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Establishing new somatic cell cultures has raised significant attention as an effective and convenient way to preserve genetic samples for different applications. Although many lines have been established in model animals, none derived from six-banded armadillo species is currently available. We report the successful isolation and characterization of fibroblasts from six-banded armadillos, evaluating the cell quality after extended culture and cryopreservation. Initially, we collected ear skin from five captive adult individuals and identified fibroblast lines by morphology, karyotyping, and immunophenotyping assays. The isolated fibroblasts were evaluated after several passages (fourth, seventh, and tenth passages) and cryopreservation by slow freezing. Cell morphology, viability, metabolism, proliferative activity, mitochondrial membrane potential, and apoptosis levels were analyzed. The skin explants had great adhesion, and cell outgrowth could be seen after 3-6 d. The cells were verified as fibroblasts at the fourth passage by vimentin expression and normal karyotype (2n = 58). The viability remained high (> 87%) and constant from the fourth to the tenth passage (p > 0.05). The passages did not change the cell morphology and metabolic and growth rates. Moreover, cryopreservation did not affect most evaluated parameters; post-thawed cells maintained their viability, growth, metabolism, and apoptosis levels. Nevertheless, cryopreservation increased mitochondrial membrane permeability and cell population doubling time compared to non-cryopreserved cells (p < 0.05). In summary, viable fibroblasts can be obtained from six-banded armadillo skin while conserving their quality as the number of passages increases and featuring few changes after cryopreservation., (© 2024. The Society for In Vitro Biology.)

The study aimed to evaluate metabolic parameters, nutrient intake, and absorption of two diets formulated for Dasypus novemcinctus armadillos under human care. Were studied two diets: D1-a diet with dry dog food, ground beef, and boiled chicken egg with shells; D2-a diet with the same ingredients as D1, with added banana and papaya. Both are mixed in water. The parameters analyzed were body weight (BW), weight gain (WG), maintenance energy requirement (MER), Lee index, biometrics, body condition score, glucose, triglycerides, total cholesterol, and cholesterol fractions for eight male armadillos. Dietary intake (DI) and efficiency, nutrient intake, metabolizable energy, and digestibility coefficient for the diets were evaluated in six male armadillos. The diet that included fruits showed higher BW, WG, MER, Lee index, and better glucose metabolism. Both diets promoted increases in WG and Lee Index, as well as improvements in glucose metabolism. The diet without fruit improved the lipid profile of the animals. D2 presented the highest DI, better dietary efficiency, and higher energy intake but also a lower crude fiber intake. However, it showed the best utilization of gross fiber and all other nutrients. In conclusion, the diets constituted an adequate nutritional option for captive armadillos and can be used in malnutrition and pathological processes recovery. Although both diets were adequate, the nonfruit diet was preferable due to the improved lipid profile., (© 2023 Wiley Periodicals LLC.)

Armadillos are bitten by several species of flea. Females of the genus Tunga penetrate the epidermis and when in place are fertilised by males, after which the abdomen swells enormously to form a 'neosome'. Within the penetrans group, T. perforans, makes lesions that perforate the osteoderms within the integument to form ~3 mm diameter cavities occupied by a discoid neosome. We examined these lesions in carapace material from animals which had died in the wild to see whether we could recruit evidence as to how they may be generated, either by the insect or by the host. We studied one species without such lesions, the nine-banded armadillo Dasypus novemcinctus, and two species with, the greater hairy armadillo Chaetophractus villosus and the southern three-banded armadillo Tolypeutes matacus, both showing the characteristic 'flea bite' holes in the external surfaces of the osteoderms. Samples were studied by three-dimensional backscattered electron mode scanning electron microscopy and X-ray microtomography. Both methods showed resorption pit complexes in the external surfaces of the osteoderms characteristic of those made by osteoclasts in active bone resorption. Lesions involved both the syndesmoses (sutures) between adjacent bones and the central regions of the osteoderms. Many lesions showed extensive repair by infilling with new bone. We conclude that the T. perforans neosome creates a local host response which causes bone resorption, creating the space in which it can grow., (© 2023 The Authors. Journal of Anatomy published by John Wiley & Sons Ltd on behalf of Anatomical Society.)

