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At least 739 records · Page 41Linked to original sources
PubMed2005

Divergent expression patterns of Sox9 duplicates in teleosts indicate a lineage specific subfunctionalization.

Sry-related HMG-box genes are key regulators of several developmental processes. Sox9 encodes a transcription factor required for cartilage formation and testis determination in mammals. In zebrafish (Danio rerio) and stickleback (Gasterosteus aculeatus) two co-orthologs of Sox9 are present. To date, only one Sox9 had been identified in medaka (Oryzias latipes). We have now isolated the second Sox9 gene. Sequence analysis, phylogenetic data, linkage mapping as well as expression pattern all together suggest that the medaka Sox9a and Sox9b are co-orthologs. During embryogenesis, the expression pattern of Sox9a and Sox9b are distinct but overlap considerably in craniofacial cartilage elements. Comparing the zebrafish Sox9a and Sox9b expression patterns with medaka Sox9a and Sox9b expression domains revealed that some are identical but others are clearly different. We conclude that Sox9 regulatory subfunctions were not partitioned before divergence of the teleosts and evolved to lineage-specific expression domains.

Amino Acid Sequence↗
PubMed2000

Temporal and spatial patterns of cbfal expression during embryonic development in the teleost, Oryzias latipes.

Cbfa1, a transcription factor of the runt family, was recently shown to be a key regulator in skeletal development in mammals. In the present study, we identified the cbfa1 gene from the medaka, Oryzias latipes. The amino acid sequence, including the runt domain, is highly conserved with that of mammalian cbfa1. Whole mount in situ hybridization showed that the medaka cbfa1 was expressed prominently in immature osteoblasts and chondrocytes of the developing skeletal structures during embryogenesis. The expression pattern suggests functional and evolutionary implications of the cbfa1 gene in chondrocyte differentiation between teleosts and mammals.

Amino Acid Sequence↗
PubMed2005

First record of Progrillotia dasyatidis Beveridge Neifar and Euzet, 2004 (Cestoda: Trypanorhyncha) plerocerci from Teleost fishes off the Portuguese coast, with a description of the surface morphology.

Plerocerci of Progrillotia dasyatidis Beveridge et al. (2004), family Progrillotiidae Palm (2004), are reported from several teleost fishes off the Portuguese coast, giving a first insight into the life cycle biology of these unique trypanorhynchs. The first description and assignment of the plerocercus to P. dasyatidis is based on morphological features, such as scolex and bothria morphology and tentacular hook arrangement, and is expanded to incorporate the surface morphology, examined by scanning electron microscopy, constituting the first ultrastructural study for a species within this family. Comparisons with other species of the genus Progrillotia are made, based on the scolex and bothria morphology and tentacular hook arrangement, in order to give an overview into the variability within this genus, whereas comparisons with adults from the same species evidence the variability within the same species. The systematic approaches of Campbell and Beveridge (1994) and Palm (1997, 2004) are discussed and emphasis is placed on the utility of microtriches and the characteristic life cycle within the genus as systematic characters.

Animals↗
PubMed2007

Genetic diversity in the trypanorhynch cestode Tentacularia coryphaenae Bosc, 1797: evidence for a cosmopolitan distribution and low host specificity in the teleost intermediate host.

Partial large subunit (28S) rRNA gene (LSU) sequences were studied from Tentacularia coryphaenae (Cestoda: Trypanorhyncha) plerocercoids from the southern Java coast, Indonesia, collected from two different localities and five different host species. The teleost hosts belonged to four fish families with an overlapping depth range of 0-885 m. The LSU sequences were identical, demonstrating that all specimens belonged to the same species. They also corresponded to a sequence of T. coryphaenae from the Blue shark Prionace glauca in the North Atlantic, giving genetic evidence for the cosmopolitan distribution of the species. A 1,851 bp region of mitochondrial (mt) DNA (coding for partial cytochrome c oxidase subunit I (cox1), complete trnT and partial 16S ribosomal RNA) showed a very low level of intra-specific variation of 1%. Pairwise comparisons of published sequences for partial LSU rDNA and the same region of mtDNA demonstrated that the same regions varied by 8% in the mtDNA for two genotypes (G1 and G4) of Echinococcus granulosus (order Cyclophyllidea), at 16% in newly sequenced Kotorella pronosoma from the same trypanorhynch family and at 23% in Grillotia pristiophori from a different superfamily. The high genetic homogeneity in T. coryphaenae is explained by a constant gene flow between different regions and hosts along the Indonesian coast caused by extensive migrations of the second intermediate/paratenic and also the final hosts. Implications for the zoogeographical distribution, host specificity of the species and future research are discussed.

