Types Of Sensory Structures Research Articles

Scanning electron microscopy of cuticular sensory structures on the legs of Micronecta haliploides (Horvath, 1904) and Hydrometra greeni (Kirkaldy, 1898) (Hemiptera: Heteroptera)

Structures on the legs of two hemipteran bugs, Micronecta haliploides (Horvath, 1904) and Hydrometra greeni (Kirkaldy, 1898), belonging to family Micronectidae and Hydrometridae of two infra orders Nepomorpha and Gerromorpha, respectively were investigated using scanning electron microscopy. Both species have a distinctive leg structure bearing specialised cuticular sensory structures. In the study, the sensilla were classified into five basic types: sensilla trichoidea, sensilla basiconidea, sensilla placoidea, porous circular sensilla and sensilla bell mouthed. These sensilla were further differentiated on the basis of shape, size, number, flexibility and type of socket attached. A total of 26 types of sensilla in the legs of these two species were observed. M. haliploides showed 18 types of sensory structures and H. greeni 8 types. A specific morphological structure of the porous circular sensilla was observed and found to be unique.

Sensory features of the human louse antenna: new contributions and comparisons between ecotypes.

Body and head lice are known to be exclusive ectoparasites of human hosts. Current genomic and transcriptomic data suggest that both louse types represent ecotypes of the same species. They exhibit morphological and physiological differences that probably arose from living in different biotopes. Sensory traits represent suitable candidates to be affected by environmental heterogeneity. Therefore, through scanning electron microscope studies, this study analysed and compared the sensory structures of both ecotypes' antennae. Seven types of sensory structures were identified in both ecotypes: bristles, tuft organs, pore organs, single pore and three morphotypes of sensilla basiconica. Notably, the single pore and the morphotypes of sensilla basiconica were described for the first time in the body louse antenna. This study's comparative analysis mainly revealed size differences across the sensory structures of the ecotypes. Bristles of the flagellomere 2 of the body louse antenna were longer than the head louse bristles. In addition, the pore organs of the head louse antenna presented a higher diameter than those of the body louse. The possible relevance of size differences regarding the biotopes exploited by the body louse and the head louse is discussed. Yet, physiological studies may help to fully understand the phenotypical differences of both ecotypes.

Different Types of Sensory Structures on the Body Cuticle of <I>Ovatametra</I> sp. (Hemiptera: Gerridae) as Revealed by Scanning Electron Microscopy

Different Types of Sensory Structures on the Body Cuticle of <I>Ovatametra</I> sp. (Hemiptera: Gerridae) as Revealed by Scanning Electron Microscopy

Topography and ultrastructure of the tegument of Aphallus tubarium (Rodolphi, 1819) Poche, 1926 (Digenea: Cryptogonimidae), intestinal parasite of the common Dentex dentex (Linnaeus 1758) from Valinco Gulf.

The tegument ultrastructure of the intestinal fluke Aphallus tubarium was studied for the first time with the use of scanning and transmission electron microscopy. New details on morphology were recorded. The ultrastructural study revealed that the tegument of A. tubarium had a syncytial organization with a distal cytoplasm lying over a basal matrix and cytons. The surface of the tegument is covered with pectinate spines arranged quincuncially. As anterior-posterior differences were observed, particular attention was given to spines. Spines decrease in size and density from the anterior part of body to posterior part. Two types of sensory structures were identified, uniciliated and dome-shaped. Type 1 sensory receptors were outgrowths bearing groups of papillae with shorter and rigid apical seta visible on the anterior part of body surface, encircling the worm. Type 2 sensory receptors was dome-shaped papillae devoid of cilia, found mainly around the oral sucker. Diagrams of spines and sensory receptors were made to help in understanding the nature of these structures. Surface morphology may prove to be useful in distinguishing Aphallus spp with other Cryptogonimidae.

Sense Organs on the Antennal Flagellum of Leptoglossus zonatus (Heteroptera: Coreidae)

Abstract For the first time, antennal sensorial organs of Leptoglossus zonatus (Dallas) (Heteroptera: Coreidae) are described through scanning electron microscopy. The antennae are formed by a scape, pedicel, and a flagellum that is composed of two flagellomeres and is the main bearer of sensorial organs. Five types of sensory structures were identified: Trichoid sensilla, basiconic sensilla, coeloconic sensilla, campaniform sensilla, and placoid sensilla. Trichoid sensilla were divided into five subtypes. The large striated trichoid sensilla have almost straight longitudinally striated cuticles and were present throughout the antenna. Flattened trichoid sensilla were variable-sized curved hairs distributed from the base of the scape to the distal end of the first flagellomere. Small striated trichoid sensilla were found mainly on the antenna distal flagellomeres. Smooth trichoid sensilla were located at the distal end of the scape and along the entire length of the pedicel, and are the least abundant type on the antenna. Small smooth trichoid sensilla were found precisely on the joints between the pedicel and scape. Based on size and shape, the basiconic sensilla were also divided into five subtypes (Bs1, Bs2, Bs3, Bs4, and Bs5). These all are rod-shaped. Coeloconic sensilla were found exclusively on the second flagellomere of the flagellum. Just one campaniform sensilla on each antenna was located on the second flagellomere of the flagellum. Finally, a group of 10 oval placoid organs were found at the scape base, in proximity to the joint connecting the antenna to the insect's head.

