PSYC 100 Lecture Notes - Amniotic Sac, Neural Tube, Morula

• School: Queen's University
• Department: Psychology
• Course: PSYC 100
• Professor: Ingrid Johnsrude

Document Summary

Germinal period: the first two weeks after the sperm and egg unite. During this time, the newly formed zygote grows and divides in a process called cleavage (which starts about 24 hours after conception). After cleavage occurs a few times, the resulting mass of cells is called the morula: a solid mass of blastomeres resulting from a number of cleavages of a zygote. Blastocyst: up until now, the developing organism has been in the fallopian tube, where conception occurs and is travelling down into the uterus. Layers of cells: after implantation in the uterine wall the embryonic period begins and lasts about 8 weeks. Neural tube: the embryo"s precursor to the central nervous system. Embryo turns in on itself and forms a small tube of ectoderm inside the embro. This tube begins to develop into the brain and spinal cord, in a process called neurulation. All cells of the central nervous system are grown inside this tube.