John W. Santrock,
University of Texas, Dallas
| amnion | the life-support system that is a bag or envelope that contains a clear fluid in which the developing embryo floats.
(See 101)
|
 |
|
|
| blastocyst | the inner layer of cells that develops during the germinal period. These cells later develop into the embryo.
(See 100)
|
|
|
|
| ectoderm | the outermost layer of cells, which becomes the nervous system, sensory receptors (ears, nose, and eyes, for example), and skin parts (hair and nails, for example).
(See 101)
|
|
|
|
| embryonic period | the period of prenatal development that occurs two to eight weeks after conception. During the embryonic period, the rate of cell differentiation intensifies, support systems for the cells form, and organs appear.
(See 101)
|
|
|
|
| endoderm | the inner layer of cells, which develops into digestive and respiratory systems.
(See 101)
|
|
|
|
| fetal alcohol syndrome (FAS) | a cluster of abnormalities that appears in the offspring of mothers who drink alcohol heavily during pregnancy.
(See 107)
|
|
|
|
| fetal period | the prenatal period of development that begins two months after conception and lasts for seven months, on the average.
(See 102)
|
|
|
|
| germinal period | the period of prenatal development that takes place in the first two weeks after conception. It includes the creation of the zygote, continued cell division, and the attachment of the zygote to the uterine wall.
(See 100)
|
|
|
|
| mesoderm | the middle layer of cells, which becomes the circulatory system, bones, muscles, excretory system, and reproductive system.
(See 101)
|
|
|
|
| organogenesis | organ formation that takes place during the first two months of prenatal development.
(See 102)
|
|
|
|
| teratogen | from the Greek word tera, meaning "monster." Any agent that causes a birth defect. The field of study that investigates the causes of birth defects is called teratology.
(See 105)
|
|
|
|
| toxoplasmosis | a disease caused by a parasite with which humans can become infected by eating raw meat or by not washing their hands after touching cats' feces or yard dirt. It can be transmitted to the fetus and can cause eye defects, brain damage, or premature birth. A mild infection that causes coldlike symptoms in adults but can be a teratogen for the unborn baby.
(See 113)
|
|
|
|
| trophoblast | the outer layer of cells that develops in the germinal period. These cells provide nutrition and support for the embryo.
(See 100)
|
2003 McGraw-Hill Higher Education