A secondary headache is a symptom of a disease that can activate the pain-sensitive nerves of the head. Any number of conditions â varying greatly in severity â may cause secondary headaches. Possible causes of secondary headaches include: Acute sinusitis. Arterial tears (carotid or vertebral dissections)
The fallopian tube is a crucial structure involved in successful reproduction and, like with all structures in the human body, sometimes problems occur that hinder the structure's ability to function properly.
Out of the approximately 1,000 sperm that enter the Fallopian tube, only about 200 reach the egg. The rest get attached to the lining of the oviduct, or just give out and die. Out of the approximately 200 sperm that reach the egg, only 1 enters the egg to fertilize it.The rest are pushed away by the zona reaction, which makes the fertilized egg impermeable to additional sperm.ut of the approximately 200 sperm that reach the egg, only 1 enters the egg to fertilize it. The rest are pushed away by the zona reaction, which makes the fertilized egg impermeable to additional sperm.