Fertilization normally occurs in the uterine tubes. Each sperm contains a large, enzyme-filled vesicle above its nucleus, known as an acrosome , that is central to this task fig. The interaction of sperm with particular molecules in the zona pellucida triggers an acrosomal reaction. This involves the progressive fusion of the acrosomal membrane with the plasma membrane of the sperm, creating pores through which the acrosomal enzymes can be released by exocytosis.
Difference Between Oocyte and Follicle
Fertilization | Anatomy and Physiology II
Human fertilization is the union of a human egg and sperm , occurring in the ampulla of the fallopian tube. Scientists discovered the dynamics of human fertilization in the nineteenth century. The process of fertilization involves a sperm fusing with an ovum. The most common sequence begins with ejaculation during copulation , follows with ovulation , and finishes with fertilization. Various exceptions to this sequence are possible, including artificial insemination , in vitro fertilization , external ejaculation without copulation, or copulation shortly after ovulation. The sperm plasma then fuses with the egg's plasma membrane, triggering the sperm head to disconnect from its flagellum as the egg travels down the Fallopian tube to reach the uterus.
Oocyte Development During the Reproductive Cycle
After sperm penetration through the zona pellucida , the sperm plasma membrane fuses with the oocyte plasma membrane in a narrow equatorial region of the head, followed by incorporation of the whole spermatozoon to the oocyte by a phagocytosis -like process 1. All components of the spermatozoon, with the exception of nuclear DNA, are subsequently dismantled in the oocyte cytoplasm. An immediate consequence of sperm-oocyte fusion is oocyte activation 2.
Egg fertilization involves a complex sequence of events that starts with the release of a mature egg from the follicle, continues with the appearance of the two pronuclei after sperm entry, and is completed with the first mitotic division. Understanding the complexities of this process in humans has been limited to a large extent by ethical constraints. However, with the advent of assisted reproductive technologies ARTs , understanding of the various mechanisms involved in successful fertilization has been greatly enhanced. As ART has developed, so has our understanding of the essentials for human reproductive success.