Many of our ideas about cellular memory of fate and position come from regeneration studies in salamanders. A popular notion is that cells of the blastema transdifferentiate to different fates during limb regeneration. In a recent issue of Nature, Tanaka and colleagues challenge this notion. Using transplant experiments with GFP-expressing axolotl, they show vividly which cells of the blastema ...

The gonadal development of the Macaca fascicularis fetus was studied between 37 and 118 days on serial semi-thin and thin sections. The testis and the ovary began to differentiate at the same age (37 days); the definitive architecture of the testis was acquired at 43 days, while a cortex and a medulla did not form in the ovary until 55 to 60 days. In spite of the time-lag and the divergent deve...

In over 50 cases the puho-ischio-tibialis muscle in mature axolotls was removed, minced and the minced fragments replaced into the site from which the muscle was removed. In 13 control animals the same muscle was removed but nothing was replaced. Regenerates were studied at postaperational intervals of up to 150 days. Both grossly and histologically the regeneration of muscles from minced fragm...

Micro RNAs (miRNAs) play an important role during renal development and show a tissue-specific enrichment in the kidney. Nephroblastomas, embryonal renal neoplasms of childhood, are considered to develop from nephrogenic rests (NRs) and resemble morphologically and genetically developing kidney. We therefore investigated the role of kidney-enriched miRNAs in the pathogenesis of nephroblastomas....

After limb amputation, urodele amphibians can regenerate lost parts perfectly throughout their life. However, Xenopus laevis shows its characteristic limb regenerative ability. Although Xenopus tadpole has the capacity to regenerate their limbs after amputation, after amputation of a froglet (a small frog after metamorphosis) limb, it can regenerate only a spike-shaped cartilage which has no pa...

The regenerating mouse digit tip is a unique model for investigating blastema formation and epimorphic regeneration in mammals. The blastema is characteristically avascular and we previously reported that blastema expression of a known anti-angiogenic factor gene, Pedf, correlated with a successful regenerative response (Yu, L., Han, M., Yan, M., Lee, E. C., Lee, J. & Muneoka, K. (2010). BMP si...

After limb amputation, urodele amphibians can regenerate lost parts perfectly throughout their life. However, Xenopus laevis shows its characteristic limb regenerative ability. Although Xenopus tadpole has the capacity to regenerate their limbs after amputation, after amputation of a froglet (a small frog after metamorphosis) limb, it can regenerate only a spike-shaped cartilage which has no pa...

Here, we used classical genetics in zebrafish to identify temperature-sensitive mutants in caudal fin regeneration. Gross morphological, histological, and molecular analyses revealed that one of these strains, emmental (emm), failed to form a functional regeneration blastema. Inhibition of emm function by heat treatment during regenerative outgrowth rapidly blocked regeneration. This block was ...

Cystic partially differentiated nephroblastoma (CPDN) is extremely rare in adults. Only 2 cases have been documented in the English literature. Herein, we present a third case of CPDN with unique morphological and immunohistochemical features. A 45-year-old man had a multicystic right renal mass, with a maximum diameter of 3 cm on magnetic resonance imaging. Being unable to rule out malignancy,...

The origin of cells that generate the blastema following appendage amputation has been a long-standing question in epimorphic regeneration studies. The blastema is thought to originate from either stem (or progenitor) cells or differentiated cells of various tissues that undergo dedifferentiation. Here, we investigate the origin of cells that contribute to the regeneration of zebrafish caudal f...