Histology and affinity of the earliest armoured vertebrate

Arandaspids are the earliest skeletonizing vertebrates known from articulated remains. Despite a wealth of data, their affinity remains questionable because they exhibit a random mixture of primitive and derived characteristics. We constrain the affinity of arandaspids by providing the first detailed characterization of their dermoskeleton which is revealed to be three-layered, composed of a basal laminated, cancellous middle and tubercular superficial layers. All three layers are composed of acellular bone but the superficial layer also includes dentine and enameloid, comprising the tubercles. As such, the composition of the arandaspid dermoskeleton is common to heterostracans and astraspids, supporting existing hypotheses of early vertebrate phylogeny. This emphasizes the peculiarity of existing interpretations of aranadaspid anatomy and there is need for a complete reappraisal of the existing anatomical data.     

Anin vitro,serum-free organ culture technique for the study of development and growth of the dermal skeleton in fish

Summary To develop a serum-free, chemically definedin vitro organ culture system enabling the study of epithelial-mesenchymal interactions in development and growth of fish dermal skeleton, we investigatedin vitro continuation of scale regeneration in the cichlid fishHemichromis bimaculatus. The culture medium in our system is based on Leibovitz medium (L-15) supplemented with vitamin C, additional amino acids and HEPES. With this basis medium, we examined the effects of all trans-retinoic acid, dexamethasone, and prostaglandin-E2 (PG-E2), factors known to exert an effect on development and growth of teeth and bone in mammalian culture systems, on thein vitro regeneration of scales. These effects were compared with those obtained by supplementation of the basis medium with newborn and fetal calf serum. To evaluate our culture system, the medium that allowed to mimick in the best possible way thein vivo regeneration of scales (i.e., the basis medium plus dexamethasone and PG-E2) was also tested on thein vitro development of teeth in the same fish species. Our serum-free, chemically defined organ culture system enablesin vitro development and growth of both scales and teeth. With this model culture system, it is possible to evaluate thein vitro effects of hormones, growth factors, and other substances on growth and development of dermal skeleton in fish.     

The evolution of early vertebrate photoreceptors

Meeting the challenge of sampling an ancient aquatic landscape by the early vertebrates was crucial to their survival and would establish a retinal bauplan to be used by all subsequent vertebrate descendents. Image-forming eyes were under tremendous selection pressure and the ability to identify suitable prey and detect potential predators was thought to be one of the major drivers of speciation in the Early Cambrian. Based on the fossil record, we know that hagfishes, lampreys, holocephalans, elasmobranchs and lungfishes occupy critical stages in vertebrate evolution, having remained relatively unchanged over hundreds of millions of years. Now using extant representatives of these ‘living fossils’, we are able to piece together the evolution of vertebrate photoreception. While photoreception in hagfishes appears to be based on light detection and controlling circadian rhythms, rather than image formation, the photoreceptors of lampreys fall into five distinct classes and represent a critical stage in the dichotomy of rods and cones. At least four types of retinal cones sample the visual environment in lampreys mediating photopic (and potentially colour) vision, a sampling strategy retained by lungfishes, some modern teleosts, reptiles and birds. Trichromacy is retained in cartilaginous fishes (at least in batoids and holocephalans), where it is predicted that true scotopic (dim light) vision evolved in the common ancestor of all living gnathostomes. The capacity to discriminate colour and balance the tradeoff between resolution and sensitivity in the early vertebrates was an important driver of eye evolution, where many of the ocular features evolved were retained as vertebrates progressed on to land.     

昆虫肠道菌群组学研究及功能和应用进展

近年来,随着昆虫微生态领域研究的发展,昆虫肠道菌群组学研究越来越受关注。由于昆虫肠道菌群种类繁杂、数量巨大、功能多样,因此,其组学研究方法的选取至关重要,与研究是否科学、高效及合理密切相关。常见的昆虫肠道菌群组学研究方法包括宏基因组学、蛋白质组学、代谢组学、培养组学及多组学技术。昆虫肠道菌群在与宿主长期共同进化中对宿主的营养代谢、生长发育、保护防御等起到了至关重要的作用,随着其功能研究的不断深入,昆虫肠道菌群应用研究也越来越广泛。本文将从昆虫肠道菌群的概述、组学研究方法的选择、昆虫肠道菌群的功能及应用4个方面,对近年来的研究进行总结,为昆虫肠道菌群的深入研究提供文献参考。     

