Comparison of different intracellular cryoprotectants on the solid surface vitrification of red-rumped agouti (Dasyprocta Leporina Lichtenstein, 1823) ovarian tissue.

In contributing to the conservation of wild rodents, the aim of this study was to evaluate the use of distinct cryoprotectants, separately or in combination, for solid surface vitrification (SSV) of red-rumped agouti ovarian tissue. Ovarian cortex from nine females was recovered and fragmented. Fresh fragments (control) were used to analyse the pre-antral follicle (PF) morphology using a histologic procedure, viability using the Trypan blue test, cell proliferation by counting the argyrophilic nucleolar organizing regions (Ag-NORs technique) and DNA integrity using the TUNEL assay. The remaining fragments were vitrified using SSV method with 3 M or 6 M ethylene glycol (EG) or dimethyl sulfoxide (DMSO), or in combination (3 M EG/3 M DMSO), and further evaluated as reported for the fresh samples. All cryoprotectants were effective at preserving PFs morphology compared to the control group (80.7 ± 5.21%), except 6 M EG and 3 M DMSO that provoked a significant (p < .05) decrease on the values of morphologically normal primary (60.0 ± 19.0%) and primordial (44 ± 4.5%) follicles, respectively. Regarding viability, all cryoprotectants provided values similar to that verified for the control group (79.0%), but a significant decrease (p < .05) was observed with EG/DMSO combination (59%). Using Ag-NORs technique, the highest (p < .05) cell proliferative capacity was detected when using EG at each tested concentration. The TUNEL proved the preservation of DNA integrity regardless of the cryoprotectant. In summary, we suggest the use of 3 M EG for the solid surface vitrification of red-rumped agouti ovarian tissue.

Development of fresh and vitrified agouti ovarian tissue after xenografting to ovariectomised severe combined immunodeficiency (SCID) mice.

The aim of the present study was to evaluate the development of fresh and vitrified agouti ovarian tissue after xenografting to C57Bl/6 severe combined immunodeficiency (SCID) female mice. Ovaries were obtained from five female agoutis and divided into 16 fragments. Five fragments were transplanted immediately to ovariectomised SCID mice and the others were vitrified, stored for 2 weeks and transplanted only after rewarming. Tissue fragments were transplanted under the kidney capsule in recipients. The return of ovarian activity in recipients was monitored by the observation of external signs of oestrus and vaginal cytology over a period of 40 days after transplantation, after which the grafts were removed and evaluated for morphology, cell proliferation and the occurrence of DNA fragmentation. Ovarian activity returned in four of five mice that received fresh ovarian tissue from agoutis and in one of six mice that had received vitrified tissue a mean (±s.e.m.) 20.6±8.6 days after xenotransplantation. After graft removal, a predominance of primordial and primary follicles was observed in all grafts. Vitrification reduced cell proliferation and increased the occurrence of DNA fragmentation in grafted agouti ovarian tissue. In conclusion, the present study demonstrates that xenografted agouti ovarian tissue, fresh or vitrified, is able to promote the return of ovarian activity in ovariectomised SCID C57B1/6 mice. However, improvements to vitrification protocols for agouti ovarian tissue are necessary.

Vitrification of ovarian tissue of Brazilian North-eastern donkeys (Equus asinus) using different cryoprotectants.

The aim of this study was to assess a vitrification protocol for asinine ovarian tissue, to preserve preantral follicles using different cryoprotectant solutions, composed of various concentrations (EG 3 M or 6 M) of dimethyl sulfoxide or ethylene glycol isolate, or as a combination (DMSO 3 M + EG 3 M). Ten pairs of ovaries from Brazilian north-eastern breed jennies were obtained through videolaparoscopy, and cortical fragments were submitted to a solid-surface vitrification (SSV) using each cryoprotectant solution. The ovarian tissue was evaluated for follicular morphology and viability, DNA integrity (TUNEL technique) and the presence of nucleolar organizing regions in granulosa cells (AgNOR technique). After thawing, the percentage of normal preantral follicles was significantly reduced in the vitrified ovarian tissue fragments compared to the fresh control (p < 0.05). When comparing treatments, the use of DMSO 3 M (81.7 ± 37.5%), EG 3 M (83.7 ± 27.4%) and the combination of both DMSO 3 M + EG 3 M (81.8 ± 46.8%) allowed a greater percentage of follicular survival in contrast to DMSO 6 M (69.8 ± 16.5%) and EG 6 M (72.3 ± 18.0%; p < 0.05). When vitrified using the DMSO + EG combination, a higher percentage (62.5 ± 29.1%) of viable follicles (trypan blue) was observed in relation to the other vitrification treatments (p < 0.05). The TUNEL technique identified that all treatments tested showed DNA fragmentation in the follicular cells, except in the case of the DMSO 3 M + EG 3 M treatment. When evaluating the presence of NORs, no significant differences were observed in the amount of NORs between the fresh and vitrified groups using DMSO 3 M + EG 3 M (p > 0.05). We concluded that the combination DMSO 3 M + EG was more efficient for the vitrification of ovarian tissue taken from Equus asinus, allowing adequate preservation of PAFs morphology, viability, DNA integrity and cell proliferative capacity.

