Ultrasonographic, endoscopic and radiographic examinations of the dromedary mammary glands and teats.

The aim of the present study was to examine the mammary gland of dromedary camels using ultrasonography, endoscopy and radiography. These techniques are easy to perform in the field and feasible to diagnose pathological conditions of the mammary gland. Udders of 49 slaughtered and 26 adult dromedary camels submitted for necropsy were used for the examinations. Additionally, 11 lactating female dromedary camels were selected for the ultrasonographic udder examination. The transition from the milk ducts into the udder cistern, the teat cistern and the teat canals were examined in individual udders. Teat cistern length, teat end width, teat wall thickness, teat cistern width and middle cistern wall thickness were measured using ultrasonography. The measurements resulted in mean values of the teat cistern length of 37.3 mm, the teat end width of 2.0 mm, the teat wall thickness of 4.4 mm, the teat cistern width of 8.2 mm and the cistern wall thickness of 3.5 mm. The teat wall was differentiated into three layers, a hyperechoic outer layer, a hypoechoic middle layer and a hyperechoic inner layer. The mid cistern wall was hyperechoic. Endoscopic examination is an easy to perform and practicable method for examining the inner structures of the teats of dead animals; however, the feasibility has not been shown in lactating animals yet. Ring-like folds were present in the teat cistern, which protruded horizontally into the lumen. It was also possible to visualize the branchlike transition of the teat cistern into the larger milk ducts. Radiographic examination using barium sulfate contrast medium showed that the teat cistern ends in a network of initially wide but branching and narrowing milk ducts. The two teat canals and cisterns are completely independent of each other and there is no communication between the glandular tissue of the two canals and cisterns.

Gross anatomy of vascular supply and drainage of mammary fat pads in mice models.

This work extensively studied the vasculature of mice mammary fat pads (BALB/c and C57BL/6) with special reference to haematogenous drainage routes. Mammary fat pads were five pairs (first cervical, second and third thoracic, fourth abdominal and fifth inguinal), bilaterally symmetrical, extending laterally and continuously with the subcutaneous fascia. The superficial cervical artery and vein primarily accomplished the blood vasculature of the first mammary fat pad, while the lateral thoracic and external thoracic arteries and veins supplied the second and third mammary fat pads. The superficial cervical vein (found parallel to the superficial cervical artery) drained into the external jugular vein. The lateral thoracic artery and external thoracic artery branched almost at the same level as the axillary artery (branch of subclavian artery), the latter being more medial in position. However, in some specimens, the branching of both arteries appeared to be at the same level, and their origins were indistinguishable. The lateral thoracic vein that was parallel to the lateral thoracic artery drained to the axillary vein close to the drainage of the external thoracic vein. The lateral thoracic, superficial caudal epigastric, iliolumbar and external thoracic arteries and veins vascularized the fourth mammary fat pad and displayed anastomosis among themselves. The iliolumbar vein (found parallel to the iliolumbar artery) drained into the inferior vena cava. The superficial caudal epigastric vein (found parallel to the superficial caudal epigastric artery (SCaEA)) drained into the femoral vein. Unlike humans, the internal thoracic artery and vein did not participate in the vasculature of mammary fat pads. The SCaEA and vein supplied blood and drained the fifth mammary fat pad. The anatomical continuity of the fourth and fifth mammary fat pads provided common drainage for both mammary fat pads. The BALB/c and C57BL/6 mice strains studied did not differ in topography and size of mammary fat pads. The vascular supply and drainage of the mammary fat pads also did not differ in the strains studied. Only minor variations could be noted in the small veins draining into the lateral thoracic vein. Lateral tributaries seen in the terminal end of the lateral thoracic vein were absent in the C57BL/6 mice.

Assessing teat canal morphology in the dry period and during lactation by high-resolution ultrasound.

