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Fibroblast cycle synchronization in G0/G1 is an essential step for nuclear reprogramming by cloning or induced cells to pluripotency. Considering the diversity among rodents and the ecological and scientific importance of these animals, we compared the contact inhibition, serum starvation, and 10 µM of roscovitine as methods of synchronization of red-rumped agouti fibroblasts. The effects of each protocol were evaluated on the percentage of cycle phase, morphology, viability, and apoptosis levels. The results showed that culturing the cells to serum starvation for 24 h (75.9%), 48 h (81.6%), 72 h (86.2%), 96 h (84.0%), and 120 h (83.7%) yielded a significantly higher percentage of cells arrested in the G0/G1 (P < 0.05) phase than cells not subjected to any cell cycle synchronization method (31.4%). Also, this effect was not different between the times of 48 and 120 h (P > 0.05). A similar response was observed for cells cultured with roscovitine for 12 h (86.9%), 24 h (74.8%), and 48 h (81.7%), with a higher percentage of synchronized cells in G0/G1 compared to cells not submitted to any synchronization treatment (52.2%). Nevertheless, this effect was best evidenced at 12 h (P < 0.05). Also, the contact inhibition for 24-120 h could not synchronize cells in G0/G1, with values ranging from 70.9 to 77.9% (P > 0.05). Moreover, no difference was observed for morphology, viability, and apoptosis levels in any synchronization method (P > 0.05). Therefore, serum starvation is as efficient as roscovitine on cycle synchronization in G0/G1 of red-rumped agouti fibroblasts.

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This study aimed to describe pronephros and mesonephros morphology during the embryonic development of Podocnemis expansa. Eggs were collected on an artificial beach at Balbina, Amazonas, Brazil, during the entire incubation period (mean of 59 days). The kidney-gonad complex was processed using light microscopy and the mesonephros using transmission electron microscopy. The pronephros was present for the first time on stage 4, composed of external glomeruli devoid of a capsule, protruding into the coelomic cavity, and internally composed of a capillary network. The pronephros degenerated after development stage 15. The first sign of the appearance of the mesonephros occurred around stage 8, indicated by the early formation of renal corpuscles. The mesonephros comprised an renal corpuscles, neck segment, proximal tubule, intermediate segment, distal tubule, collector tubule, and collector duct. Ultrastructural analysis of the mesonephros brush border was done in the proximal tubule, and the presence of cells with structural characters indicative of secretory activity was detected in the juxtatubular region. Renal corpuscles and proximal tubules were the main components that underwent morphological alterations during mesonephros degeneration. The pronephros is a transient kidney, and the mesonephros became the functional embryonic kidney in P. expansa. Mesonephros degeneration occurs in the cranial-caudal direction, and histologically, the degeneration is identified by changes in the morphology of the renal corpuscle and proximal tubule. However, the mesonephros is still present after hatching.

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Morphological studies of the oropharyngeal cavity of chelonians have become an interesting tool in the understanding of evolutionary processes associated with feeding habits in aquatic animals and the transition from aquatic to terrestrial forms. In this context, the aim of the present study was to describe the oropharyngeal cavity floor morphology of hawksbill sea turtle (Eretmochelys imbricata) hatchlings. Ten dead hatchlings of undefined sex were obtained from nests hatched on the coast of the state of Rio Grande do Norte, Brazil. The heads of each specimen were fixed, dissected, and analyzed at the macroscopic and microscopic levels. The oropharyngeal cavity floor of the hawksbill sea turtle hatchlings is formed by the tongue, pharynx, floor muscles, and hyolingual skeleton, delimited in the rostral and lateral directions by a keratinized beak, called the rhamphotheca, and in the caudal region at the limit between the pharynx and the esophagus. The tongue muscles and the muscles that support the floor of the oral cavity comprise the following: m. hypoglossohyoideus, m. hypoglossoglossus, m. hyoglossus, m. genioglossus, m. constrictor laryngis, m. geniohyoideus pars lateralis, and m. intermandibularis. The oropharyngeal cavity floor mucosa is formed by keratinized stratified squamous epithelium and the lamina propria is formed by loose connective tissue. The floor mucosa is devoid of taste buds. We believe that the basic oropharyngeal cavity floor characteristics in hawksbill sea turtle hatchlings may comprise indications that these animals are plesiomorphic and that semiaquatic and terrestrial turtles may have undergone adaptations to feed out of water.

