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Early Ontogeny (early + ontogeny)
Selected AbstractsEarly ontogeny and placentation of the grey short-tailed opossum, Monodelphis domestica (Didelphidae: Marsupialia): contribution to the reconstruction of the marsupial morphotypeJOURNAL OF ZOOLOGICAL SYSTEMATICS AND EVOLUTIONARY RESEARCH, Issue 3 2001Zeller This study provides new findings on the placenta of Monodelphis domestica and a reconstruction of the marsupial morphotype. To achieve this, early ontogeny and placentation of the grey short-tailed opossum, M. domestica, from 3 h after copulation until birth (day 15), were studied and compared with other mammals. Both the ultrastructure and histochemistry of egg membranes, foetal membranes, oviduct and uterus were examined. The results of this study provide the first detailed ultrastructural description of a trophoblastic syncytium in a marsupial. In addition, this is the first original documentation of an invasive trophectoderm and an inflammatory reaction at parturition in M. domestica. These findings were compared with literature data and included into the reconstruction of the marsupial morphotype. Based on marsupial phylogeny as proposed by Luckett (J. Mammal. Evol. 2, 255,283, 1994), characters that are consistent at least within didelphids and dasyurids were determined to be characters of the marsupial morphotype. These characters are a central yolk separated from the peripheral yolk-poor cytoplasm in the unfertilized oocyte, the presence of a zona pellucida, a mucoid coat and a shell coat, the absence of a corona radiata, oviductal mucoid secretion, no shell secretion distal to the isthmus of the oviduct, uterine shell secretion, a short tubal passage (1 day at maximum), the apposition of blastomeres to the zona pellucida prior to intercellular association, the absence of a morula stage, the polarity of the zygotic yolk, the localized segmentation of deutoplasm (yolk) during the first cleavage and subsequent extrusion of yolk vesicles during the first two cleavage stages. With regard to the marsupial morphotype, the non-polarized yolk distribution in the zygote [Hartman (J. Morphol. 27, 1,84, 1916); McCrady (Am. Anat. Mem. 16, 1,233, 1938)] is a derived character of Didelphis virginiana. Didelphis virginiana [Hartman (J. Morphol. 27, 1,84, 1916); Hartman (J. Morphol. 32, 1,139, 1919); McCrady (Am. Anat. Mem. 16, 1,233, 1938)] and Didelphis marsupialis (Hill, Q. J. Micr. Sci. 63, 91,139, 1918) share the synapomorphous reduction of deutoplasmolysis to a generalized extrusion of vesicles. The absence of separated yolk and consequently a cleavage without yolk extrusion (Renfree and Lewis, Reprod. Fert. Dev. 8, 725,742, 1996) are apomorphies of macropodids. This is possibly correlated with the association of blastomeres in early cleavage stages (Renfree and Lewis, Reprod. Fert. Dev. 8, 725,742, 1996). A yolk sac placenta and a vascularized allantochorion can be assumed for part of the ontogeny in the marsupial morphotype, irrespective of the formation of an allantoic placenta at near term stages. The character polarization of the mode of placentation and parturition needs further investigation. Frühe Ontogenie und Plazentation der grauen Hausspitzmausbeutelratte, Monodelphis domestica (Didelphidae: Marsupialia): Ein Beitrag zur Rekonstruktion des Grundplans der Marsupialia Die vorliegende Arbeit beschreibt die frühe Ontogenese und Plazentation von 3 Stunden nach der Kopulation bis zur Geburt der Beutelratte Monodelphis domestica. Es wird die Ultrastruktur und Histochemie der Eihäute, der Fetalmembranen, des Oviductes und des Uterus beschrieben. Erstmalig wird die Ultrastruktur eines trophoblastischen Syncytiums bei einem Beuteltier beschrieben. Weiterhin wird ein invasives Trophektoderm und eine Entzündungsreaktion zum Zeitpunkt der Geburt bei M. domestica festgestellt. Die Befunde dieser Studie und Literaturdaten werden verglichen und in eine Grundplanrekonstruktion integriert. Merkmale, die mindestens zwischen Vertretern der Didelphidae und Dasyuridae übereinstimmen, werden basierend auf dem phylogenetischen System der Marsupialia nach Luckett, J. Mammal. Evol. 2, 255,283, 1994, für den Grundplan der Marsupialia angenommen. Diese Merkmale sind zentral separierter Dotter und peripheres dotterarmes Zytoplasma in der unbefruchteten Eizelle, das Vorhandensein von Zona pellucida, Mucoidschicht und Schalenhaut, das Fehlen einer Corona radiata, die Mucoidsekretion