Spherocytosis in blood smear seen in-a) Haemoglobin-Cb) Mechanical traumac) Hereditary spherocytosis d) Hereditary elliptosis
Spherocytes                                                       

Spherocytes are small, spherical red blood cells (RBC).
Spherocytes are approximately two-third the diameter of normal RBC.
In comparison to normal erythrocytes, they have a decreased surface area to volume ratio.
They are more densely hemoglobinized and lack a zone of central pallor (normal erythrocytes have central 1/3rd pallor)

Causes of spherocytes 

Immunohemolytic anemia → Most common cause.
Defect in red cell membrane.
Hereditary elliptocytosis
Bums
G-6-PD deficiency
Wilson's disease
Hereditary spherocytosis
Hypophosphatemia
Toxins → Zinc toxicosis, Coral snake venom.
Trauma to erythrocytes, e.g., in microangiopathic hemolytic anemia like DIC.
Paroxysmal cold hemoglobinuria.
4-hydroxyphenolpyruvate hydroxylase deficiency.
Rhesus deficiency syndrome.
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