Embryonic Development, Gastrulation, and Neurulation Vocabulary

Flashcards covering key vocabulary from a lecture on embryonic development, gastrulation, and neurulation.

Maternal to Zygotic Transformation

The transition during early embryonic development where a eutherian embryo shifts from relying on maternal instructions (mRNA) to relying on its own genome for development.

Epiblast

One of the two layers found in mammalian development (along with the hypoblast). It consists of pink colored cells right next to the hypoblast.

Hypoblast

One of the two layers found in mammalian development (along with the epiblast). It consists of green cells.

Inner Cell Mass

The structure formed after the fourth round of cleavage that develops into the actual embryo. It consists of the epiblast and the hypoblast.

Trophoblast Cells

The outer cells surrounding the inner cell mass that have a variety of functions, including breaking down the lining of the uterus to release nutrients for the developing inner cell mass.

Endometrium

The lining of the uterus. Trophoblast cells embedded into the wall of the uterus break down some of the endometrial cells to release nutrients for the developing inner cell mass.

Blastocoel

The fluid-filled cavity inside a blastula.

Placenta

The organ that develops from the trophoblast and functions as a primary endocrine center and exchange center for the developing embryo, facilitating hormonal control, oxygen acquisition, nutrient supply, and waste removal.

Gastrulation

A phase after cleavage where cells (blastomeres) move, migrate, and are induced to become three types of tissues (endoderm, ectoderm, and mesoderm) in triploblastic organisms.

Endoderm

One of the three germ layers formed during gastrulation in triploblastic organisms.

Ectoderm

One of the three germ layers formed during gastrulation in triploblastic organisms.

Mesoderm

One of the three germ layers formed during gastrulation in triploblastic organisms.

Vegetal Pole

The bottom hemisphere of the sea urchin embryo; it becomes the archenteron.

Archenteron

The primitive gut that develops during gastrulation.

Mesenchyme Cells

Specialized cells in sea urchins that detach from the outer layer of blastula cells and form filaments that attach to the roof of the blastula, contracting to pull the archenteron upwards.

Blastopore

The opening that develops during gastrulation in deuterostomes (like sea urchins); it becomes the anus.

Animal Hemisphere

The upper hemisphere of the frog embryo containing smaller and more numerous cells due to less yolk slowing down cell division.

Vegetal Hemisphere

The bottom hemisphere of the frog embryo containing larger but fewer cells due to more yolk slowing down mitosis.

Gray Crescent

A gray strip revealed after sperm entry in frogs. It contains important cytoplasmic determinants and indicates where the blastopore will originate.

Dorsal Lip of the Blastopore

The ledge-like structure at the top of the blastopore, which plays a critical role in cell signaling during gastrulation and neurulation, inducing ectoderm to become certain tissue types.

Blasto Disc

Structure formed in very yolky eggs in avian species, such as chickens; it's a relatively flattened cellular structure.

Primitive Streak

A groove-like structure in the blastodisc of chick embryos through which cells migrate inward during gastrulation, becoming mesoderm and endoderm.

Henson's Node

A dark spot at one end of the primitive streak in chick embryos, containing important determinants for the formation of anterior structures and the head of the organism.

Coelom

A body cavity.

Neurulation

The formation of the neural tube, which develops into the central nervous system.

Notochord

A structure derived from the mesoderm that induces the overlying ectoderm to become the neural plate during neurulation.

Neural Plate

A thickened region of the ectoderm that folds inward to form the neural tube during neurulation.

Neural Tube

A hollow tube formed from the folding of the neural plate that develops into the brain and spinal cord (central nervous system).

Neural Crest Cells

Cells that dissociate from the surrounding tissue when the neural tube closes, becoming multipotent and capable of migrating long distances to differentiate into various tissues (e.g., sensory system, skull bones, pigment cells).

Somites

Clusters of mesoderm cells alongside the neural tube that give rise to serially repeating structures like vertebrae, ribs, muscles, dermis, and cartilage.

Intermediate Mesoderm

A region of the mesoderm that develops into reproductive and urinary structures.

Lateral Plate Mesoderm

A region of the mesoderm that creates the lining of body cavities and is induced to become muscles of the digestive tract and the circulatory system.

Morphogens

Inducers that affect surrounding cells through diffusion, determining their fate based on the concentration gradient.

ZPA (Zone of Polarizing Activity)

A cluster of cells that secretes morphogens.

Sonic Hedgehog

A morphogen secreted by the ZPA that determines digit formation in vertebrate limbs based on its concentration gradient.