Where are the sensory organs of Nybelinia surmenicola (Trypanorhyncha)? A comparative analysis with Parachristianella sp. and other trypanorhynchean cestodes (original) (raw)
Related papers
Sensory receptors and surface ultrastructure of trypanorhynch cestodes
Parasitology Research, 2000
The scolices of six dierent trypanorhynch species ± Heteronybelinia alloiotica (Dollfus, 1960), Pseudolacistorhynchus noodti Palm, 1995, Otobothrium cysticum (Mayer, 1842), O. penetrans Linton, 1907, Poecilancistrum caryophyllum (Diesing, 1850, and Prochristianella hispida (Linton, 1890) ± were examined for surface morphology and the occurrence of sensory receptors. Filamentous microtriches with dierent internal ultrastructural features were found. Acerosate, hooklike, and spiniform microtriches were detected on the surface of the tentaculariid H. alloiotica. Their internal structure clearly diered from that of pectinate microtriches observed in the other ®ve trypanorhynch species lacking a basal and a junctional region. All pectinate microtriches had the same general architecture, independent of the number of digitiform processes. All trypanorhynchs studied harbored ciliated sensory receptors within the tegument. Even though sensory receptors were scarce in H. alloiotica, they were more abundant in the lacistorhynchid P. noodti and the otobothriids P. caryophyllum and O. penetrans, which exhibited two, six, and three kinds of receptors, respectively. Bothridial pits in O. penetrans and O. cysticum were invaginations of the bothridial surface, being characterized by the lack of sensory receptors and the presence of characteristic microtriches. These diered from other microtriches in that they were larger and had a base consisting of a widely enlarged matrix. The occurrence of dierent kinds of microtriches and sensory receptors within trypanorhynch cestodes is summarized, and the meaning of these surface structures and of bothridial pits as characters within future trypanorhynch classi®cation is emphasized.
Journal of Parasitology, 2007
The ultrastructural organization of the mature spermatozoon of the trypanorhynch cestode Parachristianella trygonis is described by transmission electron microscopy. The spermatozoon is a long and filiform cell, tapered at both ends, lacking both mitochondrion and crested bodies. Its cytoplasm contains 2 axonemes of the 9ϩ'1' pattern of the Trepaxonemata longitudinally displaced, parallel cortical microtubules, the nucleus and glycogen in form of both ␣-glycogen rosettes and -glycogen particles. The anterior extremity of the spermatozoon is characterized by the presence of an arclike row of up to 10 parallel cortical microtubules that partially surround the first axoneme. The present study emphasizes the ultrastructural similarity between mature spermatozoa of all 4 trypanorhynchs that have been studied to date. Nevertheless, several features, i.e., the characteristics of spermatozoa extremities, the absence of crested bodies, and the possible presence of an arclike layer of cortical microtubules, need a more thorough analysis or confirmation in some of these species.
International Journal of Insect Morphology and Embryology, 1994
Sensilla are sense organs in insects, generally comprising of a group of cuticle or epidermal cells that appear as hairs or rod-shaped structures. Sensilla serve as the functional elements of sensory systems. The morphology and ultrastructure of sensilla on the antennae of mature male and female Japanese sawyer beetles, Monochamus alternatus Hope (Coleoptera: Cerambycidae), were examined by means of scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Five types of sensilla (sensilla basiconica, sensilla trichodea, sensilla digit-like, sensilla rodlike, and sensilla bottle-like) were observed on antennae of males, and four types of sensilla (sensilla basiconica, sensilla trichodea, sensilla bottle-like, and sensilla chaetica) were observed on antennae of females. Sensilla basiconica and sensilla trichodea were found to be abundant on the front elevation of the antennae. TEM micrographs of sensilla basiconica on the antennae of M. alternatus clearly showed that they had no pits in the cuticular region. Micrographs of longitudinal sections of sensilla trichodea showed them to be flat-tipped and smooth-surfaced pegs with pointed tips that are suggestive of a gustatory function. TEM micrographs of sensilla chaetica longitudinal sections showed dendrite branches and no cuticular pore; these sensilla may be involved in the perception of humidity, temperature, heat, and CO 2. These results are discussed in relation to the possible roles of the sensilla types in the host-locating behavior of M. alternatus.
