Fertile vs Ovulation
Fertilization is the fusion of male (sperm) and female (ovum) nuclei of gametes. There are two types of fertilization. One is external fertilization, where fertilization takes place outside the bodies of organisms. The other is internal fertilization, where fertilization takes place within the female organism. Internal fertilization is the method of fertilization in human. This takes place by sexual intercourse.
What is Ovulation?
After puberty and during childbearing years, about every 28 days one primary ovarian follicle matures and becomes a graafian follicle. It ruptures and releases the ovum, which is at secondary oocyte stage into the peritoneal cavity. It is called ovulation. The ovum is absorbed in to the phallopian tube through its funnel shaped end. Each graafian follicle is surrounded by a theca. Inner to this are the follicular cells. Some peripheral follicle cells are granular. In the middle is a cavity called the antrum with a fluid that contains oestroidal. The ovum, which is at secondary oocyte stage, is lined by the vitelline membrane. The perivitelline cavity and zona pellucid, which is of mucopolysaccharide surrounds it. Surrounding the zona pellucid are many cells called corona radiata. The primary follicles consist of the primary oocyte surrounded by a single layer of follicular cells. During maturity, the number of follicle cells increase. The follicle becomes larger, and the primary oocyte undergoes first meiotic division and becomes the secondary oocyte.
What is Fertilization?
Fertilization takes place in the upper part of the phallopian tube. Millions of sperms are discharged at a time. But only a few hundred will reach the phallopian tube. The sperms swim with the aid of the tail. The movement of sperms is also aided by the peristaltic movements of the uterus and phallopian wall. The hydrolytic enzymes of the acrosome are released from the sperm. These enzymes digest a pathway for the sperm through corona radiate and zona pellucid. The plasma membrane of the head of the sperm with that of the secondary oocyte and the sperm nucleus is engulfed. This fusion triggers the completion of meiosis forming the second polar body and a haploid egg cell. The paternal and maternal chromosomes come together forming the diploid zygote. When the sperm enters the secondary oocyte, cortical granules of the secondary oocyte move towards the vitelline membrane, break down releasing a substance that hardens zona pellucida. The harden membrane is called the fertilizing membrane. This prevents entry of other sperms.
What is the difference between Ovulation and Fertilization?
• In ovulation, what happens is that one primary ovarian follicle matures and becomes a graafian follicle. It ruptures and releases the ovum which is at secondary oocyte stage into the peritoneal cavity. But in fertilization what happens is the fusion of male (sperm) and female (ovum) nuclei of gametes. There is no fusion of nuclei in ovulation.
• Although both the processes takes place inside the female organism, fertilization cannot occur without sperms where as ovulation does not require sperms.
• Fertilization gives rise to a diploid zygote where as ovulation cannot give rise to a diploid zygote.