Lakhasly

The binding of "C formaldehyde to tissues is shown in Figure 2. At room temperature (25°C), formaldehyde bound to tissue sections increased with time until an equilibrium was reached. Since the tissue sections were extremely thin (16 um), pen- etration was not considered a factor in the kinetics of the reaction. At 37°C, the reaction of formaldehyde is consider- ably faster and equilibrium is reached after 18 hr or less. The thickness of tissue that will be penetrated by formaldehyde under these conditions is far greater than that which bonded to the tissue according to the Medawar constant for aqueous formaldehyde where penetration of tissue-like substances is a function of the square root of the time of cxposure. In the case of 4% formaldehyde the constant is about 5.5, which means that in 24 hr immerESion, formaldehyde may penetrate 20 or more mm. The rate of binding of "C formaldehyde to (1Ssues that thick was not measured. In a practical sense, this experiment shows that sincE COvalent binding of formaldehyde into cross links is a fundamental event in fixation, hixarion wirh formaldehyde depends on 24 hr exposure ar foom temperature or 18 hr at 3°C.

The binding of "C formaldehyde to tissues is shown in Figure 2. At room temperature (25°C), formaldehyde bound to tissue sections increased with time until an equilibrium was reached. Since the tissue sections were extremely thin (16 um), pen- etration was not considered a factor in the kinetics of the reaction. At 37°C, the reaction of formaldehyde is consider- ably faster and equilibrium is reached after 18 hr or less. The thickness of tissue that will be penetrated by formaldehyde under these conditions is far greater than that which bonded to the tissue according to the Medawar constant for aqueous formaldehyde where penetration of tissue-like substances is a function of the square root of the time of cxposure. In the case of 4% formaldehyde the constant is about 5.5, which means that in 24 hr immerESion, formaldehyde may penetrate 20 or more mm. The rate of binding of "C formaldehyde to (1Ssues that thick was not measured. In a practical sense, this experiment shows that sincE COvalent binding of formaldehyde into cross links is a fundamental event in fixation, hixarion wirh formaldehyde depends on 24 hr exposure ar foom temperature or 18 hr at 3°C.