Question

Which of the following is NOT a characteristic of human senescent cells?

-heterochromatic foci present in the nucleus

-positive staining for Ki67

-large cytoplasm

-fried egg appearance in culture

-none of the above

Answer 1

The human senescent cell remains active metabolically but they are not able to re-enter the active cell cycle. The cells spread on a monolayer cultures, have a large cytoplasm and stays for few weeks till it gets the nutrients as required by them. It appears like a fried egg. There is senescence associated heterochromatin foci formed in the nucleus and appears as specialised domains. It leads to silencing of genes that promotes the proliferation.

The answer is positive staining for Ki67 because it shows positive only during the early initiation and proliferation phase. It continues till the S-Phase but does not go beyond that which means it is not present during the late senescence phase.