Retinal folding in the term rabbit fetus—Developmental abnormality or fixation artifact?

Fixation strategies for retinal immunohistochemistry

“…Bouin’s fluid combines picric acid and acetic acid with formaldehyde. Its use as a retinal fixative predates modern immunohistochemical methods, although its use has waned due to fixation artifacts (French et al, 2008), the introduction of effective alternatives (Zamboni’s fixative: Stefanini et al, 1967; Zafra et al, 1995; modified Davidson’s fluid: Latendresse et al, 2002), and safety concerns (NIOSH, 2011, 2014). …”

“…Some investigators use mixtures of both types of fixative agents to take advantage of the strengths of each. Davidson’s fluid - a blend of ethanol, acetic acid, and formaldehyde - has yielded improved structural preservation relative to Bouin’s fluid in rabbit, rat, and monkey retinae (French et al, 2008; Latendresse et al, 2002) and is compatible with immunohistochemistry in retina (Chidlow et al, 2011; Stradleigh et al, 2011). Clarke's acetic ethanol - a blend of ethanol and acetic acid - has been found to reliably stabilize tissue and cellular structure (Kiernan, 2009), and act on a wide range of target molecules (e.g., glycoproteins and gangliosides; Bee, 1982).…”

“…Davidson’s fluid and its modifications are gaining popularity as alternatives to aldehyde fixatives in retina research, having been used in rat (Latendresse et al, 2002; Stradleigh et al, 2011), rabbit (French et al, 2008; Pfeffer et al, 2009; Saenz-de-Viteri et al, 2014), and cat studies (Villalobos et al, 2013). Davidson’s fluid is primarily a fastacting coagulant fixative due to its acetic acid and ethanol content, and the inclusion of formaldehyde grants it a secondary crosslinking activity.…”

Morphologic Analysis of Artifacts in Human Fetal Eyes Confounding Histopathologic Investigations

“…It is well known that fixation, apart from conserving tissues, also has a negative impact on the specimen itself and, therefore, induces artifacts. 2,3 In the late 19th century, the impact of different artifacts on the lens and its capsule had been described. 6,7 In general, however, these changes in tissue integrity cannot be avoided because fixation is needed as a standard procedure in pathology.…”

“…Finally, the fixative itself may also induce tissue artifacts. 2,3 Postmortem artifacts already known in the literature were also considered. Lange folds usually occur in the ora serrata region of fetal eyes (but not in adult eyes) as macroscopically and microscopically detectable circular folds.…”