Chapter 17, Problem 20P

Hydatiform moles are growths of undifferentiated tissues that form within the uterus during an abnormal molar pregnancy. These moles are usually made up of XX diploid cells, although some can be XY diploids. Surprisingly, all of the DNA in the nuclei of the cells in the mole is paternal in origin. Most hydatiform moles are benign, but because they sometimes can develop into cancers, these moles should be removed surgically when they are detected.

a.	What kinds of events could lead to the generation of a hydatiform mole?
b.	Hydatiform moles are diploid cells with the normal numbers of genes and chromosomes. Why do you think they develop as undifferentiated tissues rather than as normal embryos?