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Opis przypadku Case report
Since 1971, European bison Bison bonasus (L.), both males and females, have been caught and culled within the area of the Bia³owie¿a Forest in order to regulate the number of animals in a herd (15). Reasons for the culling of males are as follows: various injuries, encroachment on cultivated fields, aggression towards people, injuries resulting from poaching, and posthi-tis/balanoposthitis (15, 16, 20). On the basis of sam-ples collected from culled male European bison (1969--1993), the course of spermatogenesis in animals aged between 4 months and 17 years was described (3).
Many years of studies conducted on samples collected from culled male European bison made it possible to describe such development anomalies as epididymal cysts and cryptorchidism (6, 13, 14, 18, 19, 23). The first cases of cryptorchidism in the Euro-pean bison within the area of the Bia³owie¿a Forest were described in the sixties (23). In the following years, further cases of cryptorchidism in male Euro-pean bison were observed (6, 13). Krasiñska et al. (14) provide the prevalence of cryptorchidism within the area of the Bia³owie¿a Forest and the Borecka Forest. The available literature includes reports on crypt-orchidism cases in the following species: North Ame-rican bison (Bison bison) and Wood bison (Bison bison athabacoae) (7, 11), Patagonian deer (Hippo-camelus bisulcus) (4), stallions (5, 22), goats (10), bucks and rams (21), dogs (2). However, histological analysis and morphometric measurements of the testis
and epididymis have not been performed in cases of cryptorchidism in the European bison.
The aim of the present study is a histological evalu-ation and morphometric measurement of the semini-ferous tubules, testis and epididymal duct collected from a 3.5-year-old male European bison with a crypt-orchid left testis.
Material and methods
The material used for the analysis was collected from a 3.5-year-old male European bison living in a free-ranging population in the Bia³owie¿a Forest (2009). The age of the bison was established by J. Dackiewicz (BNP) according to the sequence of tooth eruption, degree of tooth wear (26) and growth of horns (17). Body weight of this animal amounted to 340 kg.
The material for histological investigations was collec-ted by employees of the Bia³owie¿a National Park (BNP). Left-side cryptorchidism and the left testis located in the inguinal canal were observed. Also, balanoposthitis was noted in this animal (15, 16, 20), but no epididymal cysts were observed (18, 19).
Each testis was weighed and the following measurements were performed: testis total length with the cauda epididymis, testis length, testis width and testis circumference (14). Sections from the right and left testis and, separately, frag-ments of the right and left epididymal corpus, were collected for examination. The material was fixed in Bouins fluid; 6 µm paraffin sections were stained with hematoxylin and eosin (H+E). Microscopic preparations of the testes and
Case of a cryptorchid left testis in a European bison:
Histological and morphometric description
EL¯BIETA CZYKIERDepartment of Histology and Embryology, Medical University of Bialystok, Waszyngton St 13, 15-269 Bialystok, Poland
Czykier E.
Case of a cryptorchid left testis in a European bison: Histological and morphometric description
Summary
The aim of the present study is a histological evaluation and morphometric measurement of seminiferous tubules, testis and the epididymal duct collected from a 3.5-year-old male European bison Bison bonasus (L.) with a cryptorchid left testis. In a microscopic preparation collected from the normal right testis of this animal, spermiogenesis with visible late spermatids was observed in the germinal epithelium of the seminiferous tubules, whereas in microscopic preparations from the left testicular cryptorchid, spermatogenesis in the seminiferous tubules appeared to be impeded. The diameter, area and perimeter of seminiferous tubules and the epididymal duct of the cryptorchid left testis and cryptorchid left epididymis were considerably smaller than those of the normal right testis and normal right epididymis of the bison.
