In recent years, habitat degradation led to the decline of some populations of brown‐throated sloth. The aim of this study was to describe morphological features of the female reproductive system of the species. The oval ovaries were partially surrounded by ovarian bursa. An external cortex and an inner medulla were present. Corpora lutea and corpora albicans together with follicles at various stages of development each with a single oocyte were found in the cortex. Uterine tubes were tortuous, tubular, travelled around the perimeter of the ovary and possessed a folded mucosa with ciliated pseudostratified epithelium. Uterus was simplex, with no horns and divided into three parts: a pear‐shaped cranial segment and a long caudal uterine segment (both forming the body of the uterus) and two cervices. Uterus presented three layers: mucosa, lined by pseudostratified epithelium, muscular and serosa. The cervices connected the uterus to the urogenital sinus, a distensible cavity with longitudinal mucosal folds lined by transitional epithelium that extended from the external urethral orifice and the external uterine ostia to the vulva, which was lined by a keratinized stratified squamous epithelium. Brown‐throated sloth presented a bipartite clitoris with paired crura, bodies and glandes. The presence of a double cervix and a bipartite clitoris was unique features of the species.
Placental characters vary among Xenarthra, one of four supraordinal clades of Eutheria. Armadillos are known for villous, haemochorial placentas similar to humans. Only the nine-banded armadillo has been well studied so far. Placentas of three species of armadillos were investigated by means of histology, immunohistochemistry including proliferation marker, and transmission and scanning electron microscopy. The gross anatomy differed: Euphractus sexcinctus and Chaetophractus villosus had extended, zonary placentas, whereas Chaetophractus vellerosus had a disk. All taxa had complex villous areas within the maternal blood sinuses of the endometrium. Immunohistochemistry indicated the validity of former interpretations that the endothelium of the sinuses was largely intact. Tips of the villi and the columns entering the maternal tissue possessed trophoblast cell clusters with proliferation activity. Elsewhere, the feto-maternal barrier was syncytial haemochorial with fetal vessels near the surface. Differences among armadillos occurred in regard to the extension of the placenta, whereas the fine structure was similar. Parallels to the human suggest that armadillos are likely to be useful animal models for human placentation.
Morphometric parameters of the digestive tract are required for an understanding of the digestive processes of the food in the animal organism, besides indicating the feeding preference of specie. This study aimed to describe morphologically the small and large intestines, organs of the digestive system of representatives of Xenarthra order to provide data for the evaluation of diet and conduct clinical procedures in these animals, whether free-living or captive. At this research, were used in total 7 specimens from three-toed sloths (Bradypus torquatus), nine-banded armadillo (Dasypus novemcinctus) and giant anteater (Myrmecophaga tridactyla). The intestines of B. torquatus were short and simple, but at the specimens of D. novemcintus and M. tridactyla the intestines were long and had some peculiarities. We notice the presence of Brunner's glands and structures to increase the surface absorption at the duodenum of all specimens. Only in B. torquatus, we notice that the mesentery remains the jejune attached to the dorsal wall of the abdominal cavity. The ileum represented the lower portion of the intestines in all studied specimens except in M. tridactyla. The cecum in D. novemcinctus and M. tridactyla showed considerable size, glands at the mucosa and was full of food debris, indicating that it was functional. In the mucosa of the colon of all specimens had crypts of Lieberkuhn, being more numerous in D. novemcinctus and M. tridactyla. Only in B. torquatus, the rectum showed greater diameter and stiffness compared to the colon. In all species studied, we notice a large glandular surface and lots of goblet cells that produce mucus to facilitate defecation. Our results demonstrate that the conformation and structure of the digestive system reflects more the kind of diet and digestive needs of the animal, than to the family he belongs.
Background: Since Xenarthra are serious candidates for being basal to Eutheria, their characteristics, e.g. the placental system, influence perceptions of evolution. However, in the subgroup containing the anteaters, data are very limited. The present study aims to elucidate the nature of the feto-maternal interface in the anteater placenta and to interpret these data within an evolutionary context. Methods: Placentas of two species were investigated with histology, immunohistochemistry and transmission electron microscopy. Results: Remnants of the maternal vessel endothelium were absent, resulting in a fully haemochorial barrier throughout the placenta. Two structurally different parts, the villous and trabecular areas were complex and intermingled. In particular, the trabeculae which consisted of cellular, proliferative trophoblast, associated with connective tissue, were attached to the decidua. The villi contained fetal capillaries and hypertrophied mesenchymal cells that occured near the surface near the end of gestation. The surface of the villi consisted of flat, syncytial trophoblast, interspersed with proliferative trophoblast cells. Conclusions: Based on fundamental differences between anteaters and armadillos, we inferred that placental evolution was more complex than previously thought. The haemochorial pattern of anteaters was likely an ancient condition of xenarthrans. Consequently, villous placentation may be attributed, at least in part, by convergent evolution, but was also characterized by some features that were widespread among xenarthrans.
