Leeuwenhoek had stolen and peeped into the fantastic sub-visible world of little things, creatures that had lived, had bred, had battled, had died, completely hidden from and unknown to all men from the beginning of time. Beasts these were of a kind that ravaged and annihilated whole races of men ten million times larger than they were themselves. Beings these were, more terrible than fire-spitting dragons or hydra-headed monsters. They were silent assassins that murdered babies in warm cradles and kings in sheltered places. It was this invisible, insignificant, but implacable-and sometimes friendly- world Leeuwenhoek had looked into for the first time of all men of all countries. ~Microbe Hunters

Saturday, 6 April 2013

Fixation


In the discipline of histology, fixation is the first thing done to human tissues once they are removed for the body. Whether it is from a biopsy, autopsy, some sort of –ectomy or amputated arm, the tissue must be fixed, usually in 10% formalin, to stop the autolysis (cell death) and putrefaction (bad smell). In fixation, the water in the tissue is replaced by the fixing agent. Have you ever dissected a frog in school? Someone probably has. The frog was placed in formalin to kill all infectious agents and make it safe for 30 rowdy grade 9's to dissect under the supervision of one teacher. You can tell it was fixed by formalin because of the distinct smell of “dissection” when you are walking down a public school hallway.

In the lab, we dissect all sorts of specimen types and make them into slides to look at them under the microscope. We look for cancer, abnormal cells, enlarged cells, and bacteria. There is an entire process which the tissue has to go through in order to make it visible under a microscope, so I don’t advise shoving a chunk of frog under a microscope to see it at a cellular level. Unless it’s an electron microscope...


Darn good and sure of it,

adot

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