Biological Development and Fertilization

A set of vocabulary flashcards summarizing key terms and definitions related to biological development, fertilization, and early embryology.

Copulation

The act of sexual intercourse, necessary for fertilization by bringing sperm and egg together.

Fertilization

The union of a sperm and an egg, typically occurring in the fallopian tubes.

Corona Radiata

A layer of cells surrounding the oocyte, formed from granulosa cells.

Zona Pellucida

A glycoprotein layer surrounding the oocyte that sperm must penetrate to achieve fertilization.

Acrosome

A cap-like structure on the head of a sperm containing digestive enzymes used to penetrate the egg's protective layers.

Polyspermia

The fertilization of an egg by multiple sperm, which can lead to developmental problems.

Fast Block (to polyspermia)

A temporary change in the egg's membrane potential post-fertilization that prevents additional sperm from entering.

Slow Block (to polyspermia)

A more permanent mechanism involving the release of granules that destroys sperm receptors on the egg surface.

Zygote

The diploid cell formed when a sperm fertilizes an egg, which eventually divides to form an embryo.

Morula

A solid ball of cells resulting from the cleavage of a zygote, typically consisting of 16 cells.

Blastocyst

A hollow sphere of cells, formed from the morula, consisting of an inner cell mass (which becomes the embryo) and an outer trophoblast.

Gastrulation

The process during embryonic development where the embryonic disc transforms into three layers: ectoderm, endoderm, and mesoderm.

Ectopic Pregnancy

A pregnancy that occurs when a fertilized egg implants outside the uterus, usually in a fallopian tube.

Human Chorionic Gonadotropin (HCG)

A hormone secreted by the syncytiotrophoblast after implantation, important for maintaining the corpus luteum and preventing menstruation.

Embryogenesis

The process of developing a zygote into an embryo with distinct structures and layers.

Amnion

A membrane surrounding the embryo filled with amniotic fluid that provides a protective cushion.

Yolk Sac

A membranous structure that provides nutrients to the embryo until the placenta is fully developed.

Placenta

An organ that develops during pregnancy, connecting the developing fetus to the uterine wall and providing nutrients and waste exchange.

Zygotic Development

The early stages of development post-fertilization where cell division occurs leading to the formation of a morula and blastocyst.