PeerJ Preprints: Histologyhttps://peerj.com/preprints/index.atom?journal=peerj&subject=1760Histology articles published in PeerJ PreprintsBone morphogenetic protein 15 induces differentiation of mesenchymal stem cell derived from human follicular fluid to oocyte like cellhttps://peerj.com/preprints/280062019-10-072019-10-07Mahin Taheri MoghadamAli Reza Eftekhari MoghadamGhasem SakiRoshan Nikbakht
Background. To study the effect of Bone morphogenetic protein 15 on differentiation potential of mesenchymal stem cell derived from human follicular fluid to oocyte like cell. Methods. Human FF derived cells were collected from 78 women in assisted fertilization program, and cultured in differentiation medium containing human recombinant BMP15 for 21 days. Mesenchymal stem cells and OLCs were characterized by real-time PCR and immunocytochemistry (ICC) staining. Results. MSCs expressed germ line stem cell markers, such as OCT4 and NANOG. After 15 days, OLCs formed and expressed zona pellucida markers (ZP2, ZP3), and reached 20 – 30 µm in diameters. Ten days after induction with BMP15, round cells remarkably developed, and the maximum size of OLCs reached 115 µm. Finally, a decrease ranging from 0.04 to 4.5 in the expression of pluripotency and oocyte specific markers was observed in the cells cultured in BMP15 supplemented medium. Our work demonstrates, FF derived MSCs have an innate potency to differentiate into OLCs, and BMP15 is effective in stimulating the differentiation of these cells, which may give an in vitro model to examine human germ cell development.
Background. To study the effect of Bone morphogenetic protein 15 on differentiation potential of mesenchymal stem cell derived from human follicular fluid to oocyte like cell. Methods. Human FF derived cells were collected from 78 women in assisted fertilization program, and cultured in differentiation medium containing human recombinant BMP15 for 21 days. Mesenchymal stem cells and OLCs were characterized by real-time PCR and immunocytochemistry (ICC) staining. Results. MSCs expressed germ line stem cell markers, such as OCT4 and NANOG. After 15 days, OLCs formed and expressed zona pellucida markers (ZP2, ZP3), and reached 20 – 30 µm in diameters. Ten days after induction with BMP15, round cells remarkably developed, and the maximum size of OLCs reached 115 µm. Finally, a decrease ranging from 0.04 to 4.5 in the expression of pluripotency and oocyte specific markers was observed in the cells cultured in BMP15 supplemented medium. Our work demonstrates, FF derived MSCs have an innate potency to differentiate into OLCs, and BMP15 is effective in stimulating the differentiation of these cells, which may give an in vitro model to examine human germ cell development.Integumentary structure and composition in an exceptionally well-preserved hadrosaur (Dinosauria: Ornithischia)https://peerj.com/preprints/276982019-05-012019-05-01Mauricio BarbiPhil R. BellFederico FantiJames J. DynesAnezka KolacekeJosef ButtigiegPhilip J. Currie
Preserved labile tissues (e.g. skin, muscle) in the fossil record of terrestrial vertebrates are increasingly becoming recognized as an important source of biological and taphonomic information. Here, we combine a variety of synchrotron radiation techniques with scanning electron and optical microscopes to elucidate the structure of 72 million-year-old squamous (scaly) skin associated with a hadrosaurid dinosaur from the Late Cretaceous of Alberta, Canada. Scanning electron and optical microscopy independently reveal that the three-dimensionally preserved scales are associated with a band of carbon-rich layers up to a total thickness of 75 μm. Compositionally, this band deviates from that of the surrounding matrix; Fourier-transform infrared spectroscopy and soft X-ray spectromicroscopy analyses indicate the presence of carboxylic compounds. The regions corresponding to the integumentary layers are distinctively enriched in iron compared to the associated sedimentary matrix and seem associated to kaolinite. These carbonyl-rich layers are apparently composed of subcircular bodies resembling preserved cell structures. Each of these structures is encapsulated by calcite/vaterite, with iron predominantly concentrated at its center. The presence of iron, calcite/vaterite and kaolinite might have played important roles in the preservation of the layered structures.