durch den Oviduct, die Schalensekretion durch den Uterus und nicht distal der Isthmusregion des Oviductes, eine kurze Tubenwanderung (maximal einen Tag), die Anlagerung der Blastomeren an die Zona pellucida vor der interzellulären Verbindung, das Fehlen eines Morulastadiums, die Dotterpolarität in der Zygote, die lokale Dotterabtrennung bei der ersten Teilung und die anschließende Dotterextrusion während der ersten beiden Teilungen. In Bezug auf den Grundplan der Marsupialia ist die unpolare Dotterverteilung in der Zygote ein abgeleitetes Merkmal von Didelphis virginiana. Didelphis virginiana und Didelphis marsupialis teilen als Synapomorphie die Reduktion der Deutoplasmolyse auf eine generelle Vesikelextrusion. Das Fehlen separierten Dotters in der Oocyte und die resultierende Furchung ohne Dotterextrusion [Renfree and Lewis, Reprod. Fert. Dev. 8, 725,742, 1996] ist eine Apomorphie der Macropodidae. Hiermit hängt möglicherweise die frühe Zusammenlagerung der Blastomeren zusammen [Renfree and Lewis, Reprod. Fert. Dev. 8, 725,742, 1996]. Ein vaskularisiertes Allantochorion und eine Dottersackplazenta können für einen Teil der Ontogenese im Grundplan der Marsupialia angenommen werden. Ob das Allantochorion neben der Respiration auch dem Stoffaustausch diente ist unklar. Die Lesrichtung für den Modus der Plazentation und der Geburt bedarf weiterer Untersuchungen. [source] ON PENTAMPLEXUSSCHINDEWOLF, 1940 (ANTHOZOA, RUGOSA) AND ITS POSSIBLE RELATIVES AND ANALOGUESPALAEONTOLOGY, Issue 2 2009JERZY FEDOROWSKI Abstract:, Three ampleximorphic taxa are revised and their most important characters are discussed in terms of possible or apparent relationships. Re-interpretation of its early ontogeny allows the assignment of Pentamplexus Schindewolf, 1940 to the family Polycoeliidae de Fromentel, 1861. Stereolasma variabilisVojnovsky-Krieger, 1934 is established as the type species of Vojnovskytes gen. nov. It resembles the family Polycoeliidae in some characters and the Antiphyllidae Ilina, 1970 or the Laccophyllidae Grabau, 1928 in others. Thus, its family status is not established. Revision of the type material of Fasciculophyllum tripusSchindewolf, 1952 allows its inclusion within the new genus Silesamplus, probably related to the family Laccophyllidae Grabau, 1928. Amplexoid morphology is further shown to be inadequate for the establishment of relationships on the family or subfamily level. Early ontogeny is most important in that respect, but biform vs normal morphology in the tabularium and free vs contratingent development of minor septa must also be considered, where appropriate. [source] Early ontogeny of the spotted wolffish (Anarhichas minor Olafsen)AQUACULTURE RESEARCH, Issue 12 2003Inger-Britt Falk-Petersen Abstract This study illustrates the embryo development of the spotted wolffish (Anarhichas minor Olafsen), an interesting candidate for cold-water aquaculture. The egg morphology (semitransparent, yellow-white with numerous oil droplets in the yolk), size (5.4,6.5 mm) and long embryogenesis (c. 800,1000 d°, depending on temperature) of A. minor are very similar to Anarhichas lupus. Cleavage is slow, and the first cell divisions take place at 12 h at 8°C. After 12 days the 2-mm embryo with the first somites is laid down and the blastopore starts closing. The fat globules in the yolk fuse into one after 22 days, and after 30 days eye pigmentation is noticeable. After 44 days, eye pigmentation is strong, the digestive tract folded and a green gall bladder can be noted in the now 11-mm-long embryo. One week later the blood is brightly red, the intestine is pigmented and the lower jaw is well developed. Premature hatching may occur from this stage. After 58 days vascularization of the yolk is complete, capillaries are noted in the fin fold, the first ray rudiments are established in the tail and pectoral fins, and the four gill arches are covered by the operculum. The preanal finfold is reduced after 72 days, stomach and gill filaments are formed, and six pigmented rows are noted on the 17-mm-long embryo body. After 86 days all fin rays are seen and the digestive tract is intensely pigmented and folded. Hatching (normal) starts after 110 days and may last for 2,3 weeks. Late embryos and early larvae of A. minor have more distinct bands of pigment along the body compared with the closely related A. lupus. An increase in both length and weight of the embryos in individual batches occurs during the hatching period. [source] Salinity