Testis, Germ Cell - Degeneration

Image of germ cell degeneration in the testis from a male F344/N rat in a chronic study
Testis, Germ cell - Degeneration in a male F344/N rat from a chronic study. Degeneration is present in multiple seminiferous tubules.
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Image of germ cell degeneration in the testis from a male F344/N rat in a chronic study
Testis, Germ cell - Degeneration in a male F344/N rat from a chronic study. This figure shows disorganized arrangement of germ cells in seminiferous tubules.
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Image of germ cell degeneration in the testis from a male B6C3F1 mouse in a subchronic study
Testis, Germ cell - Degeneration in a male B6C3F1 mouse from a subchronic study. Degeneration is characterized by disorganized arrangement of germ cells in seminiferous tubules.
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Image of germ cell degeneration in the testis from a male B6C3F1 mouse in a subchronic study
Testis, Germ cell - Degeneration in a male B6C3F1 mouse from a subchronic study. A normal spectrum of germ cells is absent in seminiferous tubules.
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Image of germ cell degeneration in the testis from a male BALB/c mouse in a 12-hour exposure study
Testis, Germ cell - Degeneration in a male BALB/c mouse 12 hours after exposure. Germ-cell-specific degeneration affecting dividing spermatocytes in a stage XII seminiferous tubule.
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Image of germ cell degeneration in the testis from a male BALB/c mouse in a 12-hour exposure study
Testis, Germ cell - Degeneration in a male BALB/c mouse 12 hours after exposure. Germ-cell-specific degeneration of pachytene spermatocytes in a stage X tubule (asterisk).
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comment:

Germ cell degeneration is a nonspecific term that generally includes a number of degenerative features, such as tubular vacuolation, partial depletion of germ cells, degenerating (multinucleated or apoptotic) germ cells, and disordered arrangement of the germ cell layers ( Figure 1image opens in a pop-up window , Figure 2image opens in a pop-up window , Figure 3image opens in a pop-up window , and Figure 4image opens in a pop-up window ). Depending on severity, there may be a macroscopic reduction in size of the testis and a reduction in organ weight. The condition may progress to total loss of germ cells (see Testis, Germinal Epithelium - Atrophy), leaving contracted tubules lined only by Sertoli cells. Frequently, there is a mixed effect on seminiferous tubules, with some showing degeneration and others having progressed to atrophy. Chemically induced germ cell degeneration can be multifocal in distribution, but it is most often a bilateral lesion that affects most of the seminiferous tubules to varying degrees ( Figure 1image opens in a pop-up window ). It can also be an incidental background finding in rats and mice of any age, but the incidence increases with age. Depending upon the toxicant, in short-duration studies (~14-28 days) the earliest evidence of germ cell degeneration may be preceded by specific degenerative features, such as germ cell vacuolation or cell-specific degeneration/depletion of germ cells.

recommendation:

In routine toxicity studies, germ cell degeneration should be diagnosed and graded and should be discussed in the pathology narrative if it is considered the primary change and if the incidence and/or severity appears to be related to chemical administration. If both testes are affected, the diagnosis should indicate the condition is bilateral, and severity should be based on the more severely affected testis. Since degeneration is thought to be a precursor to atrophy, degeneration should be diagnosed unless the majority of the tubules are devoid of germ cells, in which case atrophy is the preferred diagnosis. The concomitant presence of some germ cell atrophy or evidence that germ-cell–specific degeneration/depletion is present can be mentioned in the pathology narrative. If both terms are used in a single study, it is incumbent upon the pathologist to describe the relationship between the two lesions in the pathology narrative.

references:

Boorman GA, Chapin RE, Mitsumori K. 1990. Testis and epididymis. In: Pathology of the Fischer Rat: Reference and Atlas (Boorman GA, Eustis SL, Elwell MR, Montgomery CA, MacKenzie WF, eds). Academic Press, San Diego, 405-418.
Abstract: http://www.ncbi.nlm.nih.gov/nlmcatalog/9002563

Creasy D, Bube A, de Rijk E, Kandori H, Kuwahara M, Masson R, Nolte T, Reams R, Regan K, Rehm S, Rogerson P, Whitney K. (2012). Proliferative and nonproliferative lesions of the rat and mouse male reproductive system. Toxicol Pathol 40:40S-121S.
Abstract: http://www.ncbi.nlm.nih.gov/pubmed/22949412

Lee KP, Frame SR, Sykes GP, Valentine R. (1993). Testicular degeneration and spermatid retention in young male rats. Toxicol Pathol 21:292-302.
Abstract: http://www.ncbi.nlm.nih.gov/pubmed/8248718

Radovsky A, Mitsumori K, Chapin RE. 1999. Male reproductive tract. In: Pathology of the Mouse: Reference and Atlas (Maronpot RR, Boorman GA, Gaul BW, eds). Cache River Press, Vienna, IL, 381-407.
Abstract: http://www.cacheriverpress.com/books/pathmouse.htm

Takano H, Kazuhiro ABE. 1987. Age-related histologic changes in the adult mouse. Testis. Arch Histol Jpn 50:533-544.
Abstract: http://www.ncbi.nlm.nih.gov/pubmed/3439850

Yuan Y-D, McEntee K. 1987. Testicular degeneration, rat. In: Monographs on Pathology of Laboratory Animals: Genital System (Jones TC, Mohr U, Hunt RD, eds). Springer, Berlin, 212-217.
Abstract: http://www.springer.com/medicine/pathology/book/978-3-642-72552-4