Abstract
Fenn 1 demonstrated the ease with which erythrocytes undergo hemolysis when they come in contact with glass. Davidson 2 showed that a relatively large proportion of erythrocytes contain basophilic staining-substance. Watson 3 concluded that “the fragments of effete or damaged erythrocytes correspond in every detail to the bodies known as blood platelets.” For these reasons, we wish to record our observations on the blood platelets of the rabbit. During these experiments it was observed that there were marked variations in the platelet-counts from the same animals, and that the estimated counts from blood-smears did not agree with those calculated in the counting-chamber.
The blood platelets of normal adult rabbits were counted. Chamber-counts and smears were prepared from the same drop of blood obtained from the ear (a) without trauma, (b) after moderate trauma, and (c) after prolonged trauma. Variations between chamber- and smear-counts were studied, and the effects of time on the formation of platelets in the pipette were observed. The massage consisted of gentle, but firm, stroking of the ear at a rate of 25 strokes per minute for one minute and for 5 minute periods. A distal venous ramus of the ear was punctured and the first drop of blood withdrawn was studied. Anders Kristenson4 fluid was used to dilute the blood. It was filtered and centrifugalized for 20 minutes immediately before each experiment. An erythrocyte-counting pipette was filled as follows: diluent to the 0.5 mark; blood to the 0.5 mark; then diluent to the 101 mark. The pipette was shaken for 3 minutes and a Levi-Neubauer counting-chamber was filled and allowed to stand for 20 minutes.
Summary. Moderate massage or trauma causes an increase in the total platelet count. After prolonged trauma, the count drops to normal. These phenomena occur locally in the traumatized ear. The counting chamber method of enumerating blood platelets gives values which are 2.8 greater than the smear estimation values. The platelet count, from the same pipette after increasing intervals of time, rises at first and then falls. Anders Kristenson fluid is undesirable for counting blood platelets because it dissolves erythrocytes.
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