Animal Development Lecture Notes

Flashcards for Animal Development Lecture

Asexual Reproduction

Asexual reproduction produces genetically identical offspring and is advantageous in stable uniform environments.

Sexual Reproduction

Produces genetically variable offspring and is advantageous in patchy, variable environments.

External Fertilization

Fertilization that occurs outside the body, common in fish and frogs.

Internal Fertilization

Fertilization that occurs inside the body, common in salamanders, reptiles, birds, and mammals.

Gonads

Specialized organs where animals produce gametes.

Testes

Gonads that produce sperm.

Ovaries

Gonads that produce eggs.

Dioecious

Having separate sexes.

Monoecious

Having both male and female sex organs in a single body (hermaphroditic).

Development

All genetically-controlled changes in an individual organism from fertilization until death.

Zygote

A fertilized egg.

Cell determination

Begins when certain genes are activated or inactivated as cells become gradually committed to a certain pathway.

Cell differentiation

Results from cell determination, as gene regulation increasingly commits cells to their biochemical and structural forms.

Acrosome

Organelle that contains enzymes that help penetrate the egg.

Nucleus (Sperm)

Contains a random subset of the father’s nuclear DNA.

Mitochondrion (Sperm)

Provides energy for the sperm (but the sperm mitochondrion does not enter the egg).

Fertilization

The fusion of sperm and egg to form a zygote.

Cleavage

Rapid cell division of the zygote by mitosis into multiple cells without increasing in size.

Morula

Solid sphere of cells formed after several cell divisions during cleavage.

Blastula

Hollow sphere of cells formed when the cells of the morula rearrange themselves, containing a fluid-filled cavity.

Blastocoel

Fluid-filled cavity within the blastula.

Gastrulation

The process by which the blastula forms the gastrula.

Blastopore

The opening formed during gastrulation that will become the first opening to the digestive tract.

Archenteron

Beginning of the digestive tract (primitive gut).

Germ Layers

The three primary germ layers formed during gastrulation.

Ectoderm

The outer germ layer of an animal embryo.

Mesoderm

The middle germ layer of an animal embryo.

Endoderm

The inner germ layer of an animal embryo.

Telolecithal Eggs

Eggs with a large amount of yolk taking up most of the egg.

Mesolecithal Eggs

Eggs with a moderate amount of yolk.

Microlecithal Eggs

Eggs with minimal yolk.

Equal Cleavage

Cleavage where the cells are approximately the same size.

Holoblastic Cleavage

Cleavage where the cells are completely separated from one another.

Meroblastic cleavage

Cell division occurs only in the germinal disc.

Neurulation

Central region of the ectoderm forms the neural tube.

Neurula

Embryo with a neural tube.

Organogenesis

Development of organs and structures from the three original germ layers.

Extraembryonic Membranes

Development of organs and structures from the three original germ layers.

Morphogenesis

Progressively organized into a multicellular animal.

Pattern formation

Locates cells in different regions with different signals.

Derivatives of Ectoderm

Nervous system, sense organs, outer skin layer (epidermis), nails, feathers, hair.

Derivatives of Mesoderm

Skeleton, muscles, circulatory system, blood, excretory system, reproductive system, inner skin layer (dermis), muscular portion of digestive tract.

Derivatives of Endoderm

Inner lining of digestive tract, inner lining of respiratory system, liver and thyroid.

Amniotes

Reptiles, birds, and mammals

Amniote egg

Keeps the embryo moist on dry land.

Chorion

Encloses the entire embryo and other membranes; major organ of gas exchange.

Amnion

Encloses the embryo; secretes protective amniotic fluid that fills the amniotic cavity.

Allantois

Stores nitrogenous wastes in reptiles and birds; contributes to umbilical vessels in mammals.

Yolk Sac

Encloses the yolk, slowly digests it, and makes it available to the embryo.

Sexual Reproduction

Egg of one parent fertilized by sperm of another

Monoecious

Contains both male and female sex organs in a single body

Development

All genetically controlled changes in an individual organism from fertilization until death.

Acrosome

Organelle that contains enzymes that help penetrate egg

Cleavage

Rapid cell divison

Gastrulation

Is the beginning of the digestive tract

Animal Pole

Smaller cells of the “animal pole” that have little yolk

Vegetal Pole

The larger cells .

Primitive Streak

Equivalent of Blastopore

Pattern Formation

Cells become progressively organized into different cell types, tissues, organs etc.

Chorion

Outermost membrane encloses the entire embyo

Fertilization

Egg membrane contains recognition proteins so the egg will be recognized by sperm from the same species.

Neural Tube

Develops into brain and spinal cord

Telolecithal eggs

Has large amounts of yolk at the vegetal pole and a small amount of cytoplasm at the animal pole.

Organogenesis

Organogenesis is the development of organ and structures from the three orginal germ layers

Development

Includes all genetically controlled changes in an individual organism from fertilization until death

Zygote

Fertilized egg

Testes

Gonads that produce sperm

Ovaries

Gonads that produce an egg

Development

Sexually reproducing animals all start from a fertizlied egg

Sperm

Mitochondrion provides engery for sperm, but does not enter the egg

Allantois

stores nitrogenous wastes; also involved in mammal umbilical vessels

Amnion

amnion encloses the embryo

Epidermis

outer skin layer

Mesoderm

middle layer

Endoderm

inner layer