Intra-abdominal leiomyosarcoma in a ferret (Mustela putorius Furo): histopathological and immunohistochemical characterization

A 5 years old female ferret with an abdominal palpable mass confirmed at echo-graphic examination died during an explorative laparotomy. A single lymph-node-like nodule was found adjacent to the intestinal loops. The round mass well circumscribed, solid and white, histologically, at low magnification, appeared encapsulated and built up by a population of atypical spindle cells arranged in interwoven fascicles. The cells had high anisocytosis degree, moderate mitotic activity and prominent nucleoli. A central area of necrosis was present. To characterise the tumour immunohistochemically cytokeratin, vimentin, S-100, melan-A, vWF, desmin, actin and alpha-actin were applied. Neoplastic cells resulted positive to vimentin, actin and alpha-actin. Based on the histological and immunohistological pattern a diagnosis of leiomyosarcoma was made.     

DNA measurement and immunohistochemical characterization of epithelial and mesenchymal cells in canine mixed mammary tumours: putative evidence for a common histogenesis.

DNA measurement by image cytometry, and a detailed immunohistochemical study using monoclonal antibodies directed against different human cytokeratin types, muscle-specific actin, vimentin and S100 protein were carried out on normal canine mammary tissue (n =4), benign canine mammary mixed tumours (n =20) and malignant canine mammary mixed tumours (n =13). The results showed that ductal and alveolar luminal cells in normal and neoplastic tissue were immunoreactive with CAM5.2 and AE1/AE3 antibodies recognizing human keratins.Basal/myoepithelial cells were clearly differentiated from ductal and alveolar epithelial cells, since the latter only expressed cytokeratins, whereas the former also expressed vimentin and muscle-specific actin. This immunohistochemical study showed that there is loss of expression of muscle-specific actin and cytokeratins in areas of myoepithelial proliferation, and enhanced expression of vimentin and S100 protein in proliferative areas with osseous and/or chondroid metaplasia. The ploidy studies revealed that 20% (4/20) of benign and 54% (7/13) of malignant mixed tumours of canine mammary gland were aneuploid and that the epithelial and myoepithelial components of the mixed tumours had identical DNA content.Our results reinforce the role of myoepithelial cells in mesenchymal metaplasia in mixed mammary tumours and suggest the possibility of a common origin of both components from a totipotential stem cell with capacity for divergent differentiation.     

Alterations in the immunohistochemical localization patterns of alpha-smooth muscle actin (SMA) and vimentin in the postnatally developing bovine cryptorchid testis

Previously, we reported the normal postnatal developmental changes in immunohistochemical localization of alpha-smooth muscle actin (SMA) and vimentin in the bovine testis. In this study, we demonstrate the alterations of these cytoskeletal proteins in the bovine cryptorchid testis as compared to the contralateral scrotal testis during postnatal development. Seminiferous peritubular alpha-SMA did not appear in the cryptorchid testis until 8 months of age, except for very weak intermittent filaments in relatively larger seminiferous tubules. However, a similar peritubular pattern was observed in the 18-month-old cryptorchid and scrotal testes. Moreover, weak expression of alpha-SMA in the straight tubules and rete testes at 5 months of age did not improve until 18 months of age in the cryptorchid testes. The Sertoli cell vimentin in the cryptorchid testes revealed a highly immature pattern at 5 months of age, a pattern similar to a transforming pattern with infranuclear vimentin extensions at 8 months of age, and a pattern that was almost a transforming pattern, but with considerable weakening of the vimentin filaments, at 18 months of age. In conclusion, cryptorchidism may cause considerable delay in testicular myoid cell differentiation and in attainment of the transforming pattern of the Sertoli cell vimentin, which weakens and fails to attain the mature pattern in the cryptorchid testis. These alterations may be related to the structural immaturity and functional failure of postnatally developing bovine testes exposed continuously to body heat.     

