Fertilization

1. Fertilization
2. Stages of Fetal Growth and Development

3-4 days travel of zygote – mitotic cell division begins

*Pre-embryonic Stage

        a. Zygote- fertilized ovum. Lifespan of zygote – from fertilization to 2 months

b. Morula – mulberry-like ball with 16 – 50 cells, 4 days free floating & multiplication

c. Blastocyst – enlarging cells that forms a cavity that later becomes the embryo. Blastocyst – covering of blastocys that later becomes placenta & trophoblast

        d. Implantation/ Nidation- occurs after fertilization 7 – 10 days.

Fetus- 2 months to birth.

placenta previa – implantation at low side of uterus

Signs of implantation:

1. slight pain

2. slight vaginal spotting

- if with fertilization – corpus luteum continues to function & become source of estrogen & progesterone while placenta is not developed.

                        3 processes of Implantation

                                        1. Apposition

                                        2. Adhesion

                                        3. Invasion

C. Decidua – thickened endometrium ( Latin – falling off)

* Basalis (base) part of endometrium located under fetus where placenta is delivered

* Capsularies – encapsulate the fetus

* Vera – remaining portion of endometrium.

3. Chorionic Villi- 10 – 11^th day, finger life projections

3 vessels=

A – unoxygenated blood

V – O2 blood

A – unoxygenated blood

Wharton’s jelly – protects cord

Chorionic villi sampling (CVS) – removal of tissue sample from the fetal portion of the developing placenta for genetic screening. Done early in pregnancy. Common complication fetal limb defect. Ex missing digits/toes.

E. Cytotrophoblast – inner layer or langhans layer – protects fetus against syphilis 24 wks/6 months – life span of langhans layer increase. Before 24 weeks critical, might get infected syphilis

F. Synsitiotrophoblast – synsitial layer – responsible production of hormone

                1. Amnion – inner most layer 

                                a. Umbilical Cord- FUNIS, whitish grey, 15 – 55cm, 20 – 21”. Short cord: abruptio placenta or inverted uterus.

                                                Long cord:cord coil or cord prolapse

                                b. Amniotic Fluid – bag of H2O, clear, odor mousy/musty, with crystallized forming pattern, slightly alkaline.

                                                *Function of Amniotic Fluid:

1. cushions fetus against sudden blows or trauma

2. facilitates musculo-skeletal development

3. maintains temp

4. prevent cord compression 

5. help in delivery process

normal amt of amniotic fluid – 500 to 1000cc

polyhydramnios, hydramnios- GIT malformation TEF/TEA, increased amt of fluid

oligohydramnios- decrease amt of fluid – kidney disease