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PubMed1967

Flagellar regeneration in protozoan flagellates.

The flagella of populations of three protozoan species (Ochromonas, Euglena, and Astasia) were amputated and allowed to regenerate. The kinetics of regeneration in all species were characterized by a lag phase during which there was no apparent flagellar elongation; this phase was followed by elongation at a rate which constantly decelerated as the original length was regained. Inhibition by cycloheximide applied at the time of flagellar amputation showed that flagellar regeneration was dependent upon de novo protein synthesis. This was supported by evidence showing that a greater amount of leucine was incorporated into the proteins of regenerating than nonregenerating flagella. The degree of inhibition of flagellar elongation observed with cycloheximide depended on how soon after flagellar amputation it was applied: when applied to cells immediately following amputation, elongation was almost completely inhibited, but its application at various times thereafter permitted considerable elongation to occur prior to complete inhibition of flagellar elongation. Hence, a sufficient number of precursors were synthesized and accumulated prior to addition of cycloheximide so that their assembly (elongation) could occur for a time under conditions in which protein synthesis had been inhibited. Evidence that the site of this assembly may be at the tip of the elongating flagellum was obtained from radioautographic studies in which the flagella of Ochromonas were permitted to regenerate part way in the absence of labeled leucine and to complete their regeneration in the presence of the isotope. Possible mechanisms which may be operating to control flagellar regeneration are discussed in light of these and other observations.

Amino Acids↗
PubMed1972

Fine structural localization of cholesterol-1,2- 3 H in degenerating and regenerating mouse sciatic nerve.

The localization of (3)H-labeled cholesterol in nerves undergoing degeneration and regeneration was studied by radioautography at the electron microscope level. Two types of experiments were carried out: (a) Cholesterol-1,2-(3)H was injected intraperitoneally into suckling mice. 5 wk later, Wallerian degeneration was induced in the middle branch of the sciatic nerve, carefully preserving the collateral branches. The animals were then sacrificed at various times after the operation. During degeneration, radioactivity was found over myelin debris and fat droplets. In early stages of regeneration, radioactivity was found in myelin debris and regenerating myelin sheaths. Afterwards, radioactivity was found predominantly over the regenerated myelin sheaths. Radioactivity was also associated with the myelin sheaths of the unaltered fibers, (b) Wallerian degeneration was induced in the middle branch of the sciatic nerves of an adult mouse, preserving the collateral branches. Cholesterol-1,2-(3)H was injected 24 and 48 hr after the operation and the animal was sacrificed 6 wk later. Radioactivity was found in the myelin sheaths of the regenerated and unaltered fibers. The results from these experiments indicate that: (a) exogenous cholesterol incorporated into peripheral nerve during myelination remains within the nerve when it undergoes degeneration. Such cholesterol is kept in the myelin debris as an exchangeable pool from which it is reutilized for the formation of the newly regenerating fibers, especially myelin. (b) exogenous cholesterol incorporated into the nerves at the time that degeneration is beginning is also used in the formation of new myelin sheaths during regeneration, (c) mature myelin maintains its ability to incorporate cholesterol.

Animals↗
PubMed1974

The regeneration of cilia in partially deciliated Tetrahymena.

Partial deciliation of Tetrahymena resulted in cells losing 75% of their cilia, with the balance being paralyzed. The paralyzed cilia are resorbed in the first 20 min after partial deciliation, and regeneration of cilia begins before resorption is completed. Inhibition of protein synthesis with cycloheximide does not inhibit ciliary resorption or regeneration, whereas vinblastine sulfate inhibits regeneration but not resorption. Inhibition of regeneration occurs in completely deciliated cells when they are treated with cyclohexmimide or vinblastine sulfate. It is concluded that the resorbing cilia contribute materials which allow regeneration to occur in the absence of protein synthesis. The volume of cilia regenerated in the presence of cycloheximide in partially deciliated cells is greater than the ciliary volume which is resorbed. This suggests the Tetrahymena cells have a pool of ciliary precursors. This pool does not contribute materials for regeneration in completely deciliated cells which are treated with cycloheximide. It is concluded that resorbing cilia in partially deciliated cells contribute materials which potentiate assembly of cilia from the pool of precursors.

Amino Acids↗
PubMed1982

Synthesis and mobilization of flagellar glycoproteins during regeneration in Euglena.

