V BSCI 5052: Lecture 24 - Fertilization

These vocabulary flashcards cover the physiological events of fertilization, including sperm capacitation, acrosomal and cortical reactions, and the formation of a zygote through syngamy, as well as species-specific fertile periods.

Capacitation

Changes in the sperm plasma membrane where seminal plasma proteins coating the sperm head are stripped away by the female environment, exposing the acrosome.

Vesiculation

A step in the acrosome reaction where the acrosomal membrane fuses with the sperm plasma membrane, allowing acrosomal contents to be dispersed.

Equatorial segment

The specific region of the sperm head that is exposed during the acrosome reaction and eventually fuses with the ovum plasma membrane.

Proacrosin

An inactive form of an acrosomal enzyme that has a strong affinity for the zona pellucida.

Acrosin

An enzyme that enhances sperm binding to the zona pellucida; its conversion from proacrosin initiates the penetration of the zona pellucida.

Hypermotility

A state occurring in the ampulla after capacitation where sperm movement changes from linear progression to localized, hyperactive motility to facilitate sperm-ovum interaction.

$ZP1$ and $ZP2$

Two of the three glycoproteins in the zona pellucida that primarily serve structural functions.

$$ZP3$$

The glycoprotein in the zona pellucida that acts as the primary receptor for sperm binding and initiates the acrosome reaction.

Cortical Reaction

The release of cortical granule contents (mucopolysaccharides, proteases, plasminogen activator, and peroxidase) into the perivitelline space to prevent polyspermy.

Fast block to polyspermy

A rapid change in the plasma membrane potential of the oocyte that occurs immediately after sperm penetration.

Slow block to polyspermy

The exocytosis of cortical granules that causes biochemical changes in the zona pellucida to prevent further sperm binding; also known as the vitelline reaction.

Syngamy

The fusion of the male and female pronuclei following sperm decondensation, resulting in the formation of a zygote.

Bitch Fertile Period

The duration sperm remain fertile within the female reproductive tract of a dog, lasting approximately $9-11\,d$.

Mare Fertile Period

The duration sperm remain fertile within the female reproductive tract of a horse, lasting approximately $4-5\,d$, with a practical rule of thumb of $2\,d$.

Ovum Viability (Rule of Thumb)

Except in the dog, the period an ovum remains viable for fertilization is typically estimated to be a maximum of $12$ to $24\,hours$.

Perivitelline space

The space between the zona pellucida and the oocyte plasma membrane where the polar bodies are located and cortical granules are released.

ARPR

Acrosome Reaction Promoting Region; a ligand that initiates the acrosome reaction.

ZBR

Zona Binding Region on the sperm head that facilitates the initial binding to the zona pellucida.