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Morphological studies concerning the digestive system can further information on animal diets, thus aiding in the understanding of feeding behavior. Given the scarcity of information on sea turtle digestive system morphology, the aim of the present study was to describe the digestive tube (DT) morphology of Eretmochelys imbricata hatchlings to further understand the diet of these individuals in the wild. DT samples from 10 stillborn turtles (undefined sex) were analyzed at the macro and microscopic levels. The esophagus, stomach, small intestine (SI), and large intestine (LI) are described. Histologically, the DT is formed by four tunics, the mucosa, submucosa, muscular, and adventitia or serosa. The esophagus is lined by keratinized stratified squamous epithelium, while the remainder of the DT is lined by a simple columnar epithelium. The esophagus mucosa is marked by conical, pointed papillae. The stomach comprises three regions, the cardiac, fundic, and pyloric and is covered by neutral mucous granular cells. The intestinal mucosa presents absorptive cells with microvilli, neutral and acidic goblet cells, and mucosa-associated lymphoid tissue. The SI is significantly longer than the LI (p value = 0.006841). These morphological findings are strong indications of adaptations to a carnivorous diet in this hawksbill turtle age group.

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The tongue is a fundamental organ in feeding, vocalization, and grooming. It is characterized by evolutionary adaptations reflected by diet, habitat, and function. Rodents are a very diverse mammalian order and the tongue's morphology varies in size, form, and presence of papillae. This work aimed to describe the morphological and ultrastructural aspects of the tongue of Spix's yellow-toothed cavy (Galea spixii, Wagler, 1831). Tongues of Spix's yellow-toothed cavies were analyzed with light microscopy, scanning, and transmission electron microscopy. The results showed that the tongue was divided into apex, body, and root. There were different types of papillae, such as vallate, foliate, laterally placed fungiform, fungiform, filiform, and robust filiform. The epithelium was organized into layers, including keratinized, granulous, spinous, and basal, below were lamina propria, and musculature, which evolved mucous and serous gland clusters. The tongue of Spix's yellow-toothed cavy was structurally and ultrastructurally similar to other rodents and had papillae with similar morphologies to other Caviidae species. However, the presence of robust filiform papillary lines and laterally placed fungiform papillae showed the main differences from other species. This was the first description of the tongue of Spix's yellow-toothed cavy.