Animals↗
PubMed2002

Sperm acrosome antigen-1. Specific tissue distribution of immunoreactivity in a teleost fish, the swordtail ( Xiphophorus helleri).

The acrosome reaction is a fundamental requirement for mammalian fertilization. Its exact molecular mechanisms and cellular elements are still poorly understood. We have detected an acrosomal sperm antigen, SAA-1, by monoclonal antibodies directed against SAA-1, that appears to be critically involved in the regulation of the acrosome reaction. SAA-1 is conserved within a broad range of mammalian species, emphasizing its important role in mammalian reproduction. Here we demonstrate that SAA-1 is immunohistochemically detectable in a nonmammalian vertebrate whose sperm do not possess an acrosome. In the swordtail, a live-bearing teleost with special reproductive tactics, we were able to demonstrate immunoreactivity of sperm heads of spermatids and mature sperm in the testis using monoclonal antibodies against SAA-1. Due to the cystic spermatogenesis with synchronous sperm maturation, immunoreactive maturational stages could be clearly identified. Stored immunoreactive sperm were also identified in spermathecal tissue of the female genital tract. Interestingly, immunoreactivity was furthermore detected in defined cells of the compounded endocrine organs pituitary and endocrine pancreas. All these different cell systems are involved in paracrine regulation and exhibit exocytotic properties. The possible nature of SAA-1 is discussed. Additionally, some new aspects of the morphologic composition of the swordtail pituitary are described.

Aging↗
PubMed2003

Immunoglobulin protein and gene transcripts in ovarian follicles throughout oogenesis in the teleost Dicentrarchus labrax.

Transfer of immunoglobulins (IgM-like) from the female to the teleost embryo has been demonstrated but mechanisms of uptake into and storage within the eggs remain to be clarified. The monoclonal antibody DLIg3 against Dicentrarchus labrax Ig light chain revealed an active role of both follicle cells and oocytes in the Ig uptake. The primordial follicular cells showed DLIg3 immunoreactivity even at a pre-vitellogenetic stage. Early vitellogenetic oocytes (lipid vesicle stages) had DLIg3 staining of pore canals, plasmalemma and outer cortex and of their follicular cells. In protein yolk granule oocytes, DLIg3 staining was also detected within vesicles of the outer-mid cortex and juxtanuclear yolk granules; therefore, a centripetal transport of Ig throughout oocyte development is apparently carried out. Immunoelectron microscopy confirmed the presence of Ig within thecal and granulosa cells (and in the interposed basement membrane) of pre-vitellogenic and vitellogenic follicles. Thus, the transport of Ig to the egg apparently occurs also by transcytosis across the follicle cells. Igs were localised in the pore canals surrounding the microvilli and in vesicles of outer-mid cortex of vitellogenic oocytes. Reverse transcription/polymerase chain reaction with primers designed for the constant region of sea bass Ig light chain detected Ig mRNA in hydrated oocytes, a smaller content in released eggs and no signal in larvae at day two post-hatching. These findings show that a significant level of Ig gene transcription in the oocyte and/or a transfer of transcripts may also occur.

Animals↗
PubMed2005

Tooth development in vitro in two teleost fish, the cichlid Hemichromis bimaculatus and the cyprinid Danio rerio.

A technique for organotypic in vitro culture with serum-free medium was tested for its appropriateness to mimic normal odontogenesis in the cichlid fish Hemichromis bimaculatus and the zebrafish Danio rerio. Serial semithin sections were observed by light microscopy to collect data on tooth patterning and transmission electron microscopy was used to compare cellular and extracellular features of tooth germs developing in vitro with the situation in vivo. Head explants of H. bimaculatus from 120 h post-fertilization (hPF) to 8.5 days post-fertilization (dPF) and of zebrafish from 45 hPF to 79 hPF and adults kept in culture for 3, 4 or 7 days revealed that tooth germs developed in vitro from explants in which the buccal or pharyngeal epithelium was apparently undifferentiated and, when present at the time of explantation, they continued their development up to a stage of attachment. In addition, the medium allowed the morphogenesis and cytodifferentiation of the tooth germs similar to that observed in vivo and the establishment of a dental pattern (place and order of tooth appearance and of attachment) that mimicked that in vivo. Organotypic culture in serum-free conditions thus provides us with the means of studying epithelial-mesenchymal interactions during tooth development in teleost fish and of analysing the genetic control of either mandibular or pharyngeal tooth development and replacement in these polyphyodont species. Importantly, it allows heads from embryonically lethal (zebrafish) mutants or from early lethal knockdown experiments to develop beyond the point at which the embryos normally die. Such organotypic culture in serum-free conditions could therefore become a powerful tool in developmental studies and open new perspectives for craniofacial research.

