Jen and Human Biology: Unit 4 Online Lab- Embryonic and Fetal Development

For this lab, we were to pick what we thought were the ten (10) most important stages in embryonic/ fetal development, and then explain why we think it's important. Here are my ten:

Stage 1- 1 day post ovulation (po)- sperm penetrates an Oocyte (egg) and it ends with the creation of a Zygote- important because without fertilization, there would be no Zygote.

Stage 6- 13 days po- placenta and stalk form, and primitive streak, gastrulation, and ectoderm appear- important because without the placenta, the embryo could not survive.

Stage 10- 21 to 23 days - somites appear, neural folds begin to fuse, and heart folds begin to fuse, forming the beginning of a heart which begins to contract- important because the heart is a major part of the body, it keeps it going and things working.

Stage 13- 26 to 30 days- the first thin surface layer of skin appears covering the embryo- important because skin holds the body all together and helps keep things out of the body.

Stage 20- 51 to 53 days- the brain is connected to muscles and nerves which enable the embryo to make spontaneous movements, the nose is formed, and the reproductive organs are forming- important because the nervous system is imperative for movement, the nose for the sence of smell and for taste, and the reproductive organs for obvious reasons.

Week 14- Fetal sexual organs are now clearly visible- for me, this is important for ultrasound purposes. I like to plan ahead. It's good to remember though, that ultrasounds, especially at 14 weeks, are not always acurate.

Week 16- Finger prints and toe prints begin to develop, and circulation is completely functional- important because finger and toe prints are unique, no two are alike, and because the circulatory system is imperative for a functioning body.

Week 20- Bone marrow starts to make blood cells- WBCs are needed for the immune system, RBCs are needed for transport of O2, CO2, and other wastes, and platelets form plugs in damaged vessels for repair. All three being important in their own way.

Week 26- Lungs begin to produce Surfactant and are capable of breathing air- important because lungs are needed for O2 CO2 exchange in RBCs.

Week 32- The fetus begins to develop an immune system- important because a strong immune system is needed to fight of foreign bodies in the body (Ex: viruses and bad bacteria).