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Heterologous in vitro fertilization (IVF) is an important tool for assessing fertility of endangered mammals such as the jaguar, considering difficult access to females for artificial insemination and to obtain homologous oocytes. We aimed to evaluate the fertility of jaguar sperm cryopreserved with different extenders, using domestic cat oocytes to assess the development of hybrid embryos. Semen from four captive jaguars was obtained by electroejaculation. Samples were cryopreserved in powdered coconut water (ACP-117c) or Tris extender containing 20% egg yolk and 6% glycerol. Thawed spermatozoa were resuspended (2.0 × 106 spermatozoa/mL) in IVF medium and co-incubated with cat oocytes matured in vitro for 18 h. Presumptive zygotes were cultured for 7 days. After 48 h, cleavage rate was evaluated, and non-cleaved structures were stained for IVF evaluation. On days 5 and 7, the rate of morula and blastocyst formation was assessed. Data were analyzed using the Fisher exact test (p < 0.05). No difference was observed between ACP-117c and Tris extenders, respectively, for oocytes with 2nd polar body (2/51, 3.9 ± 2.9% vs. 2/56, 3.6 ± 3.1%), pronuclear structures (5/51, 9.8 ± 4.7% vs. 8/56, 14.3 ± 8.0%), and total IVF rates (7/36, 19.4 ± 5.0% vs. 10/37, 27.0 ± 13.8%). All the samples fertilized the oocytes, with 22.9 ± 3.2% (16/70) and 16.7 ± 3.6% (12/72) cleavage of mature oocytes for ACP-117c and Tris extenders, respectively. Morula rates of 4.3 ± 2.3% (3/70) and 5.6 ± 2.2% (4/72) were observed for ACP-117c and Tris, respectively. Only the Tris extender demonstrated blastocyst production (2/12, 16.7 ± 1.5% blastocyst/cleavage). We demonstrated that jaguar ejaculates cryopreserved using ACP-117c and Tris were suitable for IVF techniques, with blastocyst production by ejaculates cryopreserved in Tris. This is a first report of embryos produced in vitro using jaguar sperm and domestic cat oocytes through IVF.(AU)

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Duchenne Muscular Dystrophy (DMD) reproductive alterations and the influence of antioxidant treatments may aid in understanding morphometry testicular quantification. In this context, the aim of the present study was to characterize the intertubular compartment (ITC) morphometry of animal testes in mdx mice supplemented with ascorbic acid (AA). Sixteen mice were used, namely the C57BL/10 (non-dystrophic) and C57BL/10Mdx (dystrophic) lineages, distributed into the following groups: Control (C60), Dystrophic (D60), Control supplemented with AA (CS60), Dystrophic supplemented with AA (DS60). A total of 200 mg/kg of AA were administered to mice for 30 days. Subsequently, the testicles were collected, weighed, and fragmented. The obtained fragments were fixed in Karnovsky's solution (pH 7.2) and embedded in historesin for morphometric and transmission electron microscopy assessments. Leydig cells were hypertrophic in the D60 group, but was reverted by AA supplementation in the DS60 group. The DS60 group also exhibited increased intertubular volume compared to the CS60 group. The ultrastructural images identified multilamellar bodies in dystrophic animals (lipid storage) and telocyte cells (transport substances) in both control and dystrophic animals. Morphometric alterations were, therefore, noted in the intertubular compartment due to Duchenne muscular dystrophy (DMD), with AA administration capable of altering Leydig cells in this condition.(AU)

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Estrogens and progestogens are hormones produced by maternal organs and it is required for recognition and maintenance of pregnancy. In addition, the embryo may also be a source. For this, the aim was to identify steroidogenic expression on Galea spixii embryos early in the embryonic period. Embryos were collected on Days 10 and 15 of gestation; some were fixed in 4% paraformaldehyde for morphological and immunohistochemical analysis (P450arom), whereas others had RNA extracted to determine presence of CYP19a1 gene. In addition, for immunochemistry, maternal ovaries were collected as positive control tissues. Maternal tissues had positive staining for aromatase, whereas none of the embryos stained for P450 aromatase. Based on qPCR reactions, CYP19a1 gene were expressed in all embryos. Galea spixii embryos expressed steroidogenic genes during the post-implantation period, indicating they have the potential to produce steroid hormones.(AU)