Animals↗
PubMed2006

Injection of xenogeneic cells into teleost fish elicits systemic and local cellular innate immune responses.

The early innate immune response of the teleost gilthead seabream (Sparus aurata L.) against xenogeneic cells was studied. Fish received a single intraperitoneal injection of xenogeneic cells (tumour cell line), following which leucocyte mobilization, degranulation, peroxidase content, respiratory burst and phagocytic and cytotoxic activities were determined in both peritoneal exudate leucocytes (PELs) and head-kidney leucocytes (HKLs). The total number of PELs increased from 4 h post-injection until the end of the experiment (3 days). Interestingly, flow cytometric analysis of PEL and HKL suspensions revealed variations in the proportion of cell types. The percentage of HK acidophilic granulocytes significantly increased after 72 h, whereas PE acidophils increased after 4 h. Moreover, numbers of PE lymphocytes and monocyte-macrophages significantly increased during the experiment. The peroxidase content of the leucocytes was unaffected, although PEL degranulation was largely enhanced. This liberation of peroxidases correlated well with the enhancement of the oxidative respiratory burst activity in PELs, reflecting leucocyte activation. However, phagocytosis only increased in PELs 4 h after intraperitoneal injection, whereas the cytotoxic activity of HKLs increased 1 and 2 days post-injection but, in general, decreased in the PELs. Our data thus demonstrate that the appearance of xenogeneic cells involves leucocyte mobilization and innate immune-response activation at the site of invasion and in the head-kidney. Involvement of the various leucocyte types and potential modes of activation are discussed.

Animals↗
PubMed1997

Enzyme histochemical characteristics of osteoblasts and mononucleated osteoclasts in a teleost fish with acellular bone (Oreochromis niloticus, Cichlidae).

Bone resorption by mononucleated cells was studied in the acellular bone of a teleost fish (Oreochromis niloticus) by histological and enzyme histochemical observations and by transmission electron microscopy. Bone resorbing cells (osteoclasts) were identified by their location at the sites of bone resorption, their frequent association with a band of concentrated activity of tartrate-resistant acid phosphatase at the bone surface and by the presence or lack of certain enzymes. Tartrate-resistant acid phosphatase was used as a marker for osteoclasts, and alkaline phosphatase as a marker for osteoblasts. Osteoclasts in O. niloticus are not multinucleated; however, during intense bone resorption, they form cell aggregations that resemble multinucleated giant cells in mammals. Conversely, during less intense bone degradation, osteoclasts are flat, have long narrow cytoplasmic processes and resemble the bone-lining cells of mammals. All bone-resorbing cells in O. niloticus are mononucleated and lack a ruffled border. Similarities to and differences from bone resorption by mononucleated cells in mammals are discussed.

Animals↗
PubMed1997

Immunocytochemical detection and cytomorphology of lymphocyte subpopulations in a teleost fish Dicentrarchus labrax.

The monoclonal antibodies DLT15 and DLIg3 directed against thymocytes and serum immunoglobulins of the sea bass (Dicentrarchus labrax, L.) were used to study cells from the thymus, head kidney, spleen, gut-associated lymphoid tissue and peripheral blood leukocytes of this fish by immunofluorescence and pre-embedding immunoelectron microscopy. Immunofluorescence and flow cytometry of leukocyte fractions revealed a large number of DLT15-positive cells in the thymus (approximately 80%) and intestine (approximately 55%) and fewer cells in the spleen (approximately 7%), head kidney (approximately 6%) and peripheral blood (approximately 3%). DLT15-positive cells had two main morphologies, both detectable among thymocytes: a large round heterochromatic nucleus with light sparse cytoplasm (type a) and an irregular and heterocromatic nucleus with cytoplasm rich in polysomes and mitochondria (type b). Type b was most represented in spleen, head kidney, intestine and blood. We suggest that the type b morphology represents more differentiated lymphocytes. Flow cytometry revealed numerous DLIg3-positive cells in the head kidney (approximately 33%), spleen (approximately 30%) and peripheral blood leukocytes (approximately 21%) and fewer positive cells in the intestine (approximately 3%) and thymus (approximately 2%). DLIg3-positive cells had the morphology of lymphocytes (with a large round nucleus) or macrophages in all tissues. Plasma cells lacked membrane immunoreactivity. This is the first ultrastructural characterisation of putative T- and B-lymphocyte subpopulations in a fish species; these subpopulations are differentially distributed in teleost lymphoid organs.

