28. Pregnancy and Human Development

Fill in the blanks: During the pre-embryonic period, the conceptus divides into hundreds of cells by a process called ________ and becomes a/an ________ , which implants in the uterine wall.

Fill in the blanks. The blastocyst has two distinct cell populations: large, flat cells called the ________ , and a cluster of round cells called the________.

Match the extraembryonic membrane with the correct statement:

________Amnion

________Yolk sac

________Allantois

________Chorion

a. Forms part of the digestive tract and is the first extraembryonic membrane to form

b. Forms the base for the umbilical cord and later becomes part of the urinary bladder

c. Encloses the conceptus and secretes fluid to fill the sac

d. Forms outgrowths that blend with the stratum functionalis layer of the uterus

Fill in the blanks: _____+ is the process of forming the placenta, which is a disc-shaped organ that attaches to the fetus via a/an .

Match the structures of the embryo with the primary germ layer from which each developed. Each germ layer will have more than one structure.

________Endoderm

________Mesoderm

________Ectoderm

a. Nervous system

b. Linings of the digestive tract

c. Skeletal structures

d. Epidermis of the skin

e. Thyroid and parathyroid glands

f. Skeletal muscles

What are the two types of embryonic folding?

Why is the single-celled zygote approximately the same size as the multicellular blastocyst before it implants in the uterine wall?