Morphology of the Pylorus of Bombyx mori (Linnaeus) (Lepidoptera: Bombycidae)

Abstract

The pylorus is a segment of the hindgut of great morphological diversity, which is subdivided into the posterior interstitial ring, pyloric cone, and pyloric valve. There is no morphological information on Bombyx mori (L.) hybrids, which is an insect of economic interest to Brazil. Consequently, this study aimed to analyze the morphology of the pylorus of hybrid larvae of fifth instars of B. mori from crossbreeding of Chinese and Japanese races. These were anesthetized, and the pylorus was fixed and processed by light microscopy and scanning electron microscopy. The pylorus presented as a separate compartment, consisting of a simple epithelium, with large variation in cell morphology, covered on the luminal side by an intima with specializations in some areas, the spicules. The musculature was formed by bundles of striated muscle fibers in longitudinal and circular arrangement. These fibers were multinucleated with central and peripheral nuclei, operating in peristalsis. The morphology of the pylorus is a reflection of functional dynamism, and this study provided a better understanding of its physiology, which promotes the regulated movement of the bolus, preventing reflux and directing it towards the ileum in the formation of fecal pellets.

Morphological and ultrastructural characterization of the alimentary canal in larvae of Streltzoviella insularis (Staudinger) (Lepidoptera: Cossidae)

“…The morphology, histology, and physiology of the alimentary canal are all related to the feeding habits and the digestive and absorptive processes (Chen et al 2016). The alimentary canal of Lepidopteran larvae is typically a hollow cylindrical structure consisting of three main regions: the foregut, midgut, and hindgut (Baggio et al 2014).…”

“…The insect hindgut is responsible for water reabsorption and formation of feces (Levy et al 2004b(Levy et al , 2008. Baggio et al (2014) observed that the pyloric valve intima of Bombyx mori (Linnaeus) was very thin, an advantageous feature for the reabsorption of water and ions. Rigoni et al (2004) found a characteristic Lepidopteran cryptonephric excretory system in the hindgut of Diatraea saccharalis (Fabricius).…”

iTRAQ-Based Quantitative Proteomic Analysis of Digestive Juice across the First 48 Hours of the Fifth Instar in Silkworm Larvae

“…The main functions of the foregut are physical digestion, consisting of feeding, grinding, swallowing, and temporary storage of mulberry leaves. The hindgut is present in the midgut transition that is generally thought to reabsorb certain salts and amino acids from food residue to maintain water balance and/or osmotic pressure in the silkworm [5][6][7]. The midgut is the most important section and comprises approximately 78 percent of the total length of the digestive tube.…”