title: 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.
authors.affiliation: Univ do Oeste do Paraná, Cascavel, PR, Brasil.
authors.forename: M P D
authors.initials: MP
authors.lastname: Baggio
authors.affiliation: Univ do Oeste do Paraná, Cascavel, PR, Brasil.
authors.forename: S A
authors.initials: SA
authors.lastname: Vessaro-Silva
authors.affiliation: Univ do Oeste do Paraná, Cascavel, PR, Brasil.
authors.forename: L F C
authors.initials: LF
authors.lastname: Ribeiro
authors.affiliation: Centre for Biological and Health Sciences, UNIOESTE, Cascavel Campus, Rua Universitária, 2069, Cascavel, PR, 85819-110, Brasil. rosecb@gmail.com.
authors.forename: R M C
authors.initials: RM
authors.lastname: Brancalhão
mesh_terms: D000818:Animals; D012831:Bombyx; D001938:Brazil; D007814:Larva; D007915:Lepidoptera / Q000033:anatomy & histology*; D011708:Pylorus
keywords: Hindgut; posterior interstitial ring; pyloric cone; pyloric valve; spicules