Thymus, young rat.

Thymus (C: cortex, M: medulla).

Atrophic thymus.

The whole thymus is fixed and trimmed along the length of one lobe. This gives a standardized longitudinal section showing all anatomical structures of this organ.

In immuno-toxicological assays, it is advisable to embed the whole organ, ventral aspect down, and to cut both lobes. In case of thymic atrophy or involution, the whole organ / thymic region should be embedded.

See also:
      Introduction

	Djikstra CD, Sminia T (1990) Thymus. Structure and function. Normal anatomy, histology, immunohistology, ultrastructure, rat. In: Jones TC, Ward JM, Mohr U, Hunt RD (eds) Monographs on pathology of laboratory animals. Hemopoietic system. Springer, Berlin Heidelberg New York Tokyo, pp 249–256
	Kuper CF, De Heer E, Van Loveren H, et al. (2002) Immune system. In: Haschek WM, Rousseaux CG, Wallig MA (eds) Handbook of toxicologic pathology, 2nd edition, Vol 2. Academic Press, San Diego New York Boston, pp 585–646
	Kuper CF, Harleman JH, Richter-Reichelm HB, Vos JG (2000) Histopathologic approaches to detect changes indicative of immunotoxicity. Toxicol Pathol 28: 454–466
	Schuurman HJ, Kuper CF, Vos JG (1994) Histopathology of the immune system as a tool to assess immunotoxicity. Toxicology 86: 187–212
	U.S. Food and Drug Administration (2002) Guidance for industry. Immunotoxicology evaluation of investigational new drugs

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Reference: Morawietz G, Ruehl-Fehlert C, Kittel B, et al. (2004) Revised guides for organ sampling and trimming in rats and mice – Part 3. A joint publication of the RITA and NACAD groups. Exp Toxic Pathol 55: 433–449