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PubMed1992

The membranous skeleton: the role of cell condensations in vertebrate skeletogenesis.

Elements of the vertebrate skeleton are initiated as cell condensations, collectively termed the 'membranous skeleton' whether cartilages or bones by Grüneberg (1963). Condensations, which were identified as the basic cellular units in a recent model of morphological change in development and evolution (Atchley and Hall 1991) are reviewed in this paper. Condensations are initiated either by increased mitotic activity or by aggregation of cells towards a centre. Prechondrogenic (limb bud) and preosteogenic (scleral ossicle) condensations are discussed and contrasted. Both types of skeletogenic condensations arise following epithelial-mesenchymal interactions; condensations are identified as the first cellular product of such tissue interactions. Molecular characteristics of condensations are discussed, including peanut agglutinin lectin, which is used to visualize prechondrogenic condensations, and hyaluronan, hyaladherins, heparan sulphate proteoglycan, chondroitin sulphate proteoglycan, versican, tenascin, syndecan, N-CAM, alkaline phosphatase, retinoic acid and homeo-box-containing genes. The importance for the initiation of chondrogenesis or osteogenesis of upper and lower limits to condensation size and the numbers of cells in a condensation are discussed, as illustrated by in vitro studies and by mutant embryos, including Talpid3 in the chick and Brachypod, Congenital hydrocephalus and Phocomelia in the mouse. Evidence that genes specific to the skeletal type are selectively activated at condensation is discussed, as is a recent model involving TGF-beta and fibronectin in condensation formation. Condensations emerge as a pivotal stage in initiation of the vertebrate skeleton in embryonic development and in the modification of skeletal morphology during evolution.

Animals↗
PubMed1992

Evolution of the power ("squeeze") grip and its morphological correlates in hominids.

The "squeeze" form of power grip is investigated for the purposes of clarifying the hand posture and activities associated with the grip, assessing the potential in chimpanzees for using the grip, and identifying morphological correlates of an effective power grip that may be recognized in fossil hominid species. Our approaches include: (1) the analysis of the human grip, focusing on both the hand posture involved and hand movements associated with use of the grip in hammering; (2) the analysis of similar chimpanzee grips and associated movements; (3) comparative functional analysis of regions in the hand exploited and stressed by the grip and its associated movements in humans; and (4) a review of the literature on the power grip and its morphological correlates. Results of the study indicate that humans use a squeeze form of power grip effectively to wield cylindrical tools forcefully as extensions of the forearm. Several morphological features occur in high frequency among humans which facilitate the grip and are consistent with the large internal and external forces associated with it in hammering and in other tool-using activities. Chimpanzee hand postures resembling this form of human power grip are not fully comparable and lack some of these morphological correlates that facilitate its use. The hand of Australopithecus afarensis does not appear to have been stressed by use of the grip, but there is some evidence for this type of stress in the metacarpals from Sterkfontein Member 4. Hands from Olduvai and Swartkrans do not provide sufficient evidence for assessment of power grip capabilities.

Adult↗
PubMed1979

[Rule of homology and morbid anatomy (author's transl)].