Flagellar glycoprotein synthesis and mobilization of flagellar glycoprotein pools have been followed during flagellar regeneration in Euglena. The glycosylation inhibitor tunicamycin has little effect on either regeneration kinetics or the complement of flagellar peptides as seen in SDS acrylamide gels, but tunicamycin totally inhibits incorporation of exogenously supplied [14C]xylose into flagellar glycoproteins. Moreover, deflagellated cells pulsed with tunicamycin for 0 min or more, regenerated for 180 min, and then redeflagellated are completely or partially inhibited from undergoing a second regeneration even when tunicamycin is no longer present. These facts are interpreted as indicating that Euglena retains sufficient glycoprotein pool for one complete flagellar assembly. Some of this pool is present on the cell surface since [125I]-labeled surface peptides can be chased into the regenerating flagellum. Glycosylation may also be taking place in the flagellum directly because [14C]xylose has been found in three flagellar fractions: glycoprotein and two others, which are lipophilic and have properties similar to those described for lipid-carrier glycoprotein intermediates in other systems. Pulse-chase experiments also suggest a precursor-product relationship between the presumptive lipid carriers and flagellar glycoproteins. From these results a model is postulated in which Euglena is visualized as retaining sufficient pool of glycoprotein for one complete flagellar regeneration, but the pool is normally supplemented by active xylosylation in situ during regeneration.

Animals↗
PubMed2003

Addition of fibronectin to alginate matrix improves peripheral nerve regeneration in tissue-engineered conduits.

Schwann cell (SC) transplantation has been proposed to encourage peripheral nerve regeneration, but an optimal SC-carrying matrix would be needed. The aim of this study was to characterize how the addition of fibronectin to alginate would affect the outcome of nerve regeneration promoted by Schwann cells embedded in this matrix. Genetically labeled rat SCs were obtained by lacZ gene transduction. SCs were suspended in alginate hydrogel matrix with/without addition of liquid fibronectin, and their viability and growth in the different types of matrices were assessed in vitro by AlamarBlue assay. In vivo assessment of SC transplantation in the matrix was carried out with poly-3-hydroxybutyrate (PHB) conduits to bridge a sciatic nerve gap. The grafted conduits were harvested at 2, 3, and 6 weeks and assessed for the presence of labeled SCs in relation to regrowing axons. The amount and rate of axonal regeneration were assessed by quantitative immunohistochemistry. Addition of fibronectin to alginate hydrogel improved SC viability and growth profile in vitro. X-Gal staining confirmed that SCs transplanted in PHB conduits were viable throughout the time course, and that the labeled SCs were clearly associated with regenerating axons. The regeneration rate was enhanced when liquid fibronectin was added to the alginate matrix. Furthermore, the presence of SCs also enhanced regeneration and there was an additive effect when both SCs and fibronectin were combined with alginate. In conclusion, the addition of fibronectin to alginate hydrogel matrix contributed to improve nerve regeneration, supporting SC viability and augmenting their effect on axonal growth when transplanted in a bioengineered nerve conduit.

Alginates↗
PubMed1994

Gene transfer in regenerating muscle.

We have compared the efficiency of direct gene transfer in normal and regenerating rat skeletal muscle. Muscle necrosis and regeneration was induced by intramuscular injection of bupivacaine in the soleus muscle of adult rats. Plasmids containing beta-galactosidase (beta-gal) or chloramphenicol acetyltransferase (CAT) genes driven by viral promoters were injected 3 days after bupivacaine treatment into the regenerating and the contralateral uninjured muscles. Expression of CAT activity was > 80-fold higher in regenerating compared to control muscles at 7 days post-transfection, but decreased at 30 and 60 days. Southern blot analysis showed that the predominant form of CAT DNA was episomal in transfected muscles; however, CAT activity measurements performed on the same transfected muscles showed no precise correlation between enzymatic activity and amount of plasmid DNA. Expression of beta-gal was detected in numerous regenerating fibers of the injured soleus muscles at 7 days post-transfection; in contrast, only rare positive fibers were found in control muscles. Focal infiltrates of mononuclear cells, which surround and invade selectively beta-gal-positive fiber segments, were observed at 30 days post-transfection, suggesting that immune mechanisms are implicated in the progressive loss of transgenes with time. The finding that regenerating muscle fibers display a higher efficiency of transfection may be relevant to gene therapy of Duchenne muscular dystrophy, because regenerating fibers are numerous in the early stages of the disease.

Animals↗
PubMed2006

Comparison of the fastest regenerating motor and sensory myelinated axons in the same peripheral nerve.

