Fertilization and Early Embryonic Development

These flashcards cover key concepts related to fertilization and early embryonic development, as discussed in the lecture notes.

What is the embryonic period?

The embryonic period lasts for the first 8 weeks post-fertilization.

What is a zygote?

A zygote is the first cell of the new individual formed when sperm's chromosomes combine with those of the egg.

How long is an oocyte viable after ovulation?

An oocyte is viable for 12 to 24 hours after ovulation.

What happens to most ejaculated sperm?

Most ejaculated sperm do not make it to the egg due to various factors, including leakage and destruction by the vaginal environment.

What is capacitation in sperm?

Capacitation is the process that sperm must undergo to penetrate the oocyte, enhancing motility and making membranes fragile.

What role do acrosomal enzymes play in fertilization?

Acrosomal enzymes digest holes through the zona pellucida, allowing sperm to reach the oocyte membrane.

What is the cortical reaction?

The cortical reaction is triggered by increased calcium levels, leading to hardening of the zona pellucida and destruction of sperm-binding receptors.

What happens after the sperm penetrates the secondary oocyte?

After penetration, the oocyte completes meiosis II, forming the ovum and second polar body.

What is a blastocyst?

A blastocyst is a fluid-filled hollow sphere composed of approximately 100 cells that forms around days 4 or 5 after fertilization.

What are the two main components of the blastocyst?

The two main components are the trophoblast, which participates in placenta formation, and the embryoblast, which will form the embryo and extraembryonic membranes.