Morpho-functional Diversity Research Articles

Morphoanatomy and evolution of the bracteole and sepal glands of the Amazonian genus Lophanthera A. Juss. (Galphimioid clade)

Abstract The presence of diverse secretory structures is emblematic of Malpighiaceae, such as the presence of nectaries secreting sugary nectar and elaiophores secreting oil-resin. Recent studies have demonstrated the morphoanatomical and chemical similarities between these two glands but, in general, there are no comparative morphoanatomical analysis on inflorescence glands. The Galphimioid clade is an excellent model for studies on the presence of secretory tissue due to the variation found among genera with regards to both their bracteole and sepal glands. In this work, we describe the morphoanatomy and histochemistry of bracteole and sepal glands in species of Lophanthera. Furthermore, we update the species geographic distribution map and explore the morphological diversity of both sepal and bracteole glands in the Neotropical Galphimioid clade. Samples collected in the field and obtained from herbarium specimens were processed under usual anatomical techniques. The bracteole glands varied in surface shape, while the calyx glands varied mainly in size. Anatomically, both types of gland have palisade secretory epidermis and vascularized secretory parenchyma. The presence of proteins, polysaccharides, phenolic compounds, and reducing sugar was detected by histochemical tests. The bracteole glands of the inflorescences in Lophanthera were characterized as nectaries that produce a hydrophilic secretion. The sepal glands were identified as elaiophores by the presence of lipids and fixed oil. The results reinforce the functional role of floral nectaries of bracteoles and elaiophores of sepals according to the nature of the secretion, its potential visitors, and reported literature. The morphofunctional diversity reported in this work is unprecedented for the clade and is fundamental in the adaptive evolution of the family.

Phenomic Microglia Diversity as a Druggable Target in the Hippocampus in Neurodegenerative Diseases.

Phenomics, the complexity of microglia phenotypes and their related functions compels the continuous study of microglia in disease animal models to find druggable targets for neurodegenerative disorders. Activation of microglia was long considered detrimental for neuron survival, but more recently it has become apparent that the real scenario of microglia morphofunctional diversity is far more complex. In this review, we discuss the recent literature on the alterations in microglia phenomics in the hippocampus of animal models of normal brain aging, acute neuroinflammation, ischemia, and neurodegenerative disorders, such as AD. Microglia undergo phenomic changes consisting of transcriptional, functional, and morphological changes that transform them into cells with different properties and functions. The classical subdivision of microglia into M1 and M2, two different, all-or-nothing states is too simplistic, and does not correspond to the variety of phenotypes recently discovered in the brain. We will discuss the phenomic modifications of microglia focusing not only on the differences in microglia reactivity in the diverse models of neurodegenerative disorders, but also among different areas of the brain. For instance, in contiguous and highly interconnected regions of the rat hippocampus, microglia show a differential, finely regulated, and region-specific reactivity, demonstrating that microglia responses are not uniform, but vary significantly from area to area in response to insults. It is of great interest to verify whether the differences in microglia reactivity may explain the differential susceptibility of different brain areas to insults, and particularly the higher sensitivity of CA1 pyramidal neurons to inflammatory stimuli. Understanding the spatiotemporal heterogeneity of microglia phenomics in health and disease is of paramount importance to find new druggable targets for the development of novel microglia-targeted therapies in different CNS disorders. This will allow interventions in three different ways: (i) by suppressing the pro-inflammatory properties of microglia to limit the deleterious effect of their activation; (ii) by modulating microglia phenotypic change to favor anti-inflammatory properties; (iii) by influencing microglia priming early in the disease process.