Topography and ultrastructure of the tegument of Deropristis inflata Molin, 1859 (Digenea: Deropristidae), a parasite of the European eel Anguilla anguilla (Osteichthyes: Anguillidae)

The tegumental ultrastructure of the intestine fluke Deropristis inflata was studied using scanning and transmission electron microscopy. The surface of the tegument was covered by transverse cytoplasmic ridges from which protrude numerous thorn-like spines showing crenelated tips on the posterior part. Spines were arranged in staggered rows. Cobblestone-like units of the tegument were observed on a semicircle-shaped formation over the oral sucker. A tegumental excrescence was observed in the dorsal anterior side of the fluke. Ultrastructural study revealed that the tegument of D. inflata had a typical syncytial organization with a distal cytoplasm lying over a basal matrix and cytons. Cytoplasmic bridges allowed transit of secretory vesicles and granules packed in gland cells. Two types of sensory structures were examined. Type 1 sensory receptor was a button-like uniciliated papilla mounted on a folded tegumental base and surrounded by cytoplasmic ridges. This receptor consisted of a nerve bulb and a cilium that extended from a centriole. Type 2 sensory receptor was a smooth bulb-like non-ciliated papilla. It was only recovered on the ventral sucker. This receptor consisted of a nerve bulb enclosing an ovoid electron-dense structure. For both receptors, the nerve bulbs contained numerous mitochondria, nerve fibers, and electron-lucent material. Particular distributions of the sensory receptors were observed with a concentration on the anterior third of the body around the oral and ventral suckers. Diagrams were made to help in understanding the nature of these structures.

Topography and Ultrastructure of the Tegument of Bucephalus anguillae (Digenea: Bucephalidae), a Parasite of the European Eel Anguilla anguilla (Osteichthyen: Anguillidae)

The tegumental ultrastructure of the intestinal fluke Bucephalus anguillae was studied with the use of scanning and transmission electron microscopy. The surface of the tegument is covered by transverse ridges from which protrude numerous closely packed, digitated, and claw-shaped spines. Cobblestone-like units of the tegument were observed on the crescent-shaped formation of the rhynchus and at the posterior part of the body. Three types of sensory structures were examined, i.e., 2 uniciliated receptors and 1 without cilia. As anterior-posterior differences were observed, particular attention was given to spines and sensory receptors. Spine insertion zones and average cilia length are variable between anterior and posterior tegument areas. Ultrastructural study revealed that the tegument of B. anguillae has a typical syncytial organization with a distal cytoplasm lying over a basal matrix and cytons below. Cytoplasmic bridges allowed transit of secretory vesicles and granules. Diagrams of spines and sensory receptors were made to help in understanding the nature of these structures.

General morphology of the oral cavity of the Nile crocodile, Crocodylus niloticus (Laurenti, 1768). I. Palate and gingivae.

The heads of nine 2.5 to 3-year-old Nile crocodiles (Crocodylus niloticus) were obtained from a commercial farm where crocodiles are raised for their skins and meat. The animals from which these specimens originated were clinically healthy at the time they were slaughtered. A detailed description of the macroscopic and microscopic features of the palate and gingivae of the Nile crocodile is presented and the results are compared with published information on this species and other Crocodylia. The histological features are supplemented by information supplied by scanning electron microscopy. Macroscopic features of interest are the small conical process situated at the base of the first two incisors of the maxilla, the distribution of cobbled units on the palate, and the broad dentary shelf forming the rostral aspect of the mandible. Histologically the palate and gingivae did not differ significantly from each other and both regions showed a presence of Pacinian-type corpuscles. Two types of sensory structures (taste receptors and pressure receptors) were identified in the regions examined, both involving modification of the epithelium and the underlying connective tissue.

Ultrastructure of the daughter sporocyst and developing cercaria of Schistosoma japonicum in experimentally infected snails, Oncomelania hupensis hupensis.