Bilateral Sertoli and Interstitial Cell Tumours in Abdominal Testes of a Goat with Polled Intersex Syndrome (PIS)

An 8‐year‐old, mixed breed, polled goat was presented for evaluation of male‐like behaviour. Clinical findings included clitoromegaly, a heavily muscled neck, pronounced beard, and erect dorsal guard hairs, which are phenotypic characteristics commonly observed in intersex animals. Transrectal ultrasonography revealed the presence of two abdominal masses caudolateral to the uterine horns. Serum concentration of estradiol was elevated. Genetic evaluation was compatible with polled intersex syndrome defined by an XX karyotype without a Y chromosome or SRY gene. Based on gross and histologic evaluation, the abdominal masses were determined to be intra‐abdominal testes, each of which was effaced by Sertoli cell and interstitial (Leydig) cell tumours. The Sertoli cell tumours (SCTs) represented two unique histologic patterns. Regardless of pattern, neoplastic Sertoli cells were consistently lipid laden and positive for vimentin. Interstitial cell tumours (ICTs) were negative for vimentin. Clinical and histopathologic findings suggest that prolonged exposure to steroids secreted by neoplastic Sertoli cells contributed to virilization. In addition, results from immunohistochemistry indicated that vimentin may be a valuable immunodiagnostic tool for differentiation between interstitial and Sertoli cell tumours in goats.     

Vimentin expression in testes of Arabian stallions

Reasons for performing study: Specific patterns of cytoskeletal filaments reflect a functional state of the cell. In testicular cells intermediate filaments (IFs) are of the vimentin type. Since it is known that Sertoli cells regulate the spermatogenic function in the male gonad, it became important to propose a system that could quantify the state of seminiferous tubular quality. To date, a Johnsen score system has never been used to equine testes. Objectives: To demonstrate the expression pattern of vimentin in testes of mature Arabian stallions and correlate its distribution with grade of seminiferous tubule impairment as indicated by a Johnsen score. Methods: For histological examination by the Johnsen method, routine haematoxylin‐eosin staining was used. Vimentin expression and its presence in testicular sections and testicular homogenates were detected by immunohistochemistry and western blot, respectively. Both analyses were performed qualitatively and quantitatively and further validated by ANOVA tests. Results: Distinct morphology of seminiferous tubules was found in testes harvested from 3 stallions. Vimentin in IFs was immunolocalised to the cytoplasm of Sertoli, Leydig and peritubular‐myoid cells. The intensity and pattern of the IFs staining was different in individual seminiferous tubules suggesting a correlation between vimentin expression and the severity of tubule degeneration. Qualitative results by immunohistochemistry and western blot were confirmed by further quantitative analyses. Conclusions: In equine testes, differential expression of vimentin was found to be correlated with the impairment of seminiferous tubules indicated by a decrease in Johnsen score. Potential relevance: The Johnsen score system may be a useful method to facilitate the identification of tubular alterations in the stallion testes. Combined histological and immunohistochemical approach may provide a detailed phenotypic classification of stallions with decreased fertility.     

Clinical, laboratory, and histopathologic features of equine lymphoma

Clinical, laboratory and tissue findings from 37 horses with lymphoma were investigated. Horses ranged in age from 0.3 to 20.5 years (median 5.0 years) and included 18 females and 19 males. Weight loss (n = 25) and ventral edema (n = 21) were the most common historical and physical abnormalities. The most common laboratory abnormalities were hyperfibrinogenemia (n = 26), hypoalbuminemia (n = 19), anemia (n = 19), leukemia (n = 14), hyperglobulinemia (n = 13), and thrombocytopenia (n = 13). Thirty-four tumors involved multiple lymphoid tissues and abdominal or thoracic organs, and 3 tumors were restricted to cutaneous and subcutaneous sites. Histopathologically, all tumors diffusely effaced normal lymph node architecture. Tumor cell morphology was heterogeneous in 17 tumors, and 8 tumors had marked histiocytic and multinucleated giant cell infiltrates. Extensive necrosis or focal fibrosis was present in 22 and 4 lymphomas, respectively. Staining of tumor sections with antibodies against CD3 and CD79alpha molecules resulted in classification of T-cell (n = 26) or B-cell (n = 7) origin. Four tumors could not be classified. Most T-cell tumors comprised small to medium CD3(+) lymphocytes, whereas 5 of 7 B-cell tumors were infiltrated by numerous small T lymphocytes and classified as T-cell-rich B-cell lymphoma. Neither estrogen nor progesterone receptor expression was consistently identified by immunochemical assessment of tumor tissues. Fresh tumor cells from 6 horses bound antibodies reactive with equine CD4, CD5, CD8, CD21, or major histocompatibility class II molecules, confirming T-cell (n = 5) or B-cell origin (n = 1). These findings suggest that T-cell lymphoma is more common than B-cell lymphoma in horses and that inflammation, possibly from tumor cytokine production, is frequent.     

