General Integument Research Articles

Expression of 5-HT1A receptors in skin of rats under dark deprivation

The aim of the investigation was to study the dynamics of serotonin 5-HT1A receptor expression in the skin of white male rats under dark deprivation. Material and methods. 20 outbred male rats 170–220 grams by mass were used in the experiment. The animals were divided into 2 groups. The intact group included animals under standard fixed lighting conditions (12 h light / 12 h dark). The experimental group consisted of animals with simulation of dark deprivation under conditions of round-the-clock illumination (24 h light). The duration of the study was 21 days. The object of the study was the skin of rats. Using immunohistochemistry, the features of the expression of 5-HT1A receptors were studied. Results. A strong circadian dependence of the expression of serotonin 5-HT1A receptors in the general integument has been established. In the cells of the epidermis, sebaceous glands and hair follicles throughout the experiment, a decrease in the proportion of immunopositive cells was observed with a simultaneous increase in the positivity of 5-HT1A expression. Conclusion. Throughout the experiment, a strong circadian dependence of the expression of serotonin 5-HTR1A receptors in the general integument was expressed, which, apparently, determines the mechanism of an adequate response to the destabilization of circadian rhythms.

Features of the expression of melatonin MT1 receptors in the general cover of rats caused by light deprivation

Background. It has now been established that any change in the synchronized work of the circadian clock leads to a disruption of the body's regulatory systems, which consists in the development of metabolic disorders and tissue damage. Objective: to study the dynamics of the expression of the MT1 melatonin receptor in the skin of white male rats under light deprivation. Methods. In this work, using immunohistochemistry, the features of the expression of receptors for melatonin (MT1) were studied. The experiments were performed on outbred male rats weighing 170-220 g, which were divided into 2 groups; intact - animals kept under standard fixed lighting conditions (12 h light / 12 h dark); Group 2 - animals with simulated light deprivation in conditions of round-the-clock darkness (24 hours of darkness). Results. A strong circadian dependence of the expression of MT1 melatonin receptors in the general integument was established. In the cells of the epidermis and sebaceous glands, by the 14th day, MT1 expression significantly decreased, which then sharply increased by the 21st day. In the keratinocytes of the epidermis, a wavelike character of changes in indicators is noted throughout the study: an increase (7th day) - a decrease (14th day) - a sharp increase (21st day). Conclusion. Initially, light deprivation leads to a decrease in the number of immunopositive cells, and then their level increases compensatory, which is one of the manifestations of the body's adaptation mechanisms to chronodestruction.

The epidermis cells of mandible teeth in the terrestrial isopod Porcellio scaber: Differentiations for mineralisation with calcium phosphate and carbonate

Generally, the mineralisation of the crustacean cuticle occurs when the cuticle has expanded after moulting. However, in the partes incisivae of Porcellio scaber, cuticle mineralisation with calcium phosphate already occurs before the moult. We investigated the ultrastructure and distribution of organelles within the epidermis cells and searched for calcium-containing organelles using EDX and EFTEM analysis. We found two different cell types. Calcium carbonate-secreting C-cells, which resemble the epithelial cells of the general integument, and the P-cells, which, as an unusual feature, have cell extensions up to 400 μm long. During secretion of the partes incisivae, these extensions end at the unmineralised tip and the phosphate-containing middle region. Their cell bodies contain most of the mitochondria located in basal folds and a high amount of endoplasmic reticulum. The cell extensions contain many microtubules, endoplasmic reticulum, large and small vesicles and densely stained rod-shaped cisternae. The rod-shaped cisternae and the endoplasmic reticulum contain calcium. During cuticle mineralisation, vesicles, which probably belong to the endo-lysosomal system, contain calcium and phosphorus. They occur at some distance and close to the cuticle. The mineral in these vesicles has a similar composition to that within the cuticle, suggesting that they play a role in cuticle mineralisation.

