A light and electron microcopic study of pigmented corpuscles in the midgut gland and feces of Pomacea canaliculata (Caenogastropoda, Ampullariidae)

KOCH, E.; VEGA, I.A.; ALBRECHT, E.A; ORTEGA, H.H.; CASTRO-VAZQUEZ, A.

VELIGER

Año: 2006 vol. 48 p. 17 - 25

0042-3211

Abstract. Pigmented corpuscles (C and K types) and their cellular associations in the midgut gland, as well as similar pigmented corpuscles in snail’s feces and in up to 3-year-old aquarium sediments, were studied. C corpuscles are Light brown-greenish spherical bodies (diameter 14 _m) surrounded by a thick, electron dense wall, and containing inner granules and membranes. A rather large variation in the amount of these granules and membranes occurs in C corpuscles, irrespective of whether they were from gland tissue, feces or aquarium sediments. K corpuscles are dark brown, bottleshaped bodies (36 _m length, 14 _m width) which frequently show a multilamellar structure. All transitional forms between typical C and K corpuscles occur. K corpuscles occur more frequently than C corpuscles in gland tissue but not as much in feces, and are even less frequent in old aquarium sediments. Glandular C corpuscles are contained within vesicles of alveolar columnar cells, and they occur mainly in the basal half of these cells. In the cellular upper half, similar but nude (i.e., without the wall) bodies are seen. On their part, glandular K corpuscles are apparently contained within an extrusion of a columnar cell, which is in turn engulfed by a pyramidal cell. Morphological features of K corpuscles and of their hosting cells indicate that K corpuscles derive from C corpuscles and that the hosting cells partly provide their electron dense layers. Interestingly, the amount of pigmented materials in the midgut gland of females is more than double than that of males.