Animals↗
PubMed1999

Nitric oxide synthase in the glossopharyngeal and vagal afferent pathway of a teleost, Takifugu niphobles. The branchial vascular innervation.

To examine the presence of nitric oxide synthase (NOS) in the sensory system of the glossopharyngeal and vagus nerves of teleosts, nicotinamide adenine dinucleotide phosphate diaphorase (NADPHd) activity and immunoreactivity for NOS were examined in the puffer fish Takifugu niphobles. The nitrergic sensory neurons were located in the ganglia of both the glossopharyngeal and the vagal nerves. In the vagal ganglion, positive neurons were found in the subpopulations for the branchial rami and the coelomic visceral ramus, but not for the posterior ramus or the lateral line ramus. In the medulla, nitrergic afferent terminals were found in the glossopharyngeal lobe, the vagal lobe, and the commissural nucleus. In the gill structure, the nitrergic nerve fibers were seen in the nerve bundles running along the efferent branchial artery of all three gill arches. These fibers appeared to terminate in the proximal portion of the efferent filament arteries of three gill arches. On the other hand, autonomic neurons innervating the gill arches were unstained. These results suggest that nitrergic sensory neurons in the glossopharyngeal and vagal ganglia project their peripheral processes through the branchial rami to a specific portion of the branchial arteries, and they might play a role in baroreception of this fish. A possible role for nitric oxide (NO) in baroreception is also discussed.

Afferent Pathways↗
PubMed2026

A User-Friendly Protocol for Microinjection into Teleost Embryos to Study Gene Function.

Zebrafish (Danio rerio) and medaka (Oryzias latipes) are popular teleost models used in developmental biology and functional genomics. To achieve high-quality and reproducible microinjections, it is essential to have robust protocols for breeding, egg collection, and the precise delivery of genetic material. In this protocol, we present a comprehensive and optimized methodology for setting up breeding tanks under controlled photoperiod conditions to maximize egg yield while minimizing contamination. We provide detailed procedures for sex identification, pair selection, the use of grated breeding inserts, and methods to increase egg collection efficiency. We outline procedures for making injection gel beds, pulling needles, and calibration using one-microliter microcapillaries to achieve consistent nanoliter-scale injections. Our protocol outlines settings for the pico-liter injector that are optimized to deliver a precise amount per pulse with minimal variability. Finally, we demonstrate the application of these methods for gene knockdown using morpholino antisense oligonucleotides, gene knockout using CRISPR-Cas9, and gain-of-function mRNA overexpression experiments. Phenotypic assessments conducted at various developmental stages to evaluate gene-specific effects reveal consistent phenotypic outcomes between the morpholino and CRISPR-Cas9 approaches. This easy and comprehensive protocol enables efficient, precise, and scalable genetic manipulation of zebrafish and medaka embryos, thereby supporting advanced functional studies in developmental biology and disease modeling. To our knowledge, this is the first unified protocol for both zebrafish and medaka microinjection systems achieving 97.7% phenotype penetrance in CRISPR-Cas9 knockouts with precision together with a triple validation approach that confirms gene function across multiple techniques.

Animals↗
PubMed2005

First report of a bucephalid digenean from an apogonid teleost: Prosorhynchoides apogonis n. sp. from Cheilodipterus macrodon on the southern Great Barrier Reef, Australia.

Prosorhynchoides apogonis n. sp. (Digenea: Bucephalidae) is described from the intestine of the apogonid Cheilodipterus macrodon on the southern Great Barrier Reef, Australia. The new species is differentiated from other species of Prosorhynchoides Dollfus, 1929 by the configuration of its digestive system, shape and distribution of its vitelline follicles, and the shape and extent of its uterus. This is the first bucephalid to be described from the teleost family Apogonidae, and our records suggest that this species is strongly host-specific, at least to the genus Cheilodipterus. The host family is consistent with the pattern of Prosorhynchoides being reported from a very wide range of piscivorous fish families. As a result of comparisons made in the description of this species, 18 species formerly included in Bucephaloides Hopkins, 1954,Bucephalopsis Diesing, 1855 and Neobucephalopsis Dayal, 1948 are transferred to Prosorhynchoides, 16 as new combinations and two as replacement names to prevent secondary homonymy.