Effect of exogenous melatonin and flaxseed oil on the expression state of MT1 receptors in rat skin under light deprivation

Most of the skin cells have their own autonomous functional circadian system, which is able to control physiological and biochemical processes in the general integument. A special role in these processes is assigned to the “clock” hormone of the pineal gland, melatonin, which acts on target cells through specific receptors (MT1, MT2, MT3 and RORα). Any disturbance of circadian rhythms can lead to rearrangements (disturbances) in the receptor apparatus of the cells of the general cover, which require a certain correction. Consequently, there is a need to search for effective and reliable drugs that will prevent the negative consequences caused by chronodestruction. In the present work, we studied the effectiveness of the effect of exogenous melatonin and flaxseed oil on the expression of MT1 receptors in the general coat of rats under light deprivation. An experimental study was carried out on 130 white outbred male rats (170-220 g), which were randomly divided into 5 groups: intact, light deprivation animals, light deprivation animals, which were injected intragastrically with flaxseed oil and melatonin. On days 7, 14 and 21, histological material was taken (fragments of the skin of the interscapular region of the back). For immunohistochemical studies, serial sections were stained using MTNR1A polyclonal antibodies. For morphometric data analysis, the Image Scope Color and ImageJ computer programs were used. All statistical data processing was performed using the Statistica 10.0 software. Differences were considered significant at a significance level of less than 0.01 (p <0.01). In the course of the experiment, it was found that light deprivation contributes to a change in the activity of expression of the MT1 melatonin receptors in the epidermis, sebaceous glands and hair follicles. Studies have shown that the administration of flaxseed oil, melatonin, and their combination to rats with desynchronosis is accompanied by the leveling of the adverse effect of desynchronosis on the studied parameters of MT1 receptors. The most pronounced corrective effect on the expression of MT1 receptors is observed with the introduction of exogenous melatonin on the 21st day of the experiment.

Silicification of the medial tooth in the blue crab Callinectes sapidus.

Observations of cuticular structures mineralized with silica within the Crustacea have been limited to the opal teeth of copepods, mandibles of amphipods, and recently the teeth of the gastric mill in the blue crab Callinectes sapidus. Copepod teeth are deposited during premolt, with sequential elaboration of organic materials followed by secretion of silica into the tooth mold. The timing of mineralization is in stark contrast to that of the general integument of crustaceans in which calcification is completely restricted to the postmolt period. To determine the timing of molt-related deposition and silicification of the teeth of the gastric mill, the medial tooth of the blue crab C. sapidus was examined histologically and ultrastructurally across the molt cycle. Histological data revealed deposition of the organic matrix of the epicuticle and exocuticle during premolt. No evidence of postmolt changes in the thickness of the epicuticle and exocuticle, or any deposition of endocuticle, was observed. Scanning electron microscopy revealed degradation of the outer surface of the old tooth during premolt. During premolt, epithelial structures resembling papilla appeared to secrete a fibrous web that coalesces to become the matrix of the new tooth. Semi-quantitative elemental analyses indicated simultaneous deposition of silica and organic matrix, and demonstrated a homogeneous distribution of silicon throughout the epicuticle of the tooth at all stages. However, there is evidence of deposition (presumably silicification) during postmolt as spaces between the papillae become filled in. Thus, the pattern and timing of deposition and silicification of the tooth are different from both teeth of copepods and the general exoskeleton of decapods, and may facilitate rapid resumption of feeding and consumption of the exuvia in early postmolt. J. Morphol. 277:1648-1660, 2016. © 2016 Wiley Periodicals, Inc.

Unusual way of feeding by the deutonymph of Neottialges evansi (Actinotrichida, Astigmata, Hypoderatidae), a subcutaneous parasite of cormorants, revealed by fine structural analyses.

The parasitic deutonymphs of hypoderatid mites live within the subcutaneous layer of their avian hosts, where they become greatly engorged despite not having functional mouthparts. The method by which they take up nutrients has been mysterious up to now. Here, we report on the morphology of hypoderatid deutonymphs using scanning and transmission electron microscopy and describe structures that may resolve the mystery. The deutonymph of Neottialges evansi (Hypoderatidae) from the cormorant Phalacrocorax carbo is a simply organized stage lacking both mouthparts and a functional foregut. The structure of midgut and hindgut indicate that they are not capable of processing food. The midgut consists of highly branching flat cells and rarely shows a lumen. Almost the entire space between integument, gut remnants and other organs (synganglion, developing gonads) is filled by huge cells containing protein and glycogen granules and numerous lipid inclusions. The anal opening is minute. The structure of the cuticle and epidermis suggests that nutrients are not absorbed through the general integument. Thus the two main existing hypotheses about feeding modes in hypoderatid deutonymphs, anal vs. integumentary food absorbtion, are not supported. We suggest instead that two pairs of genital papillae showing peculiar microanatomical features are actively involved in movement of liquid materials between host and mite and most probably are the nutrient-intake organs. J. Morphol. 277:1368-1389, 2016. © 2016 Wiley Periodicals, Inc.

