A comparative study of the epidermis of the common carp and the three Indian major carp

A comparative study has been made of the mucogenic epidermis of the common carp, Cyprinus carpio var. communis, and the three Indian major carps, Catla catla, Labeo rohita and Cirrhina mrigala: on the basis of epidermis structural organization, these species are easily differentiated. The epithelial cells in the superficial layer, as in most fishes, show secretory activity, evidenced by positive histochemical reactions, which is high in C. carpio var. communis, moderate in C. catla and low in L. rohita and C. mrigala. The epithelial cells in the underlying two or three layers also give positive reactions, though their intensity is relatively weak. The mucous cells in C. carpio var. communis are distributed in large numbers arranged in several superimposed layers in the outer regions of the epidermis, whereas in C. catla they are fewer in number and are widely separated in the surface layers as well as in the deeper layers of the epidermis; in both species the mucous cells appear rounded, large, and open on the surface by wide pores. In contrast, in L. rohita and C. mrigala the mucous cells are smaller, restricted mainly to the superficial layer, close together in a single row, and open on the surface by narrow pores. The overall density of mucous cells in L. rohita and C. mrigala, as in C. catla, is much lower than in C. carpio var. communis. In the epidermis of C. carpio var. communis there are a large number of mucous cells, and the few club cells are restricted to the deeper layers. In contrast, in the epidermis of the three Indian major carp the overall density of the mucous cells is much lower and the club cells are very numerous. It is suggested that the high density of club cells compensates an overall low density of mucous cells as an adaptation for an effective defence mechanism. Increased mucus production in the epidermis of C. carpio var. communis, as evidenced by a large number of mucous cells in outer regions and high secretory activity of superficial layer epithelial cells, is associated with increased precipitation of mud held in suspension, needed as an adaptation to the species’peculiar bottom-scooping habits. The varied density of the taste buds in the epidermis of the four carp is associated with their feeding habits.     

Cell lineage of the midline cells in the amphipod crustacean Orchestia cavimana (Crustacea, Malacostraca) during formation and separation of the germ band

 Cell lineages of identified midline cells were traced in the amphipod Orchestia cavimana (Crustacea, Malacostraca) by in vivo labelling. Midline cells are a common phenomenon in the germ band of crustaceans and insects. Studies in midline cells of Drosophila showed an origin from separate, paired anlagen and a differentiation into three types of cells. The in vivo labelling of midline cells of Orchestia demonstrates that they originate from the same material as the neural and epidermal ectoderm, divide in a stereotyped cell division pattern and give rise to at least two different types of cells. During the following evolutionarily derived mode of germ band elongation in Orchestia, a morphogenetic process is intercalated that separates germ band halves. On the level of single cells, it can be shown that midline cells are the only ectodermal cells that bridge the large distance between the separated parts. The cells are stretched extensively but do not proliferate. Comparing the midline cells of Orchestia with non-malacostracan crustaceans and insects, the results favour the hypothesis that midline cells are a distinct population of cells homologous in crustaceans and insects. Received: 24 July 1998 / Accepted: 13 October 1998     

Ultrastructure of the taste disc in the red-bellied toad Bombina orientalis (Discoglossidae,Salientia)

The taste disc of the red-bellied toad Bombina orientalis (Discoglossidae) has been investigated by light and electron microscopy and compared with that of Rana pipiens (Ranidae). Unlike the frog, B. orientalis possesses a disc-shaped tongue that cannot be ejected for capture of prey. The taste discs are located on the top of fungiform papillae. They are smaller than those in Ranidae, and are not surrounded by a ring of ciliated cells. Ultrastructurally, five types of cells can be identified (mucus cells, wing cells, sensory cells, and both Merkel cell-like basal cells and undifferentiated basal cells). Mucus cells are the main secretory cells of the taste disc and occupy most of the surface area. Their basal processes do not synapse on nerve fibers. Wing cells have sheet-like apical processes and envelop the mucus cells. They contain lysosomes and multivesicular bodies. Two types of sensory cells reach the surface of the taste disc; apically, they are distinguished by either a brush-like arrangement of microvilli or a rod-like protrusion. They are invaginated into lateral folds of mucus cells and wing cells. In contrast to the situation in R. pipiens, sensory cells of B. orientalis do not contain dark secretory granules in the perinuclear region. Synaptic connections occur between sensory cells (presynaptic sites) and nerve fibers. Merkel cell-like basal cells do not synapse onto sensory cells, but synapse-like connections exist between Merkel cell-like basal cells (presynaptic site) and nerve fibers.     