Immunolocalization of steroidogenic enzymes P450scc, 3betaHSD, P450c17, and P450arom in Göttingen miniature pig testes

The objective of this study was to investigate immunolocalization of steroidogenic enzymes in G?ttingen miniature (GM) pig testes. Testes of 6 adult GM pigs were obtained in September 1996 (n=2), February (n=2) and June (n=2), 1997. Steroidogenic enzymes were immunolocalized using polyclonal antisera raised against bovine adrenal cholesterol side-chain cleavage cytochrome P450 (P450scc), human placental 3beta-hydroxysteroid dehydrogenase (3betaHSD), porcine testicular 17alpha-hydroxylase cytochrome P450 (P450c17), and human placental aromatase cytochrome P450 (P450arom). Histologically, all types of spermatogenic cells including mature-phase spermatozoa in seminiferous tubules were observed in all testes throughout the year. Moreover, P450scc, 3betaHSD, P450c17and P450arom were identified in Leydig cells but not in Sertoli cells of all testes. These results suggested that adult GM pig testes have the ability to produce germ cells throughout the year, and the synthesis of progestin, androgen and estrogen occurs in the Leydig cells of GM pig testes.     

Immunohistochemical Demonstration of Cytoskeletal Proteins in the Testis of the Japanese Black Bear, Ursus thibetanus japonicus

The seasonal changes of the cytoskeletal protein expressions were immunohistochemically investigated in the testes of Japanese black bear, Ursus thibetanus japonicus. A strong immunoreaction for α-smooth muscle actin is restricted to the vascular smooth muscle cells and the peritubular cells which surround the seminiferous tubules by several layers throughout the year. Weak immunoreactions for B4 antigen and desmin were observed in the vascular smooth muscle cells and in a part of peritubular cells throughout the year. A strong immunoreaction for vimentin was also detected in the fibroblasts and Leydig cells, in addition to the vascular smooth muscle and epithelial cells and the peritubular cells throughout the year. A strong α-tubulin immunoreaction was detected in the elongating spermatids during the acrosome phase of spermiogenesis in May and June. The cytoplasm of several Sertoli cells was faintly immunoreacted for vimentin in the basal and lateral region, while an intense α-tubulin reaction was seen in the entire cytoplasm in May, April and June. In November, January and March, the immunoreactions for vimentin and α-tubulin strongly accumulate in a perinuclear region of Sertoli cells when developmental spermatids are not seen in the seminiferous tubules. These accumulations in the immunoreactions for vimentin and α-tubulin seem to be caused by the reduction in size of Sertoli cells cytoplasm with season. However, the seasonal changes of distributions in the cytoskeletal proteins are obscure in the bear testes. These results suggest that the contents of cytoskeletal proteins may not change in relation to the morphological differences with season in the testes of the seasonal breeders.     

The Expression of Epidermal Growth Factor (EGF) and its Receptor (EGFR) During Post‐Natal Testes Development in the Yak

Growth factors play critical role in cell proliferation, regulate tissue differentiation and modulate organogenesis. Several growth factors have been identified in the testes of various mammalian species in last few years. In present investigation, the objective was to determine the expression of epidermal growth factor (EGF) and the epidermal growth factor receptor (EGFR) in yak testicular tissue by relative quantitative real time polymerase chain reaction (RT‐PCR), Western blot (WB) and immunohistochemistry (IHC) from mRNA and protein levels. The testicular tissues were collected from male yak at 6 and 24 months old. Results of RT‐PCR and WB showed that the expression quantity of EGF and EGFR at 24 months of age was higher than at 6 months, and the increase rate of EGFR on mRNA and protein levels was higher than the increase rate EGF during post‐natal testes development. Positive staining for EGF and EGFR was very low and mainly localized to Leydig cells testes at 6 months of age with immunohistochemistry, and seminiferous tubules were not observed. At 24 month of age, both the EGF and EGFR could be detected in Leydig cells, peritubular myoid cells, sertoli cells and germ cells of the yak testes. However, EGF and EGFR were localized to preferential adluminal compartment and basal compartment in the seminiferous tubules, respectively. In conclusion, the findings in present studies suggest that EGF and EGFR as important paracrine and/or autocrine regulators in yak testes development and spermatogenesis.     