Hyobranchial skeleton and hypobranchial muscles of rhipidistians

The hyobranchial skeleton of the porolepiform rhipidistian Laccognathus panderi Gross is described. The double composition of the ceratohyal in crossopterygians is proposed. The urohyal of porolepiforms, like that of Latimeria, consists of cartilaginous axial and membranous peripheral portions. The differences between porolepiforms and osteolepiforms in the structure of the hyobranchial skeleton, particularly, in the shape of the urohyal are attributable to different arrangements of the hypobranchial muscles. Porolepiforms and coelacanths have retained the coracomandibularis muscle inherited from early gnathostomes, whereas the same muscle of osteolepiforms was transformed into the geniohyoideus muscle. This transformation is accounted for by functional changes in the hyobranchial apparatus.     

Radiation and functional diversification of alpha keratins during early vertebrate evolution

The conquest of land was arguably one of the most fundamental ecological transitions in vertebrates and entailed significant changes in skin structure and appendages to cope with the new environment. In extant tetrapods, the rigidity of the integument is largely created by type I and type II keratins, which are structural proteins essential in forming a strong cytoplasmic network. It is expected that such proteins have undergone fundamental changes in both stem and crown tetrapods. Here, we integrate genomic, phylogenetic, and expression data in a comprehensive study on the early evolution and functional diversification of tetrapod keratins. Our analyses reveal that all type I and type II tetrapod keratins evolved from only two genes that were present in the ancestor of extant vertebrates. Subsequently, the water-to-land transition in the stem lineage of tetrapods was associated with a major radiation and functional diversification of keratin genes. These duplications acquired functions that serve rigidity in integumental hard structures and were the prime for subsequent independent keratin diversification in tetrapod lineages.     

The nature of the skeleton and skeletogenic tissues in the Cnidaria

Calcification of zooxanthellate and non-zooxanthellate corals from 2 classes and 3 orders of Cnidaria was investigated using scanning and transmission electron microscopy and light microscopy. The ultrastructure of the skeleton and skeletogenic tissues (the calicoblastic ectoderm) from areas of active and non-active skeleton deposition were investigated. The results show that the fundamental cellular mechanism of calcification is similar in all 3 orders, and that the role of endosymbiotic zooxanthellae may be one that is concerned with the removal of waste products of the calcification process. The results are discussed with respect to the concepts of calcification and its evolution in the Cnidaria.     

Histology of early somatic embryogenesis inHevea brasiliensis: The importance of the timing of subculturing

Somatic embryos ofHevea brasiliensis can be obtained by culturing thin sections of inner tegument of seed on two successive different media, MH1 and MH3. Histological study showed that in calli cultured on non-renewed medium MH1 for 40 days, the embryogenesis process initiated on the 20th day did not produce results owing to early degeneration of the cells involved in the embryogenic pathway. However, typical embryogenic cells formed when medium MH1 was renewed once during the first phase of culture (between day 20 and day 30). Proembryos developed when the calli were subcultured on medium MH3 10–15 days later. Embryogenic cells did not form when there was frequent renewal of medium MH1 or early subculturing on MH3 after less than 40 days of culture on MH1. Methodical histological monitoring of the development of embryogenic quality of calli thus made it possible to define the optimum culture sequences for the embryogenesis process and which are favourable for regular obtaining of proembryos.     

Genome duplication, extinction and vertebrate evolution

Vertebrate evolution has been punctuated by three episodes of widespread gene or genome duplication, which have been linked with the origin of vertebrates, gnathostomes and teleosts, respectively. These three events coincide with bursts of character acquisition and increases in phenotypic complexity, and many researchers have suggested a causal relationship between the two. However, this pattern is derived from data for living taxa only; we argue here that, when fossils are taken into account, bursts of character acquisition disappear and gen(om)e duplication in vertebrate phylogeny can no longer be correlated with the origin of body plans. If patterns of character acquisition or morphological gaps between higher taxa are a reflection of phenotypic complexity, then more inclusive data sets incorporating fossil taxa provide no support for hypotheses linking gen(om)e duplications and the evolution of complexity in vertebrates.     

Radiolarian skeleton: Morphology of spines,internal framework,and primary sphere

The morphology and evolution of the internal framework, primary inner sphere, and various spines of radiolarian skeletons are considered. A new scheme of successive stages of spine formation is offered. The convergent similarity of radiolarian spines and sponge spicules are discussed.     

