background: the present study was undertaken to investigate the correlation of epidermal growth factor receptor (egfr) expression with grade of transitional cell carcinoma (tcc). methods: tumor samples of 75 patients from mostafa khomaini hospital with transitional cell carcinoma of the bladder were analyzed by immunohistochemistry for expression of egfr. in this context, we assigned the bladde...

In plants, cell fate specification depends primarily on position rather than lineage. Recent results indicate that positional information can be transmitted through intercellular trafficking of transcription factors. The SHORT ROOT (SHR) gene, a member of the GRAS family of putative transcription factors, is involved in root radial patterning in Arabidopsis. Correct radial patterning depends on...

The skin is a classical example of a tissue maintained by stem cells. However, the identity of the stem cells that maintain the interfollicular epidermis and the source of the signals that control their activity remain unclear. Using mouse lineage tracing and quantitative clonal analyses, we showed that the Wnt target gene Axin2 marks interfollicular epidermal stem cells. These Axin2-expressing...

Sweat glands are abundant in the body and essential for thermoregulation. Like mammary glands, they originate from epidermal progenitors. However, they display few signs of cellular turnover, and whether they have stem cells and tissue-regenerative capacity remains largely unexplored. Using lineage tracing, we here identify in sweat ducts multipotent progenitors that transition to unipotency af...

Wnt/β-catenin activation in adult epidermis can induce new hair follicle formation and tumor development. We used lineage tracing to uncover the relative contribution of different stem cell populations. LGR6(+) and LRIG1(+) stem cells contributed to ectopic hair follicles formed in the sebaceous gland upon β-catenin activation, whereas LGR5(+) cells did not. Lgr6, but not Lrig1 or Lgr5, was exp...

Many stem cells (SCs) respond to Wnt signaling, but whether beta-catenin's DNA binding partners, the Tcfs, play a role in SCs in the absence of Wnts, is unknown. In adult skin, quiescent multipotent progenitors express Tcf3 and commit to a hair cell fate in response to Wnt signaling. We find that embryonic skin progenitors also express Tcf3. Using an inducible system in mice, we show that upon ...

The origin of novelty is one of the least understood evolutionary phenomena. One approach to study evolutionary novelty comes from developmental biology. During developmental cell fate specification of the nematode Pristionchus pacificus (Diplogastridae), five cell fates can be distinguished within a group of twelve ventral epidermal cells. The differentiation pattern of individual cells includ...

AbstractEpidermal inclusion cysts are uncommon in the breast, but the consequences can besevere when these cysts occur in the breast parenchyma. Here, we report two suchcases. The patient in case 1 was an 37-year-old woman with a 3-cm palpable mass inthe right breast. Mammography revealed a round and smoothly outlined mass, whichindicated a benign tumor, and sonography showed an irregularly sha...

Culture technology have permitted the generation of an artificial skin using human neonatal stem cells. A major advantage of this model is that epithelial-mesenchymal interactions are maintained. We have studied some morphological aspects concerning tissue organisation and cell differentiation using immunohistochemistry and electron microscopy. The epidermal equivalent was composed by a stratif...

Cell fates are determined by specific transcriptional programs. Here we provide evidence that the transcriptional coactivator, Mediator 1 (Med1), is essential for the cell fate determination of ectodermal epithelia. Conditional deletion of Med1 in vivo converted dental epithelia into epidermal epithelia, causing defects in enamel organ development while promoting hair formation in the incisors....