MCAT Biology - Embryogenesis and Development

Chapter 3

Ampulla

Widest part of the fallopian tube

Acrosomal Apparatus

Tube like struture formed when sperm comes into direct contact with secondary occytes cell membrane

Cortical Reaction

Release of calcium ions - occurs after sperm penetrate egg

Two ways of calcium increase

depolarization prevents fertilization of the ovum by multi sperm cells, increase the metabolic rate of zygote

Fertilization Membrane

The depolarized and impermable membrane

Monochorionic/Monoamniotic

Same amnioin and Chorions

Monochorionic/diamniotic

Each have own amonion, share chorion

Dichorionic/diatomic

Own amoniom and own chorion

Dizygotic Twins

Form from fertilization of two different eggs released during one ovulatory cycle by two different sperm

Monozygotic Twins

When a single zygote splits into two

Conjoined twin

Two offspring physically attached due to incomplete separation

Cleavage

Rapid mitotic cell divisions as it moves to the uterus

Indeterminate Cleavage

Results in cells that can still develop into complete organisms

Determinate cleavage

Results in cells with fate that are already determined

Morula

solid ball of cells that results from the early stages of cleavage in an embryo

Blastula

Hollow ball of cells filled with fluid filled inner cavity

Blastocoel

The fluid filled inner cavity in the blastula

Trophoblast Cells

Surround the blastocoel and give rise to the chorion and later placenta

Inner Cell Mass

Protrude into blastocoel and give rise to organism itself

Implantation

Blastula moves fallopian tube to uterus and burrows in endometrium

Chorion

Extra embryonic membrane that develops into the placenta

Chorionic Villi

Microscopic finger like projections that penetrate the endometrium

Circulation in Umbilical Cord

Two arteries and One vein

Allantois

Involved in early fluid exchnage between embryo and yolk sac

Amnion

Thing tough membrane filled with amniotic fluid

Gastrulation

Generation of three distinct layers

Archenteron

Membrane invagination into blastocoel → develop into gut

Blastopore

Opening of archentrion

Deuterosome

Blastopore develops into the anus

Protosomes

Blastopore develop into mouth

Ectoderm gives rise to…

Integumentary epidermis, hair, nail, epithelia of nose, mouth, lower anal, lens of eye, nervous system, inner ear

Mesoderm gives rise to…

Musculoskeletal circulatory and most excretory systems, muscular and connective tissue, gonads and adrenal cortex, layer digestive and respiratory

Endoderm gives rise to…

Epithelial lining of digestive and respiratory tracts, pancrease, thyroid, bladder, distal, urinary tracts and liver

Induction

the ability of one group of cells to influence fate of nearby cells

Teratogens

Substances that interfere with development causing defects or death in developing embryo

Neuroulation

Development of nervous system

Notochord

Rod of mesodermal cells forms along long axis organism, induces formation of neural folds

Neural Tube

Gives rise to CNS

Neural Crest Cells

Form peripheral nervous system as well as specific cell types in other tissue

Specification

Cell is reversibly designated as a specific cell type

Determination

Commitment of a cell to a particular function in the future, cell is irreversibly commited to a specific lineage

Differentiation

The cell must begin to undertake changes that cause the cell to develop into the determined cell type, includes changes in struture, and biochem.

Stem Cells

Cells that have not yet differentiated or give rise to other cells that will differentiate

Totipotent

Cells with greatest potency

Pluripotent

Cells after differentiation into three germ layers

Multipotent

As cells continue to become more specialized

Responder

The cell that is induced

Growth Factors

Peptides that promote differentiation and mitosis in certain tissue

Apoptosis

Programmed Cell Death

Autocrine

Signal act on same cell that secreted in signal in first place

Paracrine

Act on cells in local area

Juxtacrine

Don’t usually involve diffusion, but involve a cell directly stimulating receptors of an adjacent cell

Endocrine

Secreted hormone track trhough blood stream to target cell

Necrosis

Cell death in when cell dies in result of injury

Regenerative Capacity

Ability of an organism to regrow certain parts of body, varies species to species

Complete Regeneration

Lost or damaged tissue are replaced with identical tissue

Incomplete Regeneration

Imply newly formed tissue is not identical in structure or function to the tissue that has been injured or lost

Senescence

Biological Aging

Umbilical Arteries

Carry blood away from fetus towards the placenta

Umbilical Viens

Carry blood toward the fetus from the placenta

Foramen Ovule

Reroute blood from lung, one way valve connect right atrium to the left

Ductus Arteriosus

Shunts left over blood from the pulmonary artery to the aorta

Ductus Venosus

Shunts blood returning from placenta via umbilical vein direectly into inferior vena cava