Our objectives were to quantify the dimensions of a fully 'closed' teat canal in dry cows and to describe recovery of the teat canal between milkings in lactating cows to assess whether and when full closure is attained, since this is an important determinant of udder health. Using an ultrasound scanner, teat canal length and diameter (proximal, midpoint and distal), teat cistern width, teat end width, whole teat width and teat wall thickness in 77 dry and 39 lactating dairy cows were measured. The dry cows represented a cross section of the dry population, with days since dry off ranging from 0 to 69 (median: 27). Data from lactating cows were recorded just before milking, and every 3 h post-milking. To control for location a cross-over (parlour vs. barn) study design was used. In dry cows, teat canal length and diameter did not vary by quarter or days since dry off, but multiparous cows had significantly wider teat canals than primiparous cows. The dry cow measurements can be used as baseline for dimensions for closed teats. In lactating cows, all teat dimensions except teat end width changed significantly during the 12-h milking cycle. Location (parlour vs. barn) did not affect the measurements, except teat end width and teat wall thickness. Teat canal length increased after milking and returned to pre-milking values by 9 h. Proximal and midpoint teat canal diameters decreased slightly just after milking and then progressively increased to above the pre-milking values by 9 h. Distal teat canal diameter increased after milking, partially contracting by 9 h. We found that during the dry period the teat canal is in a steady state, but its diameter is not zero, while during the lactation, the teat canal is in a near constant state of remodelling.

A genome-wide association study for the number of teats in European rabbits (Oryctolagus cuniculus) identifies several candidate genes affecting this trait.

In the European rabbit (Oryctolagus cuniculus), a polytocous livestock species, the number of teats indirectly impacts the doe reproduction efficiency and, in turn, the sustainable production of rabbit meat. In this study, we carried out a genome-wide association study (GWAS) for the total number of teats in 247 Italian White does included in the Italian White rabbit breed selection program, by applying a selective genotyping approach. Does had either 8 (n = 121) or 10 teats (n = 126). All rabbits were genotyped with the Affymetrix Axiom OrcunSNP Array. Genomic data from the two extreme groups of rabbits were also analysed with the single-marker fixation index statistic and combined with the GWAS results. The GWAS identified 50 significant SNPs and the fixation index analysis identified a total of 20 SNPs that trespassed the 99.98th percentile threshold, 19 of which confirmed the GWAS results. The most significant SNP (P = 4.31 × 10-11 ) was located on OCU1, close to the NUDT2 gene, a breast carcinoma cells proliferation promoter. Another significant SNP identified as candidate gene NR6A1, which is well known to play an important role in affecting the correlated number of vertebrae in pigs. Other significant markers were close to candidate genes involved in determining body length in mice. Markers associated with increased number of teats could be included in selection programmes to speed up the improvement for this trait in rabbit lines that need to increase maternal performances.

Short communication: Teat wall diameter and teat tissue thickness in dairy cows are affected by intramammary pressure and by the mechanical forces of machine milking.

The objective of this study was to validate and apply 2 different methods to record changes in teat tissue related to machine milking. Teat wall diameter was measured via B-mode ultrasound cross sectioning with a 7.5-MHz linear probe. Teat tissue thickness was measured using a cutimeter (spring-loaded caliper, spring constant 6.5 N/cm, 0.5 N at closed jaws). Both methods were applied at the teat barrel, 2 cm above the teat tip. In experiment 1, 24 teats from freshly slaughtered cows were used to perform ultrasound imaging (12 teats) or cutimeter measurements (12 teats) while the teat cisterns were filled with water to increase the intracisternal pressure from 0 to 30 kPa in steps of 1 kPa. Teat tissue thickness did not change at an intracisternal pressure from 0 to 10 kPa but increased with intracisternal pressure at levels >10 kPa. In contrast, teat wall diameter decreased with intracisternal pressure between 0 and 7 kPa but did not significantly change at a pressure ≥7 kPa up to 30 kPa. Significant Pearson correlation coefficients between intracisternal pressure and teat wall diameter were observed from 0 to 7 kPa (r = -0.38), and between intracisternal pressure and teat tissue thickness from 10 to 30 kPa (r = 0.45). In experiment 2, ultrasound and cutimeter measurements were performed in 12 lactating Holstein cows. Measurements before and during milking, immediately after cluster removal, with normal milking or with a 5-min overmilking, were performed and continued at 5-min intervals for 60 min and at 10-min intervals until 120 min. Additionally, with the 5-min overmilking treatment, measurements were continued at 60-min intervals up to 10 h after milking. Teat wall diameter decreased in response to milk ejection, followed by a continuous increase during the course of milking, with highest values after 5 min overmilking. Teat tissue thickness did not change during milking but was significantly increased after overmilking. Teat wall diameter and teat tissue thickness recovered to premilking levels within 35 min after normal milking and within 60 min after overmilking. Until 10 h after overmilking, the teat wall diameter decreased steadily, whereas teat tissue thickness was unfluctuating. In the physiologically relevant range of intramammary pressure, ultrasound measurements of the teat wall were affected by both intramammary pressure and mechanical forces, whereas cutimeter measurements were not affected by the intramammary pressure.