Dental form and function in the early feeding diversification of dinosaurs

Dinosaurs evolved a remarkable diversity of dietary adaptations throughout the Mesozoic, but the origins of different feeding modes are uncertain, especially the multiple origins of herbivory. Feeding habits of early dinosaurs have mostly been inferred from qualitative comparisons of dental morphology with extant analogs. Here, we use biomechanical and morphometric methods to investigate the dental morphofunctional diversity of early dinosaurs in comparison with extant squamates and crocodylians and predict their diets using machine learning classification models. Early saurischians/theropods are consistently classified as carnivores. Sauropodomorphs underwent a dietary shift from faunivory to herbivory, experimenting with diverse diets during the Triassic and Early Jurassic, and early ornithischians were likely omnivores. Obligate herbivory was a late evolutionary innovation in both clades. Carnivory is the most plausible ancestral diet of dinosaurs, but omnivory is equally likely under certain phylogenetic scenarios. This early dietary diversity was fundamental in the rise of dinosaurs to ecological dominance.

Fossorial adaptations in African mole-rats (Bathyergidae) and the unique appendicular phenotype of naked mole-rats

Life underground has constrained the evolution of subterranean mammals to maximize digging performance. However, the mechanisms modulating morphological change and development of fossorial adaptations in such taxa are still poorly known. We assessed the morpho-functional diversity and early postnatal development of fossorial adaptations (bone superstructures) in the appendicular system of the African mole-rats (Bathyergidae), a highly specialized subterranean rodent family. Although bathyergids can use claws or incisors for digging, all genera presented highly specialized bone superstructures associated with scratch-digging behavior. Surprisingly, Heterocephalus glaber differed substantially from other bathyergids, and from fossorial mammals by possessing a less specialized humerus, tibia and fibula. Our data suggest strong functional and developmental constraints driving the selection of limb specializations in most bathyergids, but more relaxed pressures acting on the limbs of H. glaber. A combination of historical, developmental and ecological factors in Heterocephalus are hypothesized to have played important roles in shaping its appendicular phenotype.

Recent divergence in functional traits affects rates of speciation in the Neotropical Velloziaceae (Pandanales)

AbstractThe resurrection plant family Velloziaceae are an iconic element in the Brazilian campos rupestres, where Barbacenia and Vellozia have undergone episodes of explosive species accumulation. Here we focus on the patterns of evolution of growth forms, dry-season physiological strategies and morphofunctional divergence to untangle these radiations. The timings of marked ‘disparification’ (evolution of trait disparity throughout a clade) in both genera were uncoupled from the shifts towards increased diversification rates, with the former accumulating during the Plio-Pleistocene (< 5 Mya). Except for growth forms in Vellozia, the traits analysed display convergent evolution in both genera. Morphofunctional diversity is lower in Barbacenia than in Vellozia, reflecting a young radiation occurring mostly in the southern Espinhaço Province. Growth-form divergence in Vellozia coincided with the Oligocene/Miocene burst in diversification, followed by a slowdown in rate. Moreover, the recent morphofunctional disparification indicates pulses of trait divergence within a mature radiation. Both growth form and divergence in functional traits affect diversification rates in the genera, with the growth forms displaying fastest diversification usually associated with mountain radiations.

Morphological diversity and disparity in trilobite cephala and the evolution of trilobite enrolment throughout the Palaeozoic

Morphology permits the extracting of information to study patterns of disparity and diversity of a particular group of animals through time. Enrolment is a characteristic behaviour of trilobites, having been first recorded in the Cambrian and continued until their demise at the end of Permian mass extinction. Morphological trends related to enrolment strategies have been documented previously but are yet to have been analysed in a morphospace framework. Here we analyse the cephalic shape of a wide range of trilobite taxa using geometric morphometrics. These methodologies were implemented to explore whether the relationship between the shape of the head and the evolution of different enrolment styles correspond with an increase in morphospace or disparity during the Palaeozoic. Our results show distinct patterns of diversity and disparity in the functional morphology of trilobites during the Palaeozoic. Furthermore, these analyses show that enrolment types in trilobites without interlocking devices (e.g. cylindrical) permit more flexibility in the head shape, promoting higher rates of disparity, possibly leading to an enhanced ability to occupy a broad range of ecological niches. On the contrary, lower disparity cephalic shape constrains the way to enclose the body and consequently places limitations on the ability to adapt to new niches. Our results indicate that the higher rates of morpho-functional diversity and disparity coincide with the increase of morphospace in radiations in the early Palaeozoic (Cambrian and Ordovician) but also immediately after the Carboniferous-Permian biodiversification event. Low disparity rates constrain the success of trilobites with a specific enrolment type. Finally, the results show that sphaeroidal enrolment style was the most successful type that evolved independently in all trilobite orders.