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epididymes were examined histologically with a light mi-croscope (maximum magnification: 400 ×). The diameters, areas and perimeters of the seminiferous tubules and epidi-dymal duct were measured in histological preparations. The measurements were taken on 50 transverse cross-sections of the seminiferous tubules from the normal right and crypt-orchid left testis and on 50 transverse cross-sections of the normal right and cryptorchid left epididymal duct (5 vision fields from each preparation, 10 measurements of dia-meters, areas and perimeters of the seminiferous tubules on a transverse cross-section in each vision field and 10 measurements of diameters, areas and perimeters of the epididymal duct on a transverse cross-section in each vision field), using the morphometric program analysis (Olympus). Statistical analysis of the results was based on the statistical program Excel.
The presence of spermatids in the seminiferous epithe-lium or the presence of spermatozoa in the lumen of the seminiferous tubules of the testes and/or the presence of spermatozoa in the epididymal duct were considered the criteria of spermiogenesis. Data referring to the body weight of the male and to its disease, called posthitis, were obtained from the Bia³owie¿a National Park.
Results and discussion
In a microscopic preparation collected from the normal right testis of a 3.5-year-old European bison, spermiogenesis with visible late spermatids was obser-ved in the germinal epithelium of the seminiferous tubules, whereas microscopic preparations from the left testicular cryptorchid showed a predominance of Sertoli cells in the germinal epithelium of the semini-Fig. 1. Fragment of the cryptorchid left testis in a
3.5-year--old male European bison. The seminiferous tubules with a visible lumen, lined with the seminiferous epithelium showing predominance of Sertoli cells and clusters of Leydig cells between the tubules. H+E
Fig. 2. Fragment of the normal right testis in a 3.5-year-old male European bison. The seminiferous tubules show increased tortuosity, enlarged diameter and a considerably decreased amount of loose connective tissue between them. The semini-ferous tubules contain elongated late spermatids within the seminiferous epithelium. H+E
Fig. 4. Fragment of the normal right epididymis in a 3.5-year--old male European bison. The epididymal duct shows pseudostratified columnar epithelium with very long sterocilia and numerous spermatozoa in the epididymal lumen. H+E Fig. 3. Fragment of the cryptorchid left epididymis in a
3.5--year-old male European bison. The epididymal duct shows only pseudostratified columnar epithelium. H+E
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ferous tubules (figs. 1, 2). In microscopic preparations collected from the normal right epididymis of the bison, a typical pseudostratified columnar epithelium with very long sterocilia and numerous spermatozoa in the epididymal lumen was observed, while in the cryptorchid left epididymis only pseudostratified columnar epithelium was noted (figs. 3, 4).
On the basis on the measurements taken, it was observed that both the weight of the cryptorchid left testis and all other examined parameters of this testis (total length with the cauda epididymis, length, width, circumference) were lower than those of the normal right testis (tab. 1).
Similarly, the three morphometric measurements, diameter, area and perimeter, taken in the seminiferous tubules and epididymal duct of the cryptorchid left testis and cryptorchid left epididymis were considerably lower than the corresponding measurements of the animals normal right testis and epididymis (tab. 2).
Currently, it is assumed that cryptorchidism depends on a number of genetic, epigenetic and environmental factors (8, 9, 12). Cryptorchidism leads to spermato-genesis defects (1), which was observed in the present study in the cryptorchid left testis of the 3.5-year-old male European bison. In the case of cryptorchidism in bucks, the testis weight can be smaller by as much as ¼ compared with a normal testis (10). A similar effect was also observed in the present study. The smaller weight of the cryptorchid left testis in the bison was accompanied by a decrease in all parameters of this testis and epididymis: the total testis length with the cauda epididymis, the length, width, circumference and diameter of the testis, as well as the area and perimeter of the seminiferous tubules and the epididymal duct.
According to Amann and Veeramachaneni (1), crypt-orchidism is also conducive to the development of tumors found long after abnormal differentiation of anlage for germ, Sertoli, Leydig, or stromal cells.
