2-Introduction_to_embryology_2024W1__1_

Bilateral Symmetry

A body plan in which the left and right sides of an organism are mirror images of each other.

Ectoderm

The outermost embryonic germ layer that gives rise to the epidermis and nervous system.

Mesoderm

The middle embryonic germ layer that forms the skeleton, muscles, circulatory system, and more.

Endoderm

The innermost embryonic germ layer that develops into the lining of the digestive and respiratory tracts.

Blastula

A hollow ball of cells formed during the early development of an embryo.

Gastrulation

A phase early in the embryonic development during which the single-layered blastula reorganizes into a multi-layered structure.

Neurulation

The process during embryonic development that forms the neural tube, which will develop into the central nervous system.

Archenteron

The primitive gut formed during the gastrulation phase of embryonic development.

Coelom

A body cavity within animals that forms from mesoderm and is lined by mesoderm.

Synapomorphy

A shared derived characteristic that is used to define and identify groups of organisms.

Proximal

Referring to a body part that is closer to the point of attachment or origin.

Distal

Referring to a body part that is farther from the point of attachment or origin.

Mesanchyme

A loosely associated accumulation of undifferentiated mesodermal cells that can migrate throughout the body.

Chorion

An extra-embryonic membrane that forms the outer layer of the placenta in mammals.

Amnion

An extra-embryonic membrane that encloses the embryo in a fluid-filled sac, providing cushion and protection.

Vitelline vessels

Blood vessels that transport nutrients from the yolk to the developing embryo.

Primitive streak

A structure that forms during the early stages of embryonic development in birds and mammals, guiding cell migration.

Hensen's node

A specialized region at the anterior end of the primitive streak that plays an important role in the development of the embryo.

Cleavage

A series of rapid cell divisions following fertilization that leads to the formation of the blastula.

Embryonic germ layers

The three layers (ectoderm, mesoderm, and endoderm) formed during gastrulation that give rise to all tissues and organs.

Epiblast

The upper layer of the blastodisc in avian embryos that develops into the entire embryo.

Hypoblast

The lower layer of the blastodisc in avian embryos that assists in the development of the embryo but does not form part of it.

Neural crest

Cells that arise from the ectoderm during neurulation and migrate to form various structures in the body.

Myotome

The portion of the somite that gives rise to the skeletal muscles.

Dermatome

The portion of the somite that differentiates into the dermis of the skin.

Sclerotome

The portion of the somite that gives rise to the vertebrae and ribs.

Comparative Physiology

A field of study that examines differences and similarities in the structure and function of organisms.