Calorie restriction and rapamycin administration induce stem cell self-renewal and consequent development and production in the mammary gland.

Expansion of the mammary epithelial stem cell pool holds promise for consequent mammary gland development and production. Complementary analyses of bovine mammary implants maintained in de-epithelialized mouse mammary fat pad and endogenous mouse mammary gland were performed to elucidate the effect of calorie restriction (CR) on stem cell self-renewal. CR elevated propagation rate and non-adherent mammosphere generation in cultured bovine mammary cells. A corresponding decrease in progenitor-induced colony formation and differentiation marker expression was noted. In the mouse gland, CR enhanced the take rate of transplanted cells and outgrowths' fat pad occupancy. Downregulating mTOR activity by rapamycin administration reproduced CR's effects on stem cell self-renewal within a shorter period. Flow cytometry demonstrated a significant 1.5-fold increase in stem cell number and a corresponding decrease in luminal progenitor and differentiated cells. Consequent effects of rapamycin administration included enhanced ductlet generation in bovine implants and higher milk-protein gene expression in cultured mouse mammary cells. The stimulatory effect of CR on BST-1 expression in both bovine implants and mouse glands resembled that noted in the intestinal Paneth stem cell niche (Yilmaz et al., 2012). A putative niche may also exist in the mammary gland, conveying energy-status information to the insulated stem cells.

Molecular mechanism of mammary gland involution: An update.

The mammary gland (MG) is a unique organ responsible for milk synthesis, secretion, and involution to prepare the gland for subsequent lactation. The mammary epithelial cells (MECs), which are the milk synthesizing units of the MG, proliferate, differentiate, undergo apoptosis and regenerate following a cyclic pathway of lactation - involution - lactation, fine-tuning these molecular events through hormones, growth factors and other regulatory molecules. The developmental stages of the MG are embryonic, prepubertal, pubertal, pregnancy, lactation and involution, with major developmental processes occurring after puberty. The involution stage includes interesting physiological processes such as MEC apoptosis, matrix remodeling, and the generation of cells regaining the shape of a virgin MG. Signal transducer and activator of transcription 3 (STAT3) is the established master regulator of this process and aberrant expression of STAT3 leads to subnormal involution and may induce neoplasia. Several studies have reported on the molecular mechanism of MG involution with substantial knowledge being gained about this process; however, a deep understanding of this phenomenon has yet to be attained. This review focuses deeply on the molecular details of post-lactational regression, the signaling pathways involved in the lactation-involution cycle, and the latest developments in STAT3-associated MG neoplasia. Deep insight into the involution process will pave the way towards understanding the biology, apoptosis, and oncogenesis of the MG.

Estrogen Receptor-α and Progesterone Receptor Expression in Mammary Proliferative Lesions of Female Pet Rabbits.

In breast cancer of women, the estrogen receptor-α (ERα) and progesterone receptor (PR) status has prognostic and therapeutic significance. The aim of this study was (1) to characterize by immunohistochemistry the expression of ERα and PR in nonneoplastic and neoplastic mammary gland tissue of pet rabbits and (2) to correlate the ERα/PR status and histological features. All 124 rabbits included in this study had a mammary tumor; in addition, 2 rabbits had lobular hyperplasia and 25 had multiple cysts. Of the 124 neoplasms, 119 (96%) were carcinoma, 2 (2%) were carcinoma in situ, and 3 (2%) were adenoma. ERα or PR or both were detected in 2 of 2 carcinomas in situ, 3 of 3 adenomas, 19 of 25 cysts, and 2 of 2 lesions of lobular hyperplasia. Most carcinomas (75/119, 63%) were negative for both ERα and PR; 22 of 119 carcinomas (18%) were double-immunopositive. The ERα and PR expression was not influenced by histotype or histological tumor grade. In carcinomas, there was a statistically significant correlation between increased mitotic count and reduced expression of ERα and PR, and the mitotic count was higher in double-immunonegative carcinomas (75/119). The findings suggest that in rabbit mammary carcinomas, proliferative activity is mainly influenced by factors other than estrogen and progesterone and provides the basis for future investigations into the prognostic significance of the ERα and PR status of mammary tumors.