Adrenocorticotrophin secreting cells in the hypophysis of the brown spiny mouseMus platythrix (Bennett)

Adrenocorticotrophin secreting cells are identified in the hypophysis of the brown spiny mouseMus platythrix by conventional methods of light microscopy. Quantitative data showed that certain smaller acidophilic cells in thepars distalis, under conditions provoking their hypersecretion such as unilateral adrenalectomy and metopirone treatment, increase in number and size from the pre-existing corticotrophs. There is no evidence for the transmigration of these cells from the chromophobes, basophils or any other cell type. Thepars intermedia revealed two types of cells of which the type II cells are histochemically identical to adrenocorticotrophin secreting cells of thepars distalis     

Unusual Leucophore‐Like Cells Specifically Appear in the Lineage of Melanophores in the Periodic Albino Mutant of Xenopus laevis

In the periodic albino mutant (a^p/a^p) of Xenopus laevis, peculiar leucophore‐like cells appear in the skins of tadpoles and froglets, whereas no such cells are observed in the wild‐type (+/+). These leucophore‐like cells are unusual in (1) appearing white, but not iridescent, under incident light, (2) emitting green fluorescence under blue light, (3) exhibiting pigment dispersion in the presence of α‐melanocyte stimulating hormone (αMSH), and (4) containing an abundance of bizarre‐shaped, reflecting platelet‐like organelles. In this study, the developmental and ultrastructural characteristics of these leucophore‐like cells were compared with melanophores, iridophores and xanthophores, utilizing fluorescence stereomicroscopy, and light and electron microscopy. Staining with methylene blue, exposure to αMSH, and culture of neural crest cells were also performed to clarify the pigment cell type. The results obtained clearly indicate that: (1) the leucophore‐like cells in the mutant are different from melanophores, iridophores and xanthophores, (2) the leucophore‐like cells are essentially similar to melanophores of the wild‐type with respect to their localization in the skin and manner of response to αMSH, (3) the leucophore‐like cells contain many premelanosomes that are observed in developing melanophores, and (4) mosaic pigment cells containing both melanosomes specific to mutant melanophores and peculiar reflecting platelet‐like organelles are observed in the mutant tadpoles. These findings strongly suggest that the leucophore‐like cells in the periodic albino mutant are derived from the melanophore lineage, which provides some insight into the origin of brightly colored pigment cells in lower vertebrates.     

Immunocytochemical study on the triple origin of the sphincter iris in the chick embryo

The ontogenic development of the sphincter iris has been studied by immunocytochemistry and standard staining on chick embryos from stage 25 HH to the time of hatching. We have used the monoclonal antibody 13F4, a highly specific marker of muscular cells. We have observed three different regions in the iris. In the pupillary region, immunoreactive cells are in continuous contact with the inner epithelium of the pupillary margin. In the intermediate region, the outer epithelium forms buds of pigmented cells that emigrate toward the stroma. In this epithelium cells that are totally or partially unpigmented exist, and they are 13F4 positive. In the sphincter we have observed 13F4 positive cells with melanin granules. In the ciliary region, the immunoreactivity appears in dispersed mesenchymal cells. The present findings are consistent with a triple origin of the sphincter iris in the chick embryo. This muscle is derived from the inner epithelium of the pupillary margin, the intermediate region of the outer epithelium, and from the mesenchymal cells. The cells of the inner epithelium of the pupillary margin are differentiated into smooth muscle cells, and the remaining cells form striated muscle cells. Received: 17 March 1999 / Accepted: 17 May 1999     

Immunohistochemical identification of the cytoskeletal elements in the notochord cells of bony fishes

