Related to Precordial pain: costochondritis, Pulsus paradoxus, retrosternal pain. unpleasant or hurtful sensation resulting from stimulation of nerve endings. The stimulus is carried by nerve fibers to the spinal cord and then to the brain, where the nerve impulse is interpreted as pain.
Full transcript. The sperm race begins Ejaculation The race resumes A man's penis releases around 20 million sperm into the woman's vagina, where they then begin their journey.Around 2,000 sperm then travel up to the top of the vagina and through the cervix.aiting for the egg When the sperm are awakened they travel to egg and the race resumes. Time to be born The mother's Muscles contract to push the baby out. The amnion sack breaks ('water' breaks). The head moves into the entrance of the vagina.
Spermatogenesis is the process in which an animal produces spermatozoa from spermatogonial stem cells by way of mitosis and meiosis. The initial cells in this pathway are called spermatogonia, which yield primary spermatocytes by mitosis. The primary spermatocyte divides meiotically into two secondary spermatocytes; each secondary spermatocyte divides into two spermatids by Meiosis II. These develop into mature spermatozoa, also known as sperm cells. Thus, the primary spermatocyte gives rise to