Functional outcome after peripheral nerve regeneration is often poor, particularly involving nerve injuries far from their targets. Comparison of sensory and motor axon regeneration before target reinnervation is not possible in the clinical setting, and previous experimental studies addressing the question of differences in growth rates of different nerve fibre populations led to conflicting results. We developed an animal model to compare growth and maturation of the fastest growing sensory and motor fibres within the same mixed nerve after Wallerian degeneration. Regeneration of cat tibial nerve after crush (n = 13) and section (n = 7) was monitored for up to 140 days, using implanted cuff electrodes placed around the sciatic and tibial nerves and wire electrodes at plantar muscles. To distinguish between sensory and motor fibres, recordings were carried out from L6-S2 spinal roots using cuff electrodes. The timing of laminectomy was based on the presence of regenerating fibres along the nerve within the tibial cuff. Stimulation of unlesioned tibial nerves (n = 6) evoked the largest motor response in S1 ventral root and the largest sensory response in L7 dorsal root. Growth rates were compared by mapping the regenerating nerve fibres within the tibial nerve cuff to all ventral or dorsal roots and, regardless of the lesion type, the fastest growth was similar in sensory and motor fibres. Maturation was assessed as recovery of the maximum motor and sensory conduction velocities (CVs) within the tibial nerve cuff. Throughout the observation period the CV was approximately 14% faster in regenerated sensory fibres than in motor fibres in accordance with the difference observed in control nerves. Recovery of amplitude was only partial after section, whereas the root distribution pattern was restored. Our data suggest that the fastest growth and maturation rates that can be achieved during regeneration are similar for motor and sensory myelinated fibres.

Action Potentials↗
PubMedDate not supplied

Anther culture-derived regenerants of durum wheat and their cytological characterization.

Anther culture is being increasingly used in cereal crop improvement both as a source of haploids and for inducing new genetic variation. We studied the androgenetic ability and regenerability of 10 cultivars of durum wheat (Triticum turgidum L., 2n = 4x = 28; AABB), using three different growth conditions and four media. From a total of 86,400 anthers cultured, 324 plants were obtained: 248 green and 76 albino. Genotype, growth condition, and media significantly affected anther response and callus production; interactions were also significant. Green plant regeneration was influenced significantly by genotype and growth condition, as well as by genotype and growth condition interactions. Albino plant regeneration was significantly affected only by growth condition. Regenerants showed gametoclonal/somaclonal variation. Differences in morphology, growth habit, adult plant height, spike size, and development of spikes at nodes were observed. Mitotic and meiotic chromosomes were studied by conventional staining and fluorescent genomic in situ hybridization techniques. Chromosome numbers of the regenerants ranged from 14 to 70. All 76 haploid plantlets (2n = 2x = 14; AB) were albino. Some of the 28-chromosome regenerants were also albino. Chromosome number in the green plantlets ranged from 28 to 70. Chromosome number also varied in regenerants originating from the same callus. Both intergenomic and intragenomic multivalents were observed. An interesting feature was the preferential multiplication of B-genome chromosomes, which formed multivalents (trivalents, quadrivalents, and hexavalents). We observed several chromosomal abnormalities, which seemed to increase with the level of polyploidy. Translocations, dicentric chromosomes, chromatid exchanges, and Robertsonian translocations involving the A- and B-genome chromosomes were observed. Chromosome breakages resulting in centric and acentric fragments, and telocentrics were observed. Chromosome multiplication and structural aberrations induced during culture may constitute the bases of gametoclonal and somaclonal variations.

Chromosome Banding↗
PubMed2003

2,3,7,8-tetrachlorodibenzo-p-dioxin inhibits zebrafish caudal fin regeneration.

Adult zebrafish completely regenerate their caudal fins following partial amputation. Fin regrowth can easily be monitored in vivo and regenerating tissues can be used to study this dynamic developmental process. In this study we determined that fin regeneration is significantly affected by exposure to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). Zebrafish caudal fins were partially amputated, and the fish received intraperitoneal (ip) injection of 2.8, 14, or 70 ng/g weight TCDD or vehicle control. By 7 days postamputation, fish exposed to the highest concentration of TCDD regenerated 15% of their fin compared to 65% regrowth in control fish. To determine if this effect was stage specific, zebrafish were exposed to 70 ng/g TCDD on 1, 2, 3, or 4 days postamputation. Fin regeneration was significantly inhibited at all time points following TCDD exposure. TCDD exposure also induced hyperpigmentation in de novo tissue. Zebrafish were dosed with BrdU, following fin amputation and TCDD exposure, to study changes in cell proliferation. By 4 days postamputation, cell proliferation rates were significantly lower in TCDD-exposed fish. TCDD toxicity is mediated through the aryl hydrocarbon receptor (AHR), and RT-PCR experiments confirmed AHR2, ARNT2b, and TCDD-dependent CYP1A expression in the regenerating tissue. These results demonstrate that zebrafish caudal fin regeneration is a unique model to investigate molecular mechanism(s) of TCDD toxicity.

