Apoptosis of neutrophilic granulocytes of bovine virgin mammary gland in scanning electron microscopy

The objective of this work was the morphologic analysis of apoptosis of neutrophilic granulocytes (hereinafter referred to as neutrophils) in scanning electron microscopy (SEM) in comparison with morphological features distinguishable by light microscopy. This study was performed on 12 bovine virgin mammary glands washed with physiological buffered solution (PBS) prior to the induction of cell influx by PBS. Twenty-four hours after influx induction the cell suspension was obtained by the lavage of mammary glands with PBS. The particular lavages were cytologicaly and bacteriologicaly examined. all bacteriological examinations were negative. Mononuclear phagocytes (MoP), lymphocytes and neutrophils were distinguished in the cell suspension of the lavages by means of light microscopy. The neutrophils predominated in differential cell count. Neutrophil population showed some signs of structural features typical for the process of apoptosis that were distinguished in haemocytometer and light microscopy on stained microscopical smears. The process of apoptosis consisted of three structurally different stages: karyopyknosis, zeiosis and the stage of apoptotic bodies. These stages of neutrophil apoptosis were distinguished also by SEM. Karyopyknotic neutrophils assumed spherical shape while they lost all of their superficial pseudopodia. Neutrophils in zeiosis stage showed prominent surface protumberances, bubble-shaped vesicles causing a bizarre deformation of the cells. After the membrane vesicles had split off, they began to form spherical formations (apoptotic bodies). On the basis of neutrophils. specific structural properties it could easily distinguish all the three stages of neutrophil apoptosis by means of SEM technique as well as other morphological methods.