & external structures present At 9 weeks considered a fetus PLACENTA Develops during 3 rd week, completely functional by 12 th...
View Full Document
- Spring '08