Animals↗
PubMed1996

Posttranscriptional regulation of gene expression in liver regeneration: role of mRNA stability.

The rentry of hepatocytes and nonparenchymal cells from the normal quiescent G0 phase into the cell cycle during liver regeneration after 70% partial hepatectomy results in the discrete modulation of mRNA transcripts for many different genes. The modulation of steady-state levels of transcripts for genes involved in hepatocyte growth and replication during liver regeneration indicates that gene expression is regulated not only transcriptionally but also posttranscriptionally. In fact, posttranscriptional control appears to be the primary mechanism of regulating gene expression after the first 3 h after partial hepatectomy. Alteration in transcript stability is a key posttranscriptional regulatory mechanism used by the regenerating liver to modulate the steady-state transcript levels of multiple genes. Even genes that are transcriptionally activated during liver regeneration exhibit posttranscriptional control at the level of transcript stability. Moreover, the abundance of mRNA binding proteins, as well as translational activity and rate of poly(A) tail removal, are modulated and appear to influence transcript stability during liver regeneration. However, alteration of transcript stability is not the sole posttranscriptional mechanism regulating steady-state levels. Posttranscriptional control also occurs at the level of alternative splicing, stabilization of heterogeneous nuclear (hn) RNA, and hnRNA processing. Moreover, the role of nucleocytoplasmic transport of mature mRNA during liver regeneration is still undefined. Thus, during liver regeneration gene expression is regulated at multiple levels after the initial synthesis of hnRNA. By understanding the role of posttranscriptional mechanisms in regulating steady-state transcript levels in an in vivo model of normal growth, we will begin to appreciate its role in the genesis of abnormal growth.

Animals↗
PubMed2006

Hepatocyte proliferation during liver regeneration is impaired in mice with liver-specific IGF-1R knockout.

Recent evidence indicates that growth hormone (GH) is involved in liver regeneration. To test whether insulin-like growth factor I (IGF-I) mediates this effect, we studied liver regeneration induced by partial hepatectomy in liver-specific IGF type 1 receptor knockout (LIGFREKO) mice. The absence of IGF-1R caused a significant decrease in hepatocyte proliferation in males (-52%), but not in females, as assessed by Ki67 immunohistochemistry. Cyclin D1 and cyclin A protein levels in the livers of LIGFREKO males were only half those in controls, indicating that cyclin induction during liver regeneration is dependent on IGF-1R signaling. Analyzing the signaling cascade initiated by IGF-1R, we observed a lack of IRS-1 induction in LIGFREKO livers. In contrast, the induction of IRS-2 synthesis was similar in LIGFREKO and control groups, suggesting the existence of differential regulation of IRS synthesis during liver regeneration. Regenerating livers from LIGFREKO animals also showed significantly less activated ERKs than controls. Our findings demonstrate that IGF-1R makes a significant contribution to liver regeneration. Using the LIGFREKO model, we provide new evidence that IGF-1R/IRS-1/ERK signaling may be the intracellular pathway controlling the cell cycle via cyclin D1 and cyclin A in the regenerating liver.

Animals↗
PubMed2001

Functional regeneration of a gravity sensory system during development in an insect (Gryllus bimaculatus).

The efficiency of the regenerated cercal gravity sensory system was investigated in adult crickets (Gryllus bimaculatus). Regeneration was induced by amputations of cerci during different periods of development. Numbers of gravity-sensitive (clavate) sensilla on regenerated and intact cerci were identical if amputations were performed up to four times before the 6th instar. If older instars were included, regenerated cerci had fewer clavate sensilla than intact cerci. Compensatory head responses induced by stimulation of either regenerated or intact gravity sense organs were identical if cerci were amputated up to three times. However, four or more amputations caused weaker responses in the regenerated than in the intact sense organs. These experiments make the existence of a sensitive period during development of the cercal gravity sensory system unlikely. They support the postulation that functional regeneration is influenced by neuroplastic processes and proprioceptive gravity sensitive systems.