Characterisation and cryopreservation of the ovarian preantral follicle population from Spix's yellow-toothed cavies (Galea spixii Wagler, 1831).

The aim of the present study was to characterise the ovarian preantral follicle (PF) population and to establish a solid surface vitrification (SSV) process using dimethyl sulfoxide (DMSO) as a cryoprotectant for preservation of ovarian tissue from yellow-toothed cavies (Galea spixii). Ovaries were fixed for PF population analysis or were subjected to the SSV process. The mean (± s.e.m.) PF population per ovarian pair was estimated to be 416.0±342.8. There were 140.0±56.0 (63.4%) and 125.0±58.0 (64.0%) primary follicles on the right and left ovaries, respectively. The proportion of this follicle category was significantly greater than that of other follicle categories (P<0.05). The diameter of follicles (123.7±18.3µm), oocytes (50.1±5.0µm) and nuclei (14.27±2.01µm) was larger for secondary ones when compared with other PFs categories. Most PFs were morphologically normal (94.6%), with light microscopy identifying only a few atretic follicles (5.4%). After SSV, there was a reduction in the proportion of morphologically normal PFs compared with the non-vitrified group (69.5% vs 91.2%, respectively). Transmission electron microscopy revealed preservation of oocytes and granulosa cell membranes and the morphological aspect of follicles; the primary change observed in some vitrified PFs was the presence of vacuoles in the oocytes and granulosa cells cytoplasm and turgid mitochondria. In conclusion, the present study provides an estimative and characterization for the PF population in ovaries of G. spixii. Moreover, we report its PFs cryopreservation using an SSV process.

Objective assessment of the cryoprotective effects of dimethylformamide for freezing goat semen.

The aim of this work was to assess the cryoprotective effects of dimethylformamide (DMF) for freezing goat semen, using an objective analysis by computer-assisted sperm analysis (CASA). Twenty-one ejaculates (seven per animal) were collected from three stud bucks with the aid of an artificial vagina and immediately evaluated for gross and microscopic characteristics. The semen was diluted in two steps with a Tris-egg yolk extender containing 6% glycerol or 6% DMF, frozen in 0.50-mL straws, and stored in liquid nitrogen. Samples were accessed for sperm morphology, sperm membrane structural and functional integrity, and by CASA, immediately after thawing. There were differences (P<0.05) between glycerol and DMF with regard to subjective progressive motility (23.9±2.2% vs. 16.6±2.0%), objective progressive motility (3.5±0.4% vs. 1.8±0.3%), linearity (53.9±1.6% vs. 48.1±1.4%) and amplitude of lateral head (2.3±0.1 vs. 2.9±0.1 mm), which confirmed the efficiency of glycerol. In conclusion, dimethylformamide could be used as an alternative cryoprotectant for goat semen freezing. However it was showed that no benefits were derived by using dimethylformamide to replace glycerol at an equal 6% concentration.

Effect of cryoprotectant type and concentration on the vitrification of collared peccary (Pecari tajacu) ovarian tissue.

