Forestomach and glandular stomach.

Stomach spread out before fixation.

Section at localization 1: Forestomach (FS), gastric fundus (GF), antrum (A), pylorus (P).

Section at localization 2: Forestomach (FS), gastric fundus (GF).

Stomach: optional section at localization 3 through fundus (higher magnification than other images).

The stomach of the rat is opened along or paramedian to the greater curvature and placed on cardboard or a flat piece of styrofoam. The ingesta are removed and, if necessary, the mucosa is cleaned carefully with saline solution or fixative. The stomach is spread out and fixed with about six pins. This is a prerequisite for the macroscopic orientation and the reproducible microscopic evaluation of the gastric mucosal height or actually the measurement of the mucosa by morphometric means as it avoids folds in the mucosa.

The first section is cut from the cardiac region of the stomach across fundus and antrum and the pyloric sphincter to the duodenum. If the piece is too large for the normal cassette, the tissue can be cut in halves. The second section is taken from the forestomach through the fundic area, allowing the best evaluation of the limiting ridge between the forestomach and the glandular stomach. Optionally, a third section can be made through the fundic area, where the fundic glands are most bulky.

The fundic area is the thickest part of the mucosa and can vary under acid suppressing conditions or other drug-induced influences. ECL-cell hyperplasia and neuroendocrine tumors are found in the fundic mucosa.

See also:
      Introduction

	Betton GR, Dormer CS, Wells T, Pert P, Price CA, Buckley P (1988) Gastric ECL-Cell hyperplasia and carcinoids in rodents following chronic administration of H2-antagonists SK&F 93479 and oxmetidine and omeprazole. Toxicol Pathol 16: 288–298
	Brown HR, Hardisty JF (1990) Oral cavity, esophagus, and stomach. In: Boorman GA, Eustis SL, Elwell MR, Montgomery CA, Jr, MacKenzie WF (eds) Pathology of the Fischer rat. Reference and atlas. Academic Press, San Diego New York London, pp 9–30
	Hakanson R, Eklund M, Sundler F (1984) Activation and proliferation of gastric endocrine cells. In: Hakanson R, Sundler F (eds) Evolution and tumor pathology of the neuroendocrine system. Elsevier, Amsterdam, pp 371–398
	Matsukura N, Asano G (1997) Anatomy, histology, ultrastructure, stomach, rat. In: Jones TC, Popp JA, Mohr U (eds) Monographs on pathology of laboratory animals. Digestive system, 2nd edition. Springer, Berlin Heidelberg New York Tokyo, pp 343–350

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Reference: Ruehl-Fehlert C, Kittel B, Morawietz G, et al. (2003) Revised guides for organ sampling and trimming in rats and mice – Part 1. A joint publication of the RITA and NACAD groups. Exp Toxic Pathol 55: 91–106