**5. Lysosomes**

They have a diameter of 200-250 nm which places them to middle size granule (14). They can't be distinguished from alpha granules under EM observation because of the similarities in dense electron appearance. By the content of acid phosphates and arylsulphates cytochemical staining techniques can effectively distinguish lysosomes from alpha granules. In an activated platelet they expel their contents to environment as the other two granules by membrane fusing mechanisms. The difference for lysosomes to be involved in activation is that they need a more potent stimulus. The role of lysosomal components in homeostasis is not well understood as the other granules contribution. They are involved in thrombus formation and extracellular matrix remodeling (8).

It seems that lysosomes in platelets don't have any distinguished features, they share the common features with other cells lysosomes (29).

The components of dense granules are briefly given in Table 3 (8, 18, 30, 31, 32).

**Figure 2.** M: Mitochondria, αG: alfa-granules, DG: dense granules, Gly: glycogen particles and OCS: open canalicular system. The morphology can be seen in equatorial section of a human platelet. This image is referenced from Zufferey 2011 (Thanks for the kind permission of John Wiley and Sons to use this image)(33).

PF3 Acid phosphatase Glucose-6 phosphatase Arabinosidase N-Acetyl-galactosominidase ATP = adenosine triphosphate TGF CD63 Cathepsin lysosomal membrane proteins (LAMP-1, LAMP-2) acid hydrolases cathepsins

8 Blood Cell – An Overview of Studies in Hematology

formation and extracellular matrix remodeling (8).

common features with other cells lysosomes (29).

**5. Lysosomes** 

this image)(33).

Syndrome (26, 27, 28) and Chediak Higashi Syndrome. In both syndromes stoppage of

They have a diameter of 200-250 nm which places them to middle size granule (14). They can't be distinguished from alpha granules under EM observation because of the similarities in dense electron appearance. By the content of acid phosphates and arylsulphates cytochemical staining techniques can effectively distinguish lysosomes from alpha granules. In an activated platelet they expel their contents to environment as the other two granules by membrane fusing mechanisms. The difference for lysosomes to be involved in activation is that they need a more potent stimulus. The role of lysosomal components in homeostasis is not well understood as the other granules contribution. They are involved in thrombus

It seems that lysosomes in platelets don't have any distinguished features, they share the

**Figure 2.** M: Mitochondria, αG: alfa-granules, DG: dense granules, Gly: glycogen particles and OCS: open canalicular system. The morphology can be seen in equatorial section of a human platelet. This image is referenced from Zufferey 2011 (Thanks for the kind permission of John Wiley and Sons to use

The components of dense granules are briefly given in Table 3 (8, 18, 30, 31, 32).

bleeding is defective based on the impairment in dense granules (14).

**Table 3.** Some main components of platelet lysosomes
