Pathologic Increase (Or Decrease): Due to abnormal function or disease, as
contrasted to physiological (due to normal body function).
Pernicious Anemia: A chronic, macrocytic anemia caused by a defect in production of
"intrinsic factor" by the stomach. There is accompanying megaloblastic erythropoiesis,
poikilocytosis, granulocytic hypersegmentation, achlorhydia, and neurological
Petichiae: Small spots on the skin formed by subcutaneous effusion of blood (also
purpura and ecchymoses).
Phagocytosis: The destruction of organisms and extraneous matter by a process of
envelopment and absorption.
Plasma: The fluid portion of the blood composed of serum and fibrinogen, obtained
when an anticoagulant is used.
Plasma Cell: A lymphocyte-like cell with an eccentrically placed deep-staining nucleus.
The nuclear chromatin is distributed in a "wheel-spoke" fashion. The cytoplasm is deep
blue with a lighter halo about the nucleus.
Poikilocyte: A red blood cell having abnormal shape (pear-shape, sickle-shape, etc.).
Poikilocytosis: Increased number of abnormally shaped erythrocytes.
Polychromasia: Diffuse basophilia of the erythrocytes.
Polychromatophilia: The presence in the stained blood smear of immature,
nonnucleated, bluish-staining red blood cells.
Polycythemia: An increase in the total number of erythrocytes. (See erythremia.).
Precursor: A substance from which another substance is formed.
Promyelocyte: The precursor of the myelocyte having nonspecific azurophilic (red-
purple) cytoplasmic granules.
Prorubricyte: The second stage of development of the red cell.
Prothrombin: The inactive precursor of thrombin that is formed in the liver and present
normally in the plasma. Its formation depends upon adequate vitamin K.
Punctate Basophilia: Small basophilic aggregates in the erythrocytes that stain blue
with the basic dye of Wright's stain; also basophilic stippling.