BackgroundThe southern tamandua, Tamandua tetradactyla (Linnaeus, 1758), is the most common species of anteater. Even though much is known about its ecology, behavior, and parasites, there is very limited information about bone diseases in Tamandua and other anteaters. Here, we examined postcranial skeletons of 64T. tetradactyla museum specimens covering most of the material available in Brazilian collections.ResultsThe following bone diseases were identified for the first time in Tamandua and other extant and fossil vermilinguans: osteophytes, osteitis, osteoarthritis, periostitis, exostoses, enthesopathies, and a severe chronic pyogenic osteomyelitis associated with fistulae, cloacae (pus), bone loss, and neoformation processes. Musculoskeletal reconstruction revealed that an old specimen was restricted to terrestrial locomotion due to osteopathological processes that impaired its climbing.ConclusionsNew osteopathological informations are presented for T. tetradactyla, favoring a better understanding of the expression of some bone diseases in wild animals. In addition, the diagnosis of these bone diseases in living anteaters provides useful information for studies on animal health and welfare, as well as contributing to the more effective recognition of paleodiseases in fossil xenarthrans.
This is the first reported case of lethal gastric parasitism by the nematode Paraleiuris locchii in a captive sloth (Bradypus variegatus). There were more than 600 parasites in the stomach of the sloth, associated with extensive areas of ulceration and necrosis. The animal developed emaciation, dehydration, and anemia that progressed to death.
Poaching poses a threat to a wide variety of wildlife, and basic information about the biology of hunted species needs to be collected before their populations decline to the extent that requires drastic human intervention. As the survival of a species is related to its ability to reproduce, data on its reproductive cycle are necessary for the development of management strategies. The hypothesis was tested that the reproductive season of pichis ( ), small hibernating armadillos that inhabit arid environments in Argentina and Chile, is limited to spring months. Gonadal competence of semi-captive and wild-caught male pichis of Mendoza Province, Argentina was studied, by measuring fecal immunoreactive testosterone concentrations and evaluating spermatogenic activity. Results suggest that is a seasonal breeder that regulates reproduction through photoperiodic cues. Gonadal competence was limited to a period of 3–5 months in spring and early summer and was reflected in enlarged testes, increased spermatogenesis, and significantly elevated fecal immunoreactive testosterone concentrations. The reproductive season for males from southern Mendoza was almost 6 weeks shorter than in the north. This fact, along with significant morphological differences between both groups, suggests that northern and southern pichis belong to two distinct populations. It is concluded that prolonged breeding seasons and more favorable environmental conditions in northern Mendoza favor a prolongation of the reproductive season that may allow pichis to breed later in the year, thus maximizing reproductive opportunities.
Reproductive strategies vary considerably among species, but most studies have focused on a very limited number of mammalian species. Knowledge of the reproductive cycle and behavior is essential for developing and implementing and conservation strategies for threatened and endangered species. This study aimed at characterizing the seasonal reproductive pattern of female pichis , a threatened small armadillo native to arid regions of Argentina and Chile, through direct observations, histological studies, and by measuring fecal immunoreactive estrogens, progestagens and glucocorticoids in 10 wild-born, captive pichis and in free-ranging individuals. Results suggest that pichis are seasonal breeders that give birth to one yearly litter of 1–2 offspring, which do not leave the burrow until they are weaned at approximately 37 days. Ovarian follicular growth seems to occur throughout the year. Fecal progestagen, estrogen and glucocorticoid concentrations were minimal during the first half of pregnancy, increased to peak concentrations of up to 3500, 200 and 200 ng/g dry feces, respectively, and decreased before parturition. Postpartum progestagen concentrations were greater in lactating females than females that aborted or did not raise their offspring ( < 0.0001), which is probably related to an elevated corticosteroid synthesis that contributes to maintain lactation, given that fecal glucocorticoid concentrations were of similar pattern. Observations of a second pregnancy after late abortion or death of the newborn litter and sustained follicular growth during pregnancy and lactation suggest that female pichis can become receptive briefly after having lost their litter. Fecal estrogen and progestagen concentrations of non-pregnant, non-lactating females did not have a well-defined hormonal cyclic pattern, and corpora lutea were only observed in pregnant females.