Are Feeding Modes Concealing Morphofunctional Diversity? The Case of the New World Parrotfishes

In functional ecology, morphology is expected to reflect function; however, occasional decoupling of these two can be found. In the case of feeding ecology, the diversity of the diet or diversity of the feeding modes within a clade is expected to be positively related to the diversity of the morphological traits involved in the feeding performance. Parrotfishes are separated into two main groups, the “reef” clade and the “seagrass” clade. Both groups have important differences in their evolutionary history. Still, more interestingly, they have important morphological and ecological differences. The generaScarusandSparisomaare the most specious genera of parrotfishes. They belong to each of those main groups, respectively. AllScarusspecies have the same feeding mode, while inSparisoma, there are three different feeding modes. We want to test if the morphological jaw diversity of these genera corresponds with the diversity in their feeding modes. Using a disparity analysis of feeding traits within a phylogenetical framework, we did not find a relationship between functional feeding morphology and feeding modes of the American parrotfishes of the generaScarusandSparisoma. Interestingly we found that some muscular traits are the source of the high disparity in the genusScarus. We explore some possible morpho-functional reasons for this phenomenon and reappraise the parrotfishes’ scraper feeding mode’s functional diversity. We also consider that there could be more ecological differentiation betweenScarusspecies that we are aware of. Using an ancestral reconstruction of feeding modes of 52 species of parrotfishes, we found that the scraping feeding mode exhibited by allScarusspecies is an evolutionary convergence with the scraping feeding modes performed by someSparisomaspecies. Different selective pressures or ecological conditions may have shaped the differences in the feeding ecology and the feeding morphology of these two genera. Probably, key novel structures and muscular properties found in theScarusspecies’ jaw played an essential role in this genus’s morpho-functional diversification. Finally, we propose that feeding modes may not fully capture the complexity of feeding ecology in parrotfishes.

Toxicity of a chromium-enriched superfood, Spirulina platensis, assessed by taxonomic and morpho-functional diversity of marine meiofauna

A laboratory bioassay was conducted to investigate the ecotoxicity of a chromium-enriched superfood, Spirulina platensis, on the meiofauna collected from the Ghar El Melh lagoon, Tunisia. After 1 month of exposure, the abundances of meiobenthic taxa and the taxonomic and morpho-functional diversity of nematodes showed significant differences between the Spirulina and Spirulina + chromium groups. The nematodes were more tolerant of all types of stressors compared to harpacticoids, polychaetes, and oligochaetes, and the lowest taxonomic and morpho-functional diversity of nematodes was observed in the highest sedimentary concentration of S. platensis (50% DW). The mixed treatments may have been richer in micro-habitats and subject to low selective pressure, thereby hosting nematodes with a wide range of adaptations. The responses of the nematode species differed depending on their functional traits. Spirulina enriched with chromium induced two responses for the same feeding group: high toxicity for Daptonema fallax and low toxicity for two Theristus species (T. flevensis and T. modicus). The ecotoxicity of the Spirulina/chromium mixtures were lower than that of Spirulina alone, suggesting mutual neutralization between these two elements. The association between functional traits and taxonomic diversity showed that the effects of the mixtures were not additive and that one of the stressors camouflaged the effect of the other. Our findings should encourage the commercialization of chromium-enriched S. platensis owing to its lower ecotoxicity than Spirulina alone.