The aim of the present study was to establish a protocol for solid surface vitrification of peccary ovarian tissue by using different cryoprotectants. Ovarian pairs from five adult females were fragmented and two fragments (fresh control group) were immediately subjected to morphological evaluation using classical histology, transmission electron microscopy, and viability analysis using fluorescent probes. The remaining fragments (n = 18) were vitrified using a solid surface method with different concentrations (3 or 6 M) of ethylene glycol (EG), dimethyl sulfoxide (DMSO) or dimethyl formamide (DMF). After 2 weeks, samples were re-warmed and evaluated. A decrease in the percentage of morphologically normal preantral follicles (PFs) was verified for all the groups in comparison to the fresh control (92.0 ± 2.8%); however, if only the primordial follicles are considered, the most effective preservation (P < 0.05) was achieved with the use of EG at 3 M (74.2±7.3%) or DMSO at 6 M (75.0 ± 4.2%). Ultrastructural analysis indicated there were well-preserved PFs in all the groups evaluated, having well-defined membranes, a few vacuoles, and organelles that were uniformly distributed throughout the cytoplasm, mainly round and elongated mitochondria in close association with lipid droplets. Viability was preserved (P < 0.05) with the use of EG at 3 (97%) or 6 (97%) M, DMSO at 3 (100%), and DMF at 6 (97%) M. Solid surface vitrification, therefore, is an effective method for conservation of peccary female germplasm, especially with the use of EG at 3 M, which was highly effective for preservation of both the morphology and viability of PFs.

Single injection of eCG/hCG leads to successful estrous synchronization in the collared peccary (Pecari tajacu Linnaeus, 1758).

The establishment of protocols for the control of the ovarian function of collared peccaries is recommended for the development of assisted reproductive techniques. The goals were to (1) compare a gonadotropin combination with prostaglandin analogue to synchronize timing of onset of estrus among animals, and (2) elucidate the effects of the most desirable protocol for performing an artificial insemination study and macroscopic evaluation of the ovaries. Three of five females treated with a double administration of 120 µg prostaglandin (cloprostenol) at a 9-day interval expressed symptoms of estrus 9 days after the second injection. One female presented estrus after 6 days, whereas other did not respond to the treatment. All females (5/5) treated with a single dose containing 400 IU eCG and 200 IU hCG manifested estrus 6 days after the hormone injection. In a second experiment, ten females that were estrous synchronized using eCG/hCG, were artificially inseminated with fresh semen and monitored for pregnancy every 30 days. Although there was no detection of fetuses by ultrasonic examination, seven females (7/10) had greater than basal progesterone values for 60 days after the treatments were imposed. Ovaries from two females treated with eCG/hCG were collected 6 days post-injection. There was confirmation of an ovarian stimulation as a result of the presence of 88 and 25 antral follicles, as well as three and eight hemorrhagic structures in ovaries of each female, respectively. It, therefore, is proposed that eCG/hCG can be used as an effective treatment for estrous synchronization in collared peccaries.

Follicular degeneration in the ovaries of goats experimentally infected with Trypanosoma vivax from the Brazilian semi-arid region.

Infection by Trypanosoma vivax and other African trypanosomes plays an important role in reproductive disorders in male and female livestock. Outbreaks of T. vivax in the semi-arid region of northeastern Brazil are characterized by wasting disease in cattle, sheep and goats with hematological, cardiac and nervous compromises in addition to reproductive failures. Similar to reports from Africa, we previously observed a reduction in fertility rates and severe testicular degeneration and epididymitis in male sheep infected with T. vivax from this region. Although anestrus is frequently reported in goats and sheep infected with T. vivax, the effects of this infection on the female reproductive organs need clarification. In this study, we addressed this issue through a histopathological evaluation of ovarian follicular morphology and classification in goats experimentally infected with a T. vivax isolate from the Brazilian semi-arid region. The infected animals presented typical clinical signs of trypanosomosis by T. vivax, including anemia, hyperthermia, pallor of the mucous membranes, enlarged lymph nodes, and progressive loss of weight. All the infected goats remained anestrus throughout the experimental period and exhibited important disturbances in the ovaries, evidenced by reduced size and a smooth surface without follicles or corpora lutea, and abnormal follicular development. In addition, through PCR, we detected T. vivax DNA in the ovarian tissues of the infected goats. Our findings contributed to understand the female reproductive failure associated with trypanosomosis caused by T. vivax.

