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30 Cards in this Set

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Gametes

haploid reproductive cells

Development proceeds in ordered phases throughan animal’s life cycle

– Fertilization


– Cleavage


– Gastrulation


– Organogenesis

Fertilization

occurs when a haploid sperm and eggcells fuse, forming a diploid zygote

polyspermy

fertilization by more than one sperm

fertilization envelope

which keeps awayadditional sperm

Cleavage

The set of rapid cell divisions that takeplace in animal zygotes immediately after fertilization

embryogenesis

Theprocess that makes a single-celled zygote into amulticellular embryo

blastomeres

The cells created by cleavage divisions

blastula

The embryo consists of a mass of blastomere cells

What Role Do Cytoplasmic Determinants Play?

Cytoplasmic determinants are found in specificlocations within the egg cytoplasm



– They end up in specific populations of blastomeres.




Cleavage initiates the step-by-step process that results in the differentiation of cells

Cleavage occurs in the mammalian...

Oviduct


– Connects the ovary, where the egg matures


– To the uterus, where the embryo develops

Blastocyst

Results from cleavage




a specializedblastula consisting of two populations of cells

Trophoblast

The external, hollow thin-wall that surrounds the inner cell mass (ICM)

Fate of the Trophoblast

After the blastocyst embeds in the uterine wall, amixture of trophoblast and maternal cells form theplacenta

Fate of the inner cell mass (ICM)

The ICM contains the cells that undergo gastrulationand develop into the embryo

Gastrulation

Results in the formation of embryonictissue layers

Most early embryos have three primary tissue layers

Ectoderm


mesoderm


endoderm

Gastrula

extensive and highly organizedcell movements radically rearrange the embryoniccells into a structure

Blastopore

Gastrulation begins with the formation of an opening

Ectoderm

forms the outer covering of the adult body and the nervous system

Mesoderm

gives rise to muscle, most internal organs, and connective tissues such as bone and cartilage

Endoderm

produces the lining of the digestive tract or gut, along with some of the associated organs

Organogenesis

– Process of tissue and organ formation


– Begins once gastrulation is complete and theembryonic germ layers are in place

Notochord

Functions as a key organizing elementduring organogenesis

Neural tube

is the precursor to the brain and spinal cord

Somites

formed by neural tubes




mesodermal cellsbecome organized into blocks of tissues

Determination

Somite cellsdifferentiate in response to signals from nearbytissues




These signals diffuse away from cells in thenotochord, the neural tube, and nearby ectodermand mesoderm to act on specific populations oftarget cells in the somite

Myoblast

Is a cell that is determined to become amuscle cell but has not begun producing muscle-specific proteins

MyoD

Is the protein that causes muscle celldifferentiation




MyoD is a regulatory transcription factor


– It binds to enhancers upstream of muscle-specific genes

Cell Differentiation

1. Fertilization triggers cleavage, resulting in a blastocyst


2. Blastocyst cell signals trigger gene cascades, resulting inpositional changes during gastrulation


3. During organogenesis, the notochord signals specificsomite cells to begin MyoD production, targeting thesecells as belonging to specific muscles


4. These muscle cells begin expressing muscle-specific proteins