LHRH Fusion Protein Immunization Alters Testicular Development, Ultrasonographic and Histological Appearance of Ram Testis

This study was designed to evaluate the effectiveness of a luteinizing hormone releasing hormone (LHRH) fusion protein immunization on reproductive traits in ram lambs including the changes in histology and ultrasonographic appearance of testis. Thirty native ram lambs at 19 weeks of age were divided into control (C, n = 10), immunization (I, n = 10) and castration (E, n = 10) groups. Animals in immunization group were immunized against LHRH using ovalbumin‐LHRH‐7 (OL) protein generated by recombinant DNA technology as a primary and a booster injection at 19 and 23 weeks of age respectively. Animals were bled via jugular venepuncture at 2‐week intervals to determine LHRH antibody and testosterone concentrations. Bi‐weekly ultrasonographic examination of the testes was performed to determine the changes in ultrasonographic appearance as the age increased. Biopsied testicular tissues taken at 19, 29 and 41 weeks age were also evaluated. At 41 weeks of age, animals were slaughtered. Semen and epididymis were evaluated for the presence of sperm cells. Testicular development and sperm production were suppressed in the immunized animals. Semineferous tubule diameters decreased, basal membrane of the tubule was thickened and hyalinized in immunized ram lambs. While testes of control animals gained their normal ultrasonographic appearance as the age increased, immunized animals had uniform hypoechogenic testicular structure as observed at 19 weeks of age until slaughter. Simultaneous histological and ultrasonographic evaluations indicated that the changes in testicular histology could partly be monitored via ultrasonographic imaging. Nevertheless, it is difficult to claim that ultrasonographic image reflects the exact changes in such instances. In conclusion, these results indicate that recombinant OL fusion protein is effective in immunocastration in ram lambs and has a potential to be used as an alternative to physical castration. Further research studies should be conducted to help assess reproductive status of testes from ultrasound images.     

Cryptorchidism and monorchism in cats: 25 cases (1980-1989).

Of 1,345 cats admitted for orchiectomy during a 10-year period, 23 (1.7%) were cryptorchid and 2 (0.1%) were monorchid. Persian cats were over-represented in the cryptorchid population (P = 0.01). Cats were more likely to be unilaterally than bilaterally cryptorchid (P = 0.01). A predisposition for location of undescended testes (abdominal vs inguinal or right vs left side) was not identified in unilateral cryptorchids. All bilateral cryptorchids had abdominally located testes. The most common surgical approaches used for orchiectomy of cryptorchid cats were a caudal ventral midline incision for inguinal testes and a caudal ventral midline celiotomy for abdominal testes.     

Postnatal developmental changes in immunohistochemical localization of alpha-smooth muscle actin (SMA) and vimentin in bovine testes

The present study demonstrates the postnatal developmental changes in immunohistochemical localization of alpha-smooth muscle actin (SMA) and vimentin in the bovine testis. In the peritubular myoid cells of seminiferous tubules and the sub-epithelial and stromal cells of straight tubules and the rete testis, alpha-SMA starts appearing at around 4 months of age. Peritubular alpha-SMA attains the continuous mature pattern at around 5 months of age whereas sub-epithelial and stromal alpha-SMA increases with advancing age. Vimentin is localized in the perinuclear zone of Sertoli cells, peritubular and vascular wall cells, a few interstitial cells, and in the basal part of the epithelia of straight and rete tubules. Developmental changes are only evident in the Sertoli cell vimentin, which is basal and weak at birth and increases moderately until 4 months of age. From around 5 to 8 months of age when the Sertoli cells are under morphological transformation, vimentin intensity is considerably increased and the characteristic vimentin extensions connect the Sertoli nuclei to the basal membrane. These extensions get shorter at around 9 month of age as the Sertoli nuclei are positioned basally. The mature Sertoli cell perinuclear vimentin is strong and stable without infranuclear extension. In conclusion, the age of appearance of alpha-SMA coincides with the onset of postnatal division of spermatogonia, and vimentin may play a key role in stabilizing Sertoli cell nuclei during their transformation in bovine.     

Laboratory findings, histopathology, and immunophenotype of lymphoma in domestic ferrets

