Ch 44

Front 1

What factors does fertilization stimulate?

Back 1

It sets up blocks to the entry of additional sperm, it stimulates ion fluxes across the egg membrane, it changes the eggs pH, and increases metabolism and stimulates protein synthesis, it initiates the rapid series of cell division that produces a multicellular embryo

Front 2

Describe the process of gastrulation.

Back 2

Gastrulation is the process whereby the blastula is transformed by Massive movements of cells into an embryo with multiple tissue layers and distinct body axes the resulting spatial relationship between tissues make possible the inductive interactions between cells that trigger differentiation and organ formation

Front 3

Vegetal hemisphere

Back 3

Rearrangement of egg cytoplasm following fertilization is easily observed in some frog species because of the pigments in the cytoplasm the nutrients in an unfertilized frog a garden slug granules that are concentrated by gravity in the lower half of the egg called the vegetale hemisphere

Front 4

Animal hemisphere

Back 4

The haploid nucleus of the egg is located at the opposite end in the animal hemisphere the outermost cytoplasm of the animal hemisphere is heavily pigmented and the underlying cytoplasm has more diffuse pigmentation de vegetal hemisphere is not pigmented because of these differences it is easily to observe how the cytoplasm is rearranged when a frog egg is fertilized

Front 5

Gray Crescent

Back 5

This rotation brings different regions of cytoplasm into contact with each other on opposite sides of the egg, producing a band of diffusion payment and cytoplasm on the side opposite the site of sperm entry this band called The Great Crescent marks the location of important developmental events and some species of amphibians

Front 6

Cleavage

Back 6

Transformation of the diploid zygote into a mass of cells occurs through a rapid series of cell divisions called cleavage

Front 7

Blastocoel

Back 7

The embryo becomes a solid ball of smaller and smaller cells eventually this ball forms a certain fluid-filled cavity called a blastocoel.

Front 8

Blastula

Back 8

After the ball of central fluid-filled cavity is formed the embryo is known as this

Front 9

Blastomeres

Back 9

The embryos individual cells are called blastomeres

Front 10

Complete cleavage

Back 10

Occurs in most eggs that have little yolk in this pattern early cleavage first divide the egg completely in the blast of murders are of similar size the frog egg undergoes complete cleavage but because it is vegetable contains more yolk the division of the cytoplasm is unequal and the blasphemers and in the animal and Missy are smaller than those in the vegetal hemisphere

Front 11

Incomplete cleavage

Back 11

This occurs in many species in which the egg contains a lot of yoke in the cleavage bras do not penetrate it at all

Front 12

Dicoidal cleavage

Back 12

Type of incomplete cleavage common and Fishes reptiles and birds the eggs of which contain a dense yolk mask the embryo forms as a disc of cells called a blastodisc that sits on top of the yolk mask

Front 13

Superficial cleavage

Back 13

Is a variation of incomplete cleavage that occurs in insects such as the fruit fly early in development cycles of mitosis occur without cell division producing a syncytium a single cell with many nuclei

Front 14

Radial cleavage

Back 14

An incomplete cleavage if the mitotic spindles of successive cell divisions from parallel or perpendicular to the animal vegetal axis of the zygote a pattern of radial cleavage occurs as seen in the Frog the first two cell divisions are parallel to the animal vegetal axis and the third is perpendicular to it

Front 15

Spiral cleavage

Back 15

Results with them mitotic spindles are at oblique angles to the animal vegetal axis and spiral cleavage each new cell layer is shifted to the left or right depending on the orientation of the mitotic spindles

Front 16

Implantation

Back 16

When the blastocyst arrives in the uterus the trip a blast at here's to the lining of the uterus beginning the process of implantation

Front 17

Fate maps

Back 17

In many animals these movements of the blastomeres are so regular and Wilcrest rated that it is possible to label a specific glass mirror with a guy and identify the tissue and organs that form from its progeny such labeling experiments produced a fate map

Front 18

Determined

Back 18

Elastomers become determined committed to specific dates at different times and different species

Front 19

Mosaic development

Back 19

If one of these blasphemers as experimental removed a particular portion of the embryo will not form this type of development has been called Mosaic development because each blastomere seems to be contribute a specific set of tiles to the final Mosaic that is the adult animal

Front 20

Regulate of development

Back 20

In contrast to Mosaic development the loss of some cells during cleavage is regulated development this does not affect the developing embryo because the remaining cells compensate for the loss regulate of development is typical of many vertebrates species including humans

Front 21

Germ layers

Back 21

During gastrulation three germ layers also called cell layers of tissue layers form

Front 22

Endoderm

Back 22

The endoderm is the innermost germ layer created as some blasphemers move to the inside of the embryo the endoderm gives rise to the lining of the digestive tract respiratory tract pancreas and liver

