Estrutura e ultra-estrutura das glândulas salivares de Cimex hemipterus (Fabricius, 1803) (Hemiptera: Cimicidae) / Structure and ultrastructure of the salivary glands of Cimex hemipterus (Fabricius, 1803) (Hemiptera: Cimicidae)

AUTOR(ES)
DATA DE PUBLICAÇÃO

2007

RESUMO

Cimex hemipterus is a hematophagous insect that can be an experimental host of the Trypanosoma cruzi and may play a role as vector of Chagas disease. This work analyzed the structure of the salivary glands of C. hemipterus. Adults were dissected and the salivary glands were analyzed in light microscopy and transmission electron microscopy. The secretory portion of principal salivary glands has a single lobe, oval form, translucent, formed for a simple columnar epithelium lined by muscle cells. The gland cells are high, with two spherical nuclei, nucleolus and some condensed chromatin. The cell cytoplasm has a well developed rough endoplasmic reticule, electron lucent vesicles, lysosomes and glycogen deposits. The apical plasma membrane has microvilli, zonula adherens, desmosomes whereas the basal plasma membrane has some infoldings associated with mitochondria. The duct of the principal salivary glands has flattened cells with nucleus containing condensed chromatin. The secretory portion of the accessory salivary glands is a single vesicular lobe, translucent, formed for a single layer of cells that varies from flattened to cubical, onto muscle cells. The cytoplasm contains a well developed smooth endoplasmic reticule with lamellar and vesicular aspect, vacuoles of different sizes containing secretion electron lucent and abundant mitochondria. The basolateral plasma membrane of adjacent cells shows septate junctions. At the lumen of the accessory salivary gland there is a presence of myelin figures. The duct is formed for a flattened epithelium like the duct of the principal salivary gland. The structures observed at the salivary glands of C. hemipterus corroborate with the works in salivary glands and in other types of insects glands. The secretory cells of the principal salivary glands are related mainly with the protein synthesis suggested for presence the rough endoplasmic reticule, as well as transport of ions and water for presence of invaginations at the basal plasma membrane and microvilli in the cell apex. However, the secretory cells of the accessory salivary glands are related mainly with the transport of ions and water from the haemolymph to glandular lumen suggested for presence of mithocondria close to the basolateral plasma membrane, as well as the synthesis of lipids or lipoproteins suggested for presence of smooth endoplasmic reticule and electro lucent vacuoles in the cytoplasm and myelin figures in the glandular lumen. Both the substances can to act like a vehicle to the secretion produced by principal salivary glands. In conclusion, the modifications presented in the cells of the salivary glands of C. hemipterus suggest that this glands play two different functions: 1) the transport of ions and water from haemolymph to glandular lumen and 2) the synthesis and secretion of enzymes and others salivary substances, being the accessory salivary glands responsible for increase of the volume of the salivary water secreted for the principal salivary glands, however we can not reject the hypothesis of the synthesis of substances.

ASSUNTO(S)

biologia geral cimicidae cimex hemipterus cimex hemipterus glândulas salivares salivary glands cimicidae

ACESSO AO ARTIGO

Documentos Relacionados