Mineralized cartilage in the skeleton of chondrichthyan fishes

The cartilaginous endoskeleton of chondrichthyan fishes (sharks, rays, and chimaeras) exhibits complex arrangements and morphologies of calcified tissues that vary with age, species, feeding behavior, and location in the body. Understanding of the development, evolutionary history and function of these tissue types has been hampered by the lack of a unifying terminology. In order to facilitate reciprocal illumination between disparate fields with convergent interests, we present levels of organization in which crystal orientation/size delimits three calcification types (areolar, globular, and prismatic) that interact in two distinct skeletal types, vertebral and tessellated cartilage. The tessellated skeleton is composed of small blocks (tesserae) of calcified cartilage (both prismatic and globular) overlying a core of unmineralized cartilage, while vertebral cartilage usually contains all three types of calcification.     

宽体金线蛭消化道的组织学观察

运用解剖学和组织学方法对宽体金线蛭消化道的结构进行了组织学研究。结果表明,宽体金线蛭的嗉囊向两侧伸出11对侧盲囊,第6对侧盲囊狭长并延伸到直肠两侧;咽主要由黏膜层、肌层和外膜构成,外膜几乎不可见;食道、嗉囊、肠和直肠管壁由黏膜层、黏膜下层、肌层和浆膜构成;咽和直肠的上皮具纹状缘。除肠外,其他消化道的上皮细胞均无发达的纤毛,且黏膜上皮皆为单层柱状上皮;除肠和直肠外,腺体及导管较少;直肠的黏膜肌层为内环外纵两层,其他各部均为纵行肌一层;消化道各部黏膜下层较发达;外膜为浆膜,与黏膜下层分界不明显。     

骨骼的内分泌功能

既往认为骨骼是支持机体基本结构和参与运动及钙磷代谢的主要器官。近年发现组成骨骼的成骨细胞和破骨细胞能合成和分泌多种骨调节蛋白、生长因子、脂肪因子、炎症因子和心血管活性肽等多种生物活性物质,以旁/自分泌方式调节骨骼系统功能,并能通过血液循环远距分泌的方式,调节机体能量代谢、炎症反应和内分泌稳态等。     

Permanent electric polarization and pyroelectric behaviour of the vertebrate skeleton

Summary The segmental organisation of the axial skeleton of the Vertebrata according to sclerotomes and scleromites is clearly evident in the Mammalia by their varying directions of electric polarization. In the corpora vertebrae this is demonstrable until the end of the growth period, in the disci intervertebrales the phenomenon persists through life, and in the ligamenta longitudinalia communia columnae vertebralis it probably persists through life. Two types of vertebral epiphyses were found in the Mammalia.Type I has one single, continuous direction of electric polarization like, for instance, the cartilaginous plates of the vertebrae. Examples of this type are the vertebral epiphyses of the Prototheria (Monotremata) and the Metatheria (Marsupialia), the epiphyses hi the caudal vertebrae of numerous Eutheria (Placentalia) and also the bony vertebral epiphyses of man. In vertebrae having this type of epiphysis, the direction of electric polarization is reversed by 180° at the end of the growth period, both in the epiphysis itself and in the bony centre of the corpus to which it belongs.Type II consists of two layers having opposite directions of electric polarization and is comparable to the epiphyses of certain long bones. This type is found in the trunk vertebrae of the Eutheria, but it was also detected in the caudal vertebrae of the Edentata and Cetacea specimens investigated by us. (Type II occurs neither in man nor probably in the anthropoid apes).In the bony parts of the axial skeleton of the Mammalia, the electric polarization phenomena fade with age; this fading process sets in sooner or later after termination of the growth period. It invariably begins at the centre of the vertebral body and progresses, simultaneously in the two vertebral halves, towards the cranial and caudal end faces of the vertebrae. In old specimens, some weak electric polarization is normally only left in the cranial and caudal cortex. Polarization does not fade with age in the purely collagenous structures of the axial skeleton (e. g. the disci intervertebrales and the ligamenta longitudinalia communia); the polarization phenomena merely become a little less intense at a very great age, but the reduction in intensity varies greatly from one individual to another, and is probably dependent on their vitality.We investigated fossile bone material with the task of determining whether the electric polarization phenomena in the collagenous structures are maintained over long periods of time. Cervical vertebrae, thoracic vertebrae and lumbar vertebrae of juvenile and adult specimens of the cave bear (Ursus spelaeus), which lived in the glacial period known as the Würm-Eiszeit, exhibited electric polarization features that were analogous to those found in contemporary Mammalia of comparable age.The phylogenetic relationship between the Mammalia and certain Reptilia is clearly brought out by the similarity of electric polarization phenomena in the axial skeleton of the Prototheria (Monotremata) and the Crocodilia.