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Sex steroid hormones are critical in gonadal differentiation in turtles. The gonads are not the only organs responsible for producing these hormones during this phase. Mesonephros play an important role in steroidogenesis. The present study aimed to investigate the presence of steroidogenic cells in mesonephros of Podocnemis expansa during gonadal differentiation and to evaluate their morphology and ultrastructure. Ten embryos of P. expansa were collected from 5 nests on day 36 of incubation, during spawning period on an artificial beach. Embryos were extracted from eggs by slicing the shell and euthanized. They were dissected under a stereoscopic microscope to collect the gonad-mesonephro complex, in which were fixed and subsequently processed for light microscopy, immunohistochemistry and transmission electron microscopy analysis. During histological analysis was observed mesonephros has typical morphological structure. Immunohistochemistry showed immunoreaction to aromatase in cells of intertubular space. Confirming these findings, it was possible to observe a type of intertubular cell in several regions of mesonephro, being more predominant in region close to blood vessels, distal and proximal tubules. In ultrastructural analysis these cells were characterized by having a clear, large, and rounded nucleus with evident nucleolus and cytoplasm rich in electron-dense droplets. This study demonstrated for the first time the presence of cells with morphological, immunohistochemical and ultrastructural characteristics similar to steroid-producing cells in P. expansa mesonephrons, suggesting that this organ may contribute to gonadal differentiation in this species.(AU)

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Somatic resource banks play a crucial role in the conservation of genetic diversity, allowing for the preservation of biological samples from different populations. Puma somatic cells can be recovered from these banks and used in assisted techniques toward enhancing their multiplication and conservation. In response to the population reduction of this ecologically importance species, we aimed to evaluate the capacity of cryopreservation of somatic tissues on the maintenance of the integrity and quality of the cells recovered after culture, with the aim of establishing a somatic tissue bank that will allow for the safeguarding of a wide genetic sampling of pumas. Cryopreservation increased the thickness of the corneum layer in the tissues, and the number of perinuclear halos and empty gaps. Nevertheless, cryopreservation was able to maintain normal fibroblast patterns, even showing an increase in the percentage of collagen fibers. Cryopreservation maintained the proliferative potential of the tissues and the parameters evaluated during in vitro culture, mainly regarding the viability, proliferative activity, and apoptosis levels. Nevertheless, cells from cryopreserved tissues showed decreased metabolism and mitochondrial membrane potential when compared to cells from non-cryopreserved tissues. In summary, we demonstrated for the first time that puma somatic tissues subjected to cryopreservation are viable and maintain tissue integrity, featuring minimal changes after warming. Although viable somatic cells are obtained from these tissues, they undergo alterations in their metabolism and mitochondrial membrane potential. Improvements in the conservation conditions of somatic samples are needed to increase the quality of somatic tissue banks in this species.

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Reports of intussusception in sea turtles are generally linked to marine debris ingestion; therefore, only a few cases of the disease are associated with parasitic infestations. The objective of this study was to describe the necropsy findings of the first reported case of colocolic intussusception in a green sea turtle Chelonia mydas, associated with the helminth Octangium sp. A juvenile female green sea turtle, which was registered and rescued by the team from the Cetaceans Project of Costa Branca, State University of Rio Grande do Norte, was examined. The animal died 1 d after being treated and was immediately submitted for necropsy. Our findings indicated that parasitic infestation by Octangium sp. in the green sea turtle caused intussusception and consequently led to the animal's death. Early diagnosis and surgical correction are fundamental for a good prognosis and, consequently, for successful rehabilitation of marine species.

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Somatic cells can be used for rescuing wild mammals of ecological and economic importance, such as red-rumped agouti, through their application in advanced technologies. Thus, appropriate cell isolation, culture, and storage through cryopreservation can ensure the future safe use of these cells. We aimed to establish and evaluate the effects of culture time (second, fifth, and eighth passages) and cryopreservation on the morphology, viability, metabolism, proliferative activity, reactive oxygen species (ROS) levels, mitochondrial membrane potential (ΔΨm), and apoptosis on somatic cells derived from red-rumped agouti skin. Initially, we identified six dermal fibroblast lines by morphology, immunophenotyping, and karyotyping assays. In vitro culture after the second, fifth, and eighth passages, as well as the cryopreservation conditions used did not affect the metabolism or level of apoptosis. Nevertheless, cells in the fifth passage featured a reduction in proliferative activity and an increase in ROS levels when compared to second and eighth passage cells. Moreover, cryopreservation resulted in reduced ΔΨm when compared to non-cryopreserved cells. Additionally, cryopreserved cells showed a reduction in viability immediately after thawing; nevertheless, the viability of these cells was re-established after 11 days of in vitro culture and was similar to that of non-cryopreserved cells. In conclusion, we have shown that viable fibroblasts can be obtained from red-rumped agouti skin, featuring minimal changes after eight passages in in vitro culture systems. Additionally, adjustments to the cryopreservation protocol are necessary to reduce cellular oxidative stress caused by low temperatures.

