Historical Notes on Blood Platelets

Tocantins, Leandro M.

doi:10.1182/blood.v3.10.1073.1073

Cited by 36 publications

(24 citation statements)

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“…Tocantins (60) and Robb-Smith (51) pointed out that Donne (24), Addison (1), and Gulliver FIGURE 7 Spreading platelets numbered in transformation stage sequence 1-6 on the basis of cinemicrographic records of similar preparations . 1, Early pseudopodial stage.…”

Section: Light Microscope Observation Of Platelet Transformationmentioning

confidence: 99%

Transformation and motility of human platelets: details of the shape change and release reaction observed by optical and electron microscopy.

Allen¹,

Lr²,

Widirstky³

et al. 1979

The Journal of Cell Biology

182

123

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Blood platelets from 10 normal human subjects have been examined with a sensitive differential interference contrast (DIC) microscope . The entire transformation process during adhesion to glass is clearly visible and has been recorded cinematographically, including the disk to sphere change of shape, the formation of sessile protuberances, the extension and retraction of pseudopodia, and the spreading, ruffling, and occasional regression of the hyalomere . The exocytosis of intact dense bodies can be observed either by DIC microscopy, or by epifluorescence microscopy in platelets stained with mepacrine . Details offluorescent flashes indicate that the dense bodies usually release their contents extracellularly, but may do so intracytoplasmically under the influence of strong, short wavelength light on some preparations of mepacrine-stained platelets . The release of one or more dense bodies leaves a crater of variable size on the upper surface of the granulomere . Such craters represent the surface component of the open canalicular system and their formation and disappearance can be directly observed . Because these techniques permit quantitation of several parameters of motility which are not readily observable by other techniques, it is suggested that high extinction DIC microscope examination may become a rapid and useful method of studying congenital and acquired platelet disorders . Many features of platelet transformation have been confirmed and extended by scanning electron micrographs . These can in turn be interpreted by reference to time-lapse films of living platelets.KEY WORDS platelets " transformation release reaction -exocytosis pseudopodia motility -DIC microscopy scanning electron microscopy It has been known since the last century that platelets (thrombocytes) undergo a change of shape (transformation) as part of their role in hemostasis (for reviews, see references 19, 20, 22, 51, 60, 66, and 67) . Light microscope observation established that platelets formed spiky protuberances and gradually spread on glass surfaces in imitation of their spreading on damaged vascular endothelia (9) . However, the resolution and sen-J . CELL BIOLOGY C The Rockefeller University Press "

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Section: Light Microscope Observation Of Platelet Transformationmentioning

confidence: 99%

Transformation and motility of human platelets: details of the shape change and release reaction observed by optical and electron microscopy.

Allen¹,

Lr²,

Widirstky³

et al. 1979

The Journal of Cell Biology

182

123

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“…The compound 5'-azido 5'-deoxyadenosine, which has a greater vasodilator action than adenosine (Jahn, 1965) was also inactive at 2 x 10-m. DISCUSSION The first thing that happens when platelets are exposed in vitro to certain aggregating agents including ADP is a change in shape from smooth disks to more spherical forms with variously shaped protrusions. This has been established with both the light and the electron microscope (Tocantins, 1948;Zucker & Borelli, 1954;Setna & Rosenthal, 1958;Macmillan & Oliver, 1965;White & Krivit, 1967). The visual evidence of a change in shape has been correlated with two indirect measurements.…”

mentioning

confidence: 96%

Observations on the change in shape of blood platelets brought about by adenosine diphosphate

Born¹

1970

The Journal of Physiology

250

108

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SUMMARY1. An optical method used for measuring platelet aggregation was adapted for measurements of the change in shape of platelets that rapidly follows the addition of the aggregating agent adenosine diphosphate (ADP).2. Measurements were made using dilute suspension of platelets with sufficient EDTA to prevent their aggregation.3. Measurements of the velocity and magnitude of the optical effects of the shape change were highly reproducible.4. Volumetric measurements showed that the shape change is not associated with an increase in mean platelet volume.5. The velocity of the shape change had a temperature coefficient of about 4-5.6. The velocity and magnitude of the shape change were not affected by pH between 5-8 and 9-2.7. The dependence of the velocity of the shape change on the ADP concentration was in accordance with Michaelis-Menton kinetics. The Km was about 7-2 x 10-7M.8. The velocity of the shape change was inhibited competitively by ATP, adenosine and 2-chloroadenosine but not by AMP. When the inhibitors were added after the maximum of the shape change they caused a concentration-dependent diminution in the record of the change. 9. The results suggest that the shape change is initiated by reaction of the agonist ADP with specific receptor sites on the platelet membrane which leads to energy-requiring changes in the structures responsible for maintaining the disk shape of normal platelets.

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“…The close relationship between platelet shape and functional activity has been recognized for many years (Tocantins 1948). Unaltered platelets in circulating blood or citrate Flatelet-rich plasma (C-PRP) at 37" C. are characteristically discoid in form.…”

Section: Discussionmentioning

confidence: 99%

Effects of Ethylenediamine Tetracetic Acid (EDTA) on Platelet Structure

White

1968

Scandinavian Journal of Haematology

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The anticoagulant, EDTA, is known to produce changes in the external contour of platelets. In the present investigation the fine structural alterations which develop in EDTA platelets were examined in the electron microscope. Platelets exposed to EDTA at 37° C. lose their disc shape and become irregularly swollen with multiple pseudopods. This external transformation is identical to the change which occurs in platelets exposed to ADP, thrombin, or low temperature. Internal changes in EDTA platelets, however, are markedly different from those which occur under the influence of aggregating agents or cold. The differences indicate that the effects of EDTA on platelet shape are not due to dispersal of marginal band microtubules or to the trigging of an internal wave of contraction. Chelation of membrane calcium by EDTA appears to cause marked irregularities in the platelet wall and massive swelling of the canalicular system. Swelling of internal channals is the dominant alteration in EDTA platelets, and this change appears ultimately to be related to the breakdown of platelet granules.

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Historical Notes on Blood Platelets

Cited by 36 publications

References 0 publications

Transformation and motility of human platelets: details of the shape change and release reaction observed by optical and electron microscopy.

Transformation and motility of human platelets: details of the shape change and release reaction observed by optical and electron microscopy.

Observations on the change in shape of blood platelets brought about by adenosine diphosphate

Effects of Ethylenediamine Tetracetic Acid (EDTA) on Platelet Structure

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