Revista Chilena de Historia Natural 78 (1): 15-21, 2005
RESEARCH ARTICLE
Ultrastructure of the silk glands in three adult females of sphecid wasps of the genus
Microstigmus (Hymenoptera: Pemphredoninae)
The ultrastructure of silk glands in adult females of sphecid wasps is described. Individual
glands are scattered in the more posterior portion of the metasoma being each gland formed by an enlarged secretory unity with one
conducting canal. Each secretory unit is a gland cell containing a large lumen and numerous secretory granules, which are delimited
by membrane and filled with middle electron dense content of homogeneous aspect, which are exocytosed into the extra cellular
lumen. Cell cytoplasm is filled with rough endoplasmic reticulum, polyribosomes and Golgi apparatuses profiles. The basal plasma
membrane has many short infoldings and is lined by a thin basement membrane. The apical membrane is invaginated to form the
boundary of the lumen, containing scattered short microvilli. The cells are mononucleated and the nucleus is pleomorphic containing
disperse chromatin. The extracellular lumen is separated of the receiving canal by a convoluted sponge-like wall forming many villi,
which in their tip are lined by a thin single layered cuticle. In the basal region of the villi a cuticular covering is lacking. In the conducting
canal secretion acquire two different electron densities. A thin cuticle lines the lumen of conducting canal and the cell cytoplasm is
scarce and the organelles are represented for few rough endoplasmic reticulum and polyribosomes. These results are discussed in
relation to function and origin of silk gland in adult Sphecidae.
Key words:
Hymenoptera,
Microstigmus, silk glands, Sphecidae, ultrastructure
