Oogenesis and ovarian histology of the American alligator Alligator mississippiensis

Although folliculogenesis and oogenesis have been observed in numerous reptiles, these phenomena have not been described in detail in a crocodilian. Oogenesis and histological features of the adult ovary of Alligator mississippiensis are described. Using a complex process, the ovary develops telolecithal oocytes that attain a diameter of 38.8 +/- 2.4 mm. The morphology of yolk platelets shows gradual changes throughout the oogenic process. Initially, yolk platelets are seen surrounded by a vesicle. As vitellogenesis advances, the vesicles contain numerous yolk spheres, with slowly growing platelets. The yolk spheres continue to increase in size and number within the vacuoles. Differences in the animal and vegetal poles are seen based on the morphology and size of the yolk platelets. The ovary of A. mississippiensis shows a well-developed system of lacunae and bundles of smooth muscle around the follicles in all stages of development. Several features seen in the ovary of A. mississippiensis are similar to those observed in birds. In particular, the morphology of the yolk platelets, especially during the middle and late vitellogenic stages, and the presence of a ovarian system of lacunae and smooth muscle. These similarities in the reproductive biology of crocodilians and birds contribute to current studies of the evolution of archosaurian reproduction. (C) 2000 Wiley-Liss, Inc

SPERMATOGENESIS IN THE URODELE AMBYSTOMA-DUMERILII

The male reproductive cycle of this paedomorphic species that occurs only in Lake Patzcuaro, Michoacan, Mexico, was investigated by documenting changes in germinal cells during the spermatogenic cycle. Cysts of germ cells divide synchronously to complete spermatogenesis during September through December, with the proportion of evacuated cysts or cysts containing spermatozoa increasing during this period. The chromatin changes during prophase I of meiosis reveal the usual leptotene, zygotene, pachytene, and diplotene stages. A basal body at the caudal end of the spermatozoan head connects to the flagellum. After spermiation, empty cysts contain a granular substance. Spermatogenesis in this species follows an annual cycle like other north temperate salamanders, rather than the continuous spermatogenesis of some tropical salamanders. (C) 1994 Wiley-Liss, Inc

Asymptomatic infection in family contacts of patients with human visceral leishmaniasis in Três Lagoas, Mato Grosso do Sul State, Brazil Infecção assintomática em contactantes de pacientes com leishmaniose visceral humana em Três Lagoas, Mato Grosso do Sul, Brasil

The Brazilian city of Três Lagoas, Mato Grosso do Sul State, has experienced an urban outbreak of visceral leishmaniasis since 2000. In 2002, due to the increase in the number of cases, 46 families with cases of visceral leishmaniasis were studied to verify the prevalence of asymptomatic infection in household contacts. Indirect immunofluorescence and ELISA showed a 36.4% positive infection rate. There were no cases of symptomatic disease among these contacts. There was no statistically significant difference in gender or age. Median age was 21 years, and the 10-19-year age bracket was the most heavily affected (23%). As for family characteristics, no differences were observed in schooling or family income; most families (58.7%) owned their homes, which were built of masonry (97.8%) and had adequate infrastructure. All the families reported what were probably phlebotomine sand flies in the peridomicile. In conclusion, asymptomatic visceral leishmaniasis infection is frequent and occurs in both males and females, regardless of age.<br>O Município de Três Lagoas, Mato Grosso do Sul, Brasil, foi alvo de uma epidemia de leishmaniose visceral a partir de 2000. Em 2002, devido ao incremento de casos, estudou-se 46 famílias que apresentavam um caso de doença para verificar-se o percentual de positividade de infecção assintomática por leishmaniose visceral em contactantes. Encontrou-se 36,4% de positividade pelos testes sorológicos Reação de Imunofluorescência Indireta e/ou imunoenzimático ELISA, sem diferença estatisticamente significativa quanto ao sexo e faixa etária. A mediana de idade foi de 21 anos, sendo a faixa etária mais acometida de 10 a 19 anos (23%). Quanto às características familiares não observaram-se diferenças quanto ao nível de instrução e renda familiar; a moradia, em sua maioria, era própria (58,7%), em alvenaria (97,8%), com infra-estrutura adequada. Todas as famílias relataram a presença de provável flebotomíneo no peridomicílio. Conclui-se que a infecção assintomática por leishmaniose visceral é freqüente, ocorrendo em homens e mulheres, independente de faixa etária