First evidence of unicellular glands in the general epidermis of terrestrial reptiles

The general integument of reptiles is traditionally defined as being dry, but we report here the discovery of unicellular mucoid glands (UCMG) in the dorsal skin of lizards of the genus Phelsuma (Gekkonidae). To this end, the skin of these lizards and of some others for comparison was studied by scanning electron microscopy and transmission electron microscopy. These photographs showed that the development and function of the UCMGs are related to the skin's sloughing cycle. The UCMGs differentiate at scattered locations from Oberhäutchen cells of the inner (new) epidermal generation, above the differentiating beta-keratin layer. While the inner generation matures, the UCMG increases in size; unlike the surrounding Oberhäutchen cells, it does not develop the spinules that characterize gecko skin. When, upon sloughing, the inner generation becomes the new outer generation, and the Oberhäutchen forms the skin surface, the UCMGs, several per scale, dot the surface as mucus-inflated "blebs" projecting from the surrounding spinulate Oberhäutchen, each nesting in a shallow pit of the underlying beta-keratin. On the surface, the UCMGs rupture and the mucus appears to dissipate in cords, flowing over the tips of the spinules, and incorporating minute foreign bodies. It is concluded that, due to the low wettability of the spinulate surface (derived from the spacing of the spinules), the cords brush off easily, with the mucus functioning as a cleaning agent.

Testicular and androgen dependence of skin gland morphology in the anurans, Xenopus laevis and Rana pipiens.

In anuran amphibians, there is increasing evidence that exocrine glands dispersed throughout the general integument are secondary sex characters (SSC). Following the recent discovery of sexually dimorphic "breeding glands" in the dorsum of male Rana pipiens, we studied the effects of castration and testosterone treatment on the dorsal skin glands of male Xenopus laevis and R. pipiens to determine whether the dorsal breeding glands, or any other dorsal skin glands, are androgen dependent. The dorsal skin glands of X. laevis were unaffected by androgen status. By contrast, in R. pipiens, breeding, mucous, and seromucous glands responded to testosterone stimulation. Mucous glands were significantly (P < 0.05) larger in testosterone-treated frogs than in castrates. There was a large, but statistically insignificant, increase in the size of the dorsal breeding glands. Testosterone treatment also increased the epithelial cell height of breeding and seromucous glands (P < 0.05). In the skins of castrated and testosterone-treated frogs, there was a reciprocal relationship between the abundance of seromucous and breeding glands: in castrates, seromucous glands were abundant and breeding glands virtually absent, whereas in testosterone-treated frogs, breeding glands were abundant and seromucous glands less common. The total number of the two gland types was similar in both treatment groups. Glands that appeared to be intermediate in form between seromucous and breeding glands were observed in some frogs. These data suggest that seromucous glands may be the regressed form of breeding glands in the dorsal skin of R. pipiens and that the dorsal skin of R. pipiens is a SSC. © 1993 Wiley-Liss, Inc.

Pigment cell refugia in homeotherms--the unique evolutionary position of the iris.

Homeotherms are generally considered to lack classical active dermal pigment cells (chromatophores) in their integument, attributable to the development of an outer covering coat of hair or feathers. However, bright colored dermal pigment cells, comparable to chromatophores of lower vertebrates, are found in the irides of many birds. We propose that, because of its exposed location, the iris is an area in which color from pigment cells has sustained a selective advantage and appears to have evolved independently of the general integument. In birds, the iris appears to have retained the potential for the complete expression of all dermal chromatophore types. Differences in cell morphology and the presence of unusual pigments in birds are suggested to be the result of evolutionary changes that followed the divergence of birds from reptiles. By comparison, mammals appear to have lost the potential for producing iridophores, xanthophores, or erythrophores comparable to those of lower vertebrates, even though some species possess brightly colored irides. It is proposed that at least one species of mammal (the domestic cat) has recruited a novel iridial reflecting pigment organelle originally developed in the choroidal tapetum lucidum. The potential presence of classical chromatophores in mammals remains open, as few species with bright irides have been examined.