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Heart diseases in birds are frequent and generate significant production disorders. Morphometry is a valuable tool to provide fundamental information about heart conditions. Few studies have addressed morphological aspects of the heart of ratite birds, such as the Greater rhea. The present study aimed to analyse rhea heart morphometry, comparing young and adult subjects, in order to provide relevant information for the diagnosis of heart disease in this species. Hearts of young (n = 10) and adult (n = 10) female rheas were used in this research. Heart length and width and sternum length were measured using a caliper. Heart length and width and sternum length in adults were approximately three times greater than in young individuals. The left ventricular wall (LVW) was thicker than the right ventricular wall (RVW) at all ages, and the RVW was thicker in adults when compared to young subjects. The basal and middle RVW regions thicken with advancing age, and the thickness of the interventricular septum (ISW) occupies an intermediate position between the LVW and RVW. In general, an increase in rhea heart thickness and size relative to age is observed. The morphometric variations between young and adult rhea hearts observed in the present study may serve as a comparative subsidy for the diagnosis of cardiac abnormalities observed in this species.

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A ocorrência de prolapso peniano em repteis é observada tanto em quelônios terrestres, quanto em squamatas, porém há a escassez de relatos em tartarugas marinhas documentados até o momento. Desta forma, objetivou-se relatar o processo de reabilitação de uma tartaruga-verde (Chelonia mydas) com prolapso peniano, de modo a nortear procedimentos clínicos e terapêuticos que possam propiciar maior sucesso na reabilitação destes animais. Uma tartaruga-verde (C. mydas), adulto, macho, foi resgatada no dia 02 de maio de 2020 na praia de Muriú, Ceará Mirim, Rio Grande do Norte, Brasil. O espécime encontrava-se ativo, responsivo, com bom escore corpóreo, hidratação moderada, presença de prolapso peniano com mucosa associada hiperêmica e parte necrosada, além disso, encontrava-se com a nadadeira anterior esquerda amputada. O animal recebeu suporte terapêutico à base de analgésicos, antibióticos, anti-inflamatórios, polivitamínicos e fluidoterapia. Foram realizados procedimentos cirúrgicos para remoção total do úmero e redução mecânica do prolapso peniano. Após 50 dias de reabilitação o animal teve alta médica e foi reintroduzido de volta ao mar. Conclui-se que o protocolo utilizado, tanto na reabilitação, quanto no tratamento conservativo do prolapso peniano mostrou-se eficaz na redução do edema, evitando assim a recidiva do prolapso.

The occurrence of penile prolapse in reptiles has been observed both in terrestrial turtles and squamates. However, there are few reports of penile prolapse in sea turtles published to date. This study aimed at reporting the rehabilitation process of a green sea turtle (Chelonia mydas) with penile prolapse, in order to guide clinical and therapeutic measures that can provide greater success in the rehabilitation of these animals. An adult male green sea turtle (C. mydas) was rescued on May 2, 2020 at Muriú beach, Ceará Mirim, Rio Grande do Norte, Brazil. The specimen was active and responsive, with a good body score and moderate hydration, and showed the presence of penile prolapse with associated hyperemic mucosa and necrosis. It also had the left anterior fin amputated. The animal received therapeutic support based on antibiotics, analgesics, anti-inflammatories, multivitamins, and fluid therapy. The surgical procedure for the complete removal of the humerus and mechanical reduction of penile prolapse was performed. After 50 days of rehabilitation, the animal was discharged and was reintroduced back to the sea. It is concluded that the protocol used was effective in reducing edema, thus preventing the recurrence of prolapse, both in rehabilitation and in the conservative treatment of penile prolapse

