Is spontaneous conception possible? That is, is it possible for a fetus to develop in a host without sexual fertilization from a partner? I read this somewhere and couldn't believe it. The same article said it was also possible in a man.

S.

Spontaneous conception does not occur. An egg can spontaneously activate and grow, but it is not chromosomally normal, and a fetus does not develop. This situation results in the development of a cystic teratoma, a type of ovarian cyst. This abnormal mass can contain bits of recognizable human tissues, such as hair, skin, teeth, bone and nerve tissue, but it is not a fetus.

Men can also develop similar tumors, called testicular germ cell tumors. Again, these do not resemble fetuses, and they contain only abnormal tissue.