Fertilization and Implantation Practice Flashcards

This set of vocabulary flashcards covers the step-by-step processes of human fertilization and implantation, including cellular development from zygote to embryo.

Fertilization (Conception)

The joining of a sperm and an egg (ovum) to form a zygote, the first cell of a baby.

Ampulla

The outer third of the fallopian tube where fertilization usually occurs.

Ovum (Egg) Lifespan

Lives about $24\,hours$ after ovulation (up to $48\,hours$).

Sperm Lifespan

Can live $48-72\,hours$ inside the female reproductive tract.

Zona pellucida

The protective jelly-like layer surrounding the egg.

Corona radiata

The outer layer of cells surrounding the egg.

Fimbriae

Finger-like projections that catch the egg and move it toward the fallopian tube.

Capacitation

The maturation process sperm must undergo to fertilize the egg, which changes the sperm's head so it can recognize and bind to the egg.

Hyaluronidase

An enzyme released by the sperm to break through the corona radiata of the egg.

Polyspermy

The entry of multiple sperm into one egg, which is prevented by the egg immediately blocking other sperm after the first one enters.

Zygote

A fertilized egg containing $46$ chromosomes ($23$ from each parent).

Female Sex Determination

Result of an X sperm joining with an X egg ($XX$).

Male Sex Determination

Result of a Y sperm joining with an X egg ($XY$).

Implantation

The process where the blastocyst attaches to the endometrium (lining of the uterus).

Cleavage

The process occurring between Days $1-4$ where the zygote undergoes repeated cell divisions.

Morula

A solid ball of cells resembling a mulberry that forms after multiple zygote divisions.

Blastocyst

A hollow ball of cells consisting of an inner cell mass and an outer trophoblast layer.

Trophoblast

The outer cells of the blastocyst that eventually become the placenta and fetal membranes.

Embryoblast

The inner cell mass of the blastocyst that develops into the embryo.

Apposition

The first stage of implantation where the blastocyst touches the uterus.

Adhesion

The second stage of implantation where the blastocyst sticks to the uterus.

Invasion

The third stage of implantation where the blastocyst burrows into the uterine lining.

Posterior Wall

The location high on the back wall of the uterus where implantation usually occurs.

Placenta Previa

A condition caused if implantation occurs too low, leading to the placenta covering the cervix.

Proteolytic Enzymes

Enzymes released by the trophoblast to dissolve part of the uterine lining for blastocyst embedding.

Implantation Bleeding

Light spotting caused by the breakage of tiny blood vessels when the embryo attaches to the uterine lining.

Embryo

The term for the blastocyst once it has successfully implanted into the uterine lining.