1. According to J.W. Goethe, morphology is a theory of evolution, H. Braus defined it as a theory of historic incidents, and according to D. Starck morphology is the role of shapes of the organisms. 2. The term homology was coined by morphologic researchers. Of course, it is used nowadays also in mathematics, chemistry, and linguistics and other logic matters. 3. Homologies have a special position in Goethe's work on the theory of types. Goethe's morphologic research and Schiller's aesthetic speculations are considered to be the origin of a 'typologic point of view.' 4. Coherences of Platon's theory of ideas and Goethe's theory of types are scrutinized. The theory of shapes ('Gestalt theory') is inconceivable without Platon's theory, and scientic morphology is inconceivable without shapes, either, and according to C. v. Ehrenfels "Gestaltphilosophie" could not exist without the shapes of Platon's theory. 5. It is shown that without Gestalt philosophy one cannot comprehend the following coherences: Gestalt (shape) as an idea, idea as a type of Goethe's rule, type as an element of the theory of homologies and even of constitution. 6. Homology will be constituted using certain criterions: a) detection of an equal descent, b) equal position of organismic structures in individuals, c) evidence of interpositions, and d) certain qualities of parts which are compared with each other. Homologous structures may be dissimilar in their architecture. 7. The term homology is explained a) by giving an analysis of morphologic and teratologic lines, b) by scrutinizing froms of symmetry, and c) by presenting the histopathology of topographical diverse but according to the morphogenetic mode coinciding tumours which are resembling each other in their microscopic patterns. 8. The application of the rule of homology in the morphologic investigation of diseases proves to be a) valuable from a heuristic point of view, b) an instrument of communication to characterize comparable matters, c) a means of classification, and d) a basic requirement to uncover inconceivable correlations of morphologic patterns in the first instance and then a basis for the prognosis findings which may be expected in the future. So far the didactic value of proven homologies is inestimably great. 9. The application of the rules of homology in morbild anatomy requires controls by 'regulatives.' There are: a) all facts must be born in mind, b) the rules of the mathematical logic, those of demonstrative and plausible conclusions need to be taken into consideration, and c) the criterions of Ehrenfels should be applied accurately. 10. At the contact surface of two scientific fields special difficulties may emerge. As far as contemporary pathology is concerned, elements of the Arts should be assimilated. This challenge is by no means a novel one. Covered traces of it could be found in our archive 50 years ago. We should not forget but keep in mind these elements.

Biological Evolution↗
PubMed2023

Emerging trends in the study of spiralian larvae.

Many animals undergo indirect development, where their embryogenesis produces an intermediate life stage, or larva, that is often free-living and later metamorphoses into an adult. As their adult counterparts, larvae can have unique and diverse morphologies and occupy various ecological niches. Given their broad phylogenetic distribution, larvae have been central to hypotheses about animal evolution. However, the evolution of these intermediate forms and the developmental mechanisms diversifying animal life cycles are still debated. This review focuses on Spiralia, a large and diverse clade of bilaterally symmetrical animals with a fascinating array of larval forms, most notably the archetypical trochophore larva. We explore how classic research and modern advances have improved our understanding of spiralian larvae, their development, and evolution. Specifically, we examine three morphological features of spiralian larvae: the anterior neural system, the ciliary bands, and the posterior hyposphere. The combination of molecular and developmental evidence with modern high-throughput techniques, such as comparative genomics, single-cell transcriptomics, and epigenomics, is a promising strategy that will lead to new testable hypotheses about the mechanisms behind the evolution of larvae and life cycles in Spiralia and animals in general. We predict that the increasing number of available genomes for Spiralia and the optimization of genome-wide and single-cell approaches will unlock the study of many emerging spiralian taxa, transforming our views of the evolution of this animal group and their larvae.

Animals↗
PubMed1991

The evolution of placental mammals.

Based on morphological, virological, biochemical and molecular biological data, it is proposed that the presence of endogenous retrovirus particles in the placental cytotrophoblasts of many mammals is indicative of some beneficial action provided by the virus in relation to cell fusion, syncytiotrophoblast formation and the creation of the placenta. Further, it is hypothesised that the germ line retroviral infection of some primitive mammal-like species resulted in the evolution of the placental mammals.

Animals↗
PubMed1992

Is behavior analysis undergoing selection by consequences?

The legacy of B. F. Skinner's life is a natural science of behavior. The generality of its basic functional relations has led, by induction, to the unifying principle of selection by consequences, which accounts for morphological, behavioral, and cultural evolution. This principle both predicts and explains the observation that the science itself is becoming the object of differential selection in our culture. Public policy is increasingly being framed in terms of the effects of consequences on behavior, as illustrated by examples from education, economics, and politics. Survival of our culture may depend on our skill in managing this process.

Behavior Therapy↗
PubMed1992

In vitro analysis of the cellular resistance to chemotherapeutic BCNU.