Human skin biology and the search for the truth

1. Human skin consists of epidermis, pilosebaceous follicles, eccrine and apocrine sweat glands, melanocytes, Langherans cells, Merkel cells, connective tissue of the dermis and hypodermis, nerves and lymphatic and blood vessels. It means that the skin is an extremely complex organ, made up of multiple cell types and structures, with remarkable morphofunctional diversity.

Antiquity of forelimb ecomorphological diversity in the mammalian stem lineage (Synapsida)

Mammals and their closest fossil relatives are unique among tetrapods in expressing a high degree of pectoral girdle and forelimb functional diversity associated with fully pelagic, cursorial, subterranean, volant, and other lifestyles. However, the earliest members of the mammalian stem lineage, the "pelycosaur"-grade synapsids, present a far more limited range of morphologies and inferred functions. The more crownward nonmammaliaform therapsids display novel forelimb morphologies that have been linked to expanded functional diversity, suggesting that the roots of this quintessentially mammalian phenotype can be traced to the pelycosaur-therapsid transition in the Permian period. We quantified morphological disparity of the humerus in pelycosaur-grade synapsids and therapsids using geometric morphometrics. We found that disparity begins to increase concurrently with the emergence of Therapsida, and that it continues to rise until the Permo-Triassic mass extinction. Further, therapsid exploration of new regions of morphospace is correlated with the evolution of novel ecomorphologies, some of which are characterized by changes to overall limb morphology. This evolutionary pattern confirms that nonmammaliaform therapsid forelimbs underwent ecomorphological diversification throughout the Permian, with functional elaboration initially being more strongly expressed in the proximal end of the humerus than the distal end. The role of the forelimbs in the functional diversification of therapsids foreshadows the deployment of forelimb morphofunctional diversity in the evolutionary radiation of mammals.

Potential Response of Coral Reef’s Functional Structure and Snapper Abundance to Environmental Degradation in San Andres Island, Colombia

To determine the coral reef morpho-functional structure of San Andrés, regarding functional benthic diversity and fish (Lutjanidae), we evaluated the condition of the coral structure on the leeward side of the island, which is an area impacted by tourism, through diving and fishing. Three sampling sites were evaluated during two years recording the distribution of benthic organisms, environmental variables and Snappers density (Lutjanidae). A low density of Lutjanus jocu and Ocyurus chrysurus was found, with a high density of juveniles of L. apodus and L. mahogoni, which showed a preference for reefs with submassive and brain corals. Algae especially Macroalgae and octocorals were those with the greatest coverage in the reefs, followed by inert substrates, while corals were epresented by species with a wide distribution such as Agaricia agaricites and Porites astreoides. Octocorals correlated negatively with stony corals and that the most widespread fragile corals were the finger. We concluded that there is a higher density of mainly juvenile snappers where there is a greater variety of coral morpho-functional groups, and not necessarily in sites with greater coral coverage. Also, adult snappers were associated with octocoral zones. This shows that morpho-functional diversity is a crucial factor in the permanence of snappers.

Morphofunctional characteristics of Dorper sheep crossed with Brazilian native breeds

The relationship between body development and external measures in sheep could provide useful information to define the optimal slaughter time as well as the adequate nutritional management. Thus, the objective of this study was to evaluate the morpho-functional diversity of Dorper sheep crossed with Brazilian native breeds using in vivo morphometric analysis. The animals evaluated were from crosses of Dorper with Morada Nova, Rabo Largo and Santa Inês sheeps. The animals were slaughtered at 120 and 240 days of age. Body and carcass measures, weight of meat cuts and growth were evaluated. The crossbred animals were analyzed by sex, totaling six treatments. A factorial analysis was performed using two sets of data: the in vivo morphometric measures, and all the other characteristics and these factors were used as new variables. The differences among treatments were analyzed using MANOVA and canonical analysis. The meat cuts, conformation, marketability adaptation, and early maturity of the animals slaughtered at 120 days, as well as the meat cuts, conformation, adaptation, early maturity, and hindquarter of the animals slaughtered at 240 days were evaluated. As regards body measurements, at both slaughter ages, the following factors were discriminated: height, robustness, length, and thoracic circumference. Animal slaughtered at 120 days of age showed greater differences whereas at 240 days the differences diminished allowing to individuate which treatments were more adaptive or productive. Crosses ½ Dorper × ½ Santa Inês (male and female), and ½ Dorper × ½ Rabo Largo male slaughtered at 240 days seem to show higher productivity and better marketability abilities. The other crosses tend to have a more rustic profile (less productive) and smaller size, reaching however adult size earlier and showing better adaptive characteristics, which allows to decide for slaughtering at younger ages.