Preserved labile tissues (e.g. skin, muscle) in the fossil record of terrestrial vertebrates are increasingly becoming recognized as an important source of biological and taphonomic information. Here, we combine a variety of synchrotron radiation techniques with scanning electron and optical microscopes to elucidate the structure of 72 million-year-old squamous (scaly) skin associated with a hadrosaurid dinosaur from the Late Cretaceous of Alberta, Canada. Scanning electron and optical microscopy independently reveal that the three-dimensionally preserved scales are associated with a band of carbon-rich layers up to a total thickness of 75 μm. Compositionally, this band deviates from that of the surrounding matrix; Fourier-transform infrared spectroscopy and soft X-ray spectromicroscopy analyses indicate the presence of carboxylic compounds. The regions corresponding to the integumentary layers are distinctively enriched in iron compared to the associated sedimentary matrix and seem associated to kaolinite. These carbonyl-rich layers are apparently composed of subcircular bodies resembling preserved cell structures. Each of these structures is encapsulated by calcite/vaterite, with iron predominantly concentrated at its center. The presence of iron, calcite/vaterite and kaolinite might have played important roles in the preservation of the layered structures.The phylogenetic origin and evolution of acellular bone in teleost fishes: insights into osteocyte function in bone metabolismhttps://peerj.com/preprints/274062019-02-132019-02-13Donald DavesneFrançois J. MeunierArmin D. SchmittMatt FriedmanOlga OteroRoger B. J. Benson
Vertebrate bone is composed of three main cell types: osteoblasts, osteoclasts and osteocytes, the latter being by far the most numerous. Osteocytes are thought to play a fundamental role in bone physiology and homeostasis, however they are entirely absent in most extant species of teleosts, a group that comprises the vast majority of bony ‘fishes’, and approximately half of vertebrates. Understanding how this acellular (anosteocytic) bone appeared and was maintained in such an important vertebrate group has important implications for our understanding of the function and evolution of osteocytes. Nevertheless, although it is clear that cellular bone is ancestral for teleosts, it has not been clear in which specific subgroup the osteocytes were lost. This review aims at clarifying the phylogenetic distribution of cellular and acellular bone in teleosts, to identify its precise origin, reversals to cellularity, and their implications. We surveyed the bone type for more than 600 fossil and extant ray-finned fish species and optimised the results on recent large-scale molecular phylogenetic trees, estimating ancestral states. We find that acellular bone is a probable synapomorphy of Euteleostei, a group uniting approximately two-thirds of teleost species. We also confirm homoplasy in these traits: acellular bone occurs in some non-euteleosts (although rarely), and cellular bone was reacquired several times independently within euteleosts, in salmons and relatives, tunas and the opah (Lampris sp.). The occurrence of peculiar ecological (e.g. anadromous migration) and physiological (e.g. red-muscle endothermy) strategies in these lineages might explain the reacquisition of osteocytes. Our review supports that the main contribution of osteocytes in teleost bone is to mineral homeostasis (via osteocytic osteolysis) and not to strain detection or bone remodelling, helping to clarify their role in bone physiology.
Vertebrate bone is composed of three main cell types: osteoblasts, osteoclasts and osteocytes, the latter being by far the most numerous. Osteocytes are thought to play a fundamental role in bone physiology and homeostasis, however they are entirely absent in most extant species of teleosts, a group that comprises the vast majority of bony ‘fishes’, and approximately half of vertebrates. Understanding how this acellular (anosteocytic) bone appeared and was maintained in such an important vertebrate group has important implications for our understanding of the function and evolution of osteocytes. Nevertheless, although it is clear that cellular bone is ancestral for teleosts, it has not been clear in which specific subgroup the osteocytes were lost. This review aims at clarifying the phylogenetic distribution of cellular and acellular bone in teleosts, to identify its precise origin, reversals to cellularity, and their implications. We surveyed the bone type for more than 600 fossil and extant ray-finned fish species and optimised the results on recent large-scale molecular phylogenetic trees, estimating ancestral states. We find that acellular bone is a probable synapomorphy of Euteleostei, a group uniting approximately two-thirds of teleost species. We also confirm homoplasy in these traits: acellular bone occurs in some non-euteleosts (although rarely), and cellular bone was reacquired several times independently within euteleosts, in salmons and relatives, tunas and the opah (Lampris sp.). The occurrence of peculiar ecological (e.g. anadromous migration) and physiological (e.g. red-muscle endothermy) strategies in these lineages might explain the reacquisition of osteocytes. Our review supports that the main contribution of osteocytes in teleost bone is to mineral homeostasis (via osteocytic osteolysis) and not to strain detection or bone remodelling, helping to clarify their role in bone physiology.Chromatin streaming from giant polyploid nuclei in Ishikawa endometrial hollow spheroids results in the amitotic proliferation of nuclei that fill the spheroid envelopehttps://peerj.com/preprints/274632019-01-032019-01-03Honoree Fleming
