Embryo Clay Model Answers
1. Circle the stages at which the embryonic stem cells are totipotent. Underline the stage at
which cells are pluripotent.
Day 1 ZYGOTE – 8 CELL STAGE ZYGOTE – MORULA – BLASTULA – GASTRULA
2. At what stage of development do stem cells first differentiate?
Early blastocyst
3. At what stage of embryonic development are stem cells used to generate embryonic cell
lines? What type of stem cells are found at this stage?
Blastula
Pluripotent
4. What types of tissues are formed from the following primary germ layers?
a. Endoderm – lungs and digestive system
b. Ectoderm – skin, nervous system
c. Mesoderm – bone, muscle, connective tissue
5. If an embryo entered the uterus at the morula stage would it implant successfully into the
uterine wall? Explain you answer.
No,
a. The morula still has the zona pelludida membrane
b. The cells of the morula have not differentiated to form the trophoblast cells which secrete
the enzyme required to erode the uterine lining for implantation.