Characteristics Of Mammary Gland Research Articles

Investigating the Effect of Neonatal Exposure of Tamoxifen and Zearalenone on Mammary Gland structure in Female Mouse

Introduction: Exposure to estrogen like chemicals during critical periods of development particularly in the neonatal period can disrupt normal patterns of mammary tissue development later in life. In this study, the effects of neonatal exposure of tamoxifen anti-estrogen and zearalenone mycoestrogen on some histological characteristics of mammary gland in female mouse were investigated. Materials & Methods: Twenty newborn female mice of BALB/c strain were divided into four groups: three experimental and one control group (with no treatment). Treatment groups included Tamoxifen (400 μg /kg /day) group, Zearalenone treatment group (2 mg /kg /day) and group treated with tamoxifen+zearalenone treatment group. Daily treatments were started on the first day of life and continued up to 5 subcutaneously. Then about 70 days after birth, mice were deeply anesthetized and the mammary tissue was removed from the body. Following histochemical staining, the samples were studied using light and transmission electron microcopies. Findings: The result showed that epithelial thickness of milk duct and volume of the nipple in tamoxifen treatment group significantly (p less-than 0.05) reduced. In contrast, the thickness of the epithelium and the nipple volume in tamoxifen+zearalenone and zearalenone treatment groups showed no significant difference in comparison with control. The electron microscopy of nipple duct showed negative effects of Tamoxifen on epithelium of milk duct. Discusion & Conclusions: The results of this study show that neonatal administration of tamoxifen probably exerts anti-estrogenic effects and it prevents the normal development of mammary tissue, but zearalenone do not have adverse consequences on mammary tissue.

Mammary gland morphology in the northern Amazon red squirrel (Sciurus igniventris)

Sciurus igniventris is a squirrel with broad distribution in South America. We examined one female adult specimen which was donated after death by trampling. The aim of this work was describe the morphological characteristics of mammary gland of one specimen. The body was fixed using 10% aqueous formaldehyde. Tissues were processed and slides prepared following standard histological protocols. Morphological analysis of the mammary glands revealed similarities to those described in the literature for domestic and wild mammals. As special features in kind, macroscopically identified a pair of thoracic glands, followed by three pairs of abdominal glands. Microscopically the abundant presence of connective tissue dividing the alveolar-tubular glands. Similar to that described for domestic and wild mammals.

Abstract 2240: Progesterone receptor isoform ratio regulates the stem cell population in the mouse mammary gland

Abstract The ovarian steroid hormones progesterone and estrogen play vital roles in the development of normal mammary gland and are likewise linked to mammary carcinogenesis via their receptors. Progesterone receptor (PR) is expressed as two isoforms, PR-A and PR-B, both in human and mouse. It has been reported that in human breast tumors the PR-A/PR-B expression ratio is altered. To further study the role of PR isoforms on mammary gland biology, transgenic mice carrying either an additional A form of PR (PR-A) or the B form of PR (PR-B) were generated. Both mice strains present abnormal development in their mammary glands. Overexpression of the A isoform of PR leads to increased side branching and multilayered ducts, while overexpressing the B isoform leads to limited ductal growth. The characteristics of mammary glands from these mice provide direct evidence that an aberration in the mechanisms regulating the differential expression of the two isoforms of PR can have major implications to mammary carcinogenesis and might affect the stem cell population of the gland. Recent studies have shown that a hierarchy of mammary stem/progenitor cells exists among the mammary epithelium in both human and mouse and PR signaling has been shown to play a major role in the maintenance of the stem cell population. So far, however, the differential role of the PR isoforms in the regulation of the stem cell population in the breast has not been established. We propose that the altered ratio of PR A/B might affect the stem cell population expansion and self renewal in the mammary gland. We found that mammary glands of mice overexpressing the B isoform presented a higher percentage of cells positive for stem cell markers (CD24+/CD29+) than those derived from PR-A and WT mice. Furthermore cells derived from PR-B mammary glands had increased mammosphere forming capacity compared to both PR-A and WT. Moreover, when mammosphere cultures were carried out in the presence of 4-OH-tamoxifen 10-8M, the number of mammospheres formed from mammary glands of WT and PR-A mice was reduced compared to control cultures treated with vehicle, whereas there were no differences for cultures derived from mammary glands of PR-B mice. Additionally, upon ovariectomy (OVX), mammary glands from PR-A and WT mice showed a higher percentage of cells positive for stem cell markers by flow cytometry, and increase mammosphere forming capacity than control sham mice, while in mammary glands derived from PR-B OVX mice neither parameters changed. Our results suggest that the B isoform of PR, may play a predominant role in the maintenance of stem cell population of the mammary gland and in the development of hormone resistance given that ovarian regulation affected mammary glands of WT and PR-A mice, but not those derived from PR-B mice. Citation Format: Maria S. Recouvreux, Rocio Sampayo, Marina Simian. Progesterone receptor isoform ratio regulates the stem cell population in the mouse mammary gland. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 2240. doi:10.1158/1538-7445.AM2015-2240

BREAST ULTRASOUND IMAGE SEGMENTATION BASED ON PARTICLE SWARM OPTIMIZATION AND THE CHARACTERISTICS OF BREAST TISSUE

Breast cancer occurs in over 8% of women during their lifetime, and is the leading cause of death among women. Sonography is superior to mammography because it has the ability to detect focal abnormalities in the dense breasts and has no side-effect. In this paper, we propose a novel automatic segmentation algorithm based on the characteristics of breast tissue and eliminating particle swarm optimization (EPSO) clustering analysis. The characteristics of mammary gland in breast ultrasound (BUS) images are analyzed and utilized, and a method based on step-down threshold technique is employed to locate the mammary gland area. The EPSO clustering algorithm utilizes the idea of "survival of the superior and weeding out the inferior". The experimental results demonstrate that the proposed approach can segment BUS image with high accuracy and low computational time. The EPSO clustering method reduces the computational time by 32.75% compared with the standard PSO clustering algorithm. The proposed approach would find wide applications in automatic lesion classification and computer aided diagnosis (CAD) systems of breast cancer.