Estimation, morphometry and ultrastructure of ovarian preantral follicle population in agouti (Dasyprocta leporina) / Morfometria, estimativa e ultraestrutura da população folicular ovariana preantral de cutia (Dasyprocta leporina)

The aim of this study was to characterize the preantral ovarian follicular population in agoutis (D. leporina) by estimating the number of follicles at each developmental category, and also describe the morphometry and the specific features of the follicle and the oocyte by using light and transmission electron microscopy. The length of each ovary was measured using a caliper rule, longitudinally sectioned into two halves and both were immediately fixed to perform the estimation of follicular population and ultrastructural analysis. The mean (±S.E.M.) population of follicular per pair of ovary was estimated at 4419.8±532.26 and 5397.52±574.91 for right and left ovaries, respectively, but no differences were observed between them. The diameters for follicles, oocyte and nuclei were: 18.62±3.40µm, 12.28±2.37µm and 6.10±0.93µm for primordial, 23.75±5.70µm, 14.22±3.00µm and 6.70±1.24µm for primary and 88.55±17.61µm, 52.85±17.56µm and 22.33±17.61µm for secondary follicles, respectively. The most of the follicles found belonged to the primordial category (86.63%), followed by primary (13.01%) and secondary (0.35%) one. Additionally, polyovular follicles were observed in all the animals and they represented 7.51% of the total follicles counted. The ultrastructural analysis showed that the oocyte presented a central and regular nuclei, displaying a homogenous mass. Among the organelles, the mitochondria were the most abundant and the oocyte Golgi apparatus was rarely observed. In conclusion, this work shows for the first time the characterization of the population of preantral follicles in the ovary of Dasyprocta leporina. Those information will be useful for further development and adaptation of biotechniques such as germplasm cryopreservation and in vitro gametes manipulation.(AU)

O objetivo deste trabalho foi caracterizar a população folicular ovariana pré-antral em cutias (D. leporina) estimando o número de folículos em cada categoria de desenvolvimento, e também descrever a morfometria e as características específicas do folículo e oócito usando microscopia de luz e eletrônica de transmissão. O comprimento de cada ovário foi medido utilizando um paquímetro, seccionados longitudinalmente em duas metades e ambos foram imediatamente fixados para realizar a estimativa da população folicular e análise ultraestrutural. A média (±S.E.M.) da população folicular por par de ovário foi estimada em 4419,8±532,26 e 5397,52±574,91 nos ovários direito e esquerdo, respectivamente, mas não foram observadas diferenças entre eles. Os diâmetros dos folículos, oócito e núcleos, respectivamente, foram: 18,62±3,40µm, 12,28±2.37µm e 6,10±0,93µm para primordial, 23,75±5,70µm, 14,22±3,00µm e 6,70±1,24µm para primário e 88,55±17,61µm, 52,85±17,56µm e 22,33±17,61µm de folículos secundários. A maioria dos folículos encontrados pertencia à categoria primordial (86,63%), seguido pelo primário (13,01%) e um secundário (0,35%). Adicionalmente, os folículos poliovulares foram observados em todos os animais e representavam 7,51% do total de folículos contados. A análise ultra-estrutural mostrou que o oócito apresentou núcleos centrais e regulares, exibindo uma massa homogênea. Dentre as organelas, as mitocôndrias foram as mais abundantes e o aparelho de Golgi do oócito foi raramente observado. Em conclusão, este trabalho mostra pela primeira vez a caracterização da população de folículos pré-antrais do ovário da Dasyprocta leporina. Essas informações serão úteis para o desenvolvimento e adaptação de biotécnicas, como a criopreservação de germoplasma e manipulação de gametas in vitro.(AU)

Identification of ultrastructural and functional damages in sperm from six-banded armadillos (Euphractus sexcinctus) due to cryopreservation / Identificação de danos ultraestruturais e funcionais em espermatozoides de tatus-peba (Euphractus sexcinctus) oriundos da criopreservação

The aim of the study was to cryopreserve the semen of six-banded armadillos (Euphractus sexcinctus) in Tris-yolk and glycerol diluent, and to determine the damage caused by the freezing-thawing process, using fluorescent markers and ultrastructural analysis. Semen samples (n=11) collected from 4 adult six-banded armadillos by electroejaculation were cryopreserved in Tris diluent plus 20% egg yolk and 3% glycerol, in a fast freezing curve. Classical analysis of samples was performed after dilution, refrigeration and thawing, followed by fluorescence analysis, using a combination of fluorescent probes to assess membrane integrity (propidium iodide - PI and Hoechst - H342), and mitochondrial activity (CMXRos - Mito Tracker Red®). We also used the ultrastructural analysis to verify possible morphological alterations caused by cryoinjuries. When compared with fresh samples, we verified a significant decline in all the armadillos' semen parameters after thawing, in which only 6.1% motile sperm were found. However, the percentage of sperm which remained with viable (13%) and functional (24.7%) membranes after thawing suggests that some cells could be live but immotile. Analysis using fluorescent markers revealed that the mitochondria of armadillos' sperm is highly sensible to the freezing protocol and the findings through ultrastructure analysis proved this statement. Additionally, the images obtained by transmission electron microscopy revealed that frozen-thawed sperm presented damaged plasma membrane, nuclear modifications as changes in chromatin and acrossomal changes relative to sperm capacitation. In conclusion, this study is the first attempt to cryopreserve the semen of an armadillo species, and to help us to identify critical points on the freezing-thawing procedure in order to improve the protocol.(AU)

