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What are the two main patterns of cleavage?Holoblastic (complete) and meroblastic (incomplete) cleavage.
What are the 4 forms of holoblastic (complete) isolethical (sparce, evenly distributed yolk) cleavage?1. Radial cleavage (stekelhuidigen (zoals see urchin) & amphioxus (=lancetvisje)
2. Spiral cleavage (annelids (=ringwormen), mollusks (=weekdieren), flatworms)
3. Bilateral cleavage (tunicates (=manteldieren))
4. Rotational cleavage (zoogdieren, nematoden)
What are the types of meroblastic cleavage?Telolethical (dense yolk throughout most of cell)
1. Bilaterial cleavage (cephalopod molluscs (=inktvis))
2. Discoidal cleavage (fish, reptiles, birds)
Centrolecithal (yolk in center of egg): superficial cleavage (most insects)
2 Gastrulation and blastulation
What are the three germ layers?Ectoderm, mesoderm and endoderm
What are the 5 types of morphogenic rearrangements and explain themInvagination: infolding of a region of cells
involution: inward movement of an expanding outer layer
ingression: migration of individual cells from the surface layer into the inferior of the embryo
Delamination: splitting of one cellular sheet into two more or less parallel sheets.
Epiboly: movement of epithelial sheets, usually of extodermal cells, that spread as a unit to enclose the deeper layers of the embryo.
What will eventually form from endoderm?The digestive and pulmonary system
What will eventually form from mesoderm?Bones, some of the inner layers of the skin, urinary system, reproductive system and muscles (including cardiac muscle)
What are the steps in the neurulation process?Formation neural plate - folding (neural fold) - elevation neural crest (neural groove) - convergence (neural folds apposing) - Neural tube - migration neural crest cells.
What types of mesoderm are there and what are they responsible for?Intermediate mesoderm: kidney and gonads (geslachtsklieren)
paraxial mesoderm: head & somites --> somites form sclerotome (cartilage), syndrotome (tendons), myotome (skeletal musle), endothelial cells and dermatome (dermis, skeletal muscle)
Laterial plate mesoderm: splanchnic (circulatory system), somatic (body cavity) & extraembryonic
4 Cell specification, determination and morphogenesis
Explain the term 'cell specification'During early development, an
embryoniccell is set on a path of molecular changes. It becomes comittedto certain fates, and passes through the following stages: specification--> determination --> differentiation.
Cell specification is a term for the phenomenon of the embryonic cell being capable to differentiate autonomously when it is placed in a neutral environment. This means that there is something instinsic to the embryonal cell that makes sure it can specify.