Developmental Biology - Cleavage and Blastula Formation

This set of flashcards covers key terms and concepts from the lecture on cleavage and blastula formation in developmental biology.

Cleavage

The onset of wave upon wave of cell division that divides the zygote into progressively smaller cellular units.

Indeterminate Cleavage

A type of cleavage where each embryonic cell's fate is not sealed and each cell is capable of forming a complete individual.

Blastula

A hollow sphere of cells consisting of blastomeres surrounding a fluid-filled cavity called the blastocoel.

Blastocoel

The fluid-filled cavity enclosed by the blastoderm in the blastula stage.

Mitotic Spindle

Structure that determines the orientation of the cleavage plane during cell division.

Holoblastic Cleavage

Complete cleavage where the entire zygote is divided; seen in isolecithal eggs.

Meroblastic Cleavage

Incomplete cleavage where a large portion of the zygote remains uncleaved; seen in telolecithal eggs.

Cleavage Furrow

The indentation that forms during the cytokinesis of cell division, bisecting the cell.

Morula

The solid ball of cells that forms after multiple cleavages before the blastula stage.

Blastoderm

Layer of cells that form on top of the yolk in the blastodisc during development.

Epiblast

The layer of cells derived from the outer surface of the blastoderm that forms the embryo.

Trophoblast

The outer layer of cells in the blastocyst that will develop into part of the placenta.

Gap Junctions

Connections that permit the exchange of ions and small molecules between adjacent cells.

Asters

Structures that initiate cleavage and organize the mitotic spindle during cell division.

Fertilization Membrane

The layer that forms around the fertilized egg to prevent polyspermy.

Gastrulation

The process that transforms the blastula into a three-layered structure called the gastrula.

Polysomes

Complexes formed by the association of mRNA with multiple ribosomes, facilitating protein synthesis.

Maternal mRNA

RNA that is deposited in the egg and drives the early stages of development before embryonic mRNA is activated.

Conjoined Twins

Twins that share a single placenta and amnion, resulting from incomplete separation of the embryo.

Zona Pellucida

A glycoprotein layer surrounding the plasma membrane of mammalian oocytes.