The cytoplasm has large vacuoles weakly acidophilous, and the apical cell surface presents striated border (Fig.
The cell apex has a striated border and the cell cytoplasm was predominantly acidophilic.
Epithelial cells of the posterior midgut are each characterized by the presence of a well-developed striated border relative to the digestive cells of the anterior midgut, which suggests a role of nutrient absorption; moreover the occurrence of apocrine secretion or release of cytoplasmic vesicles into the lumen was not observed.
Scanning electron micrograph of the anterior midgut epithelium (ep) showing the bubbles (b) of apocrine secretion in the cell apex and the absence of striated border.
Posterior midgut epithelial cells containing vacuoles and striated border (arrow) on the apical surface and regenerative cells (r) in the basal portion.
The histological sections were used to measure the height of digestive cells, the length of the striated border, the nuclear area and the area of the regenerative cell nests.
flavicincta was formed by a single layer of columnar digestive cells with a well-developed striated border and oval nuclei possessing 1 or 2 evident nucleoli.
Alcian blue/PAS (AB/PAS) histochemical test showed a strong reaction to PAS in the striated border and cytoplasmic granules in the apical portion of digestive cells.
The midgut is constituted by a simple epithelium formed by columnar digestive cells with a well-developed striated border surrounded by 2 muscle layers similar to other Hymenoptera (Serrao & Cruz-Landim 1995; Bution et al.
flavicincta the striated border is longer in the anterior midgut region, similar to that found in the stingless bees Trigona hypogea and Trigona spinipes, which have longer microvilli in their midgut region (Serrao & Cruz-Landim 1996b).