Structural features of the epididymal region of the domestic duck (Anas plathyrynchos)

A região epididimária do pato doméstico era composta pelos ductúlos eferentes, os quais hitotopologicamente foram caracterizados como dúctulos eferentes proximal e distal e, sequencialmente, pelo ducto epididimal. O epitélio dos dúctulos eferentes era pseudo-estratificado, formado por células colunares. O epitélio dos ductos epididimários mostrou-se também pseudo-estratificado, mas não ciliado. de acordo com as análises histomorfométricas, a média da altura epitelial foi significativamente maior nos dútulos esferentes distais, diferindo das baixas médias de altura epitelial observadas nos dúctulos eferentes proximais e ducto epididimal. A média dos diâmetros máximos e mínimos foi significativamente maior nos dúctulos eferentes proximais, comparativamente as médias dos mesmos diâmetros dos outros dúctulos.

Biological features of a puzzling symbiotic association between the hermit crab Dardanus insignis and the porcellanid crab Porcellana Sayana (Crustacea)

The symbiotic lifestyle is widespread among porcellanid crabs, which maintain ecological and co-evolutionary associations with annelid polychaetes, poriferans, cnidarians, echinoderms, gastropod. mollusks, and other crustaceans such as shrimps and hermit crabs, among others. We investigated the ecological association between the hermit crab Dardanus insignis and the porcellanid Porcellana sayana, in southeastern Brazil. Porcellanid crabs, hermit crabs, and available shells were collected monthly from July 2001 to June 2003, with a shrimp boat equipped with two double-rig trawl nets. The majority of P. sayana specimens were collected in shells occupied by D. insignis (96.6%); a few were found in empty shells (3.4%). The catch of both symbionts and hosts increased with increasing depth, with the highest occurrence at 35 m. The F. sayana crabs of various sizes could be found solitary or forming aggregations of up to 14 individuals per host, showing no sex or size segregation. In spite of the high diversity of shell species occupied by the hermit crabs and also available in the field, only a few of them were also utilized by P. sayana. The majority (93%) of shells utilized by P. sayana also hosted other symbiont species, constituting the basis of extensive symbiotic complexes. Thus, the ecological relationship between D. insignis and P. sayana may be classified as a non-obligate and non-specific symbiosis that may also involve other facultative organisms such as sea anemones. (C) 2008 Elsevier B.V. All rights reserved.