This document describes the process of isolating and preparing chromosomes from white mice for analysis. Key steps included treating mice with colchicine to arrest cells in mitosis, sacrificing the mice and extracting bone marrow cells and testes tissue, suspending the cells in a hypotonic solution to spread the chromosomes, fixing and staining slides with the cell suspensions, and observing the chromosomes under a microscope. The white mice were used as model organisms because they are readily available, low-cost, easy to handle, and their chromosomes correlate well with other test organisms.

1. Process of isolating
chromosomes of White mice
By: Heydee A. Santos

2. Chromosome Preparation:
 Chromosome of the bone marrow cells and
testis were prepared afte one hour, the
treatment into 0.025% colchicine (Fig. 6) at
0.25%ml per kilogram body weight. (Fig.10)
the mice were sacrificed by cervical
dislocation. The femur yields the bone
marrow cells which were pumped out into the
isotonic solution (2.2% sodium Citrate)
through the sucking and pumping motion of
the syringe with a fine needle.

3. Each Mouse was Weighed Prior to
Colchicine Treated

4. The Mice were Pre-Treated with
0.25ml Colchicine one hour
before

5. Chromosome Preparation:
The testis was pulled just above the penile organ
through an incision, again these was placed in an
isotonic solution 2.2% (Sodium Citrate) for
teasing to a fine suspension though a syringe. The
bone marrow cells and testis suspension were
transferred to a dryer tube. Spinning for five (5)
minutes (Fig. 8), the supernatant was removed for
cell breaking and stocking in a hypotonic solution
(1.0% sodium citrate) for twelve (12) minutes.
Fixation follows, for the testis cells suspension,
three (3) fixation processed are needed. Flicking
of the tube is also needed for the recovering of
metaphase. Four (4) fixations are needed for the
bone marrow cells suspension.

6. Slide Plating:
 Dried clean microscope slides (25x 75 mm)
previously soaked in a 1:1 ratio of Ethanol – Acetic
acid solution, using a fine – tipped pasteur pipettes,
a suspension was topped on a pre cleaned slide and
dried by blowing the suspension under an infra – red
light. (Fig. 9). Slide was stained with temporary
stain Toluidine – o, and covered with cover slips, and
observed with Zeiss standard 18 microscope camera
attachment using 25 – 40x objectives and a 10x / 18
oculars with plerapo 100 / 1.3 oil immersion
objective, green filter and colpan 21 high copy film,
it is an important Panchromatic fild packed by
Comlumbia

7. Suspension was Topped o a PreCleaned Slide under an Infra – red
Light.

8. Analysing chromosome

9. Normal chromosome of testis

10. Chromosomal Aberration on
testis

11. Chromosomal Break at Control – Irridiated
Mouse Bone Marrow Cells at Mitotic Metaphase

12. Sticky Chromosome

13. Reason of using white mice as a
biological indicator
The mice were used as they are good
biological indicator organism for the
following reason:
(1) readily available (2) low cost (3) ease
of handling (4) good chromosome
condition and (5) have good
correlation with other test organism.

14. Thank You!