Zoomorphology, 1995
The organization of the nervous system of Archilopsis unipunctata Promonotus schultzei and Paramonotus hamatus (Monocelididae, Proseriata) and Stenostomum leucops (Catenulida) and Microstomum lineare (Macrostomida) was studied by immunocytochemistry, using antibodies to the authentic flatworm neuropeptide F (NPF) (Moniezia expansa). The organization of the nervous system of the Monocelididae was compared to that of the nervous system of Bothriomolus balticus (Otoplanidae), a previously studied species of another family of the Proseriata. The results show that the main nerve cords (MCs), independent of lateral or ventral position in the Monocelididae and the Otoplanidae, correspond to each other. The study also confirms the status of the lateral cords as main cords (MCs) in S. leucops and M. lineare. Common for MCs in the members of the investigated taxa are the following features: MCs consist of many fibres, originate from the brain and are adjoined to 5-HT-positive neurons. In Monocelididae and Otoplanidae, the MCs additionally have the same type of contact to the pharyngeal nervous system. Also common for both proseriate families is the organization of the two lateral nerve cords, with weaker connections to the brain, and the pair of dorsal cords running above the brain. The organization of the minor cords differs. The Monocelididae have a pair of thin ventral cords forming a mirror image of the dorsal pair. Furthermore, an unpaired ventral medial cord connecting medial commissural cells was observed in P. schultzei. Marginal nerve cords, observed in Otoplanidae, are absent in Monocelididae. All minor nerve cords are closely connected to the peripheral nerve plexus. The postulated trends of condensation of plexal fibres to cords and/or the flexibility of the peripheral nerve plexus are discussed. In addition, the immuno-reactivity (IR) pattern of NPF was compared to the IR patterns of the neuropeptide RFamide and the indoleamine, 5-HT (serotonin). Significant differences between the distribution of IR to NPF and to 5-HT occur. 5-HT-IR dominates in the submuscular and subepidermal plexuses. In the stomatogastric plexus of M. lineare, only peptidergic IR is observed in the intestinal nerve net. The distribution of NPF-IR in fibres and cells of the intestinal wall in M. lineare indicates a regulatory function for this peptide in the gut, while a relationship with ciliary and muscular locomotion is suggested for the 5-HT-IR occurring in the subepidermal and submuscular nerve plexuses. In M. lineare, the study revealed an NPF-and RFamide-positive cell pair, marking the finished development of new zooids. This finding indicates that constancy of these cells is maintained in this asexually reproducing and regenerating species.
Fine structure of nervous system in plerocercoid Ligula intestinalis (Cestoda: Diphyllobothriidea)
Invertebrate Zoology, 2010
The fine structure of the nervous system in plerocercoid Ligula intestinalis (Diphyllobothriidae) has been studied. The ultrastructure of the cerebral ganglion, the main nerve cords and peripheral nervous system has been described. The cerebral ganglion has complicated microanatomy. It consists of symmetric pair frontal and lateral lobes connected by the massive median commissure, and ventral azygos lobe, located in the center and on the ventral surface of the commissure. Two crossed ventral nerves are originated from the unpaired median (ventral) lobe. It was found, that the neurons in the lateral lobes and the commissure have asymmetrical position (localization neurons in the lateral lobes and the commissure has dorso-ventral polarity): large neurons (2040 µm) are concentrated on the dorsal surface of the cerebral ganglion. We found four types of neurons with different fine structure and size, peripheral neurosecretory cells and undifferentiated cells. Three types of synaptic contacts have revealed in neuropiles. Giant axon occurred as part of the main cord. On the surface membrane of the giant axon are numerous incoming synapses. The peripheral nervous system consists of numerous compact bunches of nerve processes taking place along the longitudinal and dorso-ventral muscle fibers. Also three types of sensory organs were found in the tegument: one type a ciliate and two types unciliate receptors. Comparative analysis of nervous system organization in representatives of the two orders Diphyllobothriidea and Bothriocephalidea showed that the cerebral ganglion L. intestinalis possesses bilateral symmetry, characterized by the presence of the ventral lobe, ventral nerves and the dorso-ventral polarity in the arrangement of neurons and exiting nerves. On the contrary, the cerebral ganglion of Triaenophorus nodulosus (Bothriocephalidea) has a double-beam symmetry: it has symmetrical lobes in ganglion with symmetrical dorsal and ventral nerves, lack of lobe in the median commissure, and send symmetrical dorso-ventral rootlets in the bothria. Our data confirm the belonging of the studied species to different groups and support the idea of separation Pseudophyllidea sensu lato into two new orders Diphyllobothriidea and Bothriocephallidea.
