Silk Secretion Research Articles

FIne structure of the tegumentary glands secreting the protective ‘shield’ in a sessile insect (Homoptera, Diaspididae)

The tegumentary pygidial glands of Aonidiella aurantii ( Homoptera, Diaspididae) produce a secretion forming the shield of these fixed parasites of plants. They are formed of seven cells: a principal unpaired secretory cell which produces an abundant glycoproteinaceous secretion; a small associated cell with a secondary reservoir for this secretion; two accessory secretory cells which have very abundant tubular extensions coming from the plasma membrane, and a flocculent secretion gathered in a large sub-cuticular space; two cells forming an enlarged part of the excretory canal, functioning like a spinneret; and finally a single cell forming the tubular duct of this complex gland. The cuticle of the secretory cells has a very special porous structure, through which the secretion passes. The final product is a ribbon formed by two hollow strands stuck together. The exact nature of this secretion is not clear. It is comparable to a silk secretion though it has its own particular characteristics.

Studies on silk secretion in the trichoptera (F. Limnephilidae): I. Histology, histochemistry, and ultrastructure of the silk glands.

As part of a study on trichopteran silk secretion, the histology, histochemistry, and ultrastructure of the silk glands of two species of limnephilid trichopteran larvae, Pycnopsyche guttifer (Walk.) and Neophylax concinnus McL., were investigated. The silk glands consist of three anatomically distinct regions: a long, posterior silk-secreting region; a shorter, anterior conducting tube; and a terminal press/common duct. In Pycnopsyche, there is also a modified bulbous region between the secreting and conducting areas. Each anatomical region has a distinct cell type. There are two structurally and histochemically different components of the secretion in the glandular lumen: a core and a peripheral layer. Both components are produced all along the gland and are principally proteinaceous. However, the peripheral layer is also PAS and alcian blue (pH. 2.5) positive and shows β-metachromasia with toluidine blue (pH 3.5), indicating the presence of both neutral and acidic polysaccharides.

Silk secretion in sawflies

AbstractThe serigenous glands of a number of different sawfly larvae have been examined. Silk is secreted by pear‐shaped cells which may be fused together in pairs or triplets, or exist simply as free, single cells. The cells are arranged in numerous groups attached to a pair of wide silk reservoirs by means of short canals. Each gland cell contains a large, irregular, ramifying nucleus and an intracellular duct which receives droplets of synthesised silk protein. Two modifications of this basic arrangement are described. It is suggested that the secretory cells are dermal gland cells, and that the intracellular duct is a rudimentary end‐apparatus. A comparison is made between these and some other types of dermal gland cell found in insects.

Studies on the secretion of liquid silk in two lepidopterous insects, Phylosamia ricini BOISD. and Antheraea pernyi GUÉR.-MÉN

Studies on the secretion of liquid silk in two lepidopterous insects, Phylosamia ricini BOISD. and Antheraea pernyi GUÉR.-MÉN

Relation between the number of silkgland-cells and the amount of silk secretion in the silkworm, Bombyx mori L.

Relation between the number of silkgland-cells and the amount of silk secretion in the silkworm, Bombyx mori L.

Erratum to : Relation between the number of silkgland-cells and the amount of silk secretion in the silkworm, Bombyx mori L.

Erratum to : Relation between the number of silkgland-cells and the amount of silk secretion in the silkworm, <i>Bombyx mori</i> L.

Cytological studies on the spinning glands of the larva of Galleria mellonella: Respective rôles played by the nucleus, the Golgi apparatus, and the mitochondria during secretion

AbstractSpining in Galleria begins shortly after hatching and continues throughout larval life. The gland cells secrete continuously, irrespective of the act of spinning.The nucleus plays a direct and an importnat rôle in silk secretion by the migration of nucleoli into the cytoplasm, where they enlarge and synthesize a fatty material in the center; the fatty material is transformed into a non‐soluble basophllic substance, which then changes into the secretory product in its final form. The processes of converting the fat into non‐soluble substance and of converting the latter into the secretory product progress inwardly from the periphery of each secretory body. The secretory bodies or masses of secretory material break up into smaller and smaller masses and eventually into a fine dispersed state before their entrance into the lumen of the gland.The mitochondria are granular in the cells of the conductive portion and filamentous in those of the reservoir and secretory portions of the gland. In the secretory portion they are orientated with the long axis toward the gland lumen. Their rǒle in silk secretion is negligible or at most a minor one.The Golgi apparatus is in the form of discrete ring‐ and half‐ring‐shaped bodies and remains so during all stages of secretion. If it plays any rǒle in silk secretion, the fact has not been detected by the author.