Oogenesis in the armadillo Chaetophractus villosus, a representative species of a mammalian basal clade, was investigated by light microscopy, transmission electron microscopy, and immunohistochemical localization of keratin. At the beginning of the growth phase, oocyte follicles showed one, and sometimes several, large bodies composed of lamellae (multilamellar bodies [MLBs]), which entrap other cytoplasmic organelles at more advanced stages. Lamellae diameter is described in cross-section (37 nm) and tangential sections (50 nm). The MLB of early oocytes is most frequently located close to the nucleus. In large oocytes, both, this body and the free organelles are relocated at the oocyte periphery. The MLB grows from the primary follicle up to its full development at the follicular phase characterized by tall granulosa cells. Mitochondria, smooth small vesicles, and lipofuscin granules are trapped between lamellae. MLBs engage in the formation of different sets of organelles, both trapped and free ones. When oocytes are well developed and the zona pellucida is formed, the MLB is reduced to small remnants detected only by transmission electron microscopy. The MLB disintegrates when an antrum develops. Immunohistochemical localization techniques showed the presence of cytokeratin in the MLBs. This cytokeratin pool may be involved in the filament and desmosome formation found in the periphery of late oocytes., (© 2021 Wiley Periodicals LLC.)

In Argentina, quantitative information on the composition and structure of assemblages of arthropod parasites in Xenarthra is scarce. The aim of this study was to describe and compare the community of arthropod parasites of Chaetophractus villosus and Zaedyus pichiy in the Argentinean Patagonia. A total of 1300 ectoparasites (1224 fleas and 76 ticks) were collected from both host species. Seven different species were found, namely Phthiropsylla agenoris, Malacopsylla grossiventris, Hectopsylla broscus, Tunga penetrans, Tunga perforans (Siphonaptera), Amblyomma pseudoconcolor and Amblyomma auricularium s.l. (Ixodida). Four species were present in both host armadillos (P. agenoris, M. grossiventris, H. broscus and A. pseudoconcolor). Phthiropsylla agenoris was the most prevalent and abundant ectoparasite showing significant differences in prevalences, mean intensities and mean abundance. Malacopsylla grossiventris only showed significant differences in mean intensity. The structure and composition of the ectoparasite assemblage and the high values of ectoparasites aggregation recorded in the Patagonian armadillos strongly suggest that these associations are stable throughout their geographical distribution., (Copyright © 2021. Published by Elsevier B.V.)

The nine-banded armadillo (Dasypus novemcinctus) is a mammal of the Xenarthra Superorder, which inhabits Central, South and North America. Few morphological descriptions are observed in this species, including the respiratory tract; therefore, the objective of this study was to describe morphologically the lower respiratory tract of the nine-banded armadillo. Five animals were dissected, and the macroscopic and microscopic aspects were analysed. In the anatomical analysis, the perfusion technique was performed with vinyl acetate and the fragments of tissue from respiratory organs (trachea, bronchi, bronchioles and pulmonary lobes) were stained with haematoxylin-eosin for visualization under optical microscopy. Containing about 30 cartilage rings, the trachea is lined internally with ciliated pseudostratified epithelial tissue. The lungs are subdivided into lobes by deep interlobar fissures, with two lobes in the right lung and three lobes in the left lung. Microscopically, the primary, secondary and tertiary bronchi have non-ciliated pseudostratified epithelium with goblet cells. It was found that macro- and microscopically the respiratory tract of this species is similar to existing xenarthras and other excavator animals. These data provide subsidies for the clinic and preservation of this species., (© 2020 Wiley-VCH GmbH.)

Out of the 20 recognized species of armadillos in the world, 11 are found in Brazil, and five of them are found in Pantanal, one of the world's largest wetlands. Beef cattle ( Bos taurus ) farming is the main economic activity in this region, which promotes intense wildlife-livestock contact and increases the likelihood of pathogen exposure, including to agents with zoonotic and economic relevance. Previous studies demonstrated that several wildlife species in Pantanal have been exposed to Brucella abortus and Leptospira spp.; however, little is known regarding the exposure and/or prevalence of zoonotic pathogens in armadillos. We used conventional PCR, the rose Bengal test (RBT), and the microscopic agglutination test (MAT) to investigate the exposure to and infection by Brucella spp. and Leptospira spp. using blood samples from four species of armadillos: nine-banded armadillo ( Dasypus novemcinctus , n =2), southern naked-tailed armadillo ( Cabassous unicinctus , n =8), yellow armadillo ( Euphractus sexcinctus , n =16), and giant armadillo ( Priodontes maximus , n =22), captured in Nhecolândia, Pantanal, Brazil. Samples were PCR- and RBT-negative for Brucella spp. infection and exposure. However, MAT revealed a Leptospira spp. seroprevalence of 31% (5/16; 95% confidence interval [CI]=0.11-0.58) in yellow armadillo and 18% (4/22; 95% CI=0.05-0.40) in giant armadillo specimens to serogroups Autumnalis, Cynopteri, and Pomona, with titers ranging from 200 to 1,600. Our results contribute to the understanding of zoonotic pathogens in armadillos in Pantanal and reinforce the importance of wildlife health surveillance in this area.