This paper describes the amitotic proliferation of nuclei that fill the envelope of Ishikawa hollow spheroids. The presence of hollow spheroids in malignant ascites fluid has intrigued cancer researchers, but little is understood about how they form. Observations in Ishikawa endometrial cell cultures demonstrate that nuclei filling the spheroid envelope are generated amitotically by the same mechanism responsible for cell formation in domes. Transient structures of aggregated chromatin surrounded by fused giant mitochondria, the initiating structure for dome formation, are also the starting point for the differentiation of unicellular polyploid hollow spheroids. Nuclei from monolayer cells are aggregated in a single enlarged cell where they become surrounding by giant fused mitochondria. A gaseous vacuole forms inside the mitonucleon extending it so that all of the cell material, including nuclei is pressed against the cell membrane. The resulting unicellular hollow spheroid detaches from the colony, capable of migration from the site of its formation. Ultimately, pressure on the aggregated chromatin results in the release of streams of chromatin granules that initially travel as if guided by microtubules through the shell of the hollow spheroid. Granules dissolve into filaments and, as initially described in dome formation, this material self-assembles into clusters of nuclei. Nuclei move out of these clusters into a regular array within the spheroid envelope, with formation of cell membranes as the final step in the creation of multicellular hollow spheroids. The curved membrane characteristic of domes and spheroids, as well as colonies of nuclei produced by amitosis have been identified in tumor tissue that survives chemotherapy, suggesting that amitotic cell proliferation may at least partially explain the population of cancer tumor cells in humans that are resistant to chemotherapy.
This paper describes the amitotic proliferation of nuclei that fill the envelope of Ishikawa hollow spheroids. The presence of hollow spheroids in malignant ascites fluid has intrigued cancer researchers, but little is understood about how they form. Observations in Ishikawa endometrial cell cultures demonstrate that nuclei filling the spheroid envelope are generated amitotically by the same mechanism responsible for cell formation in domes. Transient structures of aggregated chromatin surrounded by fused giant mitochondria, the initiating structure for dome formation, are also the starting point for the differentiation of unicellular polyploid hollow spheroids. Nuclei from monolayer cells are aggregated in a single enlarged cell where they become surrounding by giant fused mitochondria. A gaseous vacuole forms inside the mitonucleon extending it so that all of the cell material, including nuclei is pressed against the cell membrane. The resulting unicellular hollow spheroid detaches from the colony, capable of migration from the site of its formation. Ultimately, pressure on the aggregated chromatin results in the release of streams of chromatin granules that initially travel as if guided by microtubules through the shell of the hollow spheroid. Granules dissolve into filaments and, as initially described in dome formation, this material self-assembles into clusters of nuclei. Nuclei move out of these clusters into a regular array within the spheroid envelope, with formation of cell membranes as the final step in the creation of multicellular hollow spheroids. The curved membrane characteristic of domes and spheroids, as well as colonies of nuclei produced by amitosis have been identified in tumor tissue that survives chemotherapy, suggesting that amitotic cell proliferation may at least partially explain the population of cancer tumor cells in humans that are resistant to chemotherapy.Normal spermatogenesis in Fank1 (fibronectin type 3 and ankyrin repeat domains 1) mutant micehttps://peerj.com/preprints/273562018-11-182018-11-18Jintao ZhangXin ZhangYue ZhangWentao ZengShuqin ZhaoMingxi Liu
Background. The fibronectin type 3 and ankyrin repeat domains 1 gene, Fank1, is an ancient, evolutionarily conserved gene present in vertebrates. Fank1-knockdown mice have oligospermia caused by an increase in apoptotic germ cells. In this study, we investigated the in vivo function of Fank1.
Methods. In this study, we generated Fank1-knockout mice using the CRISPR/Cas9 system. We then investigated the phenotype and in vivo function of Fank1. Testes and epididymis tissues were analyzed by histological and immunofluorescence staining. Apoptotic cells were analyzed in TUNEL assays. Fertility and sperm counts were also evaluated. The GTEx database were used to assess gene expression quantitative trait loci (eQTL) and mRNA expression of candidate genes and genes neighboring single nucleotide polymorphisms was analyzed by quantitative RT-PCR.
