Journal of Animal Science and Veterinary Medicine

JOURNAL OF ANIMAL SCIENCE AND VETERINARY MEDICINE
Integrity Research Journals

ISSN: 2536-7099
Model: Open Access/Peer Reviewed
DOI: 10.31248/JASVM
Start Year: 2016
Email: jasvm@integrityresjournals.org

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Evaluation of cashew apple (Anacardium occidentale L.) aqueous extract as a natural histological counterstain in rat tissues

https://doi.org/10.31248/JASVM2026.691   |   Article Number: C408B31910   |   Vol.11 (5) - October 2026

Received Date: 15 September 2026   |   Accepted Date: 26 October 2026  |   Published Date: 30 October 2026

Authors:  Barde Israel Joshua* , Ishaku Leo Elisha , Shekaro Audu , Ashem Madi Lamba , Umoru Mada Alesa , Ugbe Aondona Dominic , Choji Tobias Peter Pwajok , Ngulukun Samuel Sati , Dashe Yakubu Gunya , Masagbor Otimize Yvonne , Lev Kolodzieyski and Zhang Maodong

Keywords: Anacardium occidentale, cashew apple extract, cytoplasmic counterstain, natural dyes, ethnohistology, rat tissue, qualitative evaluation.

ABSTRACT

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Staining histological sections prior to microscopic examination is an essential diagnostic technique in histopathology to expose fine cellular microarchitecture. Standard Hematoxylin and Eosin (H&E) staining relies heavily on synthetic eosin as a cytoplasmic counterstain; however, commercial eosin is costly, non-biodegradable, and presents potential health hazards to laboratory personnel. This exploratory pilot study evaluated the potential of an aqueous extract derived from cashew fruit (Anacardium occidentale L.) as a natural, plant-based substitute for synthetic eosin in rat tissues. Fresh cashew apples were dried at 30°C for 14 days, pulverised, and extracted in distilled water (10% w/v) for 24 hours, yielding a concentrated extract with a measured pH of 4.6. Staining formulations were prepared across five extract masses (0.15, 0.3, 1.0, 1.5, and 2.0 g) and evaluated under three chemical modifications: accentuated, unaccentuated (ammonia and alcoholic iodine), and modified with 0.4 mL glycoacetic acid. Tissue sections from five organs (intestine, kidney, lung, liver, and skin; harvested from 4 adult albino rats, 20 tissue blocks total) were counterstained at durations of 5, 10, and 20 minutes alongside standard H&E controls. Qualitative visual assessment by two blinded assessors indicated that cashew fruit extract produced readable cytoplasmic counterstaining with a silver-to-brownish pink hue, exhibiting clear nucleo-cytoplasmic contrast against hematoxylin. Formulations modified with glycoacetic acid (1.0 g and 2.0 g) achieved rapid cytoplasmic staining within 5 to 10 minutes, yielding visual clarity comparable to routine H&E controls. Intestine, lung, liver, and skin demonstrated vivid stain absorption, whereas kidney sections showed lower relative intensity. While these preliminary findings demonstrate the feasibility of cashew apple extract as a natural counterstain, formal toxicity, cost-effectiveness, and quantitative equivalence were not evaluated in this pilot study.

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