A total of 20 specimens of Tolypeutes matacus (Desmarest, 1804) from the Chaco Region in Argentina were examined. This study revealed the presence of 3 species of the genus Mathevotaenia Akumyan, 1946 (Cestoda Anoplocephalidae), two of them new for science. These species are described, illustrated, and compared with related species. Mathevotaenia chamicalensis n. sp. is characterized by having a small body with 45-65 proglottids; a globose scolex, longer than wide and well delimited from strobila; a long neck; mature and gravid proglottids longer than wide; and 20-35 testes located in a single field. Mathevotaenia yepesi n. sp. is characterized by having a small body with 86-128 proglottids; a rectangular scolex, wider than long and not well delimited from strobila; neck absent; mature and gravid proglottids wider than long; and 23-50 testes located in the medial portion of the proglottid. The finding of Mathevotaenia argentinensis Campbell et al., 2003 parasitizing T. matacus represents the first record in armadillos.

Formation and subsequent break down of ovarian germ cell (GC) cysts is a key and an evolutionary-conserved developmental event, described in phylogenetically diverse species of invertebrates and vertebrates. In mammals, cyst break down (CBD) ends at the time of, or soon after, birth with the formation of primordial follicles enclosing single oocytes, which constitute the sole reservoir of gametes available through the whole female's reproductive life. In this study, we challenge this paradigm demonstrating the constitutive presence of a large number of cysts, enclosing two-thirty GCs, in the ovary of the adult armadillo Chaetophractus villosus, belonging to the superorder Xenarthra, one of the earliest offshoots among placentals. We also describe that (a) GCs enclosed within cysts are connected by intercellular bridges-intercellular bridges-markers of their clonal origin; (b) CBD occurs through four main phases, ending with primordial follicles containing single oocytes; (c) GCs encompass meiotic prophase I stages, from leptotene to diplotene; (d) seasonal variations in the number of GCs enclosed within cysts, suggesting the presence of a GC multiplying activity. The armadillo C. villosus''s ovary emerges as an extraordinary resource to investigate folliculogenesis and to explore the evolutionary past of the mammalian ovary., (© 2019 Wiley-Liss, Inc., A Wiley Company.)

Background: Miguel Fernández was an Argentinian zoologist who published the first account of obligate polyembryony in armadillos. His contribution is here discussed in relation to his contemporaries, Newman and Patterson, and more recent work., Findings: Fernandez worked on the mulita (Dasypus hybridus). He was able to get early stages before twinning occurred and show it was preceded by inversion of the germ layers. By the primitive streak stage there were separate embryonic shields and partition of the amnion. There was, however, a single exocoelom and all embryos were enclosed in a common set of membranes comprising chorion towards the attachment site in the uterine fundus and inverted yolk sac on the opposite face. He showed that monozygotic twinning did not occur in another armadillo, the peludo (Chaetophractus villosus)., Conclusions: Fernández's work represented a major breakthrough in understanding how twinning occurred in armadillos. His work and that of others is of intrinsic interest to zoologists and has a direct bearing on the origin of monozygotic twins and birth defects in humans., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

Free-ranging yellow armadillos (Euphractus sexcinctus) from the Brazilian Pantanal were captured for surgical implantation of intra-abdominal radio transmitters. During March 2014, 11 animals were chemically immobilized with a combination of intramuscular ketamine hydrochloride, xylazine hydrochloride, midazolam maleate, and atropine sulfate. The mean induction time and initial heart rate in males was higher than in females. The sex of armadillos did not affect the respiratory rate, which increased from the beginning to end of the monitoring time. The rectal temperatures of females remained almost unchanged, whereas the rectal temperatures of males suffered a slight drop through the procedure. The mean (±SD) total surgical time was 50±6.5 min, and the total anesthetic recovery time was 2.5±0.5 h. The armadillos were monitored for 24 h after surgery and released at their capture site. The anesthetic association was effective, promoting muscle relaxation and analgesia that allowed the performance of surgical procedures.