Our assays in vitro show that BCNU inhibits cell proliferation in the C6 cell line experimental glioma and is dose-dependent, starting from 0.5 microgram/ml of the drug with just an hour of exposure. For every tested concentration of BCNU it is shown that, from the fifth day after exposure, cellular resistance appeared. This resistance is justified by the capacity of cell DNA reparation. A study of the clonogenic capacity of the C6 cells exposed to BCNU also shows the appearance of cellular resistance for doses of 0.5 microgram/ml and 1 microgram/ml. Furthermore, the exposure of C6 cell cultures to BCNU at these levels produces a cellular evolution towards more differentiated morphological patterns.

Carmustine↗
PubMed1978

[Morphological variants of alcoholic hyalin and possible ways of its evolution].

Possible ways of alcohol hyalin evolution were studied by repeated electron microscopic examinations of the livers of 2 patients with acute alcoholic hepatitis Four types of ultrastructure of alcoholic hyalin were found: parallely oriented fibrillae, randomly oriented fibrillae, fine granular and large granular (spotlike) substance. Examinations of the material from repeated biopsies showed fibrillar hyalin to be "young" and to turn into "old" hyalin of granular structure. The evolution of alcoholic hyalin from fibrillar to granular is accompanied by hepatocyte necrosis and leukotaxic effect.

Adult↗
PubMedDate not supplied

[Toxoplasmosis in agriculture workers exposed to the risk of contamination].

Five-hundred-and-eighty-eight cattle and agricultural workers were surveyed. One-hundred-and-fifty of them were randomly selected, and they underwent leukograms and absolute eosinophil counts for enabling the study of their hematologic state. A 55% positivity rate was obtained among patients studied through the toxoplasmin intradermoreaction technique from Czechoslovakia. Historical and morphologic aspects, biological characteristics, evolutive cycle, pathologic characteristics, clinical manifestations, as well as the epidemiology of Toxoplasma gondii are reviewed.

Agricultural Workers' Diseases↗
PubMed1977

Joint remodelling and the evolution of the human hand.

A funtional morphological study has been made of the joints of the primate hand, particular emphasis being placed upon the carpometacarpal and metacarpophalangeal joints. The presumptive evolutionary history of these joints has been charted by reference to a comparative series of mammals. It has been demonstrated that the human joints have been quite strikingly modified in a number of ways, and that these evolutionary changes may be logically correlated with the refined functional attributes of the human hand. The morphological background thus established has been applied in a preliminary study of the hand bones of various fossil hominids.

Animals↗
PubMed1975

[Morphological characteristics of the destructive and reparative changes in tuberculosis in those dying of nontubercular diseases].

The evolution of destructive and restorative alterations was morphologically followed up in 82 tuberculotics that died of non-tiberculous diseases. In the majority of the deceased, the restorative alterations were observed with manifested mesenchymal and immunologic reactions with morphological peculiarities as in the treated with anti tuberculous remedies. The destructive alteration are clearly manifested and the restorative manifestations are depressed in tuberculotics with non-treated diabetes and osteomyelitis treated with cortison. In a negligible part of the patients died of non-tuberculous diseases, a reactivation of the foci developed around the fibrocaseous lung foci, tracheobronchial lymph nodes, kidneys and suprarenals, manifested with filamented neutrophyils in the calcified and caseous matter, fresh necrosis, tubercula, specific granular tissue, friable capsule with appearance of lymphoid cells and specific granular tissue.

Acute Disease↗
PubMed1992

Molecular evolution of the fungi: human pathogens.