O objetivo deste estudo foi criopreservar o sêmen de tatus-peba (Euphractus sexcinctus) em diluente Tris-gema e glicerol, e determinar os danos causados pelo processo de congelação-descongelação, utilizando marcadores fluorescentes e análise ultraestrutural. As amostras de sêmen (n=11) coletadas de 4 tatus-peba adultos por eletroejaculação foram criopreservadas em diluente Tris acrescido de 20% de gema de ovo e 3% de glicerol, em curva rápida de congelação. A análise clássica das amostras foi realizada após a diluição, refrigeração e descongelação, seguida por análise de fluorescência, utilizando uma combinação de sondas fluorescentes para avaliar a integridade da membrana (Iodeto de Propídio - PI e Hoechst - H342), e a atividade mitocondrial (CMXRos - Mito Tracker RED®). Foi também utilizada a análise ultraestrutural para verificar possíveis alterações morfológicas causadas pela crioinjúria. Quando comparadas com as amostras a fresco, verificou-se uma queda significativa em todos os parâmetros seminais dos tatus após a descongelação, em que apenas 6,1% de espermatozoides móveis foram encontrados. No entanto, o percentual de espermatozoides que permaneceu com membrana viável (13%) e funcional (24,7%) após a descongelação sugere que algumas células podem estar vivas, mas imóveis. Análises utilizando marcadores fluorescentes revelaram que as mitocôndrias dos espermatozoides de tatus são altamente sensíveis ao protocolo de congelação e os achados através da análise ultraestrutural comprovaram esta afirmação. Além disso, as imagens obtidas por microscopia eletrônica de transmissão revelaram que espermatozoides congelados-descongelados apresentaram membranas plasmáticas danificadas, modificações nucleares como alterações na cromatina, e alterações acrossomais relativas à capacitação espermática. Em conclusão, este estudo é a primeira tentativa de criopreservação de sêmen em uma espécie de tatu, e nos auxiliou a identificar pontos críticos no processo de congelação-descongelação, a fim de melhorar o protocolo.(AU)

Monitoramento do ciclo estral de cutias (dasyprocta leporina lichtenstein, 1823) através de citologia esfoliativa vaginal e ultrassonografia / Monitoring of the estrous cycle of agoutis (dasyprocta leporina lichtenstein, 1823) by vaginal exfoliative cytology and ultrasonography

O objetivo deste estudo foi monitorar o ciclo estral em cutias (Dasyprocta leporina) criadas em cativeiro no semiárido brasileiro. Durante 70 dias, cinco cutias foram diariamente submetidas a citologia esfoliativa vaginal, e o monitoramento ultrassonográfico ovariano foi realizado a cada três dias. Um total de 8 ciclos estrais foi completamente monitorado, com duração de 28,2±0,7 dias, variando de 24 a 31 dias. Pela citologia esfoliativa vaginal, houve uma predominância de células superficiais nas fases de proestro e estro (P<0,05), seguida da predominância de células intermediárias no metaestro (P<0,05) e de células parabasais no diestro (P<0,05). Por ultrassonografia, não houve diferenças na morfologia ovariana durante as diferentes fases do ciclo estral (P>0,05). Os folículos foram identificados durante as fases estrogênicas (proestro e estro), com diâmetro médio de 1±0,5mm. Em apenas 12,5% das fases luteais, corpos lúteos medindo 1,4±0,9mm foram identificados. Conclui-se que a associação da citologia vaginal e da ultrassonografia ovariana constitui uma alternativa viável para o monitoramento de ciclos estrais e identificação das fases estrogênicas em cutias da espécie Dasyprocta leporina.