Morpho-functional diversity in Diaphus spp. (Pisces: Myctophidae) from the central Atlantic Ocean: Ecological and evolutionary implications

Insight into the evolutionary radiation of organisms is partly underpinned by theories on the adaptive divergence of sensory systems, and the ecological, physiological, and behavioural adaptations to both environmental conditions and to competition for limited resources. The aim of this study is to determine the degree of phenotypic variability and functional niche overlap between Diaphus (Myctophidae) species that could account for the high level of speciation within this genus. The Diaphus specimens which were used for our study, were obtained from a survey transect across the central Atlantic Ocean. We analysed the morpho-functional features of fish body shape and sagittae otolith shape of these specimens. Although our study included only 9 species, our findings revealed a high degree of morpho-functional variability in the fish body and otolith shapes, both of which are coupled with the variations of the bioluminescent organs of the head, especially the suborbital organ situated under eye and called So-photophore. Two morphotypes were identified: ‘Diaphus-deep’ (morphotype-1) with an So-photophore, and defined by a larger otolith and a deep body, larger head, eye and mouth; and ‘Diaphus-slender’ (morphotype-2) without an So-photophore, and characterized by an increased development of anterior-dorsal margin of otolith and an enlarged body with small head, eye and mouth. Our analyses supported both the sensory drive and niche hypotheses as forces promoting the radiation within the genus Diaphus. Future studies involving a greater number of species are necessary to advance the knowledge of speciation mechanisms in myctophids.

Do the morphological and functional traits of free-living marine nematodes mirror taxonomical diversity?

The taxonomical structure and diversity of nematode assemblages are the main attributes analyzed in ecology, but nematode adaptations to their habitats are still understudied. Accordingly, a survey on some known and other newly proposed morpho-functional traits was carried out in order to: determine if the morpho-functional diversity of nematodes mirrors their taxonomical diversity; and assess potential nematode adaptations to sediment type and hydrodynamic stress. Morpho-functional traits were investigated both singularly and together and showed significant differences related to these environmental factors. The greatest taxonomical and morpho-functional diversity was found in medium-coarse sand (M-CS) and at an intermedium energy level (IEL). The M-CS and IEL were probably richer in micro-habitats and subject to a low selective pressure, hosting nematodes with a wide range of adaptations. The mirroring of morpho-functional diversity with taxonomical diversity is crucial for the future growth of the use of nematodes in biomonitoring. This is because the study of their morpho-functional traits could reduce the level of work involved and the costs of any analyses.

Morphofunctional diversity of equine of varied genetic compositions raised in the Pantanal biome of Brazil

