Lack of differentiation is called -

Ans. is 'a' i.e., Anaplasia First I would like to explain following frequently asked terms ? Differentiation Differentiation refers to the process by which a less specialized cell (immature) becomes a more specialized (mature) cell type, to perform a specific function. o All specialized cells are derived from stem cells that can give rise to various type of cells. o For example, hematopoietic stem cells from the bone marrow can give rise to red blood cells, or WBCs, or platelets through various stages of development. o This process of development from stem cells to mature cells is differentiation. So, in differentiation cells acquire a type. o For neoplastic cells, differentiation refers to the extent to which neoplastic cells resemble comparabale to normal cells, both morphologically and functionally -3 well differentiated cells resemble to normal cells, while undifferentiated cells do not resemble at all, poorly differentiated cells paially resemble to normal cells. Polarity It means orientation and organization of cells in a tissue, i.e. correct positioning of cells in a tissue. Pleomorphism o Pleomorphism is variation in size and shape. It may occur in cells or / and nuclei. Hyperchromatasia o Nuclei contain an abundance of DNA and are extremely dark staining --> hyperchromatic nuclei. Anaplasia o Anaplasia means lack of differentiation. o It means "to form backward", implying a reversion from a high level of differentiation to a lower level. o This does not mean that the differentiation takes place in reverse direction, i.e. from mature specialized cells to unspecialized stem cells. o Rather, Anaplasia arise from stem cells that proliferate without differentiation (maturation). o So, anaplastic cells resemble primitive-appearing unspecialized cells. o Anaplasia is seen in malignant tumors --) Anaplasia is considered a hallmark of malignant transformation. o But, It is not necessory that all malignant tumors are anaplastic (undifferentiated or poorly differentiated) some malignant tumors may be well differentiated, eg follicular carcinoma of thyroid.