Armadillos, Xenarthras representatives, known for adaptability to different ecosystems, own specific morphophysiological characteristics that are not known and deserve to be studied. The aim of this study was to describe the morphology of cartilage of the larynx of the nine-banded armadillo (Dasypus novemcinctus). Five dead armadillos were donated by the Chico Mendes Institute of Biodiversity (ICMBio-PI) to the Federal University of Piauí. The animals were fixed and dissected for removal of the larynx. The cartilages were identified and described, photodocumented, and schematized. Fragments with about 0.5 cm of each cartilage were collected and submitted to classical histology for Hematoxylin-Eosin coloring. The slides were assembled in enterlan and analyzed under a light microscope. The larynx of the armadillo (D. novemcinctus) is located in the mentonian region, ventral to the esophagus, and due to the total positioning of the tongue in the oral cavity, there is also a cranial cervical position in this species. The larynx has five cartilages, they are: a cricoid, a thyroid, an epiglottis, and two arytenoids. The corniculate process is present; however, the cuneiform process is absent. The epiglottis has a discrete bifurcation at its apex. In all cartilages epithelial variations are observed. The tissues are varied from squamoso stratified to cylindrical pseudostratified, with propria lamina rich in mucoserosas glands. With the exception of epiglottic cartilage, predominantly elastic, the rest are hyaline. The larynx of D. novemcinctus, although the same number of cartilages, differs morphologically and microscopically from the larynx of other species., (© 2017 Wiley Periodicals, Inc.)

We describe perforations recognized in mobile osteoderms of the extinct armadillos (Cingulata, Dasypodidae) Chasicotatus ameghinoi (Euphractinae, Eutatini) and Vetelia perforata (Euphractinae, Euphractini), recovered from the late Miocene of Argentine Pampas. We interpret that fleas corresponding to the genus Tunga (Siphonaptera) produced these marks. These parasites locate in the carapace of the host, perforating the osteoderms by mechanical and chemical processes as the neosome grows. This finding constitutes the oldest record of flea/armadillos interaction. It also reflects the antiquity of this important specialization and reinforces the proposal indicating an early co-evolution between these parasites and their hosts. These traces, produced in the bone tissue when the host was still alive, provide new information on the trophic relationships in past ecosystems., (Copyright © 2016 Elsevier Inc. All rights reserved.)

The vertebral column has evolved to accommodate the broad range of locomotor pressures found across vertebrate lineages. Xenarthran (armadillos, sloths and anteaters) vertebral columns are characterized by xenarthrous articulations, novel intervertebral articulations located in the posterior trunk that are hypothesized to stiffen the vertebral column to facilitate digging. To determine the degree to which xenarthrous articulations impact vertebral movement, we passively measured compliance and range of motion during ventroflexion, dorsiflexion and lateral bending across the thoracolumbar region of the nine-banded armadillo, Dasypus novemcinctus Patterns of bending were compared with changes in vertebral morphology along the column to determine which morphological features best predict intervertebral joint mechanics. We found that compliance was lower in post-diaphragmatic, xenarthrous vertebrae relative to pre-xenarthrous vertebrae in both sagittal and lateral planes of bending. However, we also found that range of motion was higher in this region. These changes in mechanics are correlated with the transition from pre-xenarthrous to xenarthrous vertebrae, as well as with the transition from thoracic to lumbar vertebrae. Our results thus substantiate the hypothesis that xenarthrous articulations stiffen the vertebral column. Additionally, our data suggest that xenarthrous articulations, and their associated enlarged metapophyses, also act to increase the range of motion of the post-diaphragmatic region. We propose that xenarthrous articulations perform the dual role of stiffening the vertebral column and increasing mobility, resulting in passively stable vertebrae that are capable of substantial bending under appropriate loads., (© 2016. Published by The Company of Biologists Ltd.)