Evaluating phenotypic diversity makes it possible to identify discrepancies in aptitudes among animals of different genetic bases, which is an indicator of adaptive or selective differences between populations. The objective of this work was to evaluate the morphofunctional diversity of 452 male and female adult equines (Arabian, Quarter Mile, Pantaneiro, and Criollo breeds, and undefined crossbreeds of horses and mules) raised in the Pantanal biome (Brazil). Linear measurements were performed to estimate conformation indexes. Initially, a discriminant analysis was performed, regardless of the animal's size, followed by factor analysis. The factors were characterized and used as new variables. The diversity among equines and their relationship with the factors were evaluated using multivariate analysis. The factors were classified according to their decreasing importance: balance, rusticity, and robustness for the measurement factors; and load, ability, conformation, and equilibrium for the index factors. The genetic groups of equines have well-defined morphofunctional characteristics. The main differences are based on the rusticity and ability typologies in relation to those based on performance. Equines introduced to the Pantanal biome presented a more robust and compact body with good conformation. As a result, these horses may have superior athletic performance during equestrian activities when compared to the Pantaneiro local breed. However, this biotype may represent less rusticity (less adaptive capacity). Therefore, the regional breed can be equal or better in equestrian activities than breeds introduced to the Pantanal biome. Thus, breeders may cross horses from local breeds as an alternative to those introduced. Undefined crossbred male equines presented a different profile from the Pantaneiro breed, which may indicate little use of crossbreeds in breeding.

Catarrhine hallucal metatarsals from the early Miocene site of Songhor, Kenya

Songhor is an early Miocene fossil locality in Kenya known for its diverse primate assemblage that includes catarrhine species belonging to the genera Kalepithecus, Limnopithecus, Dendropithecus, Rangwapithecus, and Proconsul. Expeditions to Songhor since the 1930s have recovered unassociated catarrhine postcranial remains from both the fore- and hindlimbs, including multiple elements from the feet. In this study, we describe KNM-SO 31233, a complete left hallucal metatarsal (Mt1), along with several other fragmentary Mt1 specimens (KNM-SO 1080, 5129, 5141, 22235). These fossils were compared to extant catarrhines and platyrrhines, as well as available fossil Miocene catarrhine Mt1s. Morphometric data were obtained from 3D surface renderings and subjected to a number of analyses to assess their phenetic affinity with the comparative sample, make predictions of body mass, and to infer their functional morphology. The size and shape of the Songhor Mt1s are diverse, exhibiting a large robust morph (KNM-SO 5141) similar in size but not in shape to extant African apes, medium-sized morphs (KNM-SO 1080, 5129 and 22235), and a smaller, slender one (KNM-SO 31233) that has a shape resembling arboreal quadrupedal leaping monkeys and suspensory atelines and hylobatids. KNM-SO 31233 is unlike other known fossil Mt1s, and in general, none of the Songhor Mt1s resembled any single extant anthropoid clade or species. The morpho-functional diversity of Songhor Mt1s is consistent with an extensive morphological and phylogenetic catarrhine diversity in the early part of the Miocene epoch.

Re-description of a putative Early Cretaceous “teleosaurid” from France, with implications for the survival of metriorhynchids and teleosaurids across the Jurassic-Cretaceous Boundary

Thalattosuchia was a diverse clade of marine crocodylomorphs known from the Early Jurassic to the Early Cretaceous. Recent studies have hypothesized that their extinction was two-phased: (1) habitat loss near/at the Jurassic-Cretaceous boundary heavily reduced their morphofunctional diversity, particularly in Europe, while (2) climate change and a shift in marine fauna during the Early Cretaceous (either at the Valanginian-Hauterivian boundary or during the early Hauterivian) finished off the already stressed clade. Unfortunately, the Cretaceous fossil record of thalattosuchians is poor, with only one putative “teleosaurid” specimen and approximately ten metriorhynchid specimens. Here we re-describe the youngest known teleosaurid from the Cretaceous (Valanginian of south-eastern France). Originally considered to be a teleosaurid (possibly Steneosaurus), we demonstrate that it belongs to Metriorhynchidae, and a newly discovered subclade, Plesiosuchina. It differs from Plesiosuchus in the pattern of tooth enamel ornamentation and the variation in dentary alveoli size. Referring this specimen to Metriorhynchidae means there are no definitive Cretaceous teleosaurid specimens. Furthermore, it suggests that both durophagous and piscivorous teleosaurids became extinct at the end of the Jurassic. Interestingly, this is the fourth metriorhynchid lineage known to cross the Jurassic-Cretaceous boundary. As such, it would appear that the two thalattosuchian families responded very differently to the lowering sea levels at the end of the Jurassic: teleosaurids possibly became extinct, while metriorhynchids were seemingly unaffected.