Nuttalliella namaqua(Acarina: Ixodoidea: Nuttalliellidae): the female morphology in relation to the families Argasidae and Ixodidae: A review

Abstract The external and internal morphology of the female nuttallielid tick Nuttalliella namaqua is reviewed in relation to argasids and ixodids. External characteristics of Nuttalliellidae relating to Argasidae are the general integument structure, unarmed coxae, hypostome structure, and absence of porose areas. The anteriorly arised capitulum, presence of pseudoscutum (? true scutum), and structural similarity of dorsal and ventral integuments are ixodid characteristics. Unique features to Nuttalliellidae are 3-segmented palpi, ball and socket joints, and fenestrated spiracular plates.

Osmoregulation in Crocodilians

Recent crocodilians live primarily in freshwater habitats. However two species ( Crocodylus acutus and C. porosus ) are estuarine specialists; two others ( C. niloticus and C. johnstoni ) that are primarily found in fresh water, have estuarine populations. Routes of uptake of water and sodium include drinking, feeding and associated incidental drinking, and integumental and buccal diffusion. Routes of loss include faeces-cloacal fluid, lingual salt glands, integumental and buccal diffusion, and respiratory loss. The least understood route of salt and water exchange is that of the oral and buccal epithelia, which are much more permeable to water and sodium than the general integument. The freshwater alligator ( Alligator mississippiensis ) osmoregulates in a manner typical for an amphibious reptile. Body sodium turnover is low and the general integument is quite low in permeability to sodium. Water turnover is more rapid (in terms of molar exchange) but still relatively low for an aquatic reptile. Most water exchange occurs across the integument and buccal epithelia. The presence of lingual salt glands in freshwater crocodilians remains enigmatic, as does the failure of these exocrine glands in estuarine species to respond to saline loading. Secretion does occur after injection of the parasympathetic stimulant methacholine chloride. The “salt water crocodile” ( C. porosus ) possesses a suite of osmoregulatory adaptations similar to those found in other estuarine reptiles. Water and sodium balance are maintained primarily by an extremely low general permeability to sodium, by economies in water loss, and by excretion of excess sodium by the lingual salt glands. Further work is needed to examine newly hatched C. porosus , and the possibility of ontogenetic change in lingual gland function in C. acutus. The importance of incidental drinking of sea water during feeding (recently discovered in turtles) needs to be evaluated in crocodilians. The use of osmoregulatory data in interpretation of the evolutionary history of the genus Crocodylus needs to be viewed with caution. The hypothesis that all species of Crocodylus originated from the transoceanic migration of a saline-tolerant form may not be the most parsimonious explanation.

Calcitonin-gene-related-peptide-immunoreactive innervation of the rat head with emphasis on specialized sensory structures.

The distribution of calcitonin-gene-related peptide-like immunoreactivity (CGRP-IR) was studied in sections of decalcified rat head and selected whole-mount preparations in order to address the complex peptidergic innervation patterns in peripheral cephalic specialized zones and to examine neuronal ganglia in situ. Labeled neuron somata in trigeminal, glossopharyngeal, and vagal ganglia comprised a large proportion of small to medium size type B ganglion cells. Parasympathetic ganglia (ciliary, otic, sphenopalatine, submandibular) revealed a small population of labeled somata and numerous perisomatic IR axons, whereas sympathetic ganglion cells (superior cervical) were devoid of label though richly innervated by perisomatic IR axons. The gustatory geniculate ganglion contained only a few labeled neurons and axons. Coarse peripheral CGRP-IR axons were traced to skeletal muscle motor end plates (e.g., lingual, tensor tympani, etc.), and thin sensory axons most densely innervated the cornea, iris, general integument, all mucosal epithelia lining the tympanic, nasal, sinus and oropharyngeal cavities, and the cerebral meninges. Blood vessels, glands, ducts, and their orifices were often heavily innervated, and specific specializations and exceptions are discussed. Distinctive patterns of IR innervation characterized the various specialized sensory systems, including 1) cochlear and vestibular hair cells; 2) lingual, palatal, oropharyngeal, and laryngoepiglottal taste buds; 3) main olfactory epithelium and axons projecting to glomeruli in specific sectors of main olfactory bulb; 4) septal-olfactory organ; 5) vomeronasal organ; and 6) the nervus terminalis system. Secretory epithelia (ciliary body, choroid plexus, and stria vascularis) were notably lacking in CGRP-IR. Despite the multiplicity of functionally distinct CGRP neuronal and axonal populations, certain generalizations merit consideration. The extensive innervation of chemosensory nasal and oral epithelia may contribute to specific chemical sensitivities (e.g., relating to olfactory and gustatory senses) as well as evoking "nociceptive" responses to chemical irritants as part of a "common chemical sense." An efferent role for some of these peptidergic afferent axons may also be inferred from their specific distributions. Sites involved in regulating access to and sensitivity of sense organs to external stimuli (e.g., cochlear and vestibular hair cells, taste bud orifices, and main olfactory epithelium) are heavily innervated. Other IR axons are in position to exert control over airflow through nasal turbinates, glandular secretion, blood circulation, and duct transport systems.(ABSTRACT TRUNCATED AT 400 WORDS)