Rod monochromacy is a rare condition in vertebrates characterized by the absence of cone photoreceptor cells. The resulting phenotype is colourblindness and low acuity vision in dim-light and blindness in bright-light conditions. Early reports of xenarthrans (armadillos, sloths and anteaters) suggest that they are rod monochromats, but this has not been tested with genomic data. We searched the genomes of Dasypus novemcinctus (nine-banded armadillo), Choloepus hoffmanni (Hoffmann's two-toed sloth) and Mylodon darwinii (extinct ground sloth) for retinal photoreceptor genes and examined them for inactivating mutations. We performed PCR and Sanger sequencing on cone phototransduction genes of 10 additional xenarthrans to test for shared inactivating mutations and estimated the timing of inactivation for photoreceptor pseudogenes. We concluded that a stem xenarthran became an long-wavelength sensitive-cone monochromat following a missense mutation at a critical residue in SWS1, and a stem cingulate (armadillos, glyptodonts and pampatheres) and stem pilosan (sloths and anteaters) independently acquired rod monochromacy early in their evolutionary history following the inactivation of LWS and PDE6C, respectively. We hypothesize that rod monochromacy in armadillos and pilosans evolved as an adaptation to a subterranean habitat in the early history of Xenarthra. The presence of rod monochromacy has major implications for understanding xenarthran behavioural ecology and evolution., (© 2014 The Author(s) Published by the Royal Society. All rights reserved.)

Leptospirosis is a zoonosis of worldwide distribution. The aim of this study was to examine the presence of antibodies against 21 Leptospira reactive serovars in Chaetophractus villosus in La Pampa province, Argentina, using the microscopic agglutination test (MAT). Pathologic changes compatible with leptospirosis and in situ detection of the agent by immunohistochemistry were studied in 24 and 3 individuals respectively. Only 35/150 (23.3%) serum samples had antibodies against Leptospira sp. Six percent of the samples reacted with serovar Canicola, 4.7% with serovar Castellonis, 1.3% with serovar Icterohemorrhagieae and 0.7% with serovar Hardjo. Sixteen (10.6%) serum samples agglutinated with Castellonis-Icterohemorrhagiae and Canicola-Castellonis serovars, both with 4.7%, and Canicola-Hardjo and Castellonis-Canicola-Icterohemorrhagiae both with 0.6%. Fourteen animals had variable degrees of lesions, which were more severe in animals with higher serological titers (3200), and Leptospira sp. was detected in 3 animals by immunohistochemistry. These results represent the first record of the presence of Leptospira in C. villosus in La Pampa., (Copyright © 2015 Asociación Argentina de Microbiología. Publicado por Elsevier España, S.L.U. All rights reserved.)

Brucellosis is a zoonotic disease transmitted from an animal reservoir to humans. Both, wildlife and domestic animals, contribute to the spreading of these zoonosis. The surveillance of the animal health status is strictly regulated for domestic animals, whereas disease monitoring in wildlife does not exist. The aim of the present study was to provide data on the prevalence of anti-Brucella antibodies in Chaetophractus villosus from a region of La Pampa, Argentina to assess public health risks. The C. villosus is endemic to South America, and in Argentina it represents a food resource for human consumption. A total of 150 sera of armadillos bleeding between 2007 and 2010 were tested using buffered plate antigen test (BPAT), serum agglutination test (SAT), 2-mercaptoethanol (2-ME) and complement fixation test (CFT), for the detection of anti-Brucella antibodies. Antibodies to Brucella sp. were found in 16% (24:150) of the armadillos tested using the BPAT test. All 24 positive samples were confirmed by the SAT, 2-ME and CFT tests. Strain isolation was attempted from liver and spleen samples of two animals with positive serology. Isolates were characterized by conventional biotyping and identification of specific DNA using polymerase chain reaction (PCR). A total of 2 isolates were recovered from spleen and liver. Both of them were identified as Brucella suis biovar 1. This preliminary study provides the first report on the seroprevalence of brucellosis and describes the first isolate of B. suis biovar 1 in C. villosus in Argentina., (Copyright © 2014 Elsevier B.V. All rights reserved.)

