Centrins are present in the centrioles and pericentriolar lattice. Centrins are required for duplication of centrioles. Centrosome disorientation refers to the loss of orthogonality between the mother and daughter centrioles. Mice and rats have no recognizable sperm centrioles. Basal bodies are structurally identical to centrioles. In the first step, the connection between the two parental centrioles is destroyed. In cells without centrioles chromosomes can nucleate microtubule assembly into the mitotic apparatus. The two centrioles in the centrosome are tied to one another. However, the two centrioles are of different ages. It was suggested that subcellular neoteny could explain why sperm cells have atypical centrioles. One of the centrioles of the cell elongates to become the tail of the sperm. Most sperm cells have centrioles in the sperm neck. Many cells can completely undergo interphase without centrioles. The centrioles can self replicate during cell division. The last common ancestor of all eukaryotes was a ciliated cell with centrioles.