Final answer:
Citrate is the anticoagulant that will not alter cell morphology at the recommended dilution but can cause cell shrinkage if used excessively, due to osmotic imbalance.
Step-by-step explanation:
The anticoagulant that will not alter cell morphology at the recommended dilution but may lead to cell shrinkage if used in excess amounts is citrate. Citrate acts as an anticoagulant by chelating calcium ions, which are essential for the coagulation cascade. At the proper dilution, citrate can prevent blood coagulation without affecting cell size. However, if used in excess, it can lead to an imbalance in osmotic pressure, resulting in cell shrinkage. This shrinkage is akin to what occurs in a hypertonic solution, where water leaves the cell causing it to shrink.
On the other hand, heparin acts by opposing the conversion of prothrombin to thrombin and is not known for causing cell shrinkage when used in excess. Sodium fluoride inhibits glycolysis and is not commonly associated with alterations in cell volume at high concentrations. EDTA also acts by chelating calcium but is more known for its effects on DNA and is not specifically associated with causing cell shrinkage when used in excess.