tolerance in young Allis shad larvae (Alosa alosa L.)ECOLOGY OF FRESHWATER FISH, Issue 1 2008A. Bardonnet Abstract,,, Estuarine migration in Allis shad (Alosa alosa) usually does not take place before mid-summer, but exposure to salinity in brackish water may occur earlier as many spawning areas are of necessity located in upper estuarine zones due to the placement of dams. Therefore, Allis shad conservation programmes need to consider the risk of mortality due to the ability of young Allis shad to tolerate salinity. To evaluate larval mortality due to the inability of larvae to withstand salinity during early ontogeny, we exposed larvae of different ages (from few days old to 27 days old) to salinities ranging from 0 to 30 g·l,1. Results indicate that direct seawater exposure induces high mortality in young larvae whatever the ontogenetic stage. However, young larvae can easily deal with upper estuary salinity conditions. [source] Transgenic and knock-out mouse pups: the growing need for behavioral analysisGENES, BRAIN AND BEHAVIOR, Issue 3 2002I. Branchi Few laboratories working with transgenic and knock-out mice analyze the neurobehavioral consequences of genetic manipulation in early ontogeny. However, the study of behavioral endpoints during the early postnatal period in genetically modified mice is important not only to assess possible developmental abnormalities, but also to better understand and disentangle the effects of genetic manipulations in adulthood. We propose that the assessment of neurobehavioral development represents an appropriate strategy to identify possible compensatory and/or unexpected effects. Nowadays, a large number of experimental protocols that take into account the practical constraints imposed by the peculiar physiological and behavioral responses of an immature subject are available to assess the neurobehavioral profile of developing mice. While this knowledge should be applied to the field of transgenic and knock-out mice in general, it should be recommended, in particular, for the study of mouse models of neurodevelopmental disorders. [source] Prenatal Development of Interlimb Motor Learning in the Rat FetusINFANCY, Issue 3 2008Scott R. Robinson The role of sensory feedback in the early ontogeny of motor coordination remains a topic of speculation and debate. On E20 of gestation (the 20th day after conception, 2 days before birth), rat fetuses can alter interlimb coordination after a period of training with an interlimb yoke, which constrains limb movement and promotes synchronized, conjugate movement of the yoked limbs. The aim of this study was to determine how the ability to express this form of motor learning may change during prenatal development. Fetal rats were prepared for in vivo study at 4 ages (E18,21) and tested in a 65-min training-and-testing session examining hind limb motor learning. A significant increase in conjugate hind limb activity was expressed by El9, but not El 8 fetuses, with further increases in conjugate hind limb activity on E20 and E21. These findings suggest substantial development of the ability of fetal rats to modify patterns of interlimb coordination in response to kinesthetic feedback during motor training before birth. [source] Ontogenetic induced shifts in the ecology of sunbleak Leucaspius delineatus during early developmentJOURNAL OF FISH BIOLOGY, Issue 2005A. C. Pinder Using the non-native sunbleak Leucaspius delineatus as a model, the relationship between ontogeny and ecology was studied with a view to identifying specific morphological and physiological processes involved in influencing ecological niche shifts. Following a predefined saltatory model for the early ontogeny of sunbleak, field studies examined the temporal use of microhabitat, diet and morphological changes throughout early development. Following a dramatic shift in both morphology and ecology between the free embryo phase and the larval period, habitat use and diet showed little change during the larval period, with habitat use confined to marginal, vegetated areas and prey items associated with these habitats well represented in the diet. During the final larval step (L5), transition to the juvenile period resulted in the stabilization of relative growth, acquisition of the adult morphotype and was associated with a clear shift in diet and habitat use. During this period, sunbleak moved for the first time into open, deeper water, away from the banks, and utilized a