(fĕr-tĭl-ĭ-zā′shŭn)
[Pronunciation]
[L. fertilis, reproductive]

The process that begins with the penetration of the secondary oocyte by the spermatozoon and is completed with the fusion of the male and female pronuclei.
This usually takes place in the fallopian tube. Viable spermatozoa have been found in the tube 48 hr after the last coitus. After the ovum is fertilized and the diploid chromosome number is restored in the zygote, cell division begins. The blastocyst then enters the uterus, where it may implant for continued nurture and development.

Figure: OVULATION, FERTILIZATION, AND EARLY EMBRYONIC DEVELOPMENT

Subentries:
heterologous fertilization
homologous fertilization
in vitro fertilization