Centriole is absent in

(Liver) (37-Ganong 23rd), Centrioles in hepatocytes cellular and molecular life sciences vol-24, Number 11, 1157-59, DOI 10; 1007/BFO 214785Centrioles which are small cytoplasmic bodies of about 150-200 nm in diameter and 300-350 nm in length concerned with organization in the spindle during cell division have rarely been reported in adult mammalian liver cellsCENTROSOMES - Near the nucleus in the cytoplasm of eukaryotic aniimal cells is a centrosome. The centrosome is made up of two centrioles and surrounding amorphous pericentriolar material* The centrosomes are microtubule - organizing centers (MTOCs) that contain y- tubulin* Centrioles are responsible for the movement of chromosomes during cell divisions (10.K. Sembulingum 5th)* If there is no centriol in the cell, the cell cannot divide. Neurons of postnatal life have no centrioles hence they cannot divide; hence in the post natal life no new neuron formation can occur. But throughout life, death of individuals neurons continue Hence in old age, there is considerable loss of brain mater (8- S.K chaudhari 6th)