Sinus-like dilatations of the mammary milk ducts, Ki67 expression, and CD3-positive T lymphocyte infiltration, in the mammary gland of wild European rabbits during pregnancy and lactation.

Sinus-like dilatations of the mammary duct are recognisable in the mammary gland of pregnant and lactating wild European rabbits. These dilatations exhibit a bilaminar epithelial lining, with luminal epithelial cells expressing basal and lateral E-cadherin. Occasional binucleated mammary epithelial cells are present in the luminal layer. Underlying the luminal epithelial cells is a basal layer of cytokeratin 14-positive cells, supported by a thin layer of fibrous tissue. Multi-segmental epithelial proliferation, as indicated by Ki67 expression, is apparent in the luminal epithelial cells, suggesting a capacity for division during pregnancy and lactation. CD3-positive T lymphocytes are present both intraepithelially, suggesting exocytosis, and in foci subjacent to the ductular epithelium. We consider that sinus-like dilatations of the mammary duct may have the potential to give rise to a subset of the mammary gland neoplasms classified as ductal in origin. Milk accumulation in these sinus-like dilatations is likely to provide a niche for bacterial replication in cases of mastitis in rabbits. These structures are an important component of the innate immune system of the mammary gland, both as a physical barrier and as an interface between the milk and mammary immune cells.

Technical note: Development and evaluation of a standard operating procedure for ultrasound-based measurements of teat canal dimensions in dairy cows.

The objectives were to (1) develop a standard operating procedure (SOP) for ultrasound-based measurements of teat canal dimensions and (2) determine the precision of ultrasound-based measurements of teat canal dimensions in dairy cows. Teat scans (n = 64) of the right hind and left front teats from 16 cows were obtained with a portable ultrasound device before and after machine milking. Teat dimensions measured were teat canal length (TCL), teat canal diameter at the proximal end of the teat canal (TCDPROX), teat canal diameter at the midpoint between the proximal and distal ends of the teat canal (TCDMID), teat canal diameter at the distal end of the teat canal (TCDDIS), teat end diameter at the midpoint between the proximal and distal ends of the teat canal (TMD), and teat canal cross-sectional area (TCLAREA). An SOP was developed, reviewed, and modified by 3 operators. Measurements were performed by the same 3 operators using an open source software program. To assess the effect of implemented modifications and the precision of ultrasound-based measurements, concordance correlation coefficients (CCC) were calculated to determine interoperator reproducibility and intraoperator repeatability. Through modifications in the SOP, interoperator CCC increased from 0.45 to 0.86 for TCL, from 0.14 to 0.66 for TCDPROX, from 0.24 to 0.66 for TCDMID, from 0.06 to 0.56 for TCDDIS, from 0.64 to 0.91 for TMD, and from 0.17 to 0.64 for TCLAREA. Intraoperator CCC over all operators were 0.91 for TCL, 0.73 for TCDPROX, 0.80 for TCDMID, 0.69 for TCDDIS, 0.94 for TMD, and 0.75 for TCLAREA. Our results indicate that measurements of teat canal dimensions can be conducted with satisfactory precision when following an SOP. Development and strict implementation of an SOP has the potential to decrease inadvertent variability of ultrasound-based measurements among operators for ultrasonographic assessment of teat dimensions.

Ultrasonography and theloscopy for the diagnosis of obstructive fibrosis in the Fürstenberg venous ring in the four quarters of the udder of a cow: a case report / Ultrassonografia e teloscopia no diagnóstico de fibrose obstrutiva do anel venoso de Fürstenberg em quatro quartos mamários em bovino: relato de caso

We report an unusual case of obstructive fibrosis of the venous ring of Fürstenberg in all four quarters of the udder of a cow of the Girolando breed (3/8 Gir and 5/8 Dutch). The information was obtained through a review of medical records, anamnesis, and imaging methods such as theloscopy and ultrasonography. Histopathological analysis provided a definitive diagnosis.(AU)

Relata-se a ocorrência de um caso incomum de fibrose obstrutiva do anel venoso de Fürstenberg em quatro quartos mamários de uma vaca da raça Girolando (3/8 Gir e 5/8 Holandês). As informações foram obtidas por meio de revisão do prontuário, da anamnese e de métodos de diagnóstico por imagem, como a teloscopia e a ultrassonografia. A análise histopatológica forneceu o diagnóstico definitivo.(AU)

Understanding the Inguinal Sinus in Sheep (Ovis aries)-Morphology, Secretion, and Expression of Progesterone, Estrogens, and Prolactin Receptors.