The medulla of the unconstricted notochords of the shortnose sturgeon, Acipenser brevirostratus, and African lungfish, Protopterus annectens, and the cellular component of the intervertebral joint tissue of the teleost fish, Perca flavescens, are comprised of cells with a large central vacuole. Previous studies on the fine structure of this tissue revealed that the cytoplasm surrounding these vacuoles consists of 10-nm-diameter intermediate filaments. Since in mammals there are a large number of tissue-specific types of intermediate filaments, this study uses antibodies to mammalian intermediate filaments to determine the type of filaments present in the notochord cells of bony fishes. Positive labeling using a polyclonal antibody to human skin keratins is observed in the cytoplasm of the notochord cells in the intervertebral tissues of Perca. These tissues are also probed with the AE series antibodies that label keratins found in mammalian epithelial cells. In both Protopterus and Acipenser the peripheral cytoplasm of the notochord cells is labeled with all three AE antibodies. In Perca only the AE3 antibody probe produces positive staining. These staining patterns are consistent with previous studies on the localization of cytokeratins in fish tissues and indicate that the intermediate filaments in the notochord cells of bony fishes are immunologically similar to the mammalian keratins. J. Morphol. 236:105–116, 1998. © 1998 Wiley-Liss, Inc.     

A simulated human fovea: the L-type cells of the magnocellular pathway

A static model of the human fovea is used to study the properties of L-type amacrine cells (L-AC) that link the cones with the magnocellular pathway. Sine and square wave gratings are used to obtain response spectra of L-ACs and C-type bipolar cells (C-BC); these two types of cells are compared in both central fovea, where there are no blue-sensitive cones and parafovea, where the blue-sensitive cones represent 12% of the population. Three dispersion conditions are used: no, aberration-free, and chromatic dispersions. The abilities of L- and C-type cells to resolve a twobar image are also compared. The findings are consistent with the magnocellular pathway having higher contrast luminance and chromatic sensitivity gains than those of the parvocellular pathways, but under specified conditions. And under specified conditions the findings are also consistent with both pathways being involved in the detection of chromatic and achromatic signals. Nevertheless when all factors are considered the parvocellular pathway appears to be involved with fine spatial and chromatic tuning while the magnocellular pathway appears to deal with coarser tuning.     

A mutant affecting the crystal cells inDrosophila melanogaster

Summary Black cells (Bc, 2-80.6±) mutant larvae ofDrosophila melanogaster have pigmented cells in the hemolymph and lymph glands. In this report we present evidence that these melanized cells are a mutant form of the crystal cells, a type of larval hemocyte with characteristic paracrystalline inclusions.Bc larvae lack crystal cells. Furthermore, the distribution pattern of black cells inBc larvae parallels that of experimentally-blackened crystal cells in normal larvae (phenocopy).InBc/Bc zygotes black cells appear during mid embryonic development but inBc ⁺/Bc zygotes pigmented cells are not found until late in the first larval instar.Crystal cells are present in the heterozygous larvae until this time, and paracrystalline inclusions can be seen in some of the cells undergoing melanization in these larvae.The rate of phenol oxidase activity inBc ⁺/Bc larval cell-free extracts is less than half that ofBc ⁺/Bc ⁺extracts whereas enzyme activity is undetectable inBc/Bc larvae. We propose that theBc ⁺gene product is required for maintaining the integrity of the paracrystalline inclusions; inBc/Bc larvae either the product is absent or nonfunctional so an effective contact between substrate and enzyme results in melanization of the cells.Phenol oxidase itself is either destroyed or consumed in the melanization process accounting for the absence of enzyme activity inBc/Bc larvae. These studies confirm that the crystal cells store phenolic substrates and are the source of the hemolymph phenol oxidase activity in the larva ofD. melanogaster.     

