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g., resins) appear to result in lower shrinkage, but the proportion of volume losses should be calculated in all cases in order to correct for NV and N overestimations caused by shrinkage of the histological specimens. g., Bouin’s solution) and embedding media (e. Paraffin embedding of formaldehyde-fixed tissues has the major problem of tissue shrinkage by about 30% (Medina et al., 2007) to 50% (Dorph-Petersen et al., 2001) in volume reduction. In such circumstances, it may be useful to define a priori the function that best fits the relationship between the gonad volume and its mass, such that ovary volumes can be reliably estimated from weight data.Īnother disadvantage of these stereological procedures is that they are significantly affected by volume changes following tissue processing for microscopic examination. Measurements of the ovarian volume aboard sampling vessels are frequently difficult or impractical. The ovarian volume can be measured either directly by the fluid displacement method or obtained from the Cavalieri’s principle (Michel and Cruz-Orive, 1988). Therefore, the volume of the organ should be known. Hence, the method allows unbiased estimates of numbers irrespective of the particle’s physical features (Howard and Reed, 2005).īoth of the above methods provide estimates of the number ofparticles (N) from numerical density estimations extrapolating NV to the whole volume (V) of the reference space (N = V・NV). The disector is actually a three-dimensional technique, as it performs counts of particles in volumes delimited by pairs of parallel planes that are separated by a known distance, with a frame of known area superimposed on the sections. Unlike model-based methods, the Disector principle (Sterio, 1984) provides unbiased estimates of the number of objects in a given volume of tissue (numerical density, Nv) with no need for assumptions, models, or correction factors. As this method relies on assumptions about particle shape and size distribution, it is inadvisable in counts of objects displaying an irregular shape and/or a highly variable size, such as β-atretic follicles or POC.
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2000, Coward and Bromage, 2002 Medina et al., 2002, 2007 Murua et al., 2003 Cooper et al., 2005) is based on the equation developed by Weibel and Gomez (1962). So far, the most widely used stereological procedure to estimate fish oocyte numbers (Emerson et al., 1990 Greer Walker et al.
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The first practical stereological method was based on the Delesse’s principle, which states that the fractional volume of a component in a material is proportional to its fractional crosssectional area. So, stereological applications provide quantitative information about 3-D structures from measurements made on 2-D sections. Stereology is the science of the three-dimensional interpretation from bidimensional images. Estimates of fecundity in fishes can be obtained from counts of large yolked oocytes (potential fecundity) or postovulatory complexes (POC, =postovulatory follicles) (realized fecundity) applying stereological methods to histological sections of the ovaries.