Embryonic Development Lecture 1

During which period of human pregnancy does organogenesis primarily occur?

• First trimester (embryonic period)

• Second trimester (fetal period)

• Third trimester (fetal period)

• Menstrual cycle

One reason to study embryonic development is:

• To predict the exact birth date of all babies

• To understand organ formation and how genetic disorders affect development

• To eliminate the menstrual cycle

• To prevent all diseases in adults

Where does fertilization normally occur in humans?

• Ovary

• Uterus

• Fallopian tube

• Cervix

What is the solid ball of cells formed after the early mitotic divisions of a fertilized ovum called?

• Blastocyst

• Morula

• Zygote

• Gastrula

How many cells typically make up the morula before it forms a blastocyst?

• 2–4 cells

• 6–8 cells

• 12–15 cells

• 20–25 cells

Which of the following is a feature of the blastocyst?

• Solid ball of 12–15 cells with no cavity

• Hollow cellular mass with trophectoderm, inner cell mass, and blastocoel

• Single-celled zygote

• Fully formed embryo with organs

What will the inner cell mass of the blastocyst form?

• Placenta

• Entire embryo

• Amniotic fluid

• Trophoblast

During implantation, the blastocyst:

• Remains in the fallopian tube

• Invades the endometrium of the uterine wall

• Forms the morula

• Completes organogenesis

Which of the following processes during week 3 establishes the three germ layers of the embryo?

• Neurulation

• Somitogenesis

• Gastrulation

• Embryo folding

What is the role of the primitive streak during gastrulation?

• Site of neural tube formation

• Site where cells migrate to form the three germ layers

• Site of embryo folding into a C-shape

• Site of somite formation