Front 23

Ectoderm

Back 23

The ectoderm is the outer germ layer formed from those cells remaining on the outside of the embryo the ectoderm gives rise to the nervous system include the eyes and ears and to the epidermal layer of the skin and structures derived from the skin such as hair feathers nails or claws sweat glands old ones and even teeth

Front 24

Mesoderm

Back 24

The mesoderm is the middle layer and is made up of cells that migrate between the endoderm and the ectoderm mesoderm contributes to shoes too many organs including the heart blood vessels muscles and Bone

Front 25

Mesenchyme

Back 25

Cells of the middle germ layer of the mesoderm

Front 26

Archenteron

Back 26

The invaginated cells become endoderm and form the Primitive gut

Front 27

Blastispore

Back 27

The mouth of the animal forms where the archenteron makes contact with the overlying ectoderm the opening created by the invagination of the vegetable is called the blastopore

Front 28

Dorsal lip

Back 28

Vinyl sales Mark the spot where the dorsal lip of the blastopore will form

Front 29

Involution

Back 29

As the bottle cells move inward the dorsal lip is created in the sheet of cells move over into the blasticoel this process is called involution

Front 30

Convergent extensions

Back 30

The arrangements are due to changes and sell properties called conversion extensions

Front 31

Epiboly

Back 31

Is gastrulation precedes so from the animals hemispheres flatten and move towards the site of involution is a process called epiboly

Front 32

Primary embryonic organizer or organizer

Back 32

Because the dorsal lip of the blastopore was apparently capable of including the host tissue to form the entire embryo spemann and Mangold dubbed the dorsal lip tissue the

Front 33

Goosecoid

Back 33

Studies of early crash truth is revealed that primary embryonic organizer activity is generated by the interaction of B canteen with signals coming from the vegetable cells together they activate the expression of the transcription Factor

Front 34

Hypoblast

Back 34

Between the blastodisc and the yolk mask is a fluid-filled space some cells from the blessed is break free and move into the space these cells come together to form a continuous layer called this

Front 35

Epiblast

Back 35

The overlying cells make up this

Front 36

Hensen's node

Back 36

And the chick embryo archenteron forms but the endoderm and mesoderm migrate forward to form the gut and other structures of the anterior and other primitive Groove is a thickening called this

Front 37

OregonoGenesis

Back 37

During the next phase of development called this many organs and organ systems develop simultaneously and in coordination with one another

Front 38

Neurulation

Back 38

Is the initiation of the nervous system

Front 39

Notochord

Back 39

The other groups of cells that influence over the dorsal lip become or measured are so named because it forms a rod of mesoderm the notochord that extends down the center of the embryo

Front 40

Neural tube

Back 40

The folds fuse forming a cylinder the neural tube in a continuous overlying layer of epidermal ectoderm

Front 41

Neural crest cells

Back 41

Cells from the most lateral portion of the neural plate do not become part of the neural tube but disassociate from it and come to lie between the neural tube and the overlying epidermis these neural crest cells migrate outward to let lead the development of the connections between the central nervous system brain and spinal cord and the rest of the body

Front 42

Somites

Back 42

As the neural tube forms measure dermal tissue gather along the size of the notochord to form separate segmented blocks of cells called so mites

Front 43

Hox genes

Back 43

In vertebrates the homeotic genes that control differentiation along the anterior posterior body axes

Front 44

Extraembryonic membranes

Back 44

Which originated formed the embryo but are not part of it extreme embryonic membranes function in Nutrition gas exchange and waste removal

Front 45

Yolk sac

Back 45

Is the first to form in it does so by extension of the hypoblast layer along with some adjacent mesoderm yolk Sac grows to include the entire body of the yolk in the egg

Front 46

Allantoic membrane

Back 46

Is also an outgrowth of the extraembryonic endoderm + adjacent mesoderm it forms the allantoic sac Site for storage and metabolic waste

Front 47

Amnion and outer chorion

Back 47

Two layers of cell extend all along the inside of the eggshell both over the embryo and below the exact where they meet they fuse forming two membranes the inner amnion and the outer chorion and amnion surrounds the embryo form in the amniotic cavity the amnion secretes fluid into the cavity providing a protective environment for the embryo the outer membrane the chorion forms of continuous membrane just under the eggshell elements water loss from the egg and also works with the enlarged talented membrane to exchange respiratory gases between the embryo in the outside world

Front 48

Amniotic fluid

Back 48

The rupturing of the amnion and chorion in the loss of the amount fluid is called water breaking by humans

Front 49

Fetus

Back 49

By the end of the first trimester most organs have started to form the embryo is about 8 centimeters long and weighs about 40 grams it would fit neatly into a teaspoon at about this point it's time the human embryo is medically and legally referred to as fetus