When neutrophils shows a degenerative change in which the nucleus has undergone fragmentation. This process is known as; (AIPG 2011)
a. Karyorrhexis pattern of nuclear degradation in which a pyknotic or partially pyknotic nucleus undergoes fragmentation followed by complete lysis. Liquefactive necrosis, Caseous necrosis is seen in tuberculosis and some other granulomatous diseases; coagulative necrosis is seen following infarctions of many organs (other than the brain).
b. Karyolysis is characterized by decrease in nuclear basophilia, which is presumably the result of DNAse activity.
c. Pyknosis is characterized by nuclear shrinking and basophilia, apparently as a result of DNA condensation.