Fertilization

Front 1

Fertilization

Back 1

Successful fusion of the male and female gamete cells.
Normally occurs in the ampullary region of uterine
tube, near the ovaries

Front 2

Capacitation

Back 2

Necessary removal of glycoproteins surrounding the sperm head before fertilization.

Front 3

Corona radiata

Back 3

Also called the cumulus oophorus
Outer layer of the ovum

Front 4

Sperm penetration

Back 4

Controlled by acrosomal enzymes released by the tip of the spermatozoa

Front 5

Sperm fusion

Back 5

Sperm head and tail enter the ovum, allowing the second meiotic division to complete.
The extra chromosomal information is expelled in the second polar body.

Front 6

Mechanisms to block polyspermy

Back 6

Fast block - change in membrane potential that prevents further sperm fusion events

Slow block - at the time of sperm entry, the ovum undergoes an event called the cortical reaction.

Front 7

Cortical reaction

Back 7

This forms a space between the egg membrane and the zona pellucida, called the Perivitelline space, where digestive enzymes are released.
Prevents additional sperm from entering.

Front 8

Pro-nucleus

Back 8

The decondensed head of the sperm formed after tail degeneration.
The ovum nuclei also called pro-nucleus.
Pro-nuclei fuse to form the diploid nucleus.

Front 9

Zygote

Back 9

The diploid cell formed after fertilization and the joining the the two haploid pro-nuclei.

Front 10

Zygotic cell division

Back 10

Divides every 16-24 hours.
Early divisions happen without cell growth -> more, smaller cells
Zygotic cells will become both the embryo and extraembryotic tissues.

Front 11

Morula

Back 11

"Mulberry" stage
The 8-16 cell stage after fertilization
Initially loosely associated (can split into twins), but then compact

Front 12

Blastocyst

Back 12

Between 32 and 128 cell stage.
Cells organize around a blastocele (cavity)

Front 13

Implantation

Back 13

As the embryo continues to develop, it will move along the uterine tube towards the uterus.
At day 5-6, in the blastocyst stage, the embryo will implant.

Front 14

Trophoblast

Back 14

Formed from the outer layer of cells in blastocyst
Become 2 forms:
Cytotrophoblast, which are mononucleated, and
Synctiotrophoblasts

Front 15

Syncytiotrophoblast

Back 15

Formed from trophoblast cells near the inner cell mass.
Multinucleated, highly invasive cells.
The retroviral-derived protein, syncytin, is essential for
formation.
Binds with L-selectin to begin implantation.
Eventually these cells surround the entire embryo after implantation.