The objective of the study was to monitor the estrous cycle in agoutis (Dasyprocta leporina) bred in captivity in Brazilian semiarid. During 70 days, five agoutis were daily subjected to vaginal exfoliative cytology, and the ovarian ultrasound monitoring was conducted every three days. A total of 8 estrous cycles were completely monitored, lasting 28.2±0.7 days, ranging from 24 to 31 days. By vaginal exfoliative cytology, there was predominance of superficial cells at proestrus and estrus phases (P<0.05), followed by the predominance of intermediate cells in the metestrus (P<0.05) and parabasal cells in diestrus (P<0.05). By ultrasound, there were no differences in ovarian morphology during the different phases of the estrous cycle (P>0.05). Follicles during the estrogenic phases (proestrus and estrus) were identified, with an average diameter of 1±0.5mm. In only 12.5% of luteal phases, corpora lutea measuring 1.4±0.9mm were identified. We conclude that the association of vaginal cytology and ovarian ultrasonography is a useful alternative for monitoring the estrous cycle and identifying the estrogenic phases in Dasyprocta leporina.

Determination of semen characteristics and sperm cell ultrastructure of captive coatis (Nasua nasua) collected by electroejaculation.

Despite the wide geographical distribution of coati (Nasua nasua) from the south of Canada to the north of Argentina, studies regarding the reproductive characteristics of this species are extremely limited. The objective of this study was to describe the various characteristics of coati semen by morphometric and ultrastructural analysis. Five mature males were anesthetized and electroejaculated for the collection of semen. Semen was immediately evaluated for color, volume, pH, sperm motility, vigor, morphology, acrosomal integrity, percentage of live cells and hypo-osmotic response by light microscopy. Sperm cell morphometry and ultrastructural analyses were also performed. Observations of seminal characteristics determined by electroejaculation in captive coatis represent a valuable baseline dataset for establishing fertility standards and provide background information that may be useful for assisted breeding programmes in members of the Procyonidae family.

Sperm morphological and morphometric evaluation in captive collared peccaries (Pecari tajacu) / Avaliação morfológica e morfométrica de espermatozoides de catetos (Pecari tajacu)

The aim of this study was to compare different staining methods for the evaluation of sperm morphology by light microscopy and also to describe the morphometry of the entire sperm in collared peccaries (Pecari tajacu). Semen from 10 males was obtained by electroejaculation and evaluated for sperm motility, vigor, and concentration. Semen smears were prepared through three different staining methods: Bengal rose, brome-phenol blue, and eosin-nigrosin. Smears were evaluated under light microscopy and sperm morphologic alterations were determined in percentage. In addition, sperm morphometric analysis was conducted by light microscopy coupled to image analyzer software. The smears stained with Bengal Rose provide the best results for the visualization of the sperm tail, midpiece, and head. The use of eosin-nigrosin stain did not allow an adequate impregnation, and some sperm presented a few contrasts with the background. A higher incidence of bent coiled tails was verified in the use of brome-phenol blue staining (P<0.05). Through morphometric evaluation, it was observed that the tail occupies the greatest proportion (89%) of the sperm which presents a discretely elongated head. According to the results, the use of the Bengal Rose stain is recommended for the morphologic evaluation of the collared peccary sperm.

O objetivo deste estudo foi comparar diferentes métodos de coloração para avaliação da morfologia espermática por microscopia de luz e também descrever a morfometria completa de espermatozoides de catetos (Pecari tajacu). Sêmen de 10 machos foi obtido por eletroejaculação e avaliado quanto à motilidade espermática, vigor e concentração. Foram preparados por três diferentes métodos de coloração: Rosa de Bengala, Azul de Bromofenol e Eosina-Nigrosina. Os esfregaços foram avaliados por microscopia de luz, e determinado o percentual das alterações morfológicas. Ainda, a análise da morfometria espermática foi realizada por microscópio de luz acoplado a um softwere de análise de imagens. Os esfregaços corados com Rosa de Bengala apresentaram melhores resultados de visualização da cauda, peça intermediária e cabeça dos espermatozoides. O uso do corante Eosina-Nigrosina não permitiu uma adequada impregnação e alguns dos espermatozoides apresentaram pouco contraste com o fundo da lâmina. Uma maior incidência de cauda fortemente enrolada foi verificada com o uso do corante Azul de Bromofenol (P<0.05). Através da avaliação morfométrica foi observada que a cauda ocupa a maior proporção (89%) do espermatozoide, e a cabeça apresenta-se discretamente alongada. De acordo com os resultados, o uso do corante Rosa de Bengala é recomendado para a avaliação morfológica de espermatozoides de catetos.