如果母亲的卵细胞与父亲含有__________染色体的精子相融合，受精卵的性染色体就是________，她生下的就是女孩。否则就是男孩。可见，生男生女是由父亲的染色体决定。

Which one of the following statements about epithelia is FALSE

A．They are polarized

B．They are vascular

C．They are separated from underlying connective tissue by a basal lamina

D．They contain only a small amount of intercellular substance

E．They line the lumen of blood vessels