Cryptorchidism is not a common abnormality of the male genital system in animals. As regards European bison in the Bia³owie¿a Forest (n = 240), cryptorchi-dism develops in 8.3% of males (14), whereas the authors observed no cases of cryptorchidism in the Borecka Forest (n = 32). Krasiñska et al. (14) claim that the bison population of the Borecka Forest does not suffer from this abnormality. Compared with the European bison, other species are considerably less susceptible to this condition (14): criptorchidism has been reported in 2.9% of native goats in southern Iran (10), 4% of rams in Australia (25), 1.1% of goats in Australia (24), 2.9% of Pantagonian deer (4), 5.5% of bucks and 1.8% of rams (21), £ 1% of stallion and sheep (1). According to Bigham et al. (2), the inci-dence of cryptorchidism seems to be higher in pure-bred and inpure-bred dogs than in mixed-breed dogs. Since European bison are closely related with one another, they are highly inbred, which might explain the greater incidence of cryptorchidism in these animals than in other species.
Cryptorchidism is an abnormality that develops at a specific age. On the basis of extensive material (n = 272) Krasiñska et al. (14) observed cryptorchi-dism in 20 animals (7.35%). These authors claim that cryptorchidism does not occur in the European bison before the first year of life. According to these authors, European bison do not develop cryptorchidism before reaching one year of age. A different opinion is pre-sented by wie¿yñski (23), who describes cryptorchi-dism in a European bison under one year of age. wie¿yñski observed cryptorchidism in 3 European bison (15%) out of 20 animals described (23).Other authors claim that the incidence of cryptorchidism depends not only on the age but also on the species of the animal. Cryptorchidism develops with age in native bucks (10), Patagonian deer (4) and bucks (21), but in rams cryptorchidism is less common with age (21).
t h g i e W ) g ( h ti w h t g n e l l a t o T s i m y d i d i p e a d u a c ) m m ( h t g n e L ) m m ( W(midmth) Cofricteusmitfser(emnmce) s it s e t t h g i R 166.3 113.7 89.8 61.9 161.0 s it s e t tf e L 126.5 173.3 50.9 30.7 187.8
Tab. 1. Weight and measurements (total length with the cauda epididy-mis, length, width, circumference) of the normal right and cryptorchid left testis of a 3.5-year-old European bison
Tab. 2. Morphometric measurements of the seminiferous tubules and epididymal duct (diameter, area, perimeter) in the right testis and the cryptorchid left testis, as well as the right epididymis and the cryptorchid left epididymis of a 3.5-year-old European bison ) m µ ( r e t e m a i D Area(µm2) Peirmeter(µm) n a e M SD Min Max Mean SD Min Max Mean SD Min Max s u o r e fi n i m e S s e l u b u t t h g i R s it s e t 192.51 22.647 135.56 257.12 36915.39 4285.45 30667.79 49690.92 644.43 61.40 468.21 849.79 tf e L s it s e t 98.48 10.78 74.56 137.46 8726.20 1326.63 5737.92 13098.98 335.02 30.13 277.40 424.60 l a m y d i d i p E t c u d t h g i R s it s e t 360.90 49.56 229.85 494.64 112748.1 25153.55 65443.77 161958.0 1190.03 131.21 901.79 1419.07 tf e L s it s e t 180.22 46.54 83.99 274.83 33672.94 12894.74 9539.83 51636.22 640.08 140.35 357.49 836.34
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Cryptorchidism can be either unilateral or bilateral. The literature also describes cases of sterility with bi-lateral cryptorchidism (10). Unibi-lateral cryptorchidism occurs considerably more often than bilateral one, which is confirmed by other authors studies on Euro-pean bison, bucks, rams and dogs (2, 10, 14, 21). The present study described cryptorchidism of the left testis. Krasiñska et al. (14) claim that in male European bison cryptorchidism occurs with the same frequency on the right and left side. According to other authors, however, cryptorchidism is more common on the right side is such species as rams and bucks (10, 21). To conclude, in the analyzed case of a 3.5-year-old European bison cryptorchidism impeded spermato-genesis.
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Corresponding author: Dr. El¿bieta Czykier, Department of Histology and Embryology, Medical University of Bialystok, Waszyngton St 13, 15-269 Bialystok; e-mail: czykier@umwb.edu.pl
