Various fixation methods are aimed at maximizing the rapidity of penetration of fixative into the tissue and its interaction with cellular components.

Immersion Fixation

1. Cell Monolayers- high s/v, rapid fixation (5-10 min.)

2. Cell Suspensions- high s/v but need cohesive pellets

centrifugation--- pellets ----- encapsulation (2 % agar or

gelatin)

3. Excised Tissue- lower s/v, @ 30-40 mins. fixation

(pre slice and dice to least manipulatable unit-LMU)

In Vivo Fixation (anesthetized specimen)

1. Topical Fixation- fixative is dripped onto exposed

tissues or injected into cavities (lung or alimentary

tract)- advantage of uninterrupted blood supply.

2. Perfuse-Fixation- the circulatory system is the most

efficient means of rapid delivery of fixative to all

tissues and cells.

Anesthesia-nembutol,ether, MS222, pithing, cerv. sep.

Exsanguination-flushing of blood with BSS , heparin

Perfusion-gravity feed,syringe pump, peristaltic pump