Lymphoma is a common tumor in ferrets, but anatomic distribution, histomorphology, immunophenotype, laboratory abnormalities, and response to chemotherapy are incompletely defined. In this study, lymphoma was diagnosed by histopathology of tumor tissue in 29 ferrets ranging in age from 0.8 to 8.5 years, including 12 males and 17 females. Tumors involved the viscera of the abdominal cavity (n = 11), thoracic cavity (n = 1), or abdominal and thoracic cavities (n = 7); the skin (n = 2); or the viscera of both body cavities plus other sites (n = 8). Microscopically, all tumors had diffuse architecture. Assessment by histomorphology and immunophenotype classified tumors as peripheral T-cell lymphoma (n = 17), anaplastic large T-cell lymphoma (n = 5), anaplastic large B-cell lymphoma (n = 4), diffuse large B-cell lymphoma (n = 1), and Hodgkin-like lymphoma (n = 2). Cytologic evaluation of tumor tissue was diagnostic in 11 of 13 cases. Twenty-two of 27 ferrets had anemia, 2 had leukemia, and 5 were neutropenic. Common comorbid disorders were adrenal disease (n = 27) and insulinoma (n = 6). Tumors most frequently involved mesenteric lymph nodes, while enlargement of peripheral lymph nodes was uncommon (n = 3). Ferrets with Hodgkin-like lymphoma had massive enlargement of single lymph nodes. Mean survival of ferrets not immediately euthanized was 5.0 months (T-cell lymphoma) and 8.4 months (B-cell lymphoma). Ferrets treated with chemotherapy survived an average of 4.3 months (T-cell lymphoma, n = 9) or 8.8 months (B-cell lymphoma, n = 4). Results indicate that lymphomas in ferrets most commonly affect abdominal viscera, may be amenable to cytologic diagnosis, are frequently associated with anemia and, in some cases, may be chemosensitive, resulting in relatively long survival times.     

牦牛睾丸附睾LDH同工酶表达模式的研究

利用比色法和聚丙烯酰胺凝胶电泳技术对６、１２、１８、２４月龄半血野牦牛,横交半血野牦牛和家牦牛睾丸、附睾组织ＬＤＨ同工酶活性及谱带表达进行测析。结果表明,睾丸、附睾ＬＤＨ在相同月龄其表达模式不同,６月龄睾丸ＬＤＨ有四条酶谱,活性百分率依次（ＬＤＨ１〉ＬＤＨ３〉ＬＤＨ２〉ＬＤＨ４）附睾只有三条酶谱（ＬＤＨ１〉ＬＤＨ２〉ＬＤＨ３）;到１２、１８月龄时,睾丸ＬＤＨ有五条酶谱（ＬＤＨ１〉ＬＤＨ３〉ＬＤＨ４     

Feline mesothelioma: case report and review of cytologic,immunocytochemical, histopathologic,and immunohistochemical findings

Mesotheliomas are uncommon neoplasms that arise from mesothelial cells in either the abdominal or thoracic cavities and are rarely diagnosed in cats. A 10-y-old spayed female domestic shorthair cat was presented to the Louisiana State University oncology service for evaluation of a large amount of abdominal effusion. Abdominal ultrasound identified a large mesenteric mass with numerous ill-defined nodules. An abdominocentesis was performed with cytologic and immunocytochemical findings consistent with a neoplastic effusion, with large clusters of epithelioid cells that exhibited strong cytoplasmic expression of pancytokeratin, vimentin, and Wilms tumor 1 antigens. Further testing was declined, and meloxicam was prescribed until the cat died 23 d after initial presentation. Upon postmortem examination, the omentum was contracted into a firm mass adhered to multiple organs and accompanied by numerous small white nodules throughout the abdominal cavity. On histopathology and immunohistochemistry, neoplastic cells were found throughout the abdominal cavity; 60–95% exhibited moderate-to-strong cytoplasmic immunoreactivity for cytokeratin, vimentin, and Wilms tumor 1 protein. The final diagnosis was an epithelioid mesothelioma. Our case illustrates the utility of cytology, immunocytochemistry, and its relation to histology and immunohistochemistry. We also reviewed the reported cases of feline mesothelioma.     

Composition of intermediate filament subunit proteins in embryonic, neonatal and postnatal porcine skeletal muscle

The intermediate (10-nm) filament subunit proteins (desmin and vimentin) in samples obtained from embryonic, neonatal, and postnatal porcine skeletal muscle were examined by two-dimensional electrophoresis (isoelectric focusing/sodium dodecylsulfate polyacrylamide gel electrophoresis). The skeletal muscle samples were taken from pig embryos at 45, 73 and 102 d of gestation; from neonatal pigs and from postnatal pigs at 1, 6 and 30 mo of age. Three fractions (namely, whole homogenized muscle, purified myofibrils and myofibrillar-protein-extracted residues) were prepared from each skeletal muscle sample for analysis. Vimentin was the major (approximately 75% vimentin: 25% desmin) 10-nm filament protein present in skeletal muscle samples obtained from the 45-d-old pig embryos. The relative proportion of vimentin decreased progressively during embryogenesis. At birth, the vimentin comprised approximately 15%, and desmin, 85%, of the 10-nm filament protein. The proportional amount of vimentin continued to decline postnatally, with the 10-nm filament protein of samples from the 30-mo-old animals consisting of less than approximately 5% vimentin and over 95% desmin. These results show a developmental stage-dependent pattern in the expression of vimentin and desmin intermediate filament subunit proteins in mammalian skeletal muscle. In the adult mammal, desmin is the significant 10-nm filament protein present.     