Post-parturient behavior of mammalian females is essential for early parent-offspring contact. After delivery, lambs need to ingest colostrum for obtaining the related immunological protection, and early interactions between the mother and the lamb are crucial. Despite visual and auditory cues, olfactory cues are decisive in lamb orientation to the mammary gland. In sheep, the inguinal sinus is located bilaterally near the mammary gland as a skin pouch (IGS) that presents a gland that secretes a strong-smelling wax. Sheep IGS gland functions have many aspects under evaluation. The objective of the present study was to evaluate sheep IGS gland functional aspects and mRNA transcription and the protein expression of several hormone receptors, such as progesterone receptor (PGR), estrogen receptor 1 (ESR1), and 2 (ESR2) and prolactin receptor (PRLR) present. In addition, another aim was to achieve information about IGS ultrastructure and chemical compounds produced in this gland. All hormone receptors evaluated show expression in IGS during the estrous cycle (follicular/luteal phases), pregnancy, and the post-partum period. IGS secretion is rich in triterpenoids that totally differ from the surrounding skin. They might be essential substances for the development of an olfactory preference of newborns to their mothers.

Mammary gland morphology in the northern Amazon red squirrel (Sciurus igniventris) / Morfologia da glândula mamária em esquilo do Norte Amazônico (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.

Sciurus igniventris é um esquilo com distribuição na América do Sul. Nós examinamos uma fêmea adulta que foi doada após morte por atropelamento. O objetivo do trabalho foi descrever as características morfológicas da glândula mamária de um exemplar da espécie. O animal foi fixado utilizando solução aquosa de formoldeído a 10%. Os tecidos foram processados e lâminas foram preparadas seguindo protocolos histológicos padrões. A análise morfológica da glândula mamária revelou similaridades com o que temos descrito na literatura para animais domésticos e selvagens. Como particularidades na espécie, macroscopicamente foi identificado um par de glândulas torácicas, seguidas por três pares de glândulas abdominais. Microscopicamente ocorreu a presença abundante de tecido conectivo dividindo as glândulas túbuloalveolares. Semelhante ao descrito para mamíferos domésticos e selvagens.

The mouse mammary gland as a sentinel organ: distinguishing 'control' populations with diverse environmental histories.

BACKGROUND: There are numerous examples of laboratory animals that were inadvertently exposed to endocrine disrupting chemicals (EDCs) during the process of conducting experiments. Controlling contaminations in the laboratory is challenging, especially when their source is unknown. Unfortunately, EDC contaminations can interfere with the interpretation of data during toxicological evaluations. We propose that the male CD-1 mouse mammary gland is a sensitive bioassay to evaluate the inadvertent contamination of animal colonies. METHODS: We evaluated mammary glands collected from two CD-1 mouse populations with distinct environmental histories. Population 1 was born and raised in a commercial laboratory with unknown EDC exposures; Population 2 was the second generation raised in an animal facility with limited exposures to xenoestrogens from caging, feed, etc. Mammary glands were collected from all animals and evaluated using morphometric techniques to quantify morphological characteristics of the mammary gland. RESULTS: Population 1 (with suspected history of environmental chemical exposure) and Population 2 (with known limited history of xenoestrogen exposure) were morphologically distinguishable in adult males, prepubertal females, and pubertal females. Mammary glands from males raised in the commercial animal facility were significantly more developed, with larger ductal trees and more branching points. The appearance of these mammary glands was consistent with prior reports of male mice exposed to low doses of bisphenol A (BPA) during early development. In females, the two populations were morphologically distinct at both prepuberty and puberty, with the most striking differences observed in the number, size, and density of terminal end buds, e.g. highly proliferative structures found in the developing mammary gland. CONCLUSIONS: Collectively, these results suggest that the mouse mammary gland has the potential to be used as a sentinel organ to evaluate and distinguish animal colonies raised in different environmental conditions including potential EDC exposures. Our findings could help researchers that wish to perform a posteriori evaluations to determine whether inadvertent contamination with xenoestrogens (and potentially other EDCs) has occurred in their animal colonies, especially after new materials (feed, caging, water bottles) have been introduced. Finally, our results challenge the relatively common practice of using historical controls in toxicological experiments.

3D hydrogel-based microwell arrays as a tumor microenvironment model to study breast cancer growth.