The ultrastructure of the vomero-nasal organ in reptilia

Summary There are three types of cells in the vomero-nasal organ of Lacerta sicula and Natrix natrix: receptor cells, supporting cells and basal cells. The receptor cells bear microvilli and no cilia. In Lacerta centrioles are lacking, indicating that the ciliary apparatus can have no essential significance in the transducer process. In Natrix centrioles occur in the deeper dendritic region. The structural constituents of the dendrites are mitochondria, microtubules and characteristic vesicles the properties of which are described. The perikarya which have uniform structure send off axons of about 0.2 diameter. The supporting cells show signs of a very moderate secretory activity, which is different among the species investigated. The microvilli of the supporting cells are not distinguishable from those of the receptor cells. The dendrites of the latter are completely isolated by the apical parts of the supporting cells. The sheet-like processes of the supporting cells contain strands of tonofilaments and do not cover the perikarya of the receptor cells completely. Thus adjacent sensory cells or dendrites and sensory cells are separated among themselves only by the normal intercellular space. The ratio of sensory cells to supporting cells is about 71. The basal cells resemble the supporting cells and replace these in the lower portion of the epithelium. The typical cellular junctions between sensory cells and supporting cells are described. There are no true tight junctions in the vomero-nasal sensory epithelium, and they are most probably absent from the nasal mucosa too. This absence would seem to indicate special conditions for cellular communication and the accessibility of the intercellular space for certain molecules. There is no sign of regeneration of sensory cells. Both immature blastema cells and degenerating receptor cells are not discernible.     

Allatostatin-like peptide in the brain-retrocerebral complex of the earwig Labidura riparia: cyclic variations related to the reproductive cycle

Summary

A polyclonal antibody raised against allatostatin-3 of Blattella germanica (BLAST-3) has been used to immunolocalize allatostatin-like peptides in the brain-retrocerebral complex of Labidura riparia adult females. Strongly stained immunoreactive cells are observed in the pars intercerebralis (14 cells) and mainly in the pars lateralis (32 cells). Fibres leading to the corpus allatum are also stained. In the deutocerebrum, one cell is immunostained at the root of each antennal nerve. In the tritocerebmm two cells in each brain hemisphere are weakly immunostained. During the reproductive cycle, these cells and their axons show immunoreactivity at previtellogenic, ovulation and ovarian arrest periods. During vitellogenesis, immunoreactivity is restricted to only four perikarya in the pars intercerebralis.

When young vitellogenic females are injected with 20-hydroxyecdysone (20E), which inhibits vitellogenesis, full immunoreactivity reappears, suggesting sensibility of these cells to 20E as is expected for a negative feed-back loop (Sayah et al., 1995).

These results show that BLAST-3-like material is produced periodically in Labidura in correlation with low levels of juvenile hormone and the absence of vitellogenesis. This study contributes to provide information on the degree of homology of allatostatins across various insects.     

Cytological observations on the so-called neoblasts in the serpulid Spirorbis

The purported “neoblasts” of the serpulid Spirorbis have been studied in Spirorbis (Paradexiospira) vitreus and Spirorbis (Laeospira) borealis at both the light and electron microscopic levels. These perivasal cells occur in greatest abundance around the ventral blood vessel of the achaetous region. In light microscope preparations, the perivasal cells are intensely basophilic, containing basally situated nuclei, and relatively large nucleoli. The fine structure of the perivasal cells reveals that they contain an abundance of rough endoplasmic reticulum, well-developed Golgi complex, heterogeneous dense bodies, and cytolysomes. The respiratory pigment chlorocruorin, which has a diameter of about 230 Å and is believed to be composed of two superimposed hexagonal components, has been localized within: cisternae of the rough endoplasmic reticulum, elements of the Golgi complex, and membrane-bounded vesicles at the base of the perivasal cells. Evidence is advanced which strongly suggests that molecules of chlorocruorin are transported from the perivasal cells into the lumen of the vessel by reverse pinocytosis. It is concluded that whatever other functional role(s) the perivasal cells of Spirorbis may have, a major function is the synthesis and secretion of chlorocruorin. Whether the perivasal cells can be considered to be pluripotent is discussed.     

Ultrastructure of the coelomic lining in the podium of the starfish Stylasterias forreri