Animals↗
PubMed2006

Trypanosomes infecting cod Gadus morhua L. in the North Atlantic: a resurrection of Trypanosoma pleuronectidium Robertson, 1906 and delimitation of T. murmanense Nikitin, 1927 (emend.), with a review of other trypanosomes from North Atlantic and Mediterranean teleosts.

Trypanosomes were isolated from Atlantic cod Gadus morhua L. collected from several fjords in western Norway. Morphological studies showed that the 12 infections studied represented a single species, identified as Trypanosoma pleuronectidium Robertson, 1906 which is resurrected and redescribed. This species is characterised by its body length (57.9 +/- 5.4 microm), nearly central nucleus (NI = 1.05 +/- 0.12) and relatively short post-kinetoplastic (PK) region (3.2 +/- 0.8 microm). T. pleuronectidium is transmitted by the leech Calliobdella nodulifera (Malm). T. murmanense Nikitin, 1927 (emend.) is delimited to a species transmitted by the leech Johanssonia arctica (Johansson). This species is separated from T. pleuronectidium by its attained body length, more anterior nucleus, presence of cytoplasmic refractive granules, adnuclear vacuoles and by a longer PK region. Partial SSU rDNA sequences of T. pleuronectidium and T. murmanense from Norway (1980 nt) diverged by 1.9%. The nominal North Atlantic and Mediterranean trypanosome species are reviewed, and T. flesi Lebailly, 1904, T. bothi Lebailly, 1905 and T. limandae Brumpt & Lebailly, 1904 are considered synonyms of T. platessae Lebailly, 1904. T. triglae senegalensis Ranque, 1973 is not considered conspecific with T. triglae Neumann, 1909, and consequently raised to species status as T. senegalense Ranque, 1973. Some other likely synonymies are discussed. In addition to T. pleuronectidium and T. murmanense, the following marine teleost trypanosomes are provisionally listed as valid species pending further study: T. callionymi Brumpt & Lebailly, 1904; T. cotti Brumpt & Lebailly, 1904; T. delagei Brumpt & Lebailly, 1904; T. dorhni Yakimov, 1911; T. gobii Brumpt & Lebailly, 1904; T. laternae Lebailly, 1904; T. myoxocephali Fantham, Porter & Richardson, 1942; T. platessae Lebailly, 1904; T. scorpaenae Neumann, 1909; T. soleae Laveran & Mesnil, 1901; T. triglae Neumann, 1909; and T. yakimovi Yakimov, 1911.

Animals↗
PubMed2006

The taxonomic status of Opegaster Ozaki, 1928 and the description of four new species of Opecoelus Ozaki, 1925 (Digenea: Opecoelidae) from marine teleosts in Australian waters.

The similarities between Opecoelus Ozaki, 1925, Coitocaecum Nicoll, 1915, Opegaster Ozaki, 1928 and Paropecoelus Pritchard, 1966 and the difficulty of separating Opecoelus and Opegaster are discussed. It is proposed that Opegaster be reduced to synonymy with Opecoelus and the diagnosis of the latter amended to accommodate both forms. Four new species of Opecoelus are described from marine teleosts in Australian waters. These are Opecoelus woolcockae n. sp. from Acanthopagrus butcheri and A. australis from off South Australia, New South Wales and southern Queensland, O. pomatomi n. sp. from Pomatomus saltatrix off New South Wales, O. crowcrofti n. sp. from Atherinomorus ogilbyi off southern Queensland and O. queenslandicus n. sp. from Apogon fasciatus off southern Queensland. The following new combinations are formed: Opecoelus gonorhynchi (Gavrilyuk, 1979) n. comb., O. elongatus (Yamaguti, 1959) n. comb., O. pentadactylus (Manter, 1940) n. comb., O. apogonichthydis (Yamaguti, 1938) n. comb., O. cameroni (Caballero & Caballero, 1969) n. comb., O. dendrochiri (Yamaguti, 1970) n. comb., O. hawaiiensis (Yamaguti, 1970) n. comb., O. jamunicus (Srivastava, 1968) n. comb., O. longivesiculus (Yamaguti, 1952) n. comb., O. mastacembalii (Harshey, 1937) n. comb., O. mehrii (Harshey, 1937) n. comb., O. synodi (Manter, 1947) n. comb., O. tamori (Yamaguti, 1938) n. comb., O. bothi (Yamaguti, 1970) n. comb., O. caulopsettae (Manter, 1954) n. comb., O. beliyai (Pande, 1937) n. comb., O. brevifistulus (Ozaki, 1928) n. comb., O. cryptocentri (Yamaguti, 1958) n. comb., O. dactylopteri (Yamaguti, 1970) n. comb., O. dermatogenyos (Yamaguti, 1970) n. comb., O. ditrematis (Yamaguti, 1942) n. comb., O. gobii (Yamaguti, 1952) n. comb., O. hippocampi (Shen, 1982) n. comb., O. iniistii (Yamaguti, 1970) n. comb., O. lobulus (Wang, 1977) n. comb., O. macrorchis (Yamaguti, 1938) n. comb., O. parapristipomatis (Yamaguti, 1934) n. comb., O. pritchardae (Overstreet, 1969) n. comb., O. syngnathi (Yamaguti, 1934) n. comb., O. lutiani (Bravo-Hollis & Manter, 1957) n. comb., O. ovatus (Ozaki, 1928) n. comb., O. plotosi (Yamaguti, 1940) n. comb. and O. rectus (Ozaki, 1928) n. comb.; all the new combinations were previously species of Opegaster.

