https://www.youtube.com/watch?v=_5OvgQW6FG4

https://www.youtube.com/watch?v=8-KF0rnhKTU

Capacitation:

Capacitation is the penultimate step in the maturation of mammalian spermatozoa and is required to render them competent to fertilize an oocyte.

![Period of conditioning of the sperm in the female reproductive tract, predominantly in the uterine tube. It provides the sperms with the ability to penetrate the outer layer of the ovum. Chemical changes in the tail provide them with greater mobility.

Capacitation. (2022). Retrieved 27 July 2022, from https://www.malecontraceptive.org/blog/what-is-capacitation](https://s3-us-west-2.amazonaws.com/secure.notion-static.com/82357172-03ce-4311-aa80-f46535abb280/Untitled.png)

Period of conditioning of the sperm in the female reproductive tract, predominantly in the uterine tube. It provides the sperms with the ability to penetrate the outer layer of the ovum. Chemical changes in the tail provide them with greater mobility.

Capacitation. (2022). Retrieved 27 July 2022, from https://www.malecontraceptive.org/blog/what-is-capacitation

Fertilization

The process that begins with the penetration of the secondary oocyte by the spermatozoon and is completed with the fusion of the male and female pronuclei. This usually takes place in the fallopian tube. Viable spermatozoa have been found in the tube 48 hr after the last coitus. After the ovum is fertilized and the diploid chromosome number is restored in the zygote, cell division begins. The blastocyst then enters the uterus, where it may implant for continued nurture and development.

  1. Attachment & binding: Sperm binds to the zona pellucida through the glycoprotein ligands ZP3 and ZP2 (zona proteins)
  2. Acrosomal reaction: Binding causes release of acrosomal enzymes that allow sperm to penetrate zona pellucida. • Acrosomal enzymes: Acrosin, acid phosphatase, hyaluronidase
  3. Penetration of 3 barriers in ovum: Corona radiata, zona pellucida, oocyte cell membrane

![After a sperm cell comes in contact with the outer layers of an egg cell, the acrosome, which is a prominence at the anterior tip of the spermatozoa, undergoes a series of well-defined structural changes that opens a path for the sperm nucleus.

Encyclopædia Britannica, Inc.](https://s3-us-west-2.amazonaws.com/secure.notion-static.com/eeb973a9-6336-435f-9b37-ae7a530c8736/Untitled.png)

After a sperm cell comes in contact with the outer layers of an egg cell, the acrosome, which is a prominence at the anterior tip of the spermatozoa, undergoes a series of well-defined structural changes that opens a path for the sperm nucleus.

Encyclopædia Britannica, Inc.

Zona/Cortical reaction:

Initiated during fertilization to prevents polyspermy.

After penetrating the zona, the sperm comes in contact with the oolemma (plasma membrane of oocyte). This contact results in weak membrane depolarization and a calcium wave. Calcium wave triggers the release of lysosomal enzymes from the cortical granules lining the oolemma (cortical reaction). These enzymes hydrolyze the ZP3 receptor on the zona pellucida. Digestion of ZP3 and alteration of zona pellucida (zona reaction) prevents other sperms from binding, thus creating a block to polyspermy.

![Cortical reaction. A. Schematic illustration of cortical reaction. B. Detail from a fertilized ovum showing release of the content of cortical granules into the perivitelline space. In the ooplasm cortical granules (CG) are seen, and between the bases of the microvilli (Mv) the released spherical content of the granules (arrows) is present (magnification x 22400)

Hyttel, 1988](https://s3-us-west-2.amazonaws.com/secure.notion-static.com/0c45b87c-e775-464a-8f9f-c0a3ee7e4b24/Untitled.png)

Cortical reaction. A. Schematic illustration of cortical reaction. B. Detail from a fertilized ovum showing release of the content of cortical granules into the perivitelline space. In the ooplasm cortical granules (CG) are seen, and between the bases of the microvilli (Mv) the released spherical content of the granules (arrows) is present (magnification x 22400)

Hyttel, 1988