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Zusammenfassung Durch unterschiedliche Richtungen ihrer elektrischen Polarisation tritt bei den Mammalia die segmentale Gliederung des Vertebrata-Achsenskeletts nach Sclerotomen und Scleromiten deutlich hervor. Dies ist der Fall in den Corpora vertebrae bis zum Wachstumsabschluß, in den Processus vertebrae im juvenilen Stadium, in den Disci intervertebrales zeitlebens und in den Ligamenta longitudinalia communia columnae vertebralis wahrscheinlich zeitlebens. Es wurden zwei Typen von Wirbelepiphysen bei den Mammalia festgestellt.Typ I hat nur eine einzige, durchgehende elektrische Polarisationsrichtung, ähnlich wie z. B. die Knorpelplatten der Wirbel. Diesem Typ gehören die Wirbelepiphysen der Prototheria (Monotremata) und der Metatheria (Marsupialia), sowie die Schwanzwirbelepiphysen zahlreicher Eutheria (Placentalia) an, übrigens auch die knöchernen Wirbelepiphysen des Menschen. Bei Wirbeln mit diesem Epiphysentyp findet beim Wachstumsabschluß eine Umkehrung der elektrischen Polarisationsrichtungen um 180° sowohl in den Epiphysen selbst als auch im zugehörigen Wirbelkörperkern statt.Typ II besteht aus zwei Schichten mit einander entgegengesetzten elektrischen Polarisationsrichtungen und hat Ähnlichkeit mit den Epiphysen mancher Röhrenknochen. Er findet sich in den Rumpfwirbeln der Eutheria, wurde aber auch in den Schwanzwirbeln der untersuchten Edentata und Cetacea festgestellt. (Beim Menschen und wahrscheinlich bei den anthropoiden Affen kommt Typ II nicht vor.)Es tritt ein Altersschwund der elektrischen Polarisationserscheinungen in den knöchernen Teilen des Achsenskeletts der Mammalia früher oder später nach dem Wachstumsabschluß auf. Der Altersschwund beginnt stets in der Corpusmitte und setzt sich, in beiden Wirbelhälften gleichzeitig, nach den cranialen und caudalen Wirbelendflächen zu fort. Alte Individuen zeigen meist nur noch in der cranialen und caudalen Cortex eine schwache elektrische Polarisation. Die reinen Kollagenstrukturen des Achsenskeletts (u.a. die Disci intervertebrales und die Ligamenta longitudinalia communia) zeigen keinen Altersschwund, sondern nur eine geringe Abschwächung der elektrischen Polarisationserscheinungen im höchsten Lebensalter und mit ausgeprägter individueller, wahrscheinlich vitalitätsbedingter Unterschiedlichkeit.Um zu prüfen, ob die elektrischen Polarisationserscheinungen von Kollagenstrukturen sich auch im Laufe langer Zeiträume erhalten, wurde fossiles Knochenmaterial untersucht. Hals-, Brust- und Lendenwirbel juveniler und adulter Exemplare des Höhlenbären (Ursus spelaeus) aus der Wurm-Eiszeit zeigten analoge elektrische Polarisationsverhältnisse wie Mammalia vergleichbaren Alters von heute.Die stammesgeschichtliche Verwandtschaft der Mammalia mit bestimmten Reptilia kommt in einer Gleichartigkeit der elektrischen Polarisationsverhältnisse im Achsenskelett der Prototheria (Monotremata) und der Crocodilia zum Ausdruck.

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For Prof. Dr. W. Bargmann.

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With support from the Deutsche Forschungsgemeinschaft which is gratefully acknowledged.     