Animals↗
PubMed1992

The amino acid sequence and oxygen-binding properties of the single hemoglobin of the cold-adapted Antarctic teleost Gymnodraco acuticeps.

The complete amino acid sequence of the single hemoglobin of the Antarctic teleost Gymnodraco acuticeps has been determined. The alpha chain contains 142 amino acid residues; an acetylated seryl residue is at the amino terminal. The beta chain contains 146 residues. A very high degree of sequence identity has been found with hemoglobins of other Antarctic fishes. Oxygen binding is not modulated by pH and allosteric effectors. The Bohr and Root effects are absent, although specific amino acid residues, considered responsible of most of these functions, are conserved in the sequence, thus posing new questions about the molecular basis of these mechanisms. The low heat of oxygenation may be interpreted as one of the mechanisms involved in the process of cold adaptation.

Adaptation, Physiological↗
PubMed1990

Fine structure of the organic matrix remaining in the mature cap enameloid in Halichoeres poecilopterus, teleost.

Crystals and the organic matrix in both the enameloid and the maturation stage in this teleost fish were viewed by scanning and transmission electron microscopy. For transmission electron microscopy, specimens were demineralized by basic chromium (III) sulphate or phosphotungstic acid. Large numbers of defined compartments, thought to represent the outline of enameloid crystals, were seen in the outer layer of mature cap enameloid after this demineralization. However, the compartments were both less numerous and less well defined in the inner layer. These compartments suggest the existence of an organic enameloid matrix, which may correspond to the enamelins in mammalian enamel. As these defined compartments occurred in the areas of the tooth where large enameloid crystals were present, it is possible that the organic matrix constituting these compartments is involved in the production of large crystals.

Animals↗
PubMed1995

Fine structure of tooth germs during the formation of enameloid matrix in Tilapia nilotica, a teleost fish.

Tooth germs were examined by light and transmission electron microscopy. Collagen fibrils were relatively dispersed and thin at the early and middle stages of formation of the enameloid matrix, when the enameloid layer was thin. At the late stage, the fibrils became thicker, reaching nearly 30 nm dia, and formed the interwoven thick bundles that are characteristic of teleost cap enameloid. Abundant flocculent and/or fine, network-like material, probably representing glycosaminoglycans or proteoglycans, was located between the collagen fibrils. Tall, columnar, inner dental epithelial cells contained abundant rough endoplasmic reticulum and many mitochondria, and a well-developed Golgi apparatus was seen around the nuclei at the late stage. Elongated vesicles enclosing fine, filamentous material that resembled procollagen granules, and large granules containing fibril-like structures that were 150 nm in thickness and had periodic cross-banding at 32-nm intervals, were usually observed near the Golgi apparatus. The contents of the large granules were well stained with phosphotungstic acid, which suggests that inner dental epithelial cells synthesize collagen fibrils. At this time, odontoblasts also contained abundant rough endoplasmic reticulum and mitochondria, a well-developed Golgi, several kinds of granule including those that probably contained procollagen, and many microtubules. It is proposed that odontoblasts are involved in the formation of a considerable portion of the enameloid matrix, including collagen fibrils.

Amelogenesis↗