Large lamellar bodies and their role in the growing oocytes of the armadillo Chaetophractus villosus.

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.

Cytogenetic Characterization of Brown Howler Monkeys, Alouatta guariba clamitans (Atelidae, Platyrrhini): Meiotic Confirmation of an X1X1X2X2X3X3/X1X2X3Y1Y2 Sex Chromosome System.

For brown howler monkeys (Alouatta guariba clamitans), diploid chromosome numbers varying from 2n = 45 to 2n = 52, with XX/XY, X1X1X2X2/X1X2Y, and X1X1X2X2X3X3/X1X2X3Y1Y2 sex chromosome systems have been described by mitotic studies but still await confirmation by meiotic analyses. We analyzed 3 male individuals sampled in the wild (in the municipality of Santa Maria, RS, Brazil) as well as 1 male and 1 female individual in captivity at the São Braz breeding center. Peripheral blood samples and testicular biopsies were taken. We found different diploid numbers for both sexes in somatic cells, 2n = 45,X1X2X3Y1Y2 in males and 2n = 46,X1X1X2X2X3X3 in females, with 4 metacentric (9-12), 7 submetacentric (1-6, 8), and 9 acrocentric autosomal chromosome pairs (13-20, 22). X1 and X2 were submetacentric chromosomes, while X3, Y1, and Y2 were acrocentric ones. Spermatocyte microspreads were examined for synaptonemal complexes. Pachytene spermatocyte analysis was done to verify the chromosome number and morphologies observed in mitotic karyotypes. Immunodetection was performed using anti-SMC3 and anti-CREST antibodies. The presence of a sex chromosome pentavalent X1X2X3Y1Y2 in the males was confirmed by C-banding in metaphase I and by immunodetection in prophase I by the clear identification of 5 centromeres. The G-banded karyotype corresponded to that previously described for A. g. clamitans in the south of Brazil (Curitiba, Parana State, and Blumenau, Santa Catarina State) and for the Misiones Province, Argentina.

Comparative study of mitotic chromosomes in two blowflies, Luciliasericata and L.cluvia (Diptera, Calliphoridae), by C- and G-like banding patterns and rRNA loci, and implications for karyotype evolution.

The karyotypes of Luciliacluvia (Walker, 1849) and Luciliasericata (Meigen, 1826) from Argentina were characterized using conventional staining and the C- and G-like banding techniques. Besides, nucleolus organizer regions (NORs) were detected by fluorescent in situ hybridization (FISH) and silver staining technique. The chromosome complement of these species comprises five pairs of autosomes and a pair of sex chromosomes (XX/XY, female/male). The autosomes of both species have the same size and morphology, as well as C- and G-like banding patterns. The X and Y chromosomes of Luciliacluvia are subtelocentric and easily identified due to their very small size. In Luciliasericata, the X chromosome is metacentric and the largest of the complement, showing a secondary constriction in its short arm, whereas the Y is submetacentric and smaller than the X. The C-banding patterns reflect differences in chromatin structure and composition between the subtelocentric X and Y chromosomes of Luciliacluvia and the biarmed sex chromosomes of Luciliasericata. These differences in the sex chromosomes may be due to distinct amounts of constitutive heterochromatin. In Luciliacluvia, the NORs are placed at one end of the long-X and of the long-Y chromosome arms, whereas one of the NORs is disposed in the secondary constriction of the short-X chromosome arm and the other on the long-Y chromosome arm in Luciliasericata. Although the G-like banding technique does not yield G-bands like those in mammalian chromosomes, it shows a high degree chromosomal homology in both species because each pair of autosomes was correctly paired. This chromosome similarity suggests the absence of autosomal rearrangements during karyotype evolution in the two species studied.

Spermatogenesis is seasonal in the large hairy armadillo, Chaetophractus villosus (Dasypodidae, Xenarthra, Mammalia).

Very little is known about the distinct reproductive biology of armadillos. Very few studies have investigated armadillo spermatogenesis, with data available only for Euphractus sexcinctus and Dasypus novemcinctus. In the present study, we analysed male germ cell differentiation in the large hairy armadillo Chaetophractus villosus throughout the year, describing a cycle of the seminiferous epithelium made of eight different stages. Evaluation of the testis/body mass ratio, analysis of the architecture of the seminiferous epithelium and the frequency of defective seminiferous tubules allowed identification of a temporal interruption of spermatogenesis during the period between mid-May to July (mid-end autumn) in correlation with very low testosterone levels. Overall, these results suggest that spermatogenesis is seasonal in C. villosus.

Seasonal changes in ovarian steroid hormone concentrations in the large hairy armadillo (Chaetophractus villosus) and the crying armadillo (Chaetophractus vellerosus).

Knowledge of armadillo reproductive physiology is essential for developing ex situ and in situ assisted reproductive techniques for propagating and/or controlling populations of these animals. The present study included assessment of fecal sex steroids by radioimmunoassay, determining reproductive status via monitoring ovarian activity (in the wild) and therefore reproductive status, in wild females of the large hairy armadillo (Chaetophractus villosus) and the crying armadillo (Chaetophractus vellerosus) in the southern hemisphere. Plasma and fresh fecal progesterone concentrations were not significantly correlated in either species. However, in both species, there was a significant positive correlation between plasma progesterone and dry fecal progesterone concentrations (r = 0.82, P < 0.05 and r = 0.60, P < 0.05, respectively). Dry fecal progesterone and estradiol concentrations were measured in one captive C. villosus (average baseline progesterone and estradiol concentrations 28.72 ± 11.75 ng/g dry feces and 3.04 ± 0.80 ng/g dry feces, respectively) and one captive C. vellerosus (average baseline progesterone and estradiol concentrations 14.05 ± 3.03 ng/g dry feces and 3.46 ± 1.20 ng/g dry feces, respectively) to detect hormonal peaks over 1 y; these occurred from late fall to early summer. Feces from wild C. villosus and C. vellerosus were also collected over 1 y to determine progesterone peaks, which occurred in winter and spring in both species (with no peaks during the summer or fall). Accordingly, C. villosus and C. vellerosus had a seasonal reproductive pattern. The significant correlations between dry fecal and plasma progesterone concentrations validated this method for monitoring reproductive status in these species.