Permanent electric polarization and pyroelectric behaviour of the vertebrate skeleton

Summary The segmentation of the axial skeleton according to sclerotome and scleromite boundaries is brought out clearly in man, other mammals and vertebrates by the varying directions of electric polarization. With the aid of this physical phenomenon, the segmental division is demonstrable through life. In the ligamenta longitudinalia communia of man permanent electric polarization retains its original pattern through life: The directions of polarization are reversed in very narrow zones located at a point half-way along each vertebral body (=sclerotome boundary) and half-way along each intervertebral disk (=scleromite boundary). In the intervertebral disks, permanent electric polarization likewise persists through life, the two halves of each disk having opposite directions of polarization (when measured longitudinally); the directions of polarization change in a narrow reversal zone half-way through each disk. On the other hand, the electric polarization pattern in the bony parts of the axial skeleton, i.e. the vertebrae, untergoes characteristic changes in the course of ontogenesis. They are analogous to the changes found in the vertebrae of the other Mammalia with Type I epiphyses (Athenstaedt, 1968b).During postnatal growth, the directions of electric polarization are reversed in the ossification centre of the vertebral body and in the vertebral epiphyses. The reversal process is completed at the end of the growth period, i.e. normally between the 20th and the 25th year of life. In all the Mammalia we investigated similar reversal processes were found to take place in vertebrae having the same type of epiphyses and it is therefore logical to assume that the reversal process plays a significant part in the physiology of growth.Since the directions of polarization in the epiphyses are opposite to those in the ossification centre of the vertebral body, a clear distinction can be made between the two structures in all the Mammalia, including man. In this way the configuration of the vertebral epiphysis in man can be clearly defined, especially during those stages of its development which precede the end of the growth period. On termination of growth, the epiphysis of the vertebral body takes the shape of a biconcave bony plate which entirely covers the end face of the corpus. In the material we investigated it was found to have a thickness of approx. 1.5–3.5 mm in its centre and up to 6.0 mm at its outer edges. The bony marginal ridge proved to be part of the vertebral body's epiphysis structure proper; it is probably of secondary importance.Soon after the end of the growth period, the electric polarization phenomena in the vertebrae begin to fade and this slow fading process continues, though with marked individual variations, right up to the senium.An attempt is made to reconstruct the electric polarization pattern at the mesenchymal stage of the axial skeleton on the basis of our findings in human embryos and the results of measurements on the chorda dorsalis of the Cyclostomata and Acipenser. It is assumed that a clearly defined alignment of the permanent electrical moments of polar molecules takes place during the first few weeks of embryonic development. The alignment of electrical moments which occurs at this early stage is probably already identical to the directions of polarization which are demonstrable through life in the ligamenta longitudinalia and in the intervertebral disks.