Journal of Morphology, 2006
The anterior and posterior head sensory organs of Dactylopodola baltica (Macrodasyida, Gastrotricha) were investigated by transmission electron microscopy (TEM). In addition, whole individuals were labeled with phalloidin to mark F-actin and with anti-␣-tubulin antibodies to mark microtubuli and studied with confocal laser scanning microscopy. Immunocytochemistry reveals that the large number of ciliary processes in the anterior head sensory organ contain F-actin; no signal could be detected for ␣-tubulin. Labeling with anti-␣-tubulin antibodies revealed that the anterior and posterior head sensory organs are innervated by a common stem of nerves from the lateral nerve cords just anterior of the dorsal brain commissure. TEM studies showed that the anterior head sensory organ is composed of one sheath cell and one sensory cell with a single branching cilium that possesses a basal inflated part and regularly arranged ciliary processes. Each ciliary process contains one central microtubule. The posterior head sensory organ consists of at least one pigmented sheath cell and several probably monociliary sensory cells. Each cilium branches into irregularly arranged ciliary processes. These characters are assumed to belong to the ground pattern of the Gastrotricha. J. Morphol. 267:897-908, 2006.
Arthropod Structure & Development, 2008
Ricinulei possess movable, slender pedipalps with small chelae. When ricinuleids walk, they occasionally touch the soil surface with the tips of their pedipalps. This behavior is similar to the exploration movements they perform with their elongated second legs. We studied the distal areas of the pedipalps of the cavernicolous Mexican species Pseudocellus pearsei with scanning and transmission electron microscopy. Five different surface structures are characteristic for the pedipalps: (1) slender sigmoidal setae with smooth shafts resembling gustatory terminal pore single-walled (tp-sw) sensilla; (2) conspicuous long, mechanoreceptive slit sensilla; (3) a single, short, clubbed seta inside a deep pit representing a no pore single walled (np-sw) sensillum; (4) a single pore organ containing one olfactory wall pore singlewalled (wp-sw) sensillum; and (5) gustatory terminal pore sensilla in the fingers of the pedipalp chela. Additionally, the pedipalps bear sensilla which also occur on the other appendages. With this sensory equipment, the pedipalps are highly effective multimodal short range sensory organs which complement the long range sensory function of the second legs. In order to present the complete sensory equipment of all appendages of the investigated Pseudocellus a comparative overview is provided.
Invertebrate Zoology, 2017
The ultrastructure of the tegument, glands and sensory organs of Pyramicocephalus phocarum (Cestoda: Diphyllobothriidea) have been studied. Three types of the microthriches are found, which have a specific distribution on the scolex and body. A welldeveloped basal lamina contained radial anchoring fibrils; they are associated with the microfibrills of the lamina reticularis and form regular cross-links. In the tegument, we have found six types of sensory organs and also terminal pores of the frontal glands. It has been shown that sensory endings and secretory pores are co-localized in the bothria tegument: 30 pores and 50 sensory endings were found in one section. Frontal glands are located in the parenchyma of the scolex and body; glands are well-developed and have intensive eccrine secretion. Comparative ultrastructural analysis of four diphyllobothriidean species shows similarity in the ultrastructure of microtriches and frontal glands in the plerocercoids of P. phocarum and Diphyllobothrium latum.
International Journal for Parasitology: Parasites and Wildlife , 2019
Plerocerci of the monotypic Paranybelinia otobothrioides were found parasitizing the subtropical neritic krill Nyctiphanes simplex in the Gulf of California, Mexico. The plerocerci were recovered from two microhabitats of the intermediate host, typically embedded inside the digestive gland (hepatopancreas) or rarely in the hemocoel. The morphology of the simple, single-layered blastocyst surrounding the entire scolex is unique within the Trypanorhyncha by having four large funnel-like pori or openings possibly with feeding and/or excretory function. One of the openings is located anteriorly and three at the posterior end. Scolex surface ultrastructure shows hamulate and lineate spinitriches covering the bothrial surface, capilliform filitriches at the anterior scolex end and on the scolex peduncle, and short papilliform filitriches on the long appendix. This pattern resembles that of species of the Tentaculariidae; but differs in that the hamulate spinitriches, which appear lineate at the bothrial margins, densely cover the entire distal bothrial surface. Tegumental grooves are present on the posterior bothrial margin, lacking spinitriches. Paranybelinia otobothrioides and Pseudonybelinia odontacantha share the following unique combination of characters: two bothria with free lateral and posterior bothrial margins, homeoacanthous homeomorphous armature, tegumental grooves, the distribution of the hamulate spinitriches, and the absence of prebulbar organs. Both genera infect euphausiids as intermediate hosts. Sequence data of the partial ssrDNA gene place Pa. otobothrioides sister to the family Tentaculariidae, and the Kimura two-parameters (K2P) distance between Pa. otobothrioides and species of the family Tentaculariidae ranged from 0.027 to 0.039 (44-62 nucleotide differences). These data suggest both species be recognized in a family, the Paranybeliniidae, distinct from, albeit as sister taxon to, the Tentaculariidae. High prevalence of infection (< 14%) and ontogenetic changes of Pa. otobothrioides support N. simplex as a required intermediate host and suggest a zooplanktophagous elasmobranch as final host in the Gulf of California.