similar range of food items to the adults. Specific relationships between form and function are further discussed. [source] Variation in Reproductive Behaviour within a Sex:Neural Systems and Endocrine ActivationJOURNAL OF NEUROENDOCRINOLOGY, Issue 7 2002T. Rhen Abstract Intrasexual variation in reproductive behaviour, morphology and physiology is taxonomically widespread in vertebrates, and is as biologically and ecologically significant as the differences between the sexes. In this review, we examine the diverse patterns of intrasexual variation in reproductive behaviours within vertebrates. By illustrating the genetic, cellular, hormonal and/or neural mechanisms underlying behavioural variation in a number of species, another level of complexity is added to studies of brain organization and function. Such information increases our understanding of the unique and conserved mechanisms underlying sex and individual differences in behaviour in vertebrates as a whole. Here, we show that intrasexual variation in behaviour may be discrete or continuous in nature. Moreover, this variation may be due to polymorphism at a single genetic locus or many loci, or may even be the result of phenotypic plasticity. Phenotypic plasticity simply refers to cases where a single genotype (or individual) can produce (or display) different phenotypes. Defined in this way, plasticity subsumes many different types of behavioural variation. For example, some behavioural phenotypes are established by environmental factors during early ontogeny, others are the result of developmental transitions from one phenotype early in life to another later in life, and still other strategies are facultative with different behaviours displayed in different social contexts. [source] Early ontogeny and placentation of the grey short-tailed opossum, Monodelphis domestica (Didelphidae: Marsupialia): contribution to the reconstruction of the marsupial morphotypeJOURNAL OF ZOOLOGICAL SYSTEMATICS AND EVOLUTIONARY RESEARCH, Issue 3 2001Zeller This study provides new findings on the placenta of Monodelphis domestica and a reconstruction of the marsupial morphotype. To achieve this, early ontogeny and placentation of the grey short-tailed opossum, M. domestica, from 3 h after copulation until birth (day 15), were studied and compared with other mammals. Both the ultrastructure and histochemistry of egg membranes, foetal membranes, oviduct and uterus were examined. The results of this study provide the first detailed ultrastructural description of a trophoblastic syncytium in a marsupial. In addition, this is the first original documentation of an invasive trophectoderm and an inflammatory reaction at parturition in M. domestica. These findings were compared with literature data and included into the reconstruction of the marsupial morphotype. Based on marsupial phylogeny as proposed by Luckett (J. Mammal. Evol. 2, 255,283, 1994), characters that are consistent at least within didelphids and dasyurids were determined to be characters of the marsupial morphotype. These characters are a central yolk separated from the peripheral yolk-poor cytoplasm in the unfertilized oocyte, the presence of a zona pellucida, a mucoid coat and a shell coat, the absence of a corona radiata, oviductal mucoid secretion, no shell secretion distal to the isthmus of the oviduct, uterine shell secretion, a short tubal passage (1 day at maximum), the apposition of blastomeres to the zona pellucida prior to intercellular association, the absence of a morula stage, the polarity of the zygotic yolk, the localized segmentation of deutoplasm (yolk) during the first cleavage and subsequent extrusion of yolk vesicles during the first two cleavage stages. With regard to the marsupial morphotype, the non-polarized yolk distribution in the zygote [Hartman (J. Morphol. 27, 1,84, 1916); McCrady (Am. Anat. Mem. 16, 1,233, 1938)] is a derived character of Didelphis virginiana. Didelphis virginiana [Hartman (J. Morphol. 27, 1,84, 1916); Hartman (J. Morphol. 