Ultrastructure of the “fenestrae” specialized integumentary areas of the desert locust, Schistocerca gregaria forsk. (Orthoptera: Acrididae)

The ultrastructure of the characteristic integumentary areas, called fenestrae on the abdominal terga, was studied in S. gregaria. They exhibit thinner cuticle than the general integument, since the endocuticle is missing. The epicuticle and exocuticle are traversed by pore canals, which are more numerous than those in the exocuticle of the general integument. The fenestrae cells bear a large number of microvilli and rest on a thick basement membrane, which extends far up between them, forming loops, which almost reach the subvillous zone. The cells are tightly packed near the apical surface, where there is a desmosome of “macula adherens” type and a septate junction. In the basal portion of each cell, the plasma membrane infoldings give rise to an intracellular membrane system. As compared with the cells of the general integument, the cytoplasm of the fenestrae shows a greater number of vesicular structures. The probable function of such areas in relation to their ultrastructural appearance is discussed.

Proecdysis, Setal Development, and Molt Prediction in the American Lobster (Homarus americanus)

Setal development and proecdysial cuticular changes can be observed in the pleopods of the American lobster (Homarus americanus) from earliest D0 through stage D3, and with pleopod staging criteria it is possible to follow proecdysis from beginning to end. A technique is described for recognition of all stages and substages of proecdysis, for evaluating effects of various treatments on proecdysis, and for predicting time of ecdysis where holding temperature is known. Histological comparisons between the pleopods and the general integument suggest a universal criterion for stage D2, and a need for adjustment in some accepted molt stage criteria. Development plateaus occur in stage D0 instead of C4 in this species, and this suggests that the concept of stage C anecdysis may be incorrect.

Incorporation of [3H]-Leucine into protein by animal tissues and by endosymbzotic chloroplasts in Elysia viridis montagu

1. 1. Light microscopic and electron microscopic autoradiography have been used to study the incorporation of tritiated leucine into protein by the sacoglossan opisthobranch mollusc, Elysia viridis and its endosymbiotic chloroplasts acquired from the seaweed, Codium fragile. 2. 2. Light microscopic autoradioagraphy showed that several animal tissues incorporated [ 3H]-leucine into protein. Among these were the “secretory zones” of the digestive diverticulum, the testes and the pedal mucus gland. It is suggested that uptake of the metabolite was via the general integument. 3. 3. Electron microscopic autoradiography showed that protein in the chloroplasts becomes labelled after a 3-hr incubation, and the silver grain density over the chloroplasts does not change during a 1–12 hr “cold chase”. The possible sources of this protein are considered and evidence suggests that it is synthesized within the chloroplasts. 4. 4. Thus these chloroplasts have some degree of biochemical autonomy outside the algal cells.

Uptake of polychlorinated biphenyls from sea water by Gammarus oceanicus

The uptake of a polychlorinated biphenyl preparation containing 5 to 7 chlorine atoms/molecule, solubilized in a nonionic surfactant in sea water, by Gammarus oceanicus was measured spectrophotometrically. Uptake occurred in living animals across the general integument. It is suggested that uptake rates are dependent upon the total surface area of the integument, although no accurate method of determining this is known. The rate of uptake decreased after 4 to 6 hours exposure and uptake was dependent upon concentration of polychlorinated biphenyls in sea water. The stage of the intermoult of G. oceanicus did not affect uptake rates.