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Zusammenfassung Die segmentale Gliederung nach Sclerotomen und Scleromiten tritt im Achsenskelet des Menschen wie in dem der übrigen Mammalia und Vertebrata durch unterschiedliche Richtungen der elektrischen Polarisation deutlich in Erscheinung und läßt sich durch dies physikalische Verhalten zeitlebens nachweisen. In den Ligamenta longitudinalia communia besteht eine permanente elektrische Polarisation mit zeitlebens festliegenden, sehr schmalen Umkehrzonen der Polarisationsrichtungen jeweils in halber Höhe jedes Corpus (=Sclerotomgrenze) und in halber Höhe jedes Discus intervertebralis (=Scleromitengrenze). Auch in den Disci intervertebrales besteht zeitlebens eine permanente elektrische Polarisation mit entgegengesetzten Polarisationsrichtungen beider Discushälften (in Längsrichtung gemessen) und schmaler Umkehrzone der Polarisationsrichtungen jeweils in halber Discushöhe. Dagegen unterliegen die elektrischen Polarisationsverhältnisse in den knöchernen Anteilen des Achsenskelets, also in den Wirbeln, im Laufe der Ontogenese charakteristischen Veränderungen. Diese gehen analog vor sich wie diejenigen in den Wirbeln mit Epiphysentyp I der übrigen Mammalia (Athenstaedt, 1968b).Im Wirbelkörperkern und in den Wirbelepiphysen findet während des postnatalen Wachstums eine Umkehrung der elektrischen Polarisationsrichtungen statt, die mit dem Wachstumsabschluß, also im allgemeinen zwischen dem 20. und 25. Lebensjahr, beendet ist. Da ähnlich ablaufende Umkehrungsprozesse in den Wirbeln mit gleichem Epiphysentyp bei allen untersuchten Mammalia gefunden wurden, ist an eine wachstumsphysiologische Bedeutung dieses Umkehrungsvorganges zu denken.Die einander entgegengesetzten elektrischen Polarisationsrichtungen von Corpusepiphysen und Wirbelkörperkern erlauben eine einwandfreie Unterscheidung beider Strukturen bei allen Mammalia einschließlich des Menschen. Dadurch läßt sich die Form der menschlichen Wirbelepiphyse, besonders in den Entwicklungsstufen vor dem Wachstumsabschluß klar definieren. Die Wirbelkörperepiphyse hat beim Wachstumsabschluß die Form einer bikonkaven Knochenplatte, welche die gesamte Corpusendfläche überdeckt und bei unserem Untersuchungsmaterial in der Flächenmitte etwa 1,5–3,5 mm, an ihren verstärkten Außenrändern bis zu 6,0 mm dick war. Die knöcherne Randleiste erwies sich als eine Teilstruktur der eigentlichen Corpusepiphyse und ist wahrscheinlich von sekundärer Bedeutung.Bald nach dem Wachstumsabschluß beginnt in den Wirbeln ein Altersschwund der elektrischen Polarisationserscheinungen, der sich allmählich und mit deutlichen individuellen Unterschieden bis ins Senium fortsetzt.Auf Grund der Untersuchungsergebnisse an menschlichen Keimlingen und der Meßergebnisse an der Chorda dorsalis der Cyclostomata und von Acipenser wird versucht, die elektrischen Polarisationsverhältnisse im Mesenchymstadium des Achsenskelets zu rekonstruieren. Dabei wird angenommen, daß in den ersten Wochen der Embryonalentwicklung an den Sclerotom- und Scleromitengrenzen eine definierte Ausrichtung der permanenten elektrischen Momente von polaren Molekülen erfolgt. Die in diesem Stadium geprägte Ausrichtung der elektrischen Momente entspricht wahrscheinlich bereits den Polarisationsrichtungen, wie sie in den Ligamenta longitudinalia communia und in den Intervertebralscheiben zeitlebens unverändert nachgewiesen werden konnten.

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For Prof. Dr. W. Bargmann.

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With support from the Deutsche Forschungsgemeinschaft which is gratefully acknowledged.     

Permanent electric polarization and pyroelectric behaviour of the vertebrate skeleton

Summary Like the bones of the axial and the appendicular skeleton, the bones of the human skull are pyroelectric and hence piezoelectric, too. There are two directions of electric polarization, one at right angles to the other, which can be clearly distinguished by appropriate measurements.The first of these two directions of polarization in the cranial bones follows the longitudinal direction of the collagen fibres or the osteons which develop from them. This longitudinal polarization is particularly marked in the cranial bones of foetuses and children in their first years of life. Up to the 2nd or 3rd postnatal year the electrical axes inside the parietal bone and the frontal bone, for example, emanate like radii from a centre formed by the parietal tuber and the frontal tuber respectively, and extend right to the very periphery of the bone. The axes are aligned exactly parallel to the fibre striation of the bony tissue which is macroscopically visible at this age. After the 3rd year of life, this strictly radial orientation disappears and the electrical axes become adjusted to the partly new contours of the cranium.The second direction of polarization in the cranial bones persists through life. It goes from the external surface to the internal surface, i.e. it is at right angles to the lamellae and tissue layers of the bones. It is true that the sense of direction differs in lamina externa, diploë and lamina interna, but it never changes in the course of ontogenesis.Analogous electric polarization phenomena were found in the cranial bones which develop from connective tissue and those which are cartilaginous in origin; this was demonstrated in respect of the two types of bone forming the occipital bone. A comparative study of the dermatocranium and the various large scales of Acipenser sturio showed that the polarization pattern is similar to that found in our investigations of the human skull bones.Our findings in respect of the cranial bones are supplemented by a survey of the electric polarization pattern in the topographically adjacent structures, i.e. pericranium, galea aponeurotica and scalp and also the dura mater encephali.