32, 1,139, 1919); McCrady (Am. Anat. Mem. 16, 1,233, 1938)] and Didelphis marsupialis (Hill, Q. J. Micr. Sci. 63, 91,139, 1918) share the synapomorphous reduction of deutoplasmolysis to a generalized extrusion of vesicles. The absence of separated yolk and consequently a cleavage without yolk extrusion (Renfree and Lewis, Reprod. Fert. Dev. 8, 725,742, 1996) are apomorphies of macropodids. This is possibly correlated with the association of blastomeres in early cleavage stages (Renfree and Lewis, Reprod. Fert. Dev. 8, 725,742, 1996). A yolk sac placenta and a vascularized allantochorion can be assumed for part of the ontogeny in the marsupial morphotype, irrespective of the formation of an allantoic placenta at near term stages. The character polarization of the mode of placentation and parturition needs further investigation. Frühe Ontogenie und Plazentation der grauen Hausspitzmausbeutelratte, Monodelphis domestica (Didelphidae: Marsupialia): Ein Beitrag zur Rekonstruktion des Grundplans der Marsupialia Die vorliegende Arbeit beschreibt die frühe Ontogenese und Plazentation von 3 Stunden nach der Kopulation bis zur Geburt der Beutelratte Monodelphis domestica. Es wird die Ultrastruktur und Histochemie der Eihäute, der Fetalmembranen, des Oviductes und des Uterus beschrieben. Erstmalig wird die Ultrastruktur eines trophoblastischen Syncytiums bei einem Beuteltier beschrieben. Weiterhin wird ein invasives Trophektoderm und eine Entzündungsreaktion zum Zeitpunkt der Geburt bei M. domestica festgestellt. Die Befunde dieser Studie und Literaturdaten werden verglichen und in eine Grundplanrekonstruktion integriert. Merkmale, die mindestens zwischen Vertretern der Didelphidae und Dasyuridae übereinstimmen, werden basierend auf dem phylogenetischen System der Marsupialia nach Luckett, J. Mammal. Evol. 2, 255,283, 1994, für den Grundplan der Marsupialia angenommen. Diese Merkmale sind zentral separierter Dotter und peripheres dotterarmes Zytoplasma in der unbefruchteten Eizelle, das Vorhandensein von Zona pellucida, Mucoidschicht und Schalenhaut, das Fehlen einer Corona radiata, die Mucoidsekretion durch den Oviduct, die Schalensekretion durch den Uterus und nicht distal der Isthmusregion des Oviductes, eine kurze Tubenwanderung (maximal einen Tag), die Anlagerung der Blastomeren an die Zona pellucida vor der interzellulären Verbindung, das Fehlen eines Morulastadiums, die Dotterpolarität in der Zygote, die lokale Dotterabtrennung bei der ersten Teilung und die anschließende Dotterextrusion während der ersten beiden Teilungen. In Bezug auf den Grundplan der Marsupialia ist die unpolare Dotterverteilung in der Zygote ein abgeleitetes Merkmal von Didelphis virginiana. Didelphis virginiana und Didelphis marsupialis teilen als Synapomorphie die Reduktion der Deutoplasmolyse auf eine generelle Vesikelextrusion. Das Fehlen separierten Dotters in der Oocyte und die resultierende Furchung ohne Dotterextrusion [Renfree and Lewis, Reprod. Fert. Dev. 8, 725,742, 1996] ist eine Apomorphie der Macropodidae. Hiermit hängt möglicherweise die frühe Zusammenlagerung der Blastomeren zusammen [Renfree and Lewis, Reprod. Fert. Dev. 8, 725,742, 1996]. Ein vaskularisiertes Allantochorion und eine Dottersackplazenta können für einen Teil der Ontogenese im Grundplan der Marsupialia angenommen werden. Ob das Allantochorion neben der Respiration auch dem Stoffaustausch diente ist unklar. Die Lesrichtung für den Modus der Plazentation und der Geburt bedarf weiterer Untersuchungen. [source] ON PENTAMPLEXUSSCHINDEWOLF, 1940 (ANTHOZOA, RUGOSA) AND ITS POSSIBLE RELATIVES AND ANALOGUESPALAEONTOLOGY, Issue 2 2009JERZY FEDOROWSKI Abstract:, Three ampleximorphic taxa are revised and their most important characters are discussed in terms of possible or apparent relationships. Re-interpretation of its early ontogeny allows the assignment of Pentamplexus Schindewolf, 1940 to the family Polycoeliidae de Fromentel, 1861. Stereolasma variabilisVojnovsky-Krieger, 1934 is established as the type species of Vojnovskytes gen. nov. It resembles the family Polycoeliidae in some characters and the Antiphyllidae Ilina, 1970 or the Laccophyllidae Grabau, 1928 in others. Thus, its family status is not established. Revision of the type material of Fasciculophyllum tripusSchindewolf, 1952 allows its inclusion within the new genus Silesamplus, probably related to the family Laccophyllidae Grabau, 1928. Amplexoid morphology is further shown to be inadequate for the establishment of relationships on the family or subfamily level. Early ontogeny is most important in that respect, but biform vs normal morphology in the tabularium and free vs contratingent development of minor septa must also be considered, where appropriate. [source] Physiological and anatomical changes during the early ontogeny of the heteroblastic bromeliad, Vriesea sanguinolenta, do not concur with the morphological change from atmospheric to tank formPLANT CELL & ENVIRONMENT, Issue 11 2004G. ZOTZ ABSTRACT Two distinct morphological forms characterize the ontogeny of many epiphytic bromeliads. Smaller plants exhibit an atmospheric habit, while larger plants form water-impounding tanks. The study of the functional significance of heteroblasty in epiphytes is severely hampered by considerable size-related variation in morphological, anatomical and physiological parameters. To overcome this problem, plants of varying size of both atmospheric and tank form were included in the present study with Vriesea sanguinolenta. The results show that virtually all morphological, anatomical and physiological characteristics vary during ontogeny, but changes were rarely directly related to the step change in gross morphology. Changes were either: (1) gradual from smallest atmospheric to small tank (e.g. leaf divergence angles, reduction in photosystem II efficiency during drought, speed of recovery after drought); (2) there was no change between atmospheric and small tank, but a gradual or step change within the tank form (stomatal density, relationship of leaf N and specific leaf area); or (3) developmental patterns were more complicated with decreases and increases during ontogeny (photosynthetic capacity, carbon isotope ratios, abscisic acid levels during drought). Although the comparisons between ontogenetic phases were always confounded by size differences, a hypothetical small tank plant is expected to suffer higher water loss than a real atmospheric, whereas a hypothetical, large atmospheric plant would show reduced access to resources, such as nutrients, in comparison with the real tank. The present results are consistent with the notion of heteroblasty as an adaptation of early ontogenetic stages to drought, but highlight that size-related variation greatly modifies any difference directly associated with the step change from atmospheric to tank. [source] A comparative view on mechanisms and functions of skeletal remodelling in teleost fish, with special emphasis on osteoclasts and their functionBIOLOGICAL REVIEWS, Issue 2 2009P. Eckhard Witten ABSTRACT Resorption and remodelling of skeletal tissues is required for development and growth, mechanical adaptation, repair, and mineral homeostasis of the vertebrate skeleton. Here we review for the first time the current knowledge about resorption and remodelling of the skeleton in teleost fish, the largest and most diverse group of extant vertebrates. Teleost species are increasingly used in aquaculture and as models in biomedical skeletal research. Thus, detailed knowledge is required to establish the differences and similarities between mammalian and teleost skeletal remodelling, and between distantly related species such as zebrafish (Danio rerio) and medaka (Oryzias latipes). The cellular mechanisms of differentiation and activation of osteoclasts and the functions of teleost skeletal remodelling are described. Several characteristics, related to skeletal remodelling, distinguish teleosts from mammals. These characteristics include (a) the absence of osteocytes in most species; (b) the absence of haematopoietic bone marrow tissue; (c) the abundance of small mononucleated osteoclasts performing non-lacunar (smooth) bone resorption, in addition to or instead of multinucleated osteoclasts; and (d) a phosphorus- rather than calcium-driven mineral homeostasis (mainly affecting the postcranial dermal skeleton). Furthermore, (e) skeletal resorption is often absent from particular sites, due to sparse or lacking endochondral ossification. Based on the mode of skeletal remodelling in early ontogeny of all teleosts and in later stages of development of teleosts with acellular bone we suggest a link between acellular bone and the predominance of mononucleated osteoclasts, on the one hand, and cellular bone and multinucleated osteoclasts on the other. The evolutionary origin of skeletal remodelling is discussed and whether mononucleated osteoclasts represent an ancestral type of resorbing cells. Revealing the differentiation and activation of teleost skeletal resorbing cells, in the absence of several factors that trigger mammalian osteoclast differentiation, is a current challenge. Understanding which characters of teleost bone remodelling are derived and which characters are conserved should enhance our understanding of the process in fish and may provide insights into alternative pathways of bone remodelling in mammals. [source] | ||||||||||||||||