Aging↗
PubMed1991

Essential role of cholecystokinin in pancreatic regeneration after 60% distal resection in rats.

The essential role of cholecystokinin (CCK) in pancreatic regeneration after pancreatitis or resection has been supposed, but not yet clearly demonstrated. In rats, 6-8 weeks after 60% distal resection of the pancreas a gradual increase in pancreatic weight and contents of DNA, protein, trypsin, chymotrypsin and amylase, occurred (there was no increase in lipase); Pancreatic regeneration stopped thereafter. Nonparallel increases in enzyme values were similar to those seen after CCK administration. Indeed, basal CCK levels increased significantly by the 6th week and declined thereafter. A one month s.c. administration of CCK-octapeptide (CCK-8) (3 x 300 ng/kg/d) accelerated regeneration in the first month, but it had almost no effect during the second or third postoperative months. A two week s.c. administration of a specific CCK antagonist, CR 1409 (3 x 4 mg/kg/d) totally prevented regeneration by the fifth and sixth weeks, but did not diminish pancreatic weight or DNA and protein contents during the first two weeks. Alcohol administration (12 g/kg/d) reduced CCK release and prevented pancreatic regeneration during the three-month experimental period. These data indicate that CCK has an essential role in pancreatic regeneration and that the deleterious effect of alcohol on regeneration involves inhibition of CCK release.

Amylases↗
PubMed2003

Identification of renal progenitor-like tubular cells that participate in the regeneration processes of the kidney.

The present study was conducted to explore renal progenitor-like cells that are actively engaged in tubular regeneration after injury. For addressing this issue, the existence of label-retaining cells (LRC; slow-cycling cells) in normal rat kidneys by in vivo bromodeoxyuridine (BrdU) labeling was examined. LRC were scattering among renal epithelial tubular cells of normal rat kidneys. During the recovery after renal ischemia, LRC underwent cell division and most of them became positive for proliferating cell nuclear antigen. In contrast, proliferating cell nuclear antigen-positive but BrdU-negative tubular cells were rarely observed, suggesting that cells proliferating during tubular regeneration are essentially derived from LRC. At an early phase of tubular regeneration, descendants of LRC expressed a mesenchymal marker, vimentin, and eventually became positive for an epithelial marker, E-cadherin, after multiple cell divisions. These findings suggested that LRC function as a source of regenerating cells to replace injured cells. Collectively, it was concluded that LRC are renal progenitor-like tubular cells that provide regenerating cells, which actively proliferate and eventually differentiate into epithelial cell, during tubular regeneration. It may be possible to regenerate renal tubules in vivo through the activation of LRC.

Animals↗
PubMed2004

Sensory hair cell death and regeneration: two halves of the same equation.

PURPOSE OF REVIEW: Sensory hair cells are susceptible to ototoxic damage from a variety of sources, including antibiotic treatment. Unfortunately, this often results in permanent hearing and/or balance problems in humans. By understanding how sensory hair cells die in response to aminoglycoside treatment, preventive strategies may be developed. This review will discuss some of the key recent findings in sensory hair cell death and regeneration. RECENT FINDINGS: Aminoglycosides induce hair cell death through the initiation of apoptosis. Early and late stages of hair cell apoptosis have been defined, and several of the key molecules involved in the cascade have been identified. Moreover, specific inhibitors of apoptosis rescue hair cells from death and preserve function. Hair cell death has been shown to induce regeneration through supporting cell transdifferentiation, proliferation, and new hair cell differentiation in birds and lower vertebrates. Regeneration in the mammalian cochlea does not occur spontaneously, but genetic manipulation of cell cycle genes, induction of new hair cells through gene therapy, and introduction of stem cells into damaged cochleas suggest that repair and replacement of lost hair cells in the organ of Corti may be possible. Finally, continuing investigations of the mouse, zebrafish, and human genomes may one day enable manipulation of the cochlea so that functional regeneration is readily available as a therapeutic intervention. SUMMARY: The discovery that hair cells can regenerate in birds and other nonmammalian vertebrates has fueled a wide range of studies to find ways to restore hearing and balance in mammals. The demonstration that apoptosis and proliferation are coupled as controlling factors in regeneration and the advent of new approaches such as gene therapy, stem cell transplantation, and genomics may lead to methods for inducing hair cell regeneration and repair in the mammalian cochlear and vestibular systems.

Aminoglycosides↗
PubMed2003

Endothelial-directed hepatic regeneration after partial hepatectomy.

