Thus, fertilization can still occur if intercourse takes place a few days before ovulation. If the sperm do not encounter an oocyte immediately, they can survive in the uterine tubes for another 3–5 days. Their journey-thought to be facilitated by uterine contractions-usually takes from 30 minutes to 2 hours. Thus, the race into the uterine tubes, which is the most typical site for sperm to encounter the oocyte, is reduced to a few thousand contenders. Of those that do enter, thousands are destroyed by phagocytic uterine leukocytes. Almost immediately, millions of these sperm are overcome by the acidity of the vagina (approximately pH 3.8), and millions more may be blocked from entering the uterus by thick cervical mucus. During ejaculation, hundreds of millions of sperm (spermatozoa) are released into the vagina. Transit of Spermįertilization is a numbers game. This new single cell, called a zygote, contains all of the genetic material needed to form a human-half from the mother and half from the father. Because each of these reproductive cells is a haploid cell containing half of the genetic material needed to form a human being, their combination forms a diploid cell. ![]() Summarize the events that occur as a sperm fertilizes an oocyteįertilization occurs when a sperm and an oocyte (egg) combine and their nuclei fuse.Explain capacitation and its importance in fertilization.Describe the obstacles that sperm must overcome to reach an oocyte.By the end of this section, you will be able to:
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |