NARM Practice: Embryonic and Fetal Development Study Guide

24-28 weeks from conception (26-30 weeks from LMP) CORRECT ANSWER Legally "viable," eyelids open, and respiratory movements are present 28-32 weeks from conception (30-34 weeks from LMP) CORRECT ANSWER Fetus begins to store fat and iron. Lanugo disappears from face. Testes descend into scrotum. Skin becomes less wrinkled. 32-36 weeks from conception (34-38 weeks gestation) CORRECT ANSWER Increased fat, lanugo disappears from body, plantar creases visible, ear cartilage soft, weight gain of approximately 25 grams per day. Day 2 post fertilization CORRECT ANSWER Cleavage: zygote divides into blastomeres Day 3 post fertilization CORRECT ANSWER Morula: 12-16 cells, blastomeres clump into morula through compactation. Days 4-5 post fertilization CORRECT ANSWER Cavitation: morula forms fluid-filled cavity called blastocele. Zygote is now a "blastocyst." Trophoblast and embyroblast develop. Day 6 post fertilization CORRECT ANSWER Implantation occurs, and trophoblast differentiates into syncytiotrophoblast and cytotrophoblast. Days 8-9 post fertilization CORRECT ANSWER Bilaminar disc and yolk sac form. Days 13-14 post fertilization CORRECT ANSW