The morphological, ecological, and clinical diversity among ascomycete fungi that are pathogenic to humans suggest that the potential for pathogenicity may have arisen multiple times within these higher fungi. We have obtained 18S ribosomal DNA sequences from a diverse group of human pathogenic fungi in order to determine their evolutionary origins. The fungi studied include a skin pathogen that is confined to humans (Trichophyton rubrum) and three systemic, facultative parasites that cause histoplasmosis (Histoplasma capsulatum), blastomycosis (Blastomyces dermatitidis) and coccidioidomycosis (Coccidioides immitis) in humans and other higher animals. Also included in our analysis are representatives of non-pathogenic fungi, as well as two opportunistic pathogens, Pneumocystis carinii and Candida albicans, that cause severe disease in immunocompromised individuals, especially those with AIDS. Two of the fungi we sequenced, T. rubrum and C. immitis, are limited to asexual modes of reproduction and therefore lack the sexual structures that are most useful for evolutionary comparison as well as being essential for classification among the higher fungi. Coccidioides immitis is particularly problematic owing to its contradictory and confusing asexual morphologies, which have caused it to be placed in three fungal classes and the protista. Our analysis shows that the specialized, superficial parasite and the systemic, facultative parasites, including C. immitis, are closely related ascomycetes, which clearly demonstrates the power of molecular characters to compensate for missing or confusing reproductive morphology. Analysis also shows that the opportunistic pathogens are more distantly related, with the likely explanation that pathogenicity has arisen more than once within the Ascomycetes.

Base Sequence↗
PubMed1992

Morphologic classification of the myelodysplastic syndromes (MDS): combined utilization of bone marrow aspirates and trephine biopsies.

In a retrospective and prospective follow-up study from 1975 to 1991, bone marrow biopsies, aspirates and clinical features of 495 patients with MDS were investigated. Sections of undecalcified plastic embedded biopsies and smears of bone marrow aspirates were stained according to Giemsa. Bone marrows with MDS were characterized by three main categories of morphologic alterations: (1) cellular abnormalities, (2) architectural disorganization in the bone marrow and (3) stromal changes; the combined use of aspirates and trephine biopsies enabled a more reliable and accurate diagnosis of MDS than either one alone. The bone marrow findings fell into one of 7 subtypes, with the frequencies and median survivals in brackets: (1) MDS sideroblastic (19%, 62 months), (2) MDS megaloblastoid (13%, 56 months), (3) MDS proliferative (22%, 31 months), (4) MDS blastic (15%, 9 months), (5) MDS hypoplastic (15%, 26 months), (6) MDS fibrotic (6%, 29 months), and (7) MDS inflammatory (10%, 42 months). In follow-up studies patients with secondary MDS were excluded and the prognosis and subsequent evolution for each of the morphologic subtypes were evaluated. The conclusion is drawn that aspirates and trephine biopsies are complementary procedures and both are required for diagnosis, classification and decisions on current treatment modalities of patients with MDS.

Adolescent↗
PubMed2026

Grade progression and high-grade transformation in neuroendocrine neoplasms.

Epithelial neuroendocrine neoplasms (NENs) comprise a biologically diverse group of malignancies that span a wide spectrum of differentiation, proliferative activity, and clinical behavior. Contemporary classifications distinguish well-differentiated neuroendocrine tumors (NETs) from poorly differentiated neuroendocrine carcinomas (NECs). However, growing longitudinal data indicate that a subset of NETs may undergo temporal evolution characterized by rising Ki-67, increasing morphologic atypia, and acquisition of genomic alterations classically associated with NEC, particularly TP53 and, less commonly, RB1 inactivation. These phenomena, referred to as grade progression and high-grade transformation, can result in tumors with NEC-like behavior despite retention of a NET molecular backbone, creating diagnostic and therapeutic ambiguity. In this review, we synthesize recent evidence on the molecular, morphologic, and clinical features of gastroenteropancreatic NET grade progression and transformation, highlight the role of clonal evolution and treatment-associated selection pressure, and discuss implications for imaging, biopsy strategy, molecular profiling, and therapy selection.

Humans↗
PubMed2026

Gastric carcinoma classification in the WHO 6th edition (2026): Updated framework and emerging entities.