Transplantation of bovine germinal cells into mouse testes

To develop techniques for spermatogonial transplantation in bulls, it is essential to have an effective bioassay procedure to evaluate the transplantation efficiency of spermatogonial stem cell collection, purification, and culture techniques. The objective of the present study was to develop a mouse bioassay model to evaluate transplantation efficiency of fresh and cultured bovine germ cells. Bull calves of four ages (1, 2, 3, and 4 mo) were used as a source of donor testes cells. Two calves were used for each age point, one calf was experimentally made cryptorchidistic at 1 wk of age and the other left normal. A STO (mouse fibroblast) feeder cell line was used to culture bovine testes cells for 2 wk preceding transfer into recipient testes. Immunodeficient nude mice (nu/nu) in which endogenous spermatogenesis had been abolished by busulfan treatment served as recipient animals for transplantation. Donor bovine germ cells were microinjected into mouse seminiferous tubules. Mouse testes were analyzed 2 wk after transplant with the use of a bovine-specific antibody and whole-mount immunohistochemistry for the presence of bovine donor germ cells. Bovine testis cells were present in all recipient mouse testes analyzed. Fresh bovine testes cells were observed as colonies of round cells within mouse seminiferous tubules, indicating spermatogonial expansion and colonization; however, cultured bovine testes cells appeared as fibrous tissue and not as spermatogenic colonies. The average number of colonies resulting from donor cryptorchid testes was not different (P > 0.05) from noncryptorchid, 56+/-4 and 78+/-7, respectively. Fresh donor cells from calves older than 1 mo gave rise to a greater average number of colonies within recipient testes (P <0.05) (1 mo, 33+/-4; 2 mo, 70+/-8; 3 mo, 63+/-6; 4 mo, 87+/-9). Fresh bovine germ cells are capable of colonization in the busulfan-treated nude mouse testis, making it a suitable model for evaluation and development of spermatogonial transplant techniques in bulls.     

A vasectomy technique for Egyptian fruit bats (Rousettus aegyptiacus).

Bats in captivity reproduce well and contraceptive techniques are needed. In initial attempts at vasectomy using a prescrotal approach, it was difficult to identify the mesoductus deferens. The technique described here uses a scrotal approach with exteriorization of the testis, followed by identification and ligation of the mesoductus deferens. Nine Egyptian fruit bats (Rousettus aegyptiacus) underwent vasectomy for this study. No postoperative complications were seen (n = 18 testes), but some of the testes (5/18, 27%), which previously moved freely from the scrotum to the abdominal cavity, were still adhered to the scrotal sac 14 mo postoperatively. This technique appears safe, is fast, and is relatively easy to perform.     

Relationships of testicular iron and ferritin concentrations with testicular weight and sperm production in boars

The inverse relationship of testicular size and circulating follicle-stimulating hormone (FSH) concentrations has been documented, and accompanying this relationship is the change in color of the parenchymal tissue of the testes. Large testes (300 to 400 g) are pink to light red and small testes (100 g) are dark maroon with color gradations for weights in between. It was hypothesized that this color most likely represented an iron protein. Chromatographic analysis of testicular tissue indicated that the Fe was associated primarily with ferritin, and immunohistochemistry showed that Leydig cells were the primary location of ferritin storage within the testes. Concentrations of Fe and ferritin were higher in small testes and decreased as testes weight increased (P < 0.05). As testicular Fe concentrations increased, daily sperm production (DSP) and total DSP declined (P < 0.05). Genotyping six generations of Meishan x White composite boars (n = 288) for a quantitative trait locus that is indicative of elevated FSH and small testes in boars indicated that the Meishan genotype had elevated testicular iron concentrations and darker color in conjunction with reduced total DSP (P < 0.01). It is not thought the elevated iron concentrations affect testicular weights but are probably a result of elevated FSH and FSH inducement of Fe transport. The storage of Fe in Leydig cells may provide a reservoir of Fe for easy access by Sertoli and germ cells, but still provide a degree of protection to germ cells from ionic iron.