Evidence of Phylogenetic Canalisation of the Circulating Platelet Mass in Man

Abstract

SummaryPhylogenetically mammalian platelets are an apocrine secretion from nucleated thrombocytes, and biologically the number of circulating fragments is irrelevant compared with their total mass and biochemical function. The literature on human genetic derangements affecting the circulating platelet mass is reviewed. The product of platelet count and platelet volume is shown to be “canalised” since many congenital forms of thrombocytopenia are associated with a reciprocal increase in the mean platelet volume. Considerations of platelet size are essential since macrothrombocytopenia is a racial characteristic of many Mediterranean peoples and probably also occurs frequently in others races. The location of platelet disorders in relation to the phylogenetic canal provides an objective classification which has diagnostic, therapeutic and prognostic significance.

Biochemical studies of two patients with the gray platelet syndrome. Selective deficiency of platelet alpha granules.

“…The low platelet numbers seen in patients with the gray platelet syndromne suggests either that these platelets are being destroyed more readily than normal platelets in the circulation or that megakaryocyte production is decreasecd. Alternatively, there may be an abnormality in separationi of platelets from inegakaryocytes similar to MIediterranean macrothrombocytosis with decreased numbers of large platelets representing a normiial platelet mass (48).…”

Megakaryocyte Polyploidization in May-Hegglin Anomaly

“…Giant platelets have already been observed within the megakary ocytes [6][7][8]. The total peripheral platelet mass is regarded to be normal [1,5]. Therefore, it was postulated that the underlying defect of this dis ease is a disturbance of megakaryocyte maturation.…”

Disorders affecting megakaryocytes and platelets

“…Since his mean platelet volume was increased (11.1 µm 3 ), the thrombocytopenia was probably relative, as it is in other giant platelet syndromes, and the circulating platelet biomass (platelet number × mean platelet volume) was normal. 78 Aggregation studies revealed an essentially normal response to most aggregating agents. However, the reaction of gray platelets to collagen and thrombin was less than normal.…”

“…78 Erythrocyte stomatocytosis is also observed in high frequency in the population. Individuals with this problem do not have a bleeding tendency.…”

“…If one multiplies the platelet number by MPV to obtain the platelet mass in circulating blood, there is little difference between the values obtained in MHA and normal individuals. 78 Thus, patients with MHA are not really thrombocytopenic. The number of megakaryocytes present in bone marrow of MHA patients is not increased, and their mean volume is similar to that of normal megakaryocytes.…”