OBJECTIVE: To determine the role of the microvascular endothelium in the regulation of regenerating liver mass after partial hepatectomy. SUMMARY BACKGROUND DATA: Angiogenesis is critical for both pathologic and physiologic processes. The ability of certain tissues, such as the liver, kidney, and spleen, to regenerate after injury is poorly understood. The liver will regenerate to its normal mass within 8 days of surgical excision. Because the authors have previously shown that the endothelial cell regulates tumor mass, we hypothesized that normal adult organ mass is also controlled by the endothelial cell. METHODS: Two-thirds partial hepatectomy was performed in 7- to 8-week-old C57 BL/6 mice, followed by systemic treatment with either the angiogenesis stimulator basic fibroblast growth factor (bFGF) (1 microg/g/d intraperitoneal) or the angiogenesis inhibitor TNP-470 (30 mg/kg/qod subcutaneous). Groups of three mice were then euthanized on postoperative days 2, 4, 6, and 8, and the livers were weighed and analyzed by immunohistochemistry. RESULTS: bFGF accelerated hepatic regeneration by 42%, 19%, 16%, and 16% on postoperative days 2, 4, 6, and 8, respectively. TNP-470 inhibited hepatic regeneration by 46%, 74%, 67%, and 64% on postoperative days 2, 4, 6, and 8, respectively. Immunohistochemistry revealed that bFGF and TNP-470 primarily affected the endothelial compartment. Specifically, bFGF increased endothelial proliferation and decreased endothelial apoptosis. TNP-470, in contrast, inhibited endothelial cell proliferation. The cessation of the regenerative process correlated with a decrease in endothelial proliferation and an increase in endothelial apoptosis. CONCLUSIONS: The systemic administration of angiogenesis agents modulates the regeneration of hepatic mass primarily by affecting endothelial cell proliferation or apoptosis. Endothelial cell apoptosis is associated with the cessation of the regenerative process in control mice. These results suggest that the endothelial cell is one of the key mediators of regenerating adult tissue mass in this partial hepatectomy model.

Animals↗
PubMed2003

Liver regeneration and surgical outcome in donors of right-lobe liver grafts.

INTRODUCTION: Previous studies of healthy live-liver donors have suggested that complete liver regeneration occurs within a matter of weeks; however, there have been no long-term studies evaluating liver regeneration and few studies documenting long-term donor outcome. MATERIALS AND METHODS: Fifty-one donors who provided right-lobe grafts underwent volumetric spiral computed tomography scans preoperatively and postoperatively at time intervals of 1 week and 1, 3, 6, and 12 months. Patient demographics, surgical data, and postoperative outcome were correlated with liver regeneration data. Donor surgical outcome was followed prospectively and recorded in a comprehensive database. RESULTS: Thirty-three males and 18 females (mean age 36.0+/-9.6 years) provided 51 right-lobe grafts. Mean follow-up was 9.8+/-3.4 months. No donor operation was aborted, and surgical morbidity and mortality rates were 39% and 0%, respectively. Donor remnant liver volume was 49.4+/-5.7% of the original total liver volume (TLV). Overall liver regeneration was 83.3+/-9.0% of the TLV by 1 year. Female donors had significantly slower liver regrowth when compared with males at 12 months (79.8+/-9.3% vs. 85.6+/-8.2%, P<0.01). There was no effect of age, body mass index, operative time, estimated blood loss, postoperative complications, or perioperative liver function tests on liver regeneration. DISCUSSION: Liver regeneration continues throughout the first postoperative year. Only one donor achieved complete liver regeneration during this time period; however, all donors have maintained normal liver function without long-term complications. Longer follow-up is needed to determine whether donors ever achieve original TLV.

Adolescent↗
PubMed2006

Limb regeneration in Xenopus laevis froglet.

Limb regeneration in amphibians is a representative process of epimorphosis. This type of organ regeneration, in which a mass of undifferentiated cells referred to as the "blastema" proliferate to restore the lost part of the amputated organ, is distinct from morphallaxis as observed, for instance, in Hydra, in which rearrangement of pre-existing cells and tissues mainly contribute to regeneration. In contrast to complete limb regeneration in urodele amphibians, limb regeneration in Xenopus, an anuran amphibian, is restricted. In this review of some aspects regarding adult limb regeneration in Xenopus laevis, we suggest that limb regeneration in adult Xenopus, which is pattern/tissue deficient, also represents epimorphosis.

Animals↗