Identification of epithelial label-retaining cells at the transition between the anal canal and the rectum in mice

In certain regions of the body, transition zones exist where stratified squamous epithelia directly abut against other types of epithelia. Certain transition zones are especially prone to tumorigenesis an example being the anorectal junction, although the reason for this is not known. One possibility is that the abrupt transition of the simple columnar epithelium of the colon to the stratified squamous epithelium of the proximal portion of the anal canal may contain a unique stem cell niche. We investigated whether the anorectal region contained cells with stem cell properties relative to the adjacent epithelium. We utilized a tetracycline-regulatable histone H2B-GFP transgenic mice model, previously used to identify hair follicle stem cells, to fluorescently label slow-cycling anal epithelial cells (e.g., prospective stem cells) in combination with a panel of putative stem cell markers. We identified a population of long-term GFP label-retaining cells concentrated at the junction between the anal canal and the rectum. These cells are BrdU-retaining cells and expressed the stem cell marker CD34. Moreover, tracking the fate of the anal label-retaining cells in vivo revealed that the slow-cycling cells only gave rise to progeny of the anal epithelium. In conclusion, we identified a unique population of cells at the anorectal junction which can be separated from the other basal anal epithelial cells based upon the expression of the stem cell marker CD34 and integrin α6, and thus represent a putative anal stem cell population

Estudo comparativo entre marcadores ultra-sonográficos morfológicos preditores de parto pré-termo: sinal do afunilamento do colo e ausência do eco glandular endocervical A comparative study between morphologic ultrasonographic markers for preterm delivery: funneling sign and absence of cervical gland area

OBJETIVO: Avaliar o risco de parto pré-termo (PPT) espontâneo na população geral a partir do estudo comparativo dos marcadores ultra-sonográficos morfológicos do colo uterino, como o sinal do afunilamento e a ausência da área glandular endocervical. MATERIAIS E MÉTODOS: Foram arroladas 361 gestantes na população geral, submetidas a exame ultra-sonográfico transvaginal entre a 21ª e 24ª semana, e verificados os resultados perinatais. RESULTADOS: A incidência de PPT espontâneo foi de 5,0%. O sinal do afunilamento foi observado em 4,2% da população estudada e em 22,2% das pacientes que evoluíram para PPT espontâneo. Tal parâmetro mostrou associação significante com PPT (p < 0,001; risco relativo de 6,68). A ausência do eco glandular endocervical (EGE) foi detectada em 2,8% das pacientes estudadas e em 44,4% das pacientes que evoluíram para PPT espontâneo. Este parâmetro demonstrou forte associação com PPT espontâneo (p < 0,001; risco relativo de 28,57). A análise de regressão logística multivariada apontou a ausência do EGE como a única variável morfológica associada ao PPT espontâneo. CONCLUSÃO: A predição do PPT espontâneo a partir de sinais ultra-sonográficos deve ser realizada contemplando marcadores biométricos e morfológicos, entre estes, a ausência do EGE. Este estudo indica uma tendência clara da marcante importância da ausência do EGE como indicador do risco para PPT espontâneo, a ser confirmada futuramente em pesquisas multicêntricas.<br>OBJECTIVE: To verify if different morphological ultrasonographic markers such as the funneling sign and the cervical gland area can be predictors of spontaneous premature delivery in pregnant women between 21 and 24 weeks of gestation. MATERIALS AND METHODS: This was a prospective cross-sectional study in which 361 women with 21 to 24 weeks of gestation were examined by transvaginal ultrasonography. The gestational age at delivery was later checked by telephone or mail. RESULTS: Spontaneous preterm delivery (SPD) occurred in 5% of the patients. Cervical funneling occurred in 4.2% of the women and in 22.2% of those who had SPD. This finding was correlated to preterm delivery (p < 0.001; relative risk of 6.68). Absence of a hypoechoic area peripheral to the cervical canal consistent with endocervical epithelium glands, namely endocervical glandular echo (EGE) feature, was detected in 2.8% of all patients and in 44.4% of those who developed spontaneous preterm labor. There was a statistically significant association of this feature to SPD (p < 0.001; relative risk of 28.57). Multivariance logistic regression analysis showed that this was the feature with strongest correlation with SPD, when compared to cervical funneling. CONCLUSION: Prediction of SPD through ultrasound features should observe biometrical and morphological signs such as absence of EGE. This is a new and important ultrasound finding that can be considered a predictor of risk for SPD, and should be confirmed in future multicentric trials