Station 2: Processing Specimen

Specimens are set up in a biologic safety cabinet. These cabinets are designed to prevent specimen contamination, and to protect the technologists from infectious disease. In this cabinet specimens are mixed with culture media . They are then placed in a environmentally controlled CO2 water-jacketed incubator. At this point, mitogens may be added to specimens to encourage cell division. The amount of time the specimens remain in the incubator varies depending on tissue type and the type of study requested.

The next step in the procedure is the "harvesting" of the cells. Harvesting is necessary to yield metaphase spreads from the cells as they undergo mitosis. When the specimen is ready to be harvested, Colcemid is added to arrest the cells in the metaphase stage of mitosis. This inhibits spindle fiber formation. By inhibiting the spindle fibers from forming the chromatids are not pulled apart and the chromosomes remain intact. The Colcemid time and concentration depends on the type of specimen being studied.

Mitosis

Interphase – DNA replicates- 2 double-stranded DNA molecules
Prophase – DNA condenses into chromosomes
Metaphase – Chromosomes are maximally condensed and line up along the equatorial plate
Anaphase – Chromosomes are pulled apart into individual chromatids
Telophase – Two daughter cells are formed with exact copies of the original DNA

Animation

Cells Alive - Animal Cell Mitosis