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Letrozole is used as a therapeutic agent in reproductive disorders caused by high estrogen levels. Letrozole inhibits cytochrome P450 aromatase and reduces estrogen levels. However, the effects of longterm use on reproductive traits are unknown. The aim of this study was to evaluate the prolonged use of letrozole in the gonads of rodents (Spix's yellow-toothed cavy; Galea spixii). Forty-eight rodents (24 males and 24 females) were randomly divided into the treated and control groups. Letrozole administration started at 15 days of age and continued weekly until 30, 45, 90, and 120 days of age. The body, testis, and ovary weights were analyzed, as well as the morphological progression of spermatogenesis and folliculogenesis. Macroscopically, body weight gain and gonads weight were increased in the letrozole group. Microscopically, the ovaries of treated females showed stratified epithelium and a cellular disorder of the tunica albuginea. In the testes of treated males, the development of seminiferous tubules was delayed and sperm was absent. The collective findings indicate that the prolonged use of letrozole alters secondary sexual characteristics, and causes weight gain, reproductive changes, and male infertility.(AU)

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A ocorrência de prolapso peniano em repteis é observada tanto em quelônios terrestres, quanto em squamatas, porém há a escassez de relatos em tartarugas marinhas documentados até o momento. Desta forma, objetivou-se relatar o processo de reabilitação de uma tartaruga-verde (Chelonia mydas) com prolapso peniano, de modo a nortear procedimentos clínicos e terapêuticos que possam propiciar maior sucesso na reabilitação destes animais. Uma tartaruga-verde (C. mydas), adulto, macho, foi resgatada no dia 02 de maio de 2020 na praia de Muriú, Ceará Mirim, Rio Grande do Norte, Brasil. O espécime encontrava-se ativo, responsivo, com bom escore corpóreo, hidratação moderada, presença de prolapso peniano com mucosa associada hiperêmica e parte necrosada, além disso, encontrava-se com a nadadeira anterior esquerda amputada. O animal recebeu suporte terapêutico à base de analgésicos, antibióticos, anti-inflamatórios, polivitamínicos e fluidoterapia. Foram realizados procedimentos cirúrgicos para remoção total do úmero e redução mecânica do prolapso peniano. Após 50 dias de reabilitação o animal teve alta médica e foi reintroduzido de volta ao mar. Conclui-se que o protocolo utilizado, tanto na reabilitação, quanto no tratamento conservativo do prolapso peniano mostrou-se eficaz na redução do edema, evitando assim a recidiva do prolapso.(AU)

The occurrence of penile prolapse in reptiles has been observed both in terrestrial turtles and squamates. However, there are few reports of penile prolapse in sea turtles published to date. This study aimed at reporting the rehabilitation process of a green sea turtle (Chelonia mydas) with penile prolapse, in order to guide clinical and therapeutic measures that can provide greater success in the rehabilitation of these animals. An adult male green sea turtle (C. mydas) was rescued on May 2, 2020 at Muriú beach, Ceará Mirim, Rio Grande do Norte, Brazil. The specimen was active and responsive, with a good body score and moderate hydration, and showed the presence of penile prolapse with associated hyperemic mucosa and necrosis. It also had the left anterior fin amputated. The animal received therapeutic support based on antibiotics, analgesics, anti-inflammatories, multivitamins, and fluid therapy. The surgical procedure for the complete removal of the humerus and mechanical reduction of penile prolapse was performed. After 50 days of rehabilitation, the animal was discharged and was reintroduced back to the sea. It is concluded that the protocol used was effective in reducing edema, thus preventing the recurrence of prolapse, both in rehabilitation and in the conservative treatment of penile prolapse(AU)

