Emryogenesis and Development Flashcards
What is the cortical reaction
after penetration of the sperm through the cell membrane, a release of Ca ions occurs.
Why is depolarization important in the cortical reaction
1) prevents fertilization of the ovum by multiple sperm cells
2) increases the metabolic rate of newly formed zygote
What is the mechanism behind dizygotic twins
form from fertilization of 2 eggs released during 1 cycle by 2 different sperm.
What is the mechanism behind monozygotic twins
a single zygote splits into two.
What is the process of rapid mitotic cell divisions in a zygote
cleavage
Describe the first cleavage a zygote
creates an embryo, no longer unicellular. several rounds of mitosis occur but the size of the embryo remains unchanged
Describe indeterminate cleavage versus Determinant cleavage
determinate cleavage results in cells committed to differentiating
Describe a blastula
a fluid filled cavity where cells surround it. The blastula is what implants into the endometrium of the uterus
Gastrulation describes the
the generation of the three distinct cell layers or the 3 primary germ layers; occurs in the first 2-3 weeks after fertilization
What are the 3 germ layers and what do they give rise to
ectoderm; skin, hair, nails, epithelia of the nose, mouth, the eye, and the nervous system
mesoderm; endothelial cells, all blood cells, musculoskeletal, circulatory, and connective tissue
endoderm; epithelial lining of digestive and respiratory tracts, pancreases, thyroid, bladder,
Why are cells with the same genes able to develop into such distinct cells types? the term
selective transcription
describe neurulation
the notochord forms. which gives rise to the neural folds, neural groove. These fuse into the neural tube.
at the tip of the neural tube are _. and purpose
neural crest cells, which give rise to form the peripheral nervous system.
What are teratogens
substances that interfere with development that cause defects or even death of the developing embryo.
What is induction and how does it influence development
the process by which nearby cells influence the differentiation of adjacent cells. Ensures proper spatial location and orientation of cells that share a function or have complementary functions
What stages are important in cell specialization
specification, determination, and differentiation
Specification refers to
When the initial stage where the cell is reversibly designated as a specific cell type
Determination refers to
the commitment of a cell to a particular function. irreversible commitment to a cell lineage.
What are morphogens
the secretion of specific molecules from nearby cells that cause determination
Differentiation refers to
the cell changing the structure, function, or biochemistry to match the cell type.
List and describe the different potencies for stem cells
Totipotent= cells with the greatest potency can become any cell type Pluripotent= can differentiate to any cell except for those found in the placental structures Multipotent= can differentiate into multiple cell types in a specific group
List types of Cell to Cell communication and meaning
Autocrine= signals act on the same cell that secreted the signal
Paracrine= signals act on cells in the local or nearby area
Juxtacrine= signals directly stimulating receptors on an adjacent cell
Endocrine=signals involve secreted hormones that travel through the bloodstream to a distant tissue
Importance of PAX6
a growth factor in the ectoderm that promotes development of the lens of the eye
What is senescence
biological aging
