Morphology of apoptosis of polymorphonuclear leukocytes isolated from juvenile bovine mammary glands

Veterinarni Medicina 45, 2000, 71-81

The paper describes the occurrence and morphological pattern of apoptosis of polymorphonuclear leukocytes (PMN) of juvenile bovine mammary glands as imaged by light, fluorescence, confocal, and transmission electron microscopy. The cells were obtained by lavage of 40 juvenile bovine mammary glands stimulated with muramyl dipeptide. Twenty-four hours after the stimulation, the percentages of necrotic and apoptotic PMN were 7.9 and 4.2, respectively. Light, fluorescence and confocal microscopy of the apoptotic PMN showed morphological alterations including condensation of chromatin (karyopyknosis), cell shrinking, loss of pseudopodia, and spherical shape, while transmission electron microscopy revealed aggregation of chromatin, intact organelles and cell membrane, and vacuolisation of cytoplasm. The apoptotic PMN were eventually phagocytosed by macrophages as demonstrated by electron microscopy, and light microscopy in preparations stained for myeloperixidase, as well as by confocal microscopy. The finding of degenerating and necrotic PMN indicates that there exist two forms of death of this cell type and is suggestive of the existence of factors alterating the apoptotic programme and shortening the, life span of PMN

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