The tumor microenvironment (TME) is distinctly heterogeneous and is involved in tumor growth, metastasis, and drug resistance. Mimicking this diverse microenvironment is essential for understanding tumor growth and metastasis. Despite the substantial scientific progress made with traditional cell culture methods, microfabricated three-dimensional (3D) cell cultures that can be precisely controlled to mimic the changes occur in the TME over tumor progression are necessary for simulating organ-specific TME in vitro. In this research, to simulate the breast cancer TME, microwell arrays of defined geometry and dimensions were fabricated using photo-reactive hydrogels for a cancer cell line and primary explant tissue culture. Microwell arrays fabricated from 4-arm polyethylene glycol acrylate and methacrylated gelatin with different degrees of methacrylation for controlled cell-matrix interactions and tunable stiffness were used to create a platform for studying the effects of distinct hydrogel compositions and stiffness on tumor formation. Using these microwell arrays, size-controlled spheroids of human breast cancer cell line HCC1806 were formed and the cell attachment properties, viability, metabolic activity, and migration levels of these spheroids were examined. In addition, primary mammary organoid tissues explanted from mice were successfully cultured in these hydrogel-based microwell arrays and the organoid morphology and viability, as well as organoid branching were studied. The microwell array platform developed and characterized in this study could be useful for generating a tissue-specific TME for in vitro high throughput studies of breast cancer development and progression as well as in drug screening studies for breast cancer treatment.

Loss of caveolin-1 alters extracellular matrix protein expression and ductal architecture in murine mammary glands.

The extracellular matrix (ECM) is abnormal in breast tumors and has been reported to contribute to breast tumor progression. One factor, which may drive ongoing matrix synthesis in breast tumors, is the loss of stromal caveolin-1 (cav-1), a scaffolding protein of caveolae, which has been linked to breast tumor aggressiveness. To determine whether loss of cav-1 results in the abnormal expression of matrix proteins, mammary glands from cav- 1-/- and cav- 1 +/+ mice were investigated for differences in expression of several ECM proteins. In addition, the presence of myofibroblasts, changes in the vessel density, and differences in duct number and size were assessed in the mammary glands of both animal models. Using immunohistochemistry, expression of fibronectin, tenascin-C, collagens and αSMA were significantly increased in the mammary glands of cav-1-/- mice. Second harmonic generation revealed more organized collagen fibers in cav-1 -/- glands and supported immunohistochemical analyses of increased collagen abundance in the glands of cav-1 -/- mice. Analysis of the ductal structure demonstrated a significant increase in the number of proliferating ducts in addition to significant increases in the duct circumference and area in cav-1 -/- glands compared to cav- 1 +/+ glands. Differences in microvessel density weren't apparent between the animal models. In summary, we found that the loss of cav-1 resulted in increased ECM and α-SMA protein expression in murine mammary glands. Furthermore, we found that an abnormal ductal architecture accompanied the loss of cav-1. These data support a role for cav-1 in maintaining mammary gland structure.

Technical note: Mammary gland ultrasonography to evaluate mammary parenchymal composition in prepubertal heifers.

Bovine mammary gland development studies are often terminal or involve invasive biopsy procedures. Therefore, noninvasive means of assessing mammary development should be considered as alternative methods in live animals. The objective was to test if mammary ultrasonography can be used as a noninvasive way to estimate mammary parenchyma (PAR) composition in prepubertal dairy heifers with different average daily body weight gains. In the 84 d preceding, the ultrasound exam heifers were maintained in 1 of 3 treatment groups. Individual heifers were fed a high gain (1 kg/d; n = 6), low gain (0.5 kg/d, n = 6), or maintenance (n = 6) treatment diet. To achieve desired body weight gains, heifers were fed differing amounts of the same silage-based diet. Mammary glands of 18 crossbred heifers Holstein:Gyr underwent a single mammary ultrasound exam immediately before heifer slaughter, which took place when heifers weighed 142.0 ± 8.0 kg and were 200 d old. The 4 mammary glands of each heifer were evaluated using a real-time B-mode ultrasound machine equipped with a 6.5-MHz micro-convex transducer. Digital images (8-bit) of glands were obtained and PAR was identified within gland. Average pixel values per unit of PAR area were determined for each gland and analyzed at the level of heifer. Pixel results were interpreted on the basis that lower average pixel values reflect PAR with relatively high amounts of protein as opposed to fat. To help validate that the pixel value within PAR is associated with composition of PAR, pixel findings were compared with histological [number of adipocytes in PAR (Nad) and epithelial area in PAR (Ep)] and biochemical [percent crude protein in PAR (%CP), percent ether extract in PAR (%EE), PAR weight (WPAR), and mammary fat pad weight (WFAT)] composition of PAR in these same heifers. Within PAR, %EE and WFAT were positively correlated with pixel values, whereas %CP, Ep, and Nad were negatively correlated. Parenchyma weight did not correlate with pixel values. Regression analyses (fixed effect log-pixel value; random effect treatment) were used to estimate Nad, Ep, %CP, %EE, WPAR, and WFAT. Sensitivity analysis of regression equations revealed that accuracy of tested equations ranged from 0.77 to 0.93 and precision ranged from 0.56 to 0.82. Concordance correlation coefficients of the equations ranged from 0.41 to 0.76. In conclusion, ultrasonography of PAR can accurately measure and predict PAR composition in prepubertal dairy heifers growing at various rates of gain.