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Zusammenfassung Die Knochen des menschlichen Craniums sind, wie die Knochen des Achsen- und Extremitätenskeletts, pyroelektrisch und damit auch piezoelektrisch. Es sind zwei aufeinander senkrecht stehende elektrische Polarisationsrichtungen vorhanden, die meßtechnisch klar unterscheidbar sind.Die eine Polarisationsrichtung der Schädelknochen besteht in Längsrichtung der Kollagenfasern bzw. der aus ihnen gebildeten Osteone. Diese Längspolarisation tritt in den Schädelknochen von Feten und von Kindern der ersten Entwicklungsjahre besonders deutlich in Erscheinung. Bis zum 2. oder 3. postnatalen Lebensjahr verlaufen die elektrischen Achsen z. B. innerhalb des Os parietale und des Os frontale wie Radien, vom Tuber parietale bzw. Tuber frontale als Zentrum ausgehend, bis zur äußersten Peripherie des Knochens. Der Achsenverlauf ist exakt parallel zu der in diesem Alter makroskopisch erkennbaren Faserstreifung des Knochengewebes. Nach dem 3. Lebensjahr verliert sich die streng radiale Orientierung und paßt sich den teilweise neu entstehenden Konturen des Craniums an.Die andere Polarisationsrichtung der Schädelknochen besteht zeitlebens in Richtung von ihrer Außenfläche zur Innenfläche, also senkrecht zu den vorhandenen Lamellen und Gewebeschichten. Ihr Richtungssinn ist in Tabula externa, Diploë und Tabula interna zwar unterschiedlich, ändert sich aber im Laufe der Ontogenese nicht.Die aus Bindegewebe entstehenden und die aus Knorpel präformierten Schädelknochen verhalten sich hinsichtlich der gefundenen elektrischen Polarisationserscheinungen analog, wie an den beiden Knochenanteilen des Os occipitale gezeigt werden konnte. Eine Vergleichsuntersuchung an dem Dermatocranium und an den einzelnen großen Knochenschuppen von Acipenser sturio ergab ähnliche elektrische Polarisationsverhältnisse wie in den untersuchten Knochen des menschlichen Craniums.Zur Ergänzung der Befunde an den Schädelknochen werden die elektrischen Polarisationsverhältnisse in den topographisch benachbarten Strukturen des Pericraniums, der Galea aponeurotica und der Kopfhaut, sowie der Dura mater encephali angegeben.

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With support from the Deutsche Forschungsgemeinschaft which is gratefully acknowledged.     

Permanent electric polarization and pyroelectric behaviour of the vertebrate skeleton

Summary In a previous investigation we were able to demonstrate the presence of permanent electric polarization in human and animal tendon tissue and the existence of a permanent electric moment in tendon fibres and their collagen fibrils, as well as a pyroelectric axis in their longitudinal direction (Athenstaedt, 1967). An experimental programme has now been completed whose object it was to elucidate electric polarization in the axial and appendicular skeleton of the Vertebrata (including man). Our results will be reported in several parts of which this is the first. In addition to bony, cartilaginous and chordal tissue, our investigations also extended to other forms of supporting tissue such as intervertebral disks, periosteum and dura mater.In the chorda dorsalis of the Cyclostomata (Myxine, Petromyzon) and of Acipenser there is a permanent electric polarization in the direction of its physiologic longitudinal axis and a radial polarization in the direction of the thickness of its sheath. Both in the complete chorda dorsalis and in any random part of it (cut at right angles to its longitudinal axis) a negative electric charge is found on the cranial side and a positive charge on the caudal side. The outside of the chordal sheath has a negative charge, the inside a positive charge. These findings are correlated with the known induction effects of the chorda in embryonic development and with the structural peculiarities characterizing the chorda of vertebrates in the money-roll and in the adult stage.Both the cartilaginous axial skeleton of the Elasmobranchii and the bony axial skeleton of all examined specimens, from the Teleostei to the Aves, invariably showed the same pattern of permanent electric polarization: the two halves of each vertebral body, which correspond to the former sclerotome halves, are polarized in opposite directions. Thus the direction of polarization alternates constantly throughout the vertebral column along its longitudinal axis, this alternation being repeated in each fully developed vertebral body or each distinct beginning of vertebral structure.In cases of primary or secondary coalescence of vertebral bodies — e.g. in the synsacrum of adult Aves, in the urostyle of the Anura and in the cranially fused first part of the axial skeleton of Raiidae and Acipenser — the fused bony or cartilaginous rod has not an alternating but a continuous direction of polarization corresponding to that in the chorda dorsalis of the Cyclostomata and of Acipenser.

