100 research outputs found

    The elusive archaeology of Kongo urbanism: the case of Kindoki, Mbanza Nsundi (Lower Congo, DRC)

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    We present here results, analyses and an in-depth historical contextualisation of the fieldwork undertaken in 2012 and 2013 at the Kindoki site in the Lower Congo (DRC). This site is linked with Mbanza Nsundi, one of the Kongo Kingdom's provincial capitals, which turns out to be archaeologically 'elusive'. Pinpointing its location proved to be particularly challenging. To this end, a historically-informed excavation methodology was developed that was never implemented in Central Africa before. We combined a strategy of systematic test pits with a large-scale 50 m grid approach. A cemetery was identified on Kindoki Hill with distinct but contemporaneous quarters of a 16th-17thcenturies settlement on both sides. The cemetery itself contains mainly 18th-century burials, in all likelihood of successive Nsundi rulers. The foreign, especially Portuguese, ceramics excavated on the hilltop and the hundreds of Venetian and likely Bavarian beads found in the graves are indicative of Mbanza Nsundi's connection to trade routes linking the Atlantic coast with the Pool region. The most striking discovery is that of a previously unknown type of comb-impressed pottery, from a pit with a calibrated radiocarbon date AD 1294-1393 (2 sigma). This suggests that a settlement had been developing at Kindoki since at least the 14th century, which allows us, for the very first time, to spatially bridge Kongo history and 'prehistory'. For the entire Lower Congo region only three 14C dates posterior to AD 1000 were available before the start of the KongoKing project, twelve have been added for just Kindoki

    Trout Sertoli and Leydig cells: isolation, separation, and culture

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    Primary culture of stomatic testicular cells in the rainbow trout.

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    Cultures primaires de cellules somatiques testiculaires de truite arc-en-ciel

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    Trout sertoli cells and germ cells in primary culture: I. Morphological and ultrastructural study

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    In order to characterize trout Sertoli cells and germ cells obtained after testis dissociation and cell separation, we have studied their morphology, ultrastructure, survival, and ability to express differentiated activities in primary cultures. After dissociation, the fine structure of Sertoli cells does not differ from that observed in situ and only minor changes are shown for at least 13 days. Until they are flattened in a monolayer, they keep the ability to retain germ cells on their surface. When flattened, some of them are able to divide. At the opposite of meiotic germ cells, spermatogonia can develop independently of Sertoli cells. They are able to proliferate during at least 10 days. Spermatocytes and spermatids are obtained as single cells and multinucleated giant cells (symplasts). In the absence of somatic cells, their maximal viability is approximately 5 days, whereas spermatocytes adhering to Sertoli cells can survive at least 10-12 days, provided trout lipoproteins are present. Spermatocytes are able to differentiate to spermatids, although this process is impaired for some cells. The adhesion of spermatogonia and spermatocytes to Sertoli cells is specific, mediated by desmosome-like junctions and favored by lipoproteins. These data are compared to what is known in mammals and in amphibians

    Trout steroidogenic testicular cells in primary culture : 1. Changes in free and conjugated androgen and progestagen secretions : effects of gonadotropin serum and lipoproteins

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    International audienceIsolated trout steroidogenic testicular cells were cultured for 10-15 days, either mixed with other round cells or after enrichment in interstitial cells. Free and conjugated progestagen and androgen secretions were assayed using specific radioimmunoassays (RIA). Free progesterone, 17 alpha-hydroxyprogesterone (17 alpha-OH-P), 17 alpha-hydroxy,20 beta-dihydroprogesterone (17 alpha,20 beta-OH-P), androstenedione, testosterone (T), and 11-ketotestosterone (11KT) were produced by testicular cells prepared from testes in spermatogenesis and mature testes. Discrete amounts of dehydroepiandrosterone (DHA) and of estradiol were secreted by mixed testicular cells prepared from mature testes, but no estradiol was detected in interstitial cell media. Conjugated androgens were produced by interstitial cells. While the production of progestagens by cells from spermatogenetic and mature testes either remained constant or increased throughout culture duration, those of free and conjugated androgens progressively decreased to low values whatever the components added to the medium. When salmon gonadotropin (s-GtH) was present permanently, androgen (free and conjugated) and progestagen secretions were stimulated for 3 to 4 days. When GtH was present discontinuously (1 day in every 3 days), the sensitivity of the cells was maintained for at least 7 days. While the GtH-stimulated/basal ratio was high for androgens, it was rather low for 17 alpha 20 beta-OH-P as compared to the values obtained with testis fragments. Trout serum (5%) stimulated the secretion of free and conjugated T and 11KT when testes were mature, but not when they were in spermatogenesis, while it stimulated 17 alpha 20 beta-OH-P secretion at the two stages. Total trout lipoproteins (125-500 micrograms/ml) stimulated 17 alpha 20 beta-OH-P secretion by cells from spermatogenetic testes, but not 11KT secretion

    Controllo ormonale della produzione di gameti in maschi di pesci teleostei

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