Pioneer glutamatergic cells develop into a morpho-functionally distinct population in the juvenile CA3 hippocampus

The developing CA3 hippocampus is comprised by highly connected hub neurons that are particularly effective in achieving network synchronization. Functional hub neurons were shown to be exclusively GABAergic, suggesting that the contribution of glutamatergic neurons to physiological synchronization processes at early postnatal stages is minimal. However, without fast GABAergic transmission, a different situation may prevail. In the adult CA3, blocking fast GABAergic transmission induces the generation of network bursts that can be triggered by the stimulation of single pyramidal neurons. Here we revisit the network function of CA3 glutamatergic neurons from a developmental viewpoint, without fast GABAergic transmission. We uncover a sub-population of early-generated glutamatergic neurons that impacts network dynamics when stimulated in the juvenile hippocampus. Additionally, this population displays characteristic morpho-physiological features in the juvenile and adult hippocampus. Therefore, the apparently homogeneous glutamatergic cell population likely displays a morpho-functional diversity rooted in temporal embryonic origins.

Parasitophorous vacuole: morphofunctional diversity in different coccidian genera (a short insight into the problem).

We present a short insight into the problem of parasitophorous vacuole (PV) formation as a most peculiar kind of cell vacuolization occurring in the course of intracellular development of coccidian pathogens of the genera Eimeria, Isospora, Toxoplasma, Sarcocystis, Cryptosporidium, Epieimeria, and Karyolysus. The review focuses on the morpho-functional diversity of PVs in these parasites. By the present time, the PVs containing different parasite genera and species have been examined to different extent. The membrane of the PV (PVM) obviously derives from the host cell plasmalemma. But soon after parasite penetration, the morphofunctional organization and biochemical composition of the PVM drastically changes: its proteins are selectively excluded and those of the parasite are incorporated. As the result, the PV becomes not fusigenic for lysosomes or any other vacuoles or vesicles, because host cell surface markers necessary for membrane fusion are eliminated from the PVM during parasite invasion. The pattern of the PVs is parasite specific and demonstrates a broad diversity within the same genera and species and even at different stages of the endogenous development. The PV is far from being an indifferent membrane vesicle containing the parasite. Instead, it represents a dynamic system that reflects the innermost events of host-parasite relationships, thus promoting the accomplishing of the parasite life cycle, which, in its turn, is a necessary prerequisite of the parasite eventual survival as a species.

Comparative ultrastructure and immunolabeling of MHC-II antigens of alveolar macrophages obtained from patients with paracoccidioidomycosis and other lung diseases

Samples of alveolar macrophages (AM) obtained by bronchoalveolar lavage from patients with either paracoccidioidomycosis, silicosis, sarcoidosis, or allergic alveolitis were investigated by electron microscopy and immunocytochemistry to compare cellular ultrastructure and expression of MHC-II antigens in the AM cell surface. All samples of AM obtained from patients with these pathologies showed heterogeneous structural features. Although, this morphological diversity is also present in AM of healthy donors, our observations seem to indicate that in the diseases studied this morphofunctional diversity is associated with additional ultrastructural characteristics inherent to each disease. In paracoccidioidomycosis the proportion of vacuolated macrophages is significantly lower than in other diseases; this might indicate that in paracoccidioidomycosis the proportion of activated AM is smaller. We observed significant differences in the expression of MHC-II antigens. Silicosis, sarcoidosis, and allergic alveolitis do not differ significantly in the quantity of immunolabeled AM or in the distribution of the label. The percentage of AM from paracoccidioidomycosis that exhibit the MHC-II molecule is very low with poor immunolabeling. In this disease the low expression of the MHC-II molecule could be related to a decrease of the antigen presenting function by AM.