Summary
The initial haemostatic process in thrombocytopenic animals after transection of arterioles
and venules was investigated in a rabbit mesenteric preparation. Graded thrombocytopenia
with a bone marrow suppressant (busulphan) and anti-platelet serum gave comparable
results. With decreasing platelet counts there was progressive prolongation in haemostatic
plug formation time, and a significant non-linear relation between platelet count
and haemostatic plug formation time. Haemostatic plugs formed under thrombocytopenic
conditions were more stable than normal. The difference in stability normally seen
between plugs in arterioles and venules disappeared with decreasing platelet counts.
The relationship between venular and arteriolar haemostatic plug formation time was
also reduced with decreasing platelet counts.