Most mammals are “placental,” which is to say their embryos get nourishment within the mother through the placental system of blood vessels reviewed in the text. By contrast, amphibian and reptilian embryos are nourished by substances contained in eggs the mother lays. Can you think of any advantages mammals derive from the placental means of development? Can you think of any disadvantages?

The structure in which sperm are stored and complete their maturation is the:

a. epididymis.

b. oviduct.

c. penis.

d. prostate gland.

e. vas deferens.

Forty years after birth control pills for women came into widespread use, there is still no birth control pill for men. One reason for this is the basic difference between female production of an oocyte each month and the male production of sperm. Why should it be easier to suppress fertility in women than in men?

The tertiary follicle (select all that apply):

a. contains a maturing spermatocyte.

b. contains a maturing oocyte.

c. is transformed into the corpus luteum.

d. is washed away with the endometrial lining.

e. expels an oocyte in ovulation.

The natural degeneration of follicles during a woman’s lifetime is referred to as:

a. menopause.

b. ovulation.

c. puberty.

d. atresia.

e. apoptosis.

The portion of the blastocyst called the trophoblast eventually helps form the:

a. head of the baby.

b. legs of the baby.

c. entire baby.

d. nervous system of the baby.

e. placenta.

Birth of identical twins results from unusual events during:

a. egg production.

b. sperm production.

c. early cell divisions after fertilization.

d. ovulation.

e. second trimester.

Arrange the following events in their proper sequence:

a. uterine muscle contractions

b. birth of baby

c. assumption of fetal head-down position

d. expulsion of placenta

e. dilation of cervix

The homeobox-containing genes that are active in development have been highly _______, meaning they have remained relatively unchanged though the course of evolution. These genes contain information for producing _______.

Three tools that work in development across animal species are cell _______, cell _______, and programmed cell ______.