Evaluate the following statement: “The primary differences between early cleavage of most animal
embryos are the result of the quantity and distribution of yolk.”
Answers
Answer:
In developmental biology, cleavage is the division of cells in the early embryo. ... Cleavage differs from other forms of cell division in that it increases the number of cells and nuclear mass without increasing the cytoplasmic mass.
The pattern of embryonic cleavage particular to a species is determined by two major parameters: the amount and distribution of yolk protein within the cytoplasm, and factors in the egg cytoplasm that influence the angle of the mitotic spindle and the timing of its formation.
At the beginning of cleavage, cell divisions tend to occur at the same time in all blastomeres, and the number of cells is doubled at each division. ... Subsequent divisions may alternate between vertical and horizontal cleavage planes, but later cleavage divisions become randomly oriented.
Indeterminate Cleavage. ... with the cell fate of each blastomere determined as early as the 2- or 4-cell stage (determinate cleavage). In deuterostomes, cell fates are not determined until quite late in development (indeterminate cleavage).