Embryology - Vocabulary Flashcards (Slide Deck 3)

Vocabulary-style flashcards covering the key terms and definitions from the embryology lecture notes (germ layers, early embryology, differentiation, neurulation, and related structures).

Zygote

The fertilized egg formed by the union of sperm and ovum; the first cell of a new organism.

Fertilization

The process by which a sperm fuses with an ovum to form the zygote.

Cleavage

Rapid mitotic divisions of the zygote that produce a multicellular ball without growth.

Morula

A solid ball of cells produced by early cleavage, resembling a mulberry.

Blastocyst (Blastula)

A hollow ball with a fluid-filled cavity (blastocoel) containing trophoblast and inner cell mass.

Trophoblast

Outer cell layer of the blastocyst that contributes to the placenta and extraembryonic tissues.

Inner Cell Mass (Embryoblast)

Cluster of cells inside the blastocyst that becomes the embryo.

Blastocoel

The fluid-filled cavity inside the blastocyst.

Epiblast

The cell layer facing the amniotic cavity; forms the embryo and is part of the bilaminar disc.

Hypoblast

The cell layer adjacent to the blastocele that contributes to extraembryonic tissues.

Amniotic cavity

Fluid-filled cavity within the epiblast that surrounds the developing embryo.

Gastrulation

Formation of the three germ layers (ectoderm, mesoderm, endoderm) from the epiblast, beginning with the primitive streak.

Primitive streak

Thickened region of the epiblast marking the site of cell migration during gastrulation.

Ectoderm

The outer germ layer giving rise to epidermis, nervous system, and related structures.

Mesoderm

The middle germ layer giving rise to muscle, bone, cartilage, blood, and other tissues.

Endoderm

The inner germ layer giving rise to the epithelium of the gut and its derivatives.

Totipotent

Capacity of the zygote and early cleavage cells to form all embryonic and extraembryonic tissues.

Pluripotent

Capacity of inner cell mass cells to form derivatives of all three germ layers but not extraembryonic tissues.

Multipotent

Ability of a cell to form multiple, but limited, cell types within a lineage.

Embryonic stem cells

Pluripotent cells derived from the inner cell mass capable of differentiating into cells of all three germ layers.

Notochord

A mesoderm-derived flexible rod that defines the body axis and signals neurulation.

Neural tube

The embryonic structure that becomes the brain and spinal cord, formed during neurulation.

Somite

Segmental blocks of paraxial mesoderm that give rise to vertebrae, skeletal muscle, and dermis.

Archenteron

The primitive gut formed during gastrulation as endoderm invaginates to form the gut tube.

Coelom

The body cavity formed within the mesoderm to house organs.

Placenta

Extraembryonic organ formed from the trophoblast that provides nutrients and gas exchange.

Amnion

Membrane forming the amniotic sac surrounding the embryo.

Endometrium

Lining of the uterus where the embryo implants.

Germ layer

One of the three primary tissue layers (ectoderm, mesoderm, endoderm) formed during gastrulation.

Gastrula

Stage following the blastula where the germ layers are established (post-gastrulation concept).