Testicular cytology by fine needle aspiration in domestic cats

Abstract

In cases where semen collection in tom-cats is not possible, FNA of testes is the alternative to evaluate sperm production. Although this technique for the diagnosis of fertility problems has been well discussed in other mammals (men, dogs, stallions), data for domestic cats are limited. Therefore, the aim of this study was to verify the reliability of FNA using needles of small diameters (22G and 29G) in testes of domestic cats of different ages to assess the spermatogenesis status and to present description of germ cells and Sertoli cells for cytological examinations. Thirty-four mixed breed cats aged between four months and two years presented for neutering to a Veterinary Hospital were used in this study. Under general anesthesia, testicular measures and FNA were followed by orchiectomy and imprints of the parenchyma of testes and epididymides. Cats were assigned into 3 groups: (G1) 10 cats aged less than 6 months, (G2) 14 cats aged between 6 months and one year and (G3) 10 cats aged more than one year. Cats weighted between 1.5 and 6.0 kg. The mean testicular volume (TV cm) was 0.55 (G1), 1.18 (G2) and 2.66 (G3). Hemorrhages in the needle path were observed in more than 70% of testes. Few samples (4/68) were excluded due to blood contamination. All germ cells and Sertoli cells were identified and quantified in imprint and FNA smears. Incomplete spermatogenesis was observed in cats aged less than 6 months using both techniques (FNA and imprint); therefore, testicular FNA should not be recommended for cats at this age. Complete spermatogenesis was found in 64% of cats aged from 6 months up to one year and in all cats aged more than one year. There were no differences of Sertoli cell Index (SEI) and Spermatic Index (SI) between FNA and imprints of cats older than 6 months. In conclusion, FNA using needles of small diameter in the testes of domestic cats is viable, reliable and can be used as a tool for the analysis of the spermatogenesis status of cats older than 6 months, mainly in cases in which semen collection is not possible.

Cytological description of testicular cell populations in sexually mature cats with normal spermatogenesis

“…Few spermatogonia were identified in the present study even though, in mammals, spermatogonia are present in all stages of the spermatic cycle (França & Godinho, 2003;Senger, 2005). However, these results seemed to be consistent with those obtained by Leme in other studies, this can result from the difficulty to differentiate spermatogonia from primary spermatocytes or spermatids (Leme et al, 2018;Santos et al, 2010). In our study, the differentiation between spermatogonia and primary spermatocytes was sometimes challenging.…”

“…There are few examples of cytological analysis and germ cell count by FNA in cats (Leme et al, 2018). Besides spermatocytes II, all the cell types described by Leme et al (2018) Regarding the proportions of germ cells, the results were consistent with those reported by Leme et al (2018) in a group of ten cats of similar age. They also showed similarities with reported data in dogs and horses (Dahlbom, Mäkinen, & Suominen, 1997;Leme & Papa, 2000;Senger, 2005).…”

“…Spermatocytes II were not identified. Likewise, Leme et al (2018) reported very low proportions of spermatocytes II in cats over 1 year of age. The absence of these cells is also described in healthy dogs (Santos et al, 2010) and in humans with proven fertility (Rajwanshi et al, 1991).…”

“…Classic biases associated with FNA were found: contamination of the preparation with blood cells and artefacts due to spreading and staining (Craft et al, 1997;De Souza et al, 2004;Leme et al, 2018;Santos et al, 2010). Likewise, in cats, Leme et al (2018) mentioned a blood contamination of 70% of samples, whatever the diameter of needle used for the FNA. Besides, some of the smears showed a high cell density, probably resulting from a poor spreading technique (Martin & Ellis, 1930).…”

Infertility in purebred cats – A review of the potential causes

“…Sertoli cell only syndrome, maturation arrest, hypospermatogenesis [ 61 ]. There are some publications describing this procedure in cats [ 62 ].…”