Changes in mammary histology and transcriptome profiles by low-dose exposure to environmental phenols at critical windows of development.

Exposure to environmental chemicals has been linked to altered mammary development and cancer risk at high doses using animal models. Effects at low doses comparable to human exposure remain poorly understood, especially during critical developmental windows. We investigated the effects of two environmental phenols commonly used in personal care products - methyl paraben (MPB) and triclosan (TCS) - on the histology and transcriptome of normal mammary glands at low doses mimicking human exposure during critical windows of development. Sprague-Dawley rats were exposed during perinatal, prepubertal and pubertal windows, as well as from birth to lactation. Low-dose exposure to MPB and TCS induced measurable changes in both mammary histology (by Masson's Trichrome Stain) and transcriptome (by microarrays) in a window-specific fashion. Puberty represented a window of heightened sensitivity to MPB, with increased glandular tissue and changes of expression in 295 genes with significant enrichment in functions such as DNA replication and cell cycle regulation. Long-term exposure to TCS from birth to lactation was associated with increased adipose and reduced glandular and secretory tissue, with expression alterations in 993 genes enriched in pathways such as cholesterol synthesis and adipogenesis. Finally, enrichment analyses revealed that genes modified by MPB and TCS were over-represented in human breast cancer gene signatures, suggesting possible links with breast carcinogenesis. These findings highlight the issues of critical windows of susceptibility that may confer heightened sensitivity to environmental insults and implicate the potential health effects of these ubiquitous environmental chemicals in breast cancer.

Heritability of udder morphology and colostrum quality traits in swine.

The heritability of udder quality traits, defined as morphology and colostrum IgG concentration at farrowing, was estimated together with the genetic and phenotypic correlations of these traits with other production and reproduction criteria. Udder morphology traits were recorded in 988 Meidam sows and colostrum samples were collected from 528 sows. Teat length, teat diameter (DIA), interteat distance within the same row (SAMER), and teat distance from the abdominal midline (AML) were recorded to the nearest millimeter. For each sow, a record was also made of udder development score (DEV), the proportion of teats oriented perpendicular to the udder, and the proportion of nonfunctional teats. Colostrum IgG concentration was estimated with a Brix refractometer. Heritability of udder morphology traits varied from high ( = 0.46 for teat length and = 0.56 for DIA) to moderate ( = 0.37 for SAMER, = 0.22 for AML, = 0.25 for DEV, = 0.3 for the proportion of nonfunctional teats, = 0.1 for the proportion of teats oriented perpendicular to the udder, and = 0.35 for colostrum IgG concentration). The SAMER was negatively genetically correlated with the number of stillborns (genetic correlation [] = -0.48) and positively genetically correlated with the number of piglets born alive ( = 0.69), with the opposite for the trait AML ( = -0.40 for number of piglets born alive and = 0.40 for stillborns). The highest genetic correlation with productive traits was estimated between AML and ADG during rearing ( = 0.42), although this had a negative phenotypic correlation (; -0.11). Teat length was also moderately correlated with ADG ( = 0.27). Backfat thickness at 100 kg was positively correlated with DIA and the total number of teats present in both rows ( = 0.28 and = 0.36, respectively) and negatively correlated only with DEV ( = -0.22). The same results were found for the phenotypic correlation between backfat thickness at end of test and the total number of teats present in both rows ( = 0.03). Udder quality traits can be included in the breeding goal and appropriately weighted with other important traits in the breeding objectives to enhance maternal performance.