The sixth edition of the WHO Classification of Digestive System Tumours (2026) represents an important step in the continuing evolution of gastric carcinoma classification. While preserving morphology as the foundation of diagnosis, it incorporates advances in molecular pathology, genotype-phenotype correlations, tumour evolution, and predictive biomarker assessment. This review summarizes the development of the WHO classification from the third edition (2000) to the sixth edition (2026) and highlights its relationship with other major classification systems, including those of Laurén, Nakamura, and the Japanese Gastric Carcinoma Association (JGCA). Major histological categories remain largely unchanged; however, several important conceptual and diagnostic refinements have been introduced. These include recognition of crawling-type adenocarcinoma as a distinctive variant of tubular adenocarcinoma, subclassification of poorly cohesive carcinoma into signet-ring cell and non-signet-ring cell subtypes, introduction of the concept of pure signet-ring cell carcinoma, and increased emphasis on tumour evolution. The sixth edition also expands and refines the spectrum of uncommon gastric carcinoma subtypes, including gastric carcinoma with lymphoid stroma, AFP-producing carcinoma, micropapillary adenocarcinoma, gastric adenocarcinoma of fundic-gland type, and gastric sarcomatoid carcinoma. Crucially, molecular subgroups originally proposed by The Cancer Genome Atlas (TCGA) and actionable biomarkers-including HER2 (ERBB2), Claudin 18.2, mismatch repair deficiency/microsatellite instability (dMMR/MSI), and programmed death-ligand 1 (PD-L1)-have transitioned from research-based categories into essential tools for precision oncology. Rather than providing exhaustive diagnostic criteria, this review offers a conceptual framework and encourages consultation of the original WHO text for full details. These advances illustrate the transition of gastric carcinoma classification from a predominantly morphology-based system toward an integrated histomolecular framework that more closely links pathological diagnosis with tumour biology, prognostication, and therapeutic stratification.

Crawling-type adenocarcinoma↗
PubMed1978

Skeletal differences between pygmy (Pan paniscus) and common chimpanzees (Pan troglodytes).

Skeletal dimensions of pygmy (Pan paniscus) and common (Pan troglodytes) chimpanzees were compared. Significant differences were found in the clavicles, scapulae, pelvises, and in the humerus/femur and femur head/length ratios. No significant differences were observed in long bone lengths or talar breadths. There is extensive overlap in body weights, so that the observed differences cannot be accounted for by body size alone. We conclude that pygmy and common chimpanzees are morphologically distinct. Implications for hominoid evolution are discussed.

Animals↗
PubMed1991

A preliminary isoenzyme study on five species of phlebotomine sandflies in China.

During June to August, 1987, six species of phlebotomines were collected by aspirator from four localities in Beijing, Nanjiang and northwestern Sichuan Province. After morphological identification, five species viz., Phlebotomus chinensis, P. sichuanensis, Sergentomyia zhengjiani, S. khawi and S. squamirostris were studied starch gel electrophoresis in 10 enzymes for isoenzyme characterization. Among which four enzymes (MDH, PGM, PGI and alpha-GPD) showed varying degrees of differences. The characteristic enzyme locus of PGM can be used to identify P. sichuanensis (Sichuan strain) from P. chinensis (Sichuan and Beijing strains) two vectors of Chinese visceral leishmaniasis, the pharyngeal armatures and spermathecae of which are morphologically resemble in females. The locus of PGM for genotype AA is over 77% in P. chinensis compared with 8.3% in P. sichuanensis and genotype DD is 75% in P. sichuanensis compared with negative in P. chinensis. Distinct enzymatic differences were demonstrated between genera Phlebotomus and Sergentomyia. The alleles of MDH-1 were 100 and 95 in genus Phlebotomus and Sergentomyia respectively, meanwhile in alpha-GPD the alleles were at 100 and 97 respectively except S. squamirostris. In PGI it showed polymorphic with two loci and more alleles in Phlebotomus and monomorphic with only one locus in Sergentomyia. The similar enzyme phenotype between morphologically distinct species, S. zhengjiani and S. khawi shown that the uncorrespondence between morphological and genetic characters in evolution is present in some cases of phlebotomine such as in other insects.

Animals↗