Studies on the conservation of epidermal specificies of skin and certain mucosas in adult mammals.

To determine whether the factor(s) responsible for the conservation of epidermal specificities in adult guinea pigs and hamsters resides in the germinal layer of the epidermis or in the dermis, thin grafts of skin, possessing qualitatively distinct regional characteristics, were separated into their superficial epidermal and dermal components with the aid of trypsin. Dermis of one type was combined with epidermis of another to produce "recombinant" grafts which were then transplanted to small, full thickness cutaneous sites on the thorax of geneticaily compatible hosts. A variant of this procedure involved transplanting sheets of superficial epidermis of various types to shallow split thickness recipient areas in the skin of the thorax. All grafts were maintained for 100 days before they were excised and examined histologically. The results indicate that, whereas the dermis determines the kind of epidermis produced in recombinant grafts involving the ear, the sole of the foot, and the trunk, this is not the case in recombinants which include tongue, esophageal, or cheek pouch epithelia. The one exception to this occurred when tongue or esophagus epithelia were transplanted to split thickness beds in trunk skin. Here they appeared to produce an epidermis characteristic of their new location. It is believed that this exception is probably due to the fact that the native follicular epidermis present in trunk dermis made such a substantial contribution to the new superficial epidermis that it behaved overtly as body skin epidermis. Taken together, these results suggest that basal layer cells of the superficial epidermis of sole of foot skin, ear skin, and the hair-bearing skin of the general integument behave as if they are equipotential, and that in adult life maintenance of these particular epidermal specificities is the outcome of persistent specific inductive stimuli from the underlying dermis. The results of subsidiary experiments are reported which indicate that the epithelial component of mammary gland tissue is also pluripotential, being capable of producing, under appropriate conditions, a normal-looking, fully stratified superficial epidermis.

Cutaneous Respiration in Woodlice

ABSTRACT Oxygen uptake and carbon dioxide output were measured in the woodlice Ligia oceanica, Oniscus asellus, Porcellio scaber and Armadillidium vulgare, in moist and in dry air, using normal animals and animals whose pleopods had been blocked by emulsion paint. In moist air, the rate of oxygen uptake which occurred through the general integument in animals whose pleopods had been blocked was about 50 % of normal in Ligia and Oniscus, but less than this in Porcellio and Armadillidium. After exposure to moving dry air, oxygen uptake in dry air was below normal in intact animals and nearly ceased in animals with blocked pleopods. Both showed a somewhat higher uptake if the oxygen tension was raised. Carbon dioxide output in moist air was not immediately inhibited by blocking the pleopods, suggesting free diffusion through the integument. Output fell during the first hour, but the R.Q. remained above 1 in all species. Survival times of blocked animals in moist air corresponded qualitatively with rates of oxygen absorption in the four species. In dry air survival was further curtailed, but prolonged again by an increased oxygen tension. Blocked animals of all species survived for a shorter time in moist nitrogen than in moist air. Injection of reduced indigo showed that oxygen was absorbed by intact animals through the thin ventral integument and bases of the legs in Ligia, and to a lesser extent, through the ventral abdominal integument in Oniscus and Porcellio. The ecological implications of these results are discussed, particularly with reference to the relation between survival and humidity. The dehydration death point is probably affected by the level of oxygen deficit and vice versa. A water-permeable integument is of value for respiration as well as for temperature control, but restricts the habitat range of terrestrial animals.

Spread of redox potentials over the skin.

Dermatologists daily see evidence seeming to show that distant sites on the skin, if not the general integument, come under the influence of some local involvement. The tendency to so-called ids, as from a leg ulcer, appears to be such an effect. Various theories to explain such phenomena have been offered, but none has been accepted. Some of the available evidence is in favor of an explanation by allergy and hypersensitization. Another possibility takes into consideration alterations in electrolyte patterns of sodium, potassium, calcium, and magnesium. Still another involves changes in enzyme reactions. Probably more than one cause will finally be found for these associated changes at distant parts of the skin stemming from some local one. In our program of investigation of some of the electrical characteristics and properties of the skin we turned our attention to the spread of changes in electric potentials