Week 1: Preconception/Wellness & Prevention/Conception
Chapter 14-15 (P. 250-260)
Prenatal development (3 stages): pre-embryonic, embryonic, and fetal.
Pre-embryonic
 Begins with conception and ends ~2 weeks later with establishment of fetal membranes. After
fertilization, the fertilized ovum (now diploid, half chromosomes from mother & the other from
father) is referred to as a zygote.
 Zygote divides and generates new cells via mitosis or cleavage. It travels down the fallopian tube
toward the uterus. The pre-embryonic mass develops into collection of 12 to 32 small cells referred to
as blastomeres.
 Stages of Pregnancy and Cell Division Status
 Morula (day 3-4): 12-32 blastomeres combine.
 Blastocyst (day 5-9): ending with implantation; 200-300 cells differentiates, trophoblast
(outer cells) becomes the placenta and the inner cell mass adherent to the trophoblastic
ring called embryoblast  embryo. Fluid-filled cavity
 Embryo (day 10-week 8): implantation; many cells; differentiation is completed. Inner
cells differentiate into germ layers: ectoderm, mesoderm, and endoderm which originate
all organs and other structures.
 Fetus (week 9-end): many cells; significant growth and development occurs.
Chapter 19 (P. 401-407)
Chapter 26 (P. 601-604)
Chapter 27 (P. 631-636 and P. 644-649)
Chapter 29 (P. 701-706)