Red blood cells are not considered fully mature until they have lost their nucleus, ribosomes, and mitochondria. This may seem strange, and it is very odd for a cell not to have a nucleus, ribosomes, or mitochondria, but in the case of red blood cells, they don't really need them.fter all, red blood cells have to come from somewhere, and cells do need mitochondria and a nucleus with DNA to go through mitosis, make new cells, and make all of that hemoglobin protein. As it turns out, immature red blood cells do have mitochondria and a nucleus for just those reasons.
Definition of a Trapezoid. A trapezoid is a 2-dimensional geometric figure with four sides, at least one set of which are parallel. The parallel sides are called the bases, while the other sides are called the legs.
1 A trapezoid is a quadrilateral with one pair of opposite sides parallel. 2  It can have right angles (a right trapezoid), and it can have congruent sides (isosceles), but those are not required.