One hundred and twenty-seven eyes from 66 Mycobacterium leprae inoculated armadillos were studied histologically and some ultrastructurally. Inflammatory reactions were found in the following extraocular tissues: the eyelid, including the orbicularis muscle and the third eyelid, extraocular muscles, tear gland and Harder's gland. The early and slight changes of the intraocular tissues, small amounts of lymphocytes, plasma cells and macrophage infiltrations were confined to the area around the anterior angle specifically within the trabeculae and the adjacent ciliary body, the root of the iris and the limbus region of the cornea. But in the cases with severe lesions the whole uvea was densely infiltrated with large, foamy macrophages intermingled with small amounts of lymphocytes, plasma cells and frequently, neutrophils. No specific necrosis of the granulomas was seen. No explanation for the neutrophil infiltrations was given. The lesions in the cornea were significantly less severe than those in the uvea. Retinal lesions comprised of macrophage infiltrations were all obvious extensions of the adjacent uvea lesions. Acid-fast bacilla (AFB) were found within all tissues. The infection of the intraocular tissues in the armadillo eyes seemed to be mainly, if not solely, haematogenous.

Ears from 853 nine-banded armadillos (Dasypus novemcinctus) from Alabama, Arkansas, Florida, Georgia and Mississippi were examined microscopically for evidence of leprosy. All were negative for both acid-fast bacteria (Mycobacterium leprae) and lesions compatible with leprosy.

Out of six armadillos infected intravenously with 4.66 x 10(8) M. leprae, one developed a delayed hypersensitivity tissue response with the formation of an epithelioid cell granuloma. It is suggested that, although 80% of armadillos are susceptible to infection with M. leprae, some among these susceptible ones will exhibit varying degrees of delayed hypersensitivity reactions. These animals may go through a borderline phase before ultimately undergoing lepromatous degeneration.

At varying periods of time following the successful establishment of systemic infections with Mycobacterium leprae or M. lepraemurium in the mouse and the nine-banded armadillo eyes were examined by light microscopy. Inoculation of bacilli was by the intravenous or intraperitoneal route or directly into the hind footpads; eyes were not directly inoculated in this study. During periods of up to 3 years under laboratory conditions no animal showed evidence of impaired vision or blindness, and the external appearance of both eyes was normal. The ocular histopathology and the sites of accumulation of bacilli are described. In immunologically normal mice infected with M. lepraemurium bacilli were much commoner in extraorbital tissues, but they were, nevertheless, found in various tissues within the orbit, including the ciliary body and sclera. In immunologically normal mice (and one rat) injected with M. leprae of human origin no bacilli were found in the eye, but in mice immunologically depressed by thymectomy and total body irradiation considerable numbers of bacilli were present in the iris and ciliary body and also in the limbal cornea. In the armadillo bacilli were found in large numbers in virtually all tissues except the lens, retina, optic nerve, and aqueous and vitreous humours, but the uveal tract was heavily involved. Findings are discussed in relation to the great frequency of ocular involvement and the importance of immune-complex disease in patients with lepromatous leprosy, and to factors wihch may favour the localisation and multiplication of Mycobacterium leprae in the eye.

Renal lesions were present in 34 (68%) of 50 armadillos (Dasypus novemcinctus) collected for a survey of the prevalence of leptospires in Louisiana wildlife. The renal lesions were not associated with elevations in the renal function tests of blood urea nitrogen or serum creatinine or with consistent serologic or cultural evidence of leptospires.

Samples from 77 nine-banded armadillos (Dasypus novemcinctus) inhabiting a 16.7 km portion of the East Atchafalaya River Levee, Point Coupee Parish, Louisiana, were serologically tested and/or histopathologically examined for evidence of naturally acquired leprosy. Five of 67 (7.5%) armadillos tested sero-positive with ELISA test for IGM class antibodies to the phenolic-glycolipid-1 antigen of Mycobacterium leprae. One of 74 (1.3%) was histopathologically positive as determined by presence of acid-fast bacteria in nerves.

Impact resistant polyethylene cages were evaluated in these laboratories as replacements for plywood boxes for housing nine-banded armadillos. They were found to be less expensive, easier to sanitize, and to require less than one-third as much floor space per animal as the boxes. This innovation has made it practical to house large numbers of armadillos economically and conveniently in almost any animal facility.

