Term
| The development of the zygote into a body is known as: |
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Definition
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Term
| The vegetal pole is yolk ___?, the animal pole is yolk ___? |
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Definition
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Term
Define determination, differentiation and induction
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Definition
Determination: process by which a cell's fate is determined (frequently happens well before cell differentiation)
Differentiation: process by which cells become morphologically and functionally different from each other
Induction: process by which chemical signals released from one cell cause a change in the development of another cell |
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Term
| Define the key stages from fertilization to a organogenesis and growth |
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Definition
| ovum>zygote>blastula>gastrula>neurula>mature embryo |
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Term
| From the 9 cell stage onward, cells are not identical in terms of their content. Why is this and what distributions are uneven? |
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Definition
Polarisation of fertilised egg causes this.
maternal mRNA
maternal proteins
mitochondria
nutrients (yolk) |
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Term
| Cleavage transforms one large cell into many ____ |
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Definition
| blastomeres (smaller cells) |
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Term
| Pattern of cell division is influenced by yolk content. The greater the amount of yolk, the easier cell division becomes. True or false? |
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Definition
| False, becomes more difficult |
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Term
| What are the large and small cells called in a blastula, which poles are they found and what type of cleavage do they exhibit for all the different yolk concentrations? |
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Definition
Microlecithal (little yolk) and isolecithal (evenly distributed) = holoblastic cleavage (complete cleavage), equal sized cells (Amphioxus mammals)
Mesolecithal (moderate yolk) = Holoblastic cleavage, uneven sized cells (macromeres at vegetal pole (bottom), micromeres at animal pole (top)) (amphibians)
Macrolecithal (large yolk) and telolecithal (yolk dense at vegetal pole) = meroblastic cleavage (incomplete), embryo a disc of cells on top of large yolk (most fish, all reptiles and birds) |
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Term
| In blastulation, cells form a ball surrounding a ____ in amphibians and mammals, or a disk of cells (_____) on top of the yolk in fish, reptiles and birds |
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Definition
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Term
____ becomes outer layer of skin and nervous system
____ becomes gut and its derivatives
____ becomes muscle and connective tissue including circulatory system, skeleton and gonads
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Definition
| Ectoderm, endoderm, mesoderm |
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Term
| In gastrulation, what forms the archenteron? |
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Definition
| Invagination of the blastula |
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Term
| What is involution during gastrolation? |
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Definition
| Movement of cells into the archenteron over the lips of the blastopore, cells become determined |
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Term
| The first cells to move into the archenteron become the ____, which will form the ____ |
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Definition
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Term
| What triggers the process of neurulation in a frog embryo? |
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Definition
| Chordomesoderm induces the over-lining ectoderm to form neural plate and trigger neurulation |
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Term
| In a macrolecithal egg, what process forms the three tissue layers? |
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Definition
| Ingression (in folding and cell streaming, occurs along "the primitive streak") |
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Term
| What occurs during neurulation? |
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Definition
Formation of neural tube (beginning of nervous system)
Formation of gut tube
Beginning of mesoderm differentiation
Somite formation, creation of neural crest cells
Layout of basic body plan |
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Term
| What does the mesoderm differentiate into during gastrulation of a frog? |
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Definition
Epimere (forms somites - muscles and skeleton)
Mesomere (forms urogenital system (kidneys and gonads))
Hypomere (body cavity connective tissues (coelom and mesenteries)) |
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Term
| What happens to the hypomere during neurulation of a frog? |
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Definition
| Begins to split in the middle to form coelom |
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Term
| What cells migrate as individual cells throughout the developing embryo, forming (or inducing other cells to form) many different structures associated with the nervous system and other tissues? |
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Definition
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