1 Transmission: neurons transmit these signals to pain-processing structures of the spinal cord and brain. 2  Modulation: the signals can be amplified or dampened at various points in the pathway to facilitate or inhibit transmission, thereby enhancing or reducing the sensation of pain.
The sperm usually fertilizes the egg in the Fallopian tubes. Then, the fertilized egg moves down to the uterus where it implants, causing pregnancy. The segment of the Fallopian Tube where fertilization commonly occurs is the ampulla..
When the fertilized egg attaches itself to the uterine wall and begins to produce hCG it is called implantation. This typically occurs between 6 and 8 days after ovulation. The egg is fertilized in the outer part of the fallopian tube, generally within 12 hours of ovulation.After it is fertilized, the egg travels down the fallopian tube. The fertilized egg grows as it travels. It doubles, the grows to four cells and then to eight cells as it enters the uterus.Implantation occurs in the upper third of the uterus.Implantation sometimes can cause bleeding or minor spotting.fter it is fertilized, the egg travels down the fallopian tube. The fertilized egg grows as it travels. It doubles, the grows to four cells and then to eight cells as it enters the uterus. Implantation occurs in the upper third of the uterus. Implantation sometimes can cause bleeding or minor spotting.