Sperm cells cannot divide and have a limited life span, but after fusion with egg cells during fertilization, a new organism forms, beginning as a totipotent zygote.
During fertilization, the sperm provides three essential parts to the oocyte: a signalling or activating factor, which causes the metabolically dormant oocyte to activate; the haploid paternal genome; and the centrosome, which is responsible for maintaining the microtubule system.
Sperm quantity and quality are the main parameters in semen quality, which is a measure of the ability of semen to accomplish fertilization.
Possible problems could be that the egg is not released at the optimum time for fertilization, that it may not enter the fallopian tube, sperm may not be able to reach the egg, fertilization may fail to occur, transport of the zygote may be disturbed, or implantation fails.
It is increasingly recognized that egg quality is of critical importance and women of advanced maternal age have eggs of reduced capacity for normal and successful fertilization.
In these methods, fertilization occurs inside the body.
If conservative medical treatments fail to achieve a full term pregnancy, the physician may suggest the patient undergo in vitro fertilization (IVF).
Fertilization takes place outside the body, and the fertilized egg is reinserted into the woman's reproductive tract, in a procedure called embryo transfer.
Most chemical tests for pregnancy look for the presence of the beta subunit of hCG or human chorionic gonadotropin in the blood or urine. hCG can be detected in urine or blood after implantation, which occurs six to 12 days after fertilization.
The test for pregnancy that can give the quickest result after fertilization is a rosette inhibition assay for early pregnancy factor (EPF).
EPF can be detected in blood within 48 hours of fertilization.