Which one is enucleated?
A. Squamous epithelial cells
B. Mature leucocyte of man
C. Mature erythrocyte of frog
D. Mature erythrocyte of man
E. Osteocyte in man

Hint: Enucleated cells are those cells in which the cells have no nuclease. Enucleation is the process where the cell's nucleus is removed. Cells become enucleated when they attain maturity.

Complete answer: Squamous epithelial cells- The most common type of cell seen in the sediments of urine is the urine squamous epithelial cells. They are large flattened cells with a large quantity of cytoplasm and a small nucleus.
Mature leucocytes of man- also called white blood cells (WBC’s) are part of the immune system which is involved in protecting the body against infectious diseases and pathogens. All white blood cells have a nucleus.
Mature erythrocyte of frog- The frog’s erythrocytes is nucleated.
Mature erythrocytes of man- RBC are nucleated biconcave cells that have haemoglobin pigments that transport oxygen.
Osteocyte in man- It is a star-shaped type of bone cell, and they are commonly found in mature bone tissue and they have a nucleus in the middle.
Hence, the answer is option D, the Mature erythrocyte of man.

Note: RBCs are biconcave in shape that is both sides surface curved inside a sphere. This shape will help the erythrocytes to manoeuvre the RBC cells into tine capillaries to deliver oxygen to organs and tissues. RBC is very important in determining human blood type. Blood type is determined by certain surface antigens present on the RBC cells. A minimum of 2.4 million new RBCs is produced per second. These cells originate from bone marrow, they circulate for about 120 days, and then they are recycled.