Summary Ultrastructural examination of the podium of the asteroid echinoderm Stylasterias forreri reveals that cells of the coelomic epithelium and cells of the retractor muscle are, in fact, components of a single epithelium. The basal lamina of this unified epithelium adjoins the connective tissue layer of the podium.The principal epithelial cells in the coelomic lining are the flagellated adluminal cells and the myofilament-bearing retractor cells. Adluminal cells interdigitate extensively with each other and form zonular intermediate and septate junctions at their apicolateral surfaces. The adluminal cells emit processes which extend between the underlying retractor cells and terminate on the basal lamina of the epithelium. Retractor cells exhibit unregistered arrays of thick and thin myofilaments. The periphery of the retractor cell is characteristically thrown into keel-like folds which interdigitate with the processes of neighboring cells. Specialized intermediate junctions bind the retractor cells to each other and anchor the retractor cells to the basal lamina of the epithelium. The retractor cells are not surrounded by external laminae or connective tissue envelopes.It is concluded that the coelomic lining in the podium of S. forreri is a bipartite epithelium and that the retractor cells of the podium are myoepithelial in nature. There are no detectable communicating (gap) junctions between the epithelial cells of the coelomic lining.This investigation was supported by general research funds from the Department of Anatomy of the University of Southern California (R.L.W.) and by Research Operating Grant A0484 from the Natural Sciences and Engineering Research Council of Canada (M.J.C.). Ms. Aileen Kuda and Mr. Steve Osborne provided technical assistance. A portion of this study was conducted at the Friday Harbor Laboratories of the University of Washington, and the authors gratefully acknowledge the cooperation and hospitality of the Director, Dr. A.O. Dennis Willows     

Ultrastructure of neuroendocrine cells in the lungs of three anuran species

Neuroendocrine cells in the lungs of three species of anurans, Bombina variegata, Bufo bufo and Bu. viridis, occur both as single cells and in the form of neuroepithelial bodies. Neuroendocrine cells are covered by ciliated cells or pneumocytes, which separate them from the lumen of the lung. Neuroepithelial bodies are dispersed in the apical part of the main septa of lungs of Bo. variegata and Bu. bufo or are situated on special protrusions of septa in the lungs of Bu. viridis. Neuroepithelial bodies are innervated by intraepithelial nerve endings of afferent and efferent types.     

Submicroscopic structure of the membranous labyrinth

Summary Investigations were performed by light and electron microscope on the submicroscopic structure of the epithelium of Corti's organ in the white rat.Morphological and structural differences between the inner hair cells and the outer hair cells are revealed.The inner hair cells are closely inter-related with the inner supporting cells and have a polyhedral shape, whereas the outer hair cells look like cylinders and are surrounded by an intraepithelial fluid.The structural peculiarities consist of differences in the dimensions of the hairs, in the arrangement of cytoplasmic organoids and in the aspect of the receptoneural junction. In both sensory hair cells 4 zones of different structure can be distinguished from the surface inwards: apical zone, intermediate zone, perinuclear zone and receptoneuronal junction. The functional value of these different zones is discussed and compared with what has been demonstrated in other receptors.The pillar cells and the Deiters' cells are supporting cells which have a filamentous skeleton, composed of submicroscopic individual filaments. These filaments have a diameter of about 215 Å and present some analogies with the tonofilaments of the stratified squamous epithelium. The filaments are arranged differently in the pillar cells and in the Deiters' cells. Possible functional differences between these patterns are discussed.The reticular membrane is not an extracellular cuticle. It consists of intracellular cementitious material (like the terminal bars of the epithelial cells).The Hensen's and Claudius cells, the Böttcher's cells, the inner supporting cells, the inner and outer spiral sulcus cells are regular prismatic cells with few endoplasmic organoids and without filaments.This work is dedicated to the memory of the late Prof. L. Pietrantoni.     

Receptive field mechanisms of ganglion cells in the cat retina

On the basis of anatomical and physiological results of the vertebrate retina, a method is proposed for analysing the respective fields of ganglion cells in the cat retina. In the model, we assume the following: (a) Ganglion cells receive their input from bipolar and/or amacrine cells. (b) The nonlinearity of ganglion cell responses is due to the activities of transient type amacrine cells. The method has been proved to be effective. According to the results of this investigation, the receptive field properties of X type and Y type ganglion cells are heterogeneous. Thus, it may be considered that their receptive fields consist of center and surround mechanisms. The receptive field properties of X-cells are almost linear and the X-cells seem to receive most of their input from bipolar cells. On the other hand, the ones of Y-cells are highly nonlinear. Consequently, it is conceivable that the Y-cells receive their input mainly from transient type amacrine cells.     