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Abstract Letrozole is used as a therapeutic agent in reproductive disorders caused by high estrogen levels. Letrozole inhibits cytochrome P450 aromatase and reduces estrogen levels. However, the effects of long-term use on reproductive traits are unknown. The aim of this study was to evaluate the prolonged use of letrozole in the gonads of rodents (Spix's yellow-toothed cavy; Galea spixii). Forty-eight rodents (24 males and 24 females) were randomly divided into the treated and control groups. Letrozole administration started at 15 days of age and continued weekly until 30, 45, 90, and 120 days of age. The body, testis, and ovary weights were analyzed, as well as the morphological progression of spermatogenesis and folliculogenesis. Macroscopically, body weight gain and gonads weight were increased in the letrozole group. Microscopically, the ovaries of treated females showed stratified epithelium and a cellular disorder of the tunica albuginea. In the testes of treated males, the development of seminiferous tubules was delayed and sperm was absent. The collective findings indicate that the prolonged use of letrozole alters secondary sexual characteristics, and causes weight gain, reproductive changes, and male infertility.

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BACKGROUND: Biobanking of cell lines is a promising tool of support for wildlife conservation. In particular, the ability to preserve fibroblast cell lines derived from collared peccaries is of significance as these wild mammals are unique to the Americas and play a large role in maintaining the ecosystem. We identified collared peccary fibroblasts by immunofluorescence and evaluated their morphology, growth and adherence capacity. Further, we monitored the viability and metabolic activity of the fibroblasts to determine the effects of passage number and cryopreservation on establishment of cell lines. METHODS: Skin biopsies were collected from the peripheral ear region from five adult animals in captivity. Initially, cells were isolated from fragments and cultured in the Dulbecco's modified Eagle medium supplemented with 10% fetal bovine serum and 2% antibiotic-antimycotic solution under a controlled atmosphere (38.5 °C, 5% CO2). We evaluated the maintenance of primary cells for morphology, adherence capacity of explants, explants in subconfluence, cell growth and absence of contamination. Moreover, we identified the fibroblast cells by immunofluorescence. Additionally, to evaluate the influence of the number of passages (first, third and tenth passage) and cryopreservation on establishment of cell lines, fibroblasts were analysed for the viability, metabolic activity, population doubling time (PDT), levels of reactive oxygen species (ROS), and mitochondrial membrane potential (ΔΨm). RESULTS: All explants (20/20) adhered to the dish in 2.4 days ± 0.5 with growth around the explants in 4.6 days ± 0.7, and subconfluence was observed within 7.8 days ± 1.0. Moreover, by morphology and immunocytochemistry analyses, cells were identified as fibroblasts which presented oval nuclei, a fusiform shape and positive vimentin staining. No contamination was observed after culture without antibiotics and antifungals for 30 days. While there was no difference observed for cell viability after the passages (first vs. third: P = 0.98; first vs. tenth: P = 0.76; third vs. tenth: P = 0.85), metabolic activity was found to be reduced in the tenth passage (23.2 ± 12.1%) when compared to that in the first and third passage (100.0 ± 24.4%, P = 0.006). Moreover, the cryopreservation did not influence the viability (P = 0.11), metabolic activity (P = 0.77), or PDT (P = 0.11). Nevertheless, a greater ΔΨm (P = 0.0001) was observed for the cryopreserved cells (2.12 ± 0.14) when compared to that in the non-cryopreserved cells (1.00 ± 0.05). Additionally, the cryopreserved cells showed greater levels of intracellular ROS after thawing (1.69 ± 0.38 vs. 1.00 ± 0.22, P = 0.04). CONCLUSIONS: This study is the first report on isolation, characterization and cryopreservation of fibroblasts from collared peccaries. We showed that adherent cultures were efficient for obtaining fibroblasts, which can be used as donor cells for nuclei for species cloning and other applications.