| A | B |
|---|
| cell | the smallest unit of life that is able to reproduce itself |
| sperm | the male sex cell |
| ovum | the female sex cell; also called the egg |
| conception | the union of the ovum and sperm cells |
| zygote | the single cell formed at conception; also called a fertilized egg |
| fallopian tubes | two hollow tubes that connect to the uterus and have fingerlike projections that reach toward each ovary |
| uterus | the organ in which the baby develops and is protected until birth |
| genetic factors | traits that are passed through the genes |
| chromosomes | threadlike structures that carry genes in living cells |
| dominant traits | traits that always show in a person even if only one gene of the pair is inherited for that trait |
| recessive traits | traits that typically do not show in a person unless both genens for the trait are inherited |
| multiple pregnancy | pregnancy in which two or more babies develop |
| fraternal | term describing children from multiple pregnancies who develop from two ova and differ in genetic makeup |
| chorion | membrane that surrounds the baby in the uterus |
| identical | term describing children from multiple pregnancies who develop from one ovum and have identical genetic makeups |
| prenatal development | the development that takes plasce between conception and birth |
| germinal stage | the first stage of prenatal development, which lasts about two weeks after conception |
| amnion | a fluid-filled sac that surrounds the baby in the uterus |
| placenta | an organ filled with blood vessels that nurishes the baby in the uterus |
| umbilical cord | the cord that connects the baby to the placenta |
| embryonic stage | the second stage of prenatal development, which lasts about six weeks |
| embryo | term used to descibe a baby in the embryonic stage of development |
| cartilage | soft, elastic, flexible tissue that provides structure of the body |
| fetal stage | the third stage of prergnancy, lasting from about nine weeks after conception until birth |
| fetus | term used to describe a baby in the fetal stage of development |
| quickening | movements of the fetus that can be felt by the mother |
| age of viability | the age at which most babies could survive if they were born (28th week of pregnancy) |
