A system for quantitative evaluation of fixatives for light microscopy using paraffin sections of kidney and brain

Abstract

A numerical scoring system is presented for evaluating structural fixation of certain mammalian tissues for light microscopy. Small pieces of rat's kidney and brain, tissues for which artifacts of fixation are well documented, were fixed in various fluids. Random code numbers hid their identities, and paraffin sections were stained to show nuclear chromatin, cytoplasm and extracellular materials. Two sections of each specimen were examined and awarded scores according to described schemes, for microanatomical and cytological fixation. The assessment was confined to preservation of structure; chemical changes were not taken into account. When the code was broken, the scores for both sections of each specimen from each fixative were added. The scores obtained (24 best to eight worst) are generally comparable to the grades (I-V) given for traditional fixatives by JR Baker. The criteria for quality of fixation were defined more explicitly than those for Baker's grading method, which used mouse testis as the test object. Assessments are presented for several traditional fixatives and for four zinc-formaldehyde mixtures. The scoring system should be useful for evaluating newly developed fixatives for animal tissues for light microscopic examination of paraffin sections. In an evaluation of four traditional fixatives and four zinc-formaldehyde mixtures, variation among three different observers was only +/-1 point on either side of the median score for microanatomical or cytological preservation by any of the eight fixatives. This approach has certain limitations, notably that the criteria for cytological fixation do not include the preservation of chromosomes or specific cytoplasmic organelles.

Label-Free Imaging and Biochemical Characterization of Bovine Sperm Cells

“…Indeed, AI allows controlling the genetic quality of breeding herds and preselecting the sex of offspring. Sperm morphology assessment is one of the most important criteria for determining the quality of the semen sample: semen with high levels of morphological sperm abnormalities could reflect genital dysfunction, and it is one of the most common factors of male infertility; therefore, it is not recommended for AI [ 1 , 2 ]. Besides, application of AI using semen with preselected sex could have several potential benefits as: higher production levels with reduced costs, improvement in animal health and welfare, reduction of environmental impact due to the elimination of the unwanted sex before they grow to adulthood, and faster genetic progress [ 3 ].…”

Fixation strategies for retinal immunohistochemistry

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