Results. In contrast to the Fank1-knockdown model, no significant changes in epididymal sperm content and the number of apoptotic cells were observed in Fank1-/- homozygotes. In addition, a different pattern of Dusp1, Klk1b21 and Klk1b27 mRNA expression was detected in Fank1-knockout testis. These results reveal differences in the molecular changes between Fank1-knockdown mice and Fank1 -knockout mice and provide a basic resource for population genetics studies.
Background. The fibronectin type 3 and ankyrin repeat domains 1 gene, Fank1, is an ancient, evolutionarily conserved gene present in vertebrates. Fank1-knockdown mice have oligospermia caused by an increase in apoptotic germ cells. In this study, we investigated the in vivo function of Fank1.Methods. In this study, we generated Fank1-knockout mice using the CRISPR/Cas9 system. We then investigated the phenotype and in vivo function of Fank1. Testes and epididymis tissues were analyzed by histological and immunofluorescence staining. Apoptotic cells were analyzed in TUNEL assays. Fertility and sperm counts were also evaluated. The GTEx database were used to assess gene expression quantitative trait loci (eQTL) and mRNA expression of candidate genes and genes neighboring single nucleotide polymorphisms was analyzed by quantitative RT-PCR.Results. In contrast to the Fank1-knockdown model, no significant changes in epididymal sperm content and the number of apoptotic cells were observed in Fank1-/- homozygotes. In addition, a different pattern of Dusp1, Klk1b21 and Klk1b27 mRNA expression was detected in Fank1-knockout testis. These results reveal differences in the molecular changes between Fank1-knockdown mice and Fank1 -knockout mice and provide a basic resource for population genetics studies.Ampelisca eschrichtii Krøyer, 1842 (Ampeliscidae) of the Sakhalin Shelf in the Okhotsk Sea starve in summer and feast in winterhttps://peerj.com/preprints/34962018-04-222018-04-22Valentina B. DurkinaJohn W. ChapmanNatalia L. Demchenko
Background. Ampelisca eschrichtii Krøyer, 1842 of the Sakhalin Shelf of the Okhotsk Sea, Far Eastern Russia, comprise the highest known biomass concentration of any amphipod population in the world and are a critically important prey source for western gray whales. Growth and reproduction in this population has not been apparent in summer. However, they are not accessible for sampling in winter to test a previous default conclusion that they grow and reproduce in winter.
Methods. We tested the default winter growth and reproduction hypothesis by detailed comparisons of the brood and gonad development among 40 females and 14 males and brood sizes among females observed since 2002. Our test included six predictions of reproductive synchrony that would be apparent from gonad and brood morphology if active reproduction occurs in summer.
Results. We found high prevalences of undersized and damaged oocytes, undersized broods, a lack of females brooding fully formed juveniles, atrophied ovaries, and males with mature sperm but lacking fully developed secondary sex morphologies required for pelagic mating. All of these conditions are consistent with trophic stress and starvation.
Discussion. These A. eschrichtii populations therefore appear to starve in summer and to grow and reproduce in winter. The Offshore A. eschrichtii populations occur in summer below water strata bearing high phytoplankton biomasses. These populations are more likely to feed successfully in winter when storms mix phytoplankton to their depths.
