Hendry Rao, 012012111007, Histology Technique, Lab Report

LAB REPORT 1

TITLE : Dissection & Fixation

RESULTS:

Hendry Rao, 012012111007, Histology Technique, Lab Report

Sterile Bottle Used to Fix Organs

DISCUSSION:

Hendry Rao, 012012111007, Histology Technique, Lab Report

The procedure starts from the dissection of rats. The method of choice used for sacrificing the

rat was cervical dislocation. Cervical dislocation reduced the stress and trauma to the rats prior to

sacrificing. It is done by ensuring the rats are on a surface that it can grab. Then locating the base of

its skull, the left thumb and index finger was used to hold its head down. The right hand was used to

hold the base of its tail. The dislocation was performed by pushing forward down the hand restraining

the head and pulling backwards the right hand holding the base of the tail. The dislocation was

verified by feeling the separation of cervical tissue. The process was confirmed when there is no

breathing or heart beat.

In the lab, the rats were first knocked out with chloroform as the rats were too agitated. After a

few minutes, cervical dislocation was performed. Due to lack of experience, the process was deemed

failed as the rat’s spine lumbar region was dislocated causing paralysis. The rat woke up and had to

be knocked out again before the tutor assisted the dislocation and this time around the breathing of

the rat ceased. Thusly, killing the rat.

A few safety precautions should be observed during dissection of the rat. A sharp scalpel sized

at 22 blades was used. The large blade also ensured accidental cuts on the dissector could be

minimized. Obviously proper PPE was used, such as lab coat and latex gloves. The sharp

instruments are wielded carefully and used only for dissection. During dissection, the blunt end of the

blade was used ad to the edged one, to minimize the damage to the tissue and also the animal’s

body. The skin aren’t removed fully and carefully splayed and pinned to expose the organs in the

abdominal region. Sharp tipped scissors were used to reduce the damage to the organs due to its

simplicity and practicality. Importantly, instruction on how to dissect the animal was taught and

observed when the tutor was explaining. The animal wasn’t splayed fully, but opened up like a book

to harvest the organs needed. This ensures we abided to the animal ethics code and as well as for

easy clean up and disposal or the animal’s body.

Fixation was done after the needed organs were harvested, cleaned and prepped. Any excess

fat or connective tissue was cleaned off and washed in running water to remove as much blood from

the organs as presence of blood may obscure the processes following suit. The type of fixative used

was 10% Formalin. The volume used was 10 times the volume of organs used to ensure proper

fixation. The organs are fixed after needed sections of the organs are sliced and cut into manageable

size was done. Organs that were harvested were the testis, heart, lungs, kidney, pancreas and liver.

Hendry Rao, 012012111007, Histology Technique, Lab Report

Importance of fixation is to ensure halting of autolysis and putrefaction of the tissue after

dissection. By doing this process, majority of the cellular and chemical composition of the tissue cell

may be preserve for histological techniques to be done. So during the staining and observation

process, a proper cellular morphology can be viewed.

CONCLUSION:

Dissection and fixation process is learned.

QUESTION:

Why the size of tissue does has influence on the rate of fixation?

The size of tissue will actually dictate the amount of fixative agent used. The smaller the tissue the

faster the infiltration of the fixative agent. Big and thick tissues generally takes a longer time to fix and

if not adequate time or amount of fixative used, the tissue wouldn’t be fully fixed causing the next

process of dehydration and later on the sectioning process complicated.

REFERENCE:

Kernian J.A,2008.Histological and Histochemical Methods,4th Edition. Reprint 2010. Scion Publishing

Limited,Oxfordshire, England

Guidelines for the Use of Cervical Dislocation for Rodent Euthanasia, Revised, 13 th May 2013,

Institutional Animal Care and Use Committee, The University of Texas, Austin

Approved Euthanasia Methods for Small Lab Animals: Tools and Techniques, Uploaded 3rd

November 2009, watched on 24th April 2014, 2.14am http://www.youtube.com/watch?

v=QDaDX5F973Q