Ultrastructure of daughter sporocysts and cercariae of Schistosoma japonicum were studied 2 and 4 months after infection of Oncomelania hupensis hupensis. The body walls of daughter sporocysts are similar at all infectious stages. They consist of an external syncytial tegument on a basement membrane, and an internal cellular subtegument surrounding a body cavity containing developing cercariae. The cercariae embryos develop 2 months after infection from germinal balls in the brood chamber of the daughter sporocyst. They are at first enveloped by a primitive epithelium rising from the daughter sporocyst. Four months after infection, the cercariae were almost fully developed and the primitive epithelium had degenerated. The body wall of the cercaria consists of a thin tegument covered by a surface coat of fibrous material and connected to the subtegumental cells by cytoplasmic processes. The matrix of the tegument contains numerous dense bodies, vacuoles, and spines. Two types of sensory structures - uniciliated and multiciliated - are found at the anterior tip of the cercaria. There are five pairs of penetration gland cells of two distinct types differentiated by the morphology of secretory granules. Flame cells are found in both daughter sporocysts and in cercariae. The cilia of the flame cells are characterized by the typical 9 and 2 cilium pattern.

Functional morphology and surface topography of Leucochloridium sp. (Digenea), revealed by scanning electron microscopy

A detailed study on macro- and microtopography, body form and tegument architecture, of Leucochloridium sp. has been carried out by SEM. Three types of sensory structures (presumed) have been distinguished on body tegument: a domed aciliate papillae, pits and depressions in the body surface. The distribution of these is described and their function discussed. Both single-and multipointed spines were found. The development, size, shape and distribution of these are described and also discussed in relation to functional morphology. These results on tegument topography of Leucochloridium sp. revealed by SEM, have also been compared with the existing, scattered information on this topic on other species of Leucochloridiidae.

Argentophilic "Papillae" of Schistosoma mansoni Cercariae

Argentophilic papillae, presumed to be sensory, were studied by light microscopy and scanning electron microscopy. Particular attention was paid to body papillae in an effort to determine their number, distribution, and structure, and to determine whether sex of cercariae could be detected by their papillae. Distribution of body papillae was plotted on 30 male and 30 female cercariae from 6 snails infected with single miracidia (10 cercariae from each snail); tail papillae of 10 male and 10 female cercariae were studied. No difference between sexes was noted. The basic number of body papillae (excluding those at the anterior tip) is 62: 18 ventral, 4 acetabular, 20 dorsal, and 20 lateral (10 on each side). Numbers and patterns of papillae were relatively constant. At the anterior tip there are 14 papillae in two groups of 7. Each group of papillae is associated with a group of apparently 7 gland duct openings. There appear to be at least 3 types of papillae: raised, uniciliated ones (the most numerous); pits; and a disklike elevation with a small knob in the center. Papillae projecting from the surface of the tegument, or capsules embedded within the tegument, have been reported in light microscope studies from cercariae and other stages of a wide variety of trematodes, including schistosomes. These papillae have been generally interpreted as being sensory in nature because of their distribution, morphology, and innervation (noted in some cases), and because they resemble similar structures shown to be sensory in other invertebrates. Various authors have stained these structures with silver nitrate (Seitner, 1951; Wagner, 1961; Ginetsinskaya and Dobrovolskii, 1963; Heyneman and Umathevy, 1966; Lie, 1966; Richard, 1968a, b, 1971; Rohde, 1968; Chapman and Wilson, 1970; Mohandas, 1971) and some workers have indicated that patterns of papillae may be of systematic value (Vercammen-Granjean, 1951; Kuntz, 1955; Wagner, 1961; Ginetsinskaya and Dobrovolskii, 1963; Heyneman and Umathevy, 1966; Lie, 1966; Richard, 1968a, b, 1971). Careful study with light microscopy has shown that there are several types of these so-called papillae which become stained with silver nitrate (Wagner, 1961; Lie, 1966; Mohandas, 1971), and, in fact, all do not appear to be projections or elevations, as the word papilla implies. For this reason the term "argentophilic cuticular structures" was preferred by Heyneman and Umathevy (1966). Received for publication 7 May 1973. * This study was supported by grants from NSF (GB-30903) and the USPHS-NIH (AI 10435). In the present paper we will use the term papilla for these argentophilic structures, for the sake of convenience. Other structures also ar commonly stained with silver nitrate, e.g., gla d duct openings, excretory pores, and the mouth opening. In some cercariae, gland duct openings may possibly be confused with "papillae" but with schistosome cercariae this does not seem to be a problem. Argentophilic papillae on schistosome cercariae have been studied by Wagner (1961), Capron et al. (1965), and more recently by Richard (1968a, b, 1971) who, in a comprehensive study of various groups of cercariae, described papillar patterns of cercariae of five s ecies of schistosomes, including S. mansoni. Little information has been reported on extent of variation of papillar pattern within a species and, to our knowledge, no one has reported an attempt to distinguish sex of cercariae by papillar pattern, although Wagner (1961) suggested this possibility. Recent fine structural studies have revealed different types of presumed sensory structures in a number of cercariae (Matricon-Gondran, 1971), including cercariae of S. mansoni (Morris, 1971; Nuttman, 1971), but apparently little systematic effort has been made to determine the range of types of sensory structures and the distribution of the various types over the cercarial body. This paper involves a description, by means of light microscopy and scanning electron microscopy, of the papillae of cercariae of S. mansoni. Attention was paid almost entirely