Background. Ampelisca eschrichtii Krøyer, 1842 of the Sakhalin Shelf of the Okhotsk Sea, Far Eastern Russia, comprise the highest known biomass concentration of any amphipod population in the world and are a critically important prey source for western gray whales. Growth and reproduction in this population has not been apparent in summer. However, they are not accessible for sampling in winter to test a previous default conclusion that they grow and reproduce in winter.Methods. We tested the default winter growth and reproduction hypothesis by detailed comparisons of the brood and gonad development among 40 females and 14 males and brood sizes among females observed since 2002. Our test included six predictions of reproductive synchrony that would be apparent from gonad and brood morphology if active reproduction occurs in summer.Results. We found high prevalences of undersized and damaged oocytes, undersized broods, a lack of females brooding fully formed juveniles, atrophied ovaries, and males with mature sperm but lacking fully developed secondary sex morphologies required for pelagic mating. All of these conditions are consistent with trophic stress and starvation.Discussion. These A. eschrichtii populations therefore appear to starve in summer and to grow and reproduce in winter. The Offshore A. eschrichtii populations occur in summer below water strata bearing high phytoplankton biomasses. These populations are more likely to feed successfully in winter when storms mix phytoplankton to their depths.Polyploid monolayer Ishikawa endometrial cells form unicellular hollow spheroids capable of migrationhttps://peerj.com/preprints/267932018-03-292018-03-29Honoree Fleming
The results in this paper demonstrate that Ishikawa endometrial monolayer cells become multinucleated by a process of nuclear “donation” from neighboring cells. As the resulting polyploid cell detaches from the colony in which it was formed, it is possible to detect mitonucleon(s) in the center of the cell. The mitonucleon is a transient mitochondrial superstructure surrounding aggregated chromatin (Fleming et al. 1998) with characteristics of the family of mitochondrial superstructures that are sometimes called spheroids or cup-shaped mitochondria (Fleming, 2016a). As was recently demonstrated gas vacuoles form within mitonucleons (Fleming, 2018). In the free-floating single cell, the retained gas creates a central vacuole, and the cell becomes a spheroid that floats above the monolayer. It resembles a “signet ring cell” in being characterized by a central vacuole and chromatin compressed against the vacuole membrane. The resulting structure is a spheroids that is hollow and unicellular, albeit polyploid. But whereas signet ring cells are assumed to be undergoing apoptosis, that is not the case for unicellular spheroids. Complete spheres with chromatin and cytosolic cell contents compressed against the cell membrane can be found floating independently above Ishikawa monolayers. When an isolated sphere settles back onto the surface of the petri dish, it is possible to observe dissipating gas bubbles within the now flattened sphere for a short period of time. When the gas is discharged the resulting cell looks like a typical giant polyploid cell.
The results in this paper demonstrate that Ishikawa endometrial monolayer cells become multinucleated by a process of nuclear “donation” from neighboring cells. As the resulting polyploid cell detaches from the colony in which it was formed, it is possible to detect mitonucleon(s) in the center of the cell. The mitonucleon is a transient mitochondrial superstructure surrounding aggregated chromatin (Fleming et al. 1998) with characteristics of the family of mitochondrial superstructures that are sometimes called spheroids or cup-shaped mitochondria (Fleming, 2016a). As was recently demonstrated gas vacuoles form within mitonucleons (Fleming, 2018). In the free-floating single cell, the retained gas creates a central vacuole, and the cell becomes a spheroid that floats above the monolayer. It resembles a “signet ring cell” in being characterized by a central vacuole and chromatin compressed against the vacuole membrane. The resulting structure is a spheroids that is hollow and unicellular, albeit polyploid. But whereas signet ring cells are assumed to be undergoing apoptosis, that is not the case for unicellular spheroids. Complete spheres with chromatin and cytosolic cell contents compressed against the cell membrane can be found floating independently above Ishikawa monolayers. When an isolated sphere settles back onto the surface of the petri dish, it is possible to observe dissipating gas bubbles within the now flattened sphere for a short period of time. When the gas is discharged the resulting cell looks like a typical giant polyploid cell.Endogenous expression of thermo-sensitive ion channels TRPV1 and TRPV4 in immune tissues of avian species (duck, Anas platyrhynchos)https://peerj.com/preprints/266142018-03-042018-03-04Rakesh Kumar MajhiApratim MaityManas R SenapatiPrakash Chandra BeheraArun Kumar MandalSunil C GiriChandan - Goswami
Calcium signaling and body temperature are two important factors governing activation of immune cells. However, molecular identities of major players involved in such critical regulations are still unknown, especially in avian systems. In this work we explored the endogenous expression of Transient Receptor Potential Vanilloid subtype 1 and subtype 4 (TRPV1 and TRPV4) channels, in the immune cells and different tissues of duck (Anas platyrhynchos). TRPV1 and TRPV4 represent two important non-selective ion channels which are also thermo sensitive in nature. Using confocal microscopy we demonstrate that TRPV1 and TRPV4 are expressed endogenously in the duck immune system such as thymus, spleen, caecum and bursa. In thymus, bursa of Fabricius and caecum, these channels are differentially localized in the plasma membrane and intra-cellular regions. In addition, using Flow cytometry we demonstrate very specific expression of these two channels in Peripheral Blood Mononuclear Cells (PBMCs) and CD3+ve T cells. This result is the first report of endogenous expression of TRPV channels in cells and tissues relevant for avian immune system. Such findings may have importance in the context of immune functions and responses to pathological challenges faced by birds. Presence of these two important ion channels in the duck immune system may also have commercial importance in the context of livestock management, food supplement and production of quality poultry products.
