Shrinkage of Nasal Mucosa and Cartilage during Formalin Fixation

Abstract

Background:After resection, specimens are subjected to formalin fixation during histological processing. This procedure can result in tissue shrinkage, with the amount of shrinkage related to tissue composition and tissue type.Aims:To evaluate the shrinkage of nasal mucosa and cartilage tissue and compare differences in shrinkage after resection, after formalin fixation, and during microscopic examination to understand differences in the rate of shrinkage of different tissue types.Study Design:Animal experimentation.Methods:Fresh nasal septa were excised from sheep (10 mm diameter in 40 sheep and 20 mm diameter in 40 sheep). The mucosa was separated from one side of the cartilage, with the contralateral mucosa remaining attached to the cartilage. Specimen diameters were measured in situ, after resection, after fixation for 6 or 24 hours (10% formalin), and during microscopic examination.Results:There were no differences between the in situ and after resection diameters of any tissue components (free mucosa, mucosa attached to cartilage, and cartilage) of all nasal specimens (10- or 20-mm diameter and 6- or 24-hour fixation). However, significant shrinkage occurred between resection and after-fixation. Regarding tissue specimens that were fixed for different durations (6 or 24 hours), we observed a significantly smaller mean tissue diameter in specimens fixed for 24 hours versus those fixed for 6 hours for mucosa attached to cartilage (in the 10-mm diameter after-fixation samples), free mucosa (in the 20-mm diameter after-fixation samples), mucosa attached to cartilage (in the 20-mm diameter after-fixation and microscopic measurement samples), and cartilage (in the 20-mm diameter after-fixation samples). Tissue shrinkage was greatest in free mucosal tissue and least in cartilage.Conclusion:These results should be considered when evaluating patients undergoing surgical procedures for nasal cavity and paranasal sinus malignancies. Surgical margins should be measured before fixation or evaluated if possible before fixation and shrinkage.

Longitudinal study of rat volar fat pad fixation and ethanol storage: implications for the use of fluid‐preserved specimens in morphological studies

“…Kansu et al. () found a similar size effect for preserved 10‐ and 20‐mm diameter nasal mucosa and cartilage samples. Others specifically report no that discrepancies between differently sized specimens exist and suggest the phenomenon may be taxon‐specific or the result of incomplete fixation (Lee et al.…”

“…), yet Kansu et al. () report that leaving it attached to excised and preserved nasal mucosa (90% water, Schmidt, ) significantly reduces shrinkage of the mucosa. This was not the case when muscle (65–70% water per unit volume, Schmidt, ) was left attached to excised skin (65% water, Schmidt, ); no reduction in shrinkage for either tissue was noted (Jeyakumar et al.…”

“…This, too, is well illustrated through comparisons of preserved specimens of different seasonal body compositions (Butler, 1992;Takizawa et al 1994), as well as documentation of differential changes in gross shape and proportion within individual specimens comprising multiple tissue types (Vervust et al 2009;Weisbecker, 2012;Berbel-Filho et al 2013;Gaston et al, 2013). This unequal warping affects soft tissues more drastically than hard tissues, which comprise lower percentages of water and receive additional support from rigid minerals in their matrices (Schmidt, 1989;Butler, 1992;Takizawa et al 1994;Margo & Lee, 1995;Vervust et al 2009;Korwin-Kossakowski, 2014;Kansu et al 2017;Hedrick et al 2018). These disparities also highlight the potential for inconsistent artifact formation when full and partial specimens are preserved, as well as the potential for allometric size effects in the formation of preservation artifacts (Fox et al 1985;Fey, 1999Fey, , 2012Edwards et al 2009;Vickerton et al 2013;Korwin-Kossakowski, 2014;Jeyakumar et al 2015).…”

“…; Hedrick, 2018) , but composite tissues experience small, predictable changes in dimensions that may be mitigated through extension of joints during preservation (Bininda‐Emonds & Russell, , ; Kansu et al. ). With so few mammalian studies, it remains difficult for morphologists to use fluid‐preserved specimens with confidence.…”

“…This combination of chemical fixation and subsequent transfer to an antimicrobial media has proven highly effective at halting metabolic and autolytic processes and providing a sterile environment for long-term storage (Hopwood, 1969;Fox et al 1985;Suvarna et al 2013). However, the process of chemical infiltration often produces changes in the size and shape of the preserved tissues, and a wealth of preservation artifacts have been documented in the morphological and histological literature (Parker, 1963;Hopwood, 1969;Kirkeby & Moe, 1986;Steedman, 1976;Fowler & Smith, 1983;Fox et al 1985;Leslie & Moore, 1986;Kruse & Dalley, 1990;Bininda-Emonds & Russell, 1993, 1994Lasenby et al 1994;Takizawa et al 1994;Fox, 1996;Shields & Carlson, 1996;Fisher et al 1998;Fey, 1999Fey, , 2012Moku et al 2004;Buchheister & Wilson, 2005;Fey & Hare, 2005;Gagliano et al 2006; Thorstad et al 2007;Edwards et al 2009;Santos et al 2009;Vervust et al 2009;Yokogawa, 2009;Beamish et al 2011;Lee et al 2012;Berbel-Filho et al 2013;Gaston et al 2013;Vickerton et al 2013;G omez et al 2014;Kansu et al 2017;Hedrick et al 2018). Thus, morphologists interested in the study of soft...…”