The cycle of the seminiferous epithelium of the nine-banded armadillo can be divided into ten stages. As in most mammals, only one stage is observed per tubular cross-section. The process of spermiogenesis can be divided into thirteen steps according to the development of the acrosomal system and the flagellum. Four generations of spermatogonia are abserved in the germinal epithelium: 1) stem cells, 2)type "A", 3) intermediate, and 4) type "B" spermatogonia. The stem cell is characterized by a highly irregular nucleus and the presence of glycogen in its cytoplasm. The type "A" spermatogonium contains an oblong nucleus with one or two shallow infoldings of the nuclear membrane. The intermediate spermatogonium contins an ovoid nucleus characterized by one or two nuclei and heterochromatin scattered in the nuceoplasm. The nucleus of the type "B" spermatogonium is more spherically shaped with a centrally placed nucleolus and heterochromatin associated with the nuclear envelope.

This experiment compares spatial learning in the South American opossum (Didelphis albiventris) and armadillo (Chaetophractus villosus) in a Y-maze. Ss learned to turn to one arm of the maze for food reinforcement. To earn further reinforcements, they had to return to the start-box (after consuming the food) where they were restrained for a fixed intertrial interval. The number of entries to the unbaited arm en route to the goal-box (Ri errors), and in the way back to the start-box (Rf errors) were the dependent measures. Opossums and armadillos did not differ in Ri errors. However, only armadillos mastered the task of returning directly to the start-box after each reinforcement. Moreover, a significant within-session improvement in Rf errors was observed in armadillos, but failed to appear in opossums. Results are discussed in terms of species differences in sensitivity to temporal delays.

The internal organs of nine-banded armadillos were examined histologically before and after inoculation of the animals with M. leprae. 3--4 months after the inoculation two animals developed tuberculoid structures in the lungs, liver and skin. A conclusion is made that experimental leprosy infection in nine-banded armadillos may run its course not only in the lepromatous but also in the tuberculoid form of the disease.

An adult male Nine-banded armadillo (Dasypus nonemcintus) had a large tumour between the first and second phalanges of the right fore-foot. The tumour was of dermal origin, consisted of dense interlacing bundles of collagen, and contained numerous fibroblasts with elongate nuclei and sparse cytoplasm. Mitotic figures were not observed, there was no evidence of lipid accumulation, and there was no metastasis to regional lymph nodes or other tissues. Electron microscopy showed that the major cells of the tumour were fibroblasts. These did not contain nuclear or cytoplasmic inclusions but had dense bodies in the nucleus and there was a conspicuous absence of lysosomes. This lesion was considered to be a benign fibroma of undetermined aetiology.

Peripheral nerves of armadillos were studied 16 to 30 months after intradermal or intravenous inoculation with Mycobacterium leprae. Numerous bacilli were found within macrophages, Schwann cells, and perineurial cells; endothelial cells, pericytes and fibroblasts were involved as well. The bacilli were characteristically contained in membrane-limited vacuoles that were interpreted as being phagosomes. Some of the phagosomes contained granular, membranous, and vesicular debris considered to be bacillary degradation products, suggesting that lysosomal activity was present within the phagosomes. Multivesicular bodies, a few of which contained bacilli, were abundant in macrophages and perineurial cells. An unusual proliferation of irregular tubulovesicular profiles was noted, especially in Schwann and perineurial cell cytoplasm, surrounding and within phagosomes containing bacilli. The pattern of cellular involvement of neural structures with M leprae was similar to that observed in lepromatous leprous neuritis in humans.

Morphological and histochemical characteristics of reverse reactions in M. leprae-infected armadillos are reviewed. The reverse reactions develop in generalized lepromatous disease and are characterized by a dramatic decrease in mycobacterial macrophage load and the appearance of lymphocytes, epithelioid and giant multinuclear cells with peripheral nucleus distribution. Histochemical investigation has shown a decrease in the activity of redox enzymes and alpha-naphthyl acetate esterase and an increase in beta-glucuronidase activity. The reverse reactions in the liver are accompanied by hepatic granuloma and hepatocyte destruction.

In order to determine the suitability of the armadillos as a model of human leprosy for chemotherapeutic studies, especially in evaluating newer anti-leprosy drugs, uninfected Armadillos were used to study the metabolic disposition of DDS. Serum DDS levels ranged from 500 ng/ml at 3 hours to 13 ng/ml at 96 hours after intravenous administration of DDS (1 mg/kg). In an ad libitum feeding trial of DDS it was found that the level of serum DDS varied according to the dose of DDS, and even at a dose of 0.0001%, the animals maintained MIC of DDS against M. leprae. Finally, it was demonstrated that armadillos acetylate DDS to MADDS and 7-9% of DDS is acetylated by armadillos.