Remember these terms having to do with the events of pregnancy.

a. Amnion–the thin, tough, innermost layer of the membranous sac that surrounds the fetus. This sac, also called the bag of waters, contains amniotic fluid.

b. Chorion–the outermost membrane enclosing the fetus.

c. Embryo–an organism in the earliest stages of development; in humans, from the time of conception to the end of the second month in the uterus.

d. Fetus–the developing offspring in the uterus, from the second month of pregnancy to birth.

e. Gestation–the name for pregnancy; the period of time between conception and birth of the child. The normal duration of human pregnancy is about 280 days, 10 lunar months (months of 28 days each), or 9 calendar months.

f. Hyaluronidase–an enzyme found in sperm (also in snake and bee venom) that causes the breakdown of hyaluronic acid in the tissue spaces of the ovum, thus enabling sperm to enter the cells and tissues of an ovum.

g. Organogenesis–the origin and development of organs.

h. Ovum (sg), Ova (pl)–female reproductive cells capable of developing, after fertilization, into new individuals.

i. Parturition–the act of giving birth; also called childbirth.

j. Placenta–the organ within the pregnant uterus through which the fetus is nourished.

k. Semen–a white fluid produced by the male sex organs as a vehicle for sperm. Another name for semen is seminal fluid. This fluid is mostly composed of sperm plus secretions from the seminal vesicles, the prostate gland, and the Bulbourethral glands.

l. Sperm–A mature reproductive cell of the male.

m. Zygote–the new cell which is formed when a sperm nuclei and an ovum fuse.