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Zusammenfassung In einer vorausgegangenen Untersuchung konnte nachgewiesen werden, daß menschliches und tierisches Sehnengewebe eine permanente makroskopische elektrische Polarisation besitzt, und daß die Sehnenfasern bzw. ihre Kollagenfibrillen ein permanentes elektrisches Moment und eine pyroelektrische Achse in ihrer Längsrichtung aufweisen (Athenstaedt, 1967). Die vorliegende Arbeit bildet den ersten Teilabschnitt einer inzwischen abgeschlossenen Untersuchungsreihe über die elektrischen Polarisationsverhältnisse im Achsen- und Extremitätenskelett der Vertebrata (einschließlich des Menschen). In die Untersuchungen wurden außer Knochen-, Knorpel- und Chordagewebe auch andere geformte Stützgewebe, u.a. Zwischenwirbelscheiben, Periost und Dura mater einbezogen.Die Chorda dorsalis der Cyclostomata (Myxine, Petromyzon), und von Acipenser weist eine permanente elektrische Polarisation in ihrer physiologischen Längsrichtung, sowie radial in Richtung ihrer Wandungsdicke auf. Dabei zeigt die Chorda dorsalis als Ganzes und in jedem beliebigen Teilabschnitt (quer zu ihrer Längsrichtung) auf der cranialen Seite eine negative, auf der jeweils caudalen Seite eine positive elektrische Ladung. Die Außenseite der Chordascheide besitzt eine negative, die Innenseite eine positive Ladung. Mit diesen Befunden werden die bekannten Induktionswirkungen der Chorda in der Embryonalentwicklung und die Struktureigentümlichkeiten der Chorda der Vertebrata im Geldrollenstadium und im adulten Stadium in Beziehung gebracht. Sowohl das knorpelige Achsenskelett der Elasmobranchii als auch das knöcherne Achsenskelett von den Teleostei bis zu den Aves einschließlich zeigt ein stets gleichbleibendes Schema seiner permanenten elektrischen Polarisation: Die beiden Hälften jedes einzelnen Wirbelkörpers, welche den ehemaligen Sklerotomhälften entsprechen, haben eine entgegengesetzte Polarisationsrichtung zueinander. Die Wirbelsäule als Ganzes zeigt daher in Richtung ihrer Längsachse ein fortgesetztes Alternieren der Polarisationsrichtung, das sich in jedem fertigen Wirbelkörper bzw. in jeder ausgeprägten Wirbelanlage wiederholt.Bei primären oder sekundären Verschmelzungen von Wirbelkörpern — u.a. im Synsacrum adulter Aves, im Urostyl der Anura und in den verschmolzenen cranialen Anfangsstücken des Achsenskeletts der Rajidae und von Acipenser — zeigt der verschmolzene Knochen- oder Knorpelstab keine alternierende, sondern eine kontinuierliche Polarisationsrichtung, deren Richtungssinn demjenigen der Chorda dorsalis der Cyclostomata und von Acipenser entspricht.

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For Prof. Dr. W. Bargmann.

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With support from the Deutsche Forschungsgemeinschaft which is gratefully acknowledged.     

Comparing levels of homoplasy in the primate skeleton

Hard-tissue morphological characters (bones and teeth) are a primary source of information about the evolutionary history of primates. These tissues are commonly found as isolated elements in the fossil record and studied as three separate partitions: the dentition, the cranium, and the postcranium. The relative phylogenetic utility of characters from each partition is often called into question with respect to varying amounts of homoplasy. In this paper, the consistency index (CI) was used to measure levels of homoplasy in each data partition for a sample of fossil and living primates. Sources of bias in the collection and treatment of data and in the internal structure of the data set are addressed. These biases include number of taxa, number of characters, ordering of characters, amounts of polymorphically scored or missing data, and character-state distribution. The results of this study suggest that the levels of homoplasy are very similar, though the postcranial data may be slightly less homoplastic than either the dental or cranial data.     

Functional morphology of the caudal skeleton in teleostean fishes

The basic function of the caudal skeleton in teleostean fishes is to support the caudal fin, but its parts contribute to this function in somewhat different ways. The main axis for this support is the upturned terminal end of the vertebral column, which ends at the base of the uppermost principal rays. The uroneural struts just ahead of this axis provide support for it. The parts of the caudal skeleton behind and below this upturned axis, the hypurals and parhypural, not only support the caudal rays but also provide a means for differential movements between the upper and lower parts of the fin base. This basic caudal skeleton varies with the position of the fish in the sequence of teleosten evolution, the way in which the fish uses its caudal fin, and to some extent with the shape of the fin.