Structural organization of ovarian follicle cells in the cotton bug (Dysdercus intermedius) and the honeybee (Apis mellifera)

Summary The somatic epithelia of Dysdercus and Apis follicles were analyzed by electron microscopy, and the patterns of F-actin and microtubules were studied by fluorescence microscopy. The epithelia in both species differ considerably in shape and in the organization of the cytoskeleton. During previtellogenic stages, the epithelium consists of columnar-shaped cells with small (Dysdercus) or no (Apis) lateral intercellular spaces. During vitellogenesis, the follicle cells round up; the intercellular spaces increase in size in Dysdercus follicles, whereas in Apis follicles they remain small. Along the basal surface of the follicle cells, there are conspicuous parallel bundles of microfilaments perpendicular to the anteroposterior axis of the follicles. In the honeybee, these microfilament bundles are present in long filopodia, most of which are embedded in thickenings of the basement membrane and extend over the surfaces of neighbouring cells. In the cotton bug, the basal surface of the follicle cells is thrown into parallel folds. The microfilament bundles are located just underneath the cell membrane where the folds contact the basement membrane. In the polar regions of the Dysdercus follicle, the epithelial cells become flat and adhere to each other without forming intercellular spaces. The basement membrane is particularly thick in the polar areas; this has also been observed in Apis follicles around the intercellular bridge connecting oocyte and nurse cells.     

Clonal analysis of the blastoderm anlage of the Malpighian tubules in Drosophila melanogaster

Summary Genetically marked maroon-like (mal) clones were induced by mitotic recombination with X-rays at the blastoderm stage in mal/mal ⁺ heterozygotes and were analysed in differentiated Malpighian tubules (MT). Marked cells were not confined to single anterior (MA) or posterior (MP) tubules, but were distributed among the four tubules. About 70% of the clones with two or more cells were fragmented, i.e. mal cells were separated by wild-type cells. Since the clones contain, on average, 6 cells and the differentiated MT consist of 484 cells (2 × 136 MA cells, 2 × 106 MP cells), we estimate that there are about 80 cells in the blastoderm anlage which on average pass through two to three mitoses. With increasing radiation doses (254 R, 635 R, 1270 R) a linear increase in clone frequency is observed. The mean sizes and size distributions of clones, however, remain unchanged. Since the increasing radiation dose also results in fewer differentiated Malpighi cells, we assume that regeneration does not occur. Therefore, size distributions of marked clones presumably represent real mitotic patterns in normogenesis. We suggest that essentially three successive mitoses take place, with a decreasing fraction of cells showing mitotic activity. Only a small fraction of cells goes through a fourth or even a fifth mitosis. Marked non-Minute clones induced in Minute heterozygotes are more frequent, but are not larger than non-Minute clones in wild-type background. Therefore, compartment boundaries cannot be recognized by this method. However, frequencies of marked cells found simultaneously in MA and MP pairs or in several single tubules of the same individuals are significantly higher than frequencies of multiple recombination events predicted by the Poisson distribution. From this, we conclude that neither the MA pair nor the MP pair nor single tubules represent compartments of the MT anlage.On the occasion of his 60th birthday, this work is dedicated to Prof. Dr. H.J. Becker, who initiated cell lineage studies in Drosophila     

Stellate cells in the Malpighian tubules of Drosophila hydei and D. melanogaster larvae (Insecta, Diptera)

 The Malpighian tubules of Drosophila hydei and D. melanogaster larvae are composed of two types of cell, principal cells and stellate cells. In the anterior larval Malpighian tubules approximately 26% (D. hydei) and 18% (D. melanogaster), respectively, of all cells are stellate cells. In the larvae of D. melanogaster, the stellate cells are fenestrated and the hemolymph space and tubule lumen are separated only by the basal lamina. Injection of dyes into the hemolymph did not indicate any facilitated transfer of substances through the fenestrated cells. The principal cells of the distal segment are carbonic anhydrase positive indicating transport activity, whereas the stellate cells lack this enzyme. In the stellate cells of the transitional segment, the sodium content is strikingly high in comparison to the neighbouring principal cells and lumen where no sodium was detected. This finding indicates that stellate cells reabsorb sodium as supposed earlier in 1969 by Berridge and Oschman (Tissue Cell 1:247–272). Accepted: 12 February 1999