Testis, recommended transverse section (green), optional section (blue).

Testis, transverse section left, optional longitudinal section right.

Rete testis (R), rat (V: vasculature).

Rete testis (R), mouse (V: vasculature, L: Leydig cells).

Near the capsule, focal tubules with flat or incomplete epithelium can be found. These should not be confused with atrophic or degenerating tubules, as they represent tubules of the rete testis. Generally, the rete testis is very small in rodents and not well visible in the histological section. In mice it is slightly more prominent than in rats and hyperplasia of the rete testis can be observed in older animals. For inclusion of the rete testis in the histological section orientation is given by the vasculature.

In short-term studies, fixation with Davidson's or Bouin's solutions is highly recommended to detect less extensive toxicity.

Leydig cells (interstitial cells) are present in small groups in the interstitium between the seminiferous tubules. They are found in a similar distribution in all sections proposed.

See also:
      Introduction

	Boorman GA, Chapin RE, Mitsumori K (1990) Testis and epididymis. 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 405–418
	Chapin RE, Heindel JJ (1993) Methods in Toxicology. Volume 3. Part A: Male Reproductive Toxicology. Academic Press Inc, San Diego, pp xx–yy
	Creasy DM, Foster PMD (2002) Male reproductive system. In: Haschek WM, Rousseaux CG (eds) Handbook of toxicologic pathology. Academic Press, San Diego, New York, Boston, pp 829–889
	Ferm VH (1987) Embryology and comparative anatomy, rodent reproductive tract. In: Jones TC, Mohr U, Hunt RD (eds) Monographs on pathology of laboratory animals. Genital system. Springer, Berlin, Heidelberg New York Tokyo, pp 3–7
	Foley GL (2001) Overview of male reproductive pathology. Toxicol Pathol 29: 49–63
	Lanning LL, Creasy DM, Chapin RE, Mann PC, Barlow NJ, Regan KS, Goodman DG (2002) Recommended approaches for the evaluation of testicular and epididymal toxicity. Toxicol Pathol 30: 507–520
	Latendresse JR, Warbrittion AR, Jonassen H, Creasy DM (2002) Fixation of testes and eyes using a modified Davidson's fluid: comparison with Bouin's fluid and conventional Davidson's fluid. Toxicol Pathol 30: 524–533
	Russell LD, Ettling LA, SinhaHikim AP, Clegg ED (1990) Histological and histopathological evaluation of the testis. Cache River Press, U.S.

Trm V 5.00

Reference: Kittel B, Ruehl-Fehlert C, Morawietz G, et al. (2004) Revised guides for organ sampling and trimming in rats and mice – Part 2. A joint publication of the RITA and NACAD groups. Exp Toxic Pathol 55: 413–431