Calcium signaling and body temperature are two important factors governing activation of immune cells. However, molecular identities of major players involved in such critical regulations are still unknown, especially in avian systems. In this work we explored the endogenous expression of Transient Receptor Potential Vanilloid subtype 1 and subtype 4 (TRPV1 and TRPV4) channels, in the immune cells and different tissues of duck (Anas platyrhynchos). TRPV1 and TRPV4 represent two important non-selective ion channels which are also thermo sensitive in nature. Using confocal microscopy we demonstrate that TRPV1 and TRPV4 are expressed endogenously in the duck immune system such as thymus, spleen, caecum and bursa. In thymus, bursa of Fabricius and caecum, these channels are differentially localized in the plasma membrane and intra-cellular regions. In addition, using Flow cytometry we demonstrate very specific expression of these two channels in Peripheral Blood Mononuclear Cells (PBMCs) and CD3+ve T cells. This result is the first report of endogenous expression of TRPV channels in cells and tissues relevant for avian immune system. Such findings may have importance in the context of immune functions and responses to pathological challenges faced by birds. Presence of these two important ion channels in the duck immune system may also have commercial importance in the context of livestock management, food supplement and production of quality poultry products.Aquatic training in menopause experimental model promote changes in the sarcomeres of the myotendinous junctionshttps://peerj.com/preprints/266012018-03-022018-03-02Gabriel FavaroLuan Rissattolara RochaSonia MadreIi WatanabeAdriano Ciena
Myotendinous junction (MTJ) is the largest area of force transmission between skeletal muscle and bone tissue, which is directly associated with physical exercise that possible promotes morphological changes in muscle and tendon tissues. The aim of this study is to describe the ultrastructural characteristics of myotendinous junction and morphometric alterations in length sarcomeres of the anterior tibial muscle of ovariectomized aged female Wistar rats submitted to a swimming protocol. Twenty aged rats with 1 year and 8 months old randomly divided into four groups (n=5): Sedentary (S); Exercised (E); Menopause (M) and Menopause Exercised (ME). The exercising protocol consists at 40 sessions, one hour daily for a two months period and overload 5 % body weight of animals with adjustments weekly measured. Histological images were analyzed by transmission electron microscopy to demonstrate morphometric characteristics and ultrastructural elements of the cellular components. From the results obtained by transmission electron microscopy ultrastructural adaptations were observed in the MTJ region. The S and M groups demonstrated tissue disorganization in addition to lower density and length of sarcoplasmatic invaginations. The E and ME groups showed greater density, length and tissue organization, besides presenting sub-levels and communications between the sarcoplasmatic projections. Besides, they present adaptations in the plasticity of the MTJ evidenced by increase in the length of the distal sarcomeres. We concluded that the MTJ region presented adaptations in relation to the physical exercise during aging associated with ovariectomy, increasing sarcoplasmatic invaginations and changing length sarcomere distal, by improving the resistance and the transmission of force in the main injured area.
Myotendinous junction (MTJ) is the largest area of force transmission between skeletal muscle and bone tissue, which is directly associated with physical exercise that possible promotes morphological changes in muscle and tendon tissues. The aim of this study is to describe the ultrastructural characteristics of myotendinous junction and morphometric alterations in length sarcomeres of the anterior tibial muscle of ovariectomized aged female Wistar rats submitted to a swimming protocol. Twenty aged rats with 1 year and 8 months old randomly divided into four groups (n=5): Sedentary (S); Exercised (E); Menopause (M) and Menopause Exercised (ME). The exercising protocol consists at 40 sessions, one hour daily for a two months period and overload 5 % body weight of animals with adjustments weekly measured. Histological images were analyzed by transmission electron microscopy to demonstrate morphometric characteristics and ultrastructural elements of the cellular components. From the results obtained by transmission electron microscopy ultrastructural adaptations were observed in the MTJ region. The S and M groups demonstrated tissue disorganization in addition to lower density and length of sarcoplasmatic invaginations. The E and ME groups showed greater density, length and tissue organization, besides presenting sub-levels and communications between the sarcoplasmatic projections. Besides, they present adaptations in the plasticity of the MTJ evidenced by increase in the length of the distal sarcomeres. We concluded that the MTJ region presented adaptations in relation to the physical exercise during aging associated with ovariectomy, increasing sarcoplasmatic invaginations and changing length sarcomere distal, by improving the resistance and the transmission of force in the main injured area.The anatomy of the foveola reinvestigatedhttps://peerj.com/preprints/265182018-02-132018-02-13Alexander V. TschulakowTheo OltrupThomas BendeSebastian SchmelzleUlrich Schraermeyer
Objective. In the foveola of the eye, photoreceptors and Müller cells with a unique morphology have been described, but little is known about their 3D structure and orientation. Considering that there is an angle-dependent change in the foveolar photoreceptor response for the same light beam, known as the Stiles Crawford Effect of the first kind (SCE I), which is still not fully understood, a detailed analysis of the anatomy of the foveolar cells might help to clarify this phenomenon. Methods. Serial semithin and ultrathin sections, and focused ion beam (FIB) tomography were -prepared from 32 foveolae from monkeys (Macaca fascicularis) and humans. Foveolae were also analyzed under the electron microscope. Serial sections and FIB analysis were then used to construct 3D models of central Müller and photoreceptor cells. In addition, we measured the transmission of collimated light under the light microscope at different angles after it had passed through human foveae from flat mounted isolated retinae. Results. In monkeys, outer segments of central foveolar cones are twice as long as those from parafoveal cones and do not run completely parallel to the incident light. Unique Müller cells are present in the central foveolae (area of 200 µm in diameter) of humans and monkeys. Light entering the fovea center, which is composed only of cones and Müller cells, at an angle of 0 degrees causes a very bright spot after passing through this area. However, when the angle of the light beam is changed to 10 degrees, less light is measured after transpasssing through the retina, the foveolar center becomes darker and the SCE-like phenomenon is directly visible. Measurements of the intensities of light transmission through the central foveola for the incident angles 0 and 10 degrees resemble the relative luminance efficiency for narrow light bundles as a function of the location where the beam enters the pupil as reported by Stiles and Crawford. The effect persisted after carefully brushing away the outer segments. Conclusion. We show that unique cones and Müller cells with light fibre-like properties are present in the center of the fovea. These unique Müller cells cause an angle dependent, SCE-like drop in the intensity of light guided through the foveola. Outer segments from the foveola cones of monkeys are not straight.
Objective. In the foveola of the eye, photoreceptors and Müller cells with a unique morphology have been described, but little is known about their 3D structure and orientation. Considering that there is an angle-dependent change in the foveolar photoreceptor response for the same light beam, known as the Stiles Crawford Effect of the first kind (SCE I), which is still not fully understood, a detailed analysis of the anatomy of the foveolar cells might help to clarify this phenomenon. Methods. Serial semithin and ultrathin sections, and focused ion beam (FIB) tomography were -prepared from 32 foveolae from monkeys (Macaca fascicularis) and humans. Foveolae were also analyzed under the electron microscope. Serial sections and FIB analysis were then used to construct 3D models of central Müller and photoreceptor cells. In addition, we measured the transmission of collimated light under the light microscope at different angles after it had passed through human foveae from flat mounted isolated retinae. Results. In monkeys, outer segments of central foveolar cones are twice as long as those from parafoveal cones and do not run completely parallel to the incident light. Unique Müller cells are present in the central foveolae (area of 200 µm in diameter) of humans and monkeys. Light entering the fovea center, which is composed only of cones and Müller cells, at an angle of 0 degrees causes a very bright spot after passing through this area. However, when the angle of the light beam is changed to 10 degrees, less light is measured after transpasssing through the retina, the foveolar center becomes darker and the SCE-like phenomenon is directly visible. Measurements of the intensities of light transmission through the central foveola for the incident angles 0 and 10 degrees resemble the relative luminance efficiency for narrow light bundles as a function of the location where the beam enters the pupil as reported by Stiles and Crawford. The effect persisted after carefully brushing away the outer segments. Conclusion. We show that unique cones and Müller cells with light fibre-like properties are present in the center of the fovea. These unique Müller cells cause an angle dependent, SCE-like drop in the intensity of light guided through the foveola. Outer segments from the foveola cones of monkeys are not straight.