Analysis of structure and gene expression in developing kidneys of male and female rats exposed to low protein diets in utero

A maternal low protein (LP) diet in rodents often results in low nephron endowment and renal pathophysiology in adult life, with outcomes often differing between male and female offspring. Precisely how a maternal LP diet results in low nephron endowment is unknown. We conducted morphological and molecular studies of branching morphogenesis and nephrogenesis to identify mechanisms and timepoints that might give rise to low nephron endowment. Sprague–Dawley rats were fed a normal protein (19.4% protein, NP) or LP (9% protein) diet for 3 weeks prior to mating and throughout gestation. Embryonic day 14.25 (E14.25) kidneys from males and females were either cultured for 2 days after which branching morphogenesis was quantified, or frozen for gene expression analysis. Real-time PCR was used to quantify expression of key nephrogenesis and branching morphogenesis genes at E14.25 and 17.25. At E17.25, nephron number was determined in fixed tissue. There was no effect of either maternal diet or sex on branching morphogenesis. Nephron number at E17.25 was 14% lower in male and female LP offspring than in NP controls. At E14.25 expression levels of genes involved in branching morphogenesis (Gfrα1, Bmp4, Gdnf) and nephrogenesis (Hnf4a, Pax2, Wnt4) were similar in the dietary groups, but significant differences between sexes were identified. At E17.25, expression of Gfrα1, Gdnf, Bmp4, Pax2 and Six2 was lower in LP offspring than NP offspring, in both male and female offspring. These findings provide new insights into how a LP diet leads to low nephron endowment and renal sexual dimorphism.     

Heart Fields: Spatial Polarity and Temporal Dynamics

In chick and mouse, heart fields undergo dynamic morphological spatiotemporal changes during heart tube formation. Here, the dynamic change in spatial polarity of such fields is discussed and a new perspective on the heart fields is proposed. The heart progenitor cells delaminate through the primitive streak and migrate in a semicircular trajectory craniolaterally forming the bilateral heart fields as part of the splanchnic mesoderm. They switch their polarity from anteroposterior to mediolateral. The anterior intestinal portal posterior descent inverts the newly formed heart field mediolateral polarity into lateromedial by 125° bending. The heart fields revert back to their original anteroposterior polarity and fuse at the midline forming a semi heart tube by completing their half circle movement. Several names and roles were assigned to different portions of the heart fields: posterior versus anterior, first versus second, and primary versus secondary heart field. The posterior and anterior heart fields define basically physical fields that form the inflow–outflow axis of the heart tube. The first and second heart fields are, in contrast, temporal fields of differentiating cardiomyocytes expressing myosin light chain 2a and undifferentiated and proliferating precardiac mesoderm expressing Isl1 gene, respectively. The two markers present a complementary pattern and are expressed transiently in all myocardial lineages. Thus, Isl1 is not restricted to a portion of the heart field or one of the two heart lineages as has been often assumed. Anat Rec, 297:175–182, 2014. © 2013 Wiley Periodicals, Inc.     

长期应用糖皮质激素对新生大鼠肺泡形态结构及IGFBP-2的影响

目的:探讨长期应用糖皮质激素 (ICSs) 对新生大鼠肺形态结构及其对肺内胰岛素样生长因子结合蛋白2 (IGFBP-2) 表达的影响?方法:新生SD大鼠48只随机分为3组:对照 (CONT) 组 (雾化吸入生理盐水);雾化吸入布地奈德 (BUD) 组;腹腔注射地塞米松 (DEX) 组?每个干预组内设7 d给药组与14 d给药组?大鼠5日龄时开始干预,各组在连续给药7?14 d 后,测量大鼠体重及肺组织重量,计算肺系数,通过肺组织形态学分析评估肺发育程度,应用蛋白免疫印迹技术 (WB) 检测IGFBP-2在肺组织中的表达?结果:① 大鼠体重及肺系数:BUD组与CONT组体重间差异无统计学意义 (P > 0.05),但DEX组体重较CONT组明显下降 (P < 0.01)?BUD组肺系数低于CONT组 (P < 0.01)?给药14 d后,DEX组肺系数与CONT组间无统计学差异 (P > 0.05);② 肺组织形态学:BUD组?DEX组肺泡囊数量较CONT组减少 (P < 0.01),间隔变薄 (P < 0.01),囊腔增大 (P < 0.05),BUD组?DEX组肺泡形态学指标间无统计学差异(P > 0.05);③肺组织IGFBP-2蛋白表达:IGFBP-2在BUD组?DEX组表达强于CONT组?结论:长期应用糖皮质激素可抑制新生大鼠肺泡化过程,该现象可能与糖皮质激素上调IGFBP-2在肺组织中的表达有关?     

A right-sided pathway involving FGF8/Snai1 controls asymmetric development of the proepicardium in the chick embryo

The proepicardium (PE) is a transient structure that forms at the venous pole of the embryonic vertebrate heart. This cardiac progenitor cell population gives rise to the epicardium, coronary vasculature, and fibroblasts. In the chicken embryo, the PE displays left-right (L-R) asymmetry and develops only on the right side, while on the left only a vestigial PE is formed, which subsequently gets lost by apoptosis. In this study, we analyzed how the L-R asymmetry pathway affects PE formation. Experimental manipulation of left-side determinants such as Shh, Nodal, and Cfc as well as forced expression of Pitx2 had no effect on the sidedness of PE development. In contrast, inhibition of early-acting regulators of L-R axis formation such as H⁺/K⁺-ATPase or primitive streak apoptosis affected the sidedness of PE development. Experimental interference with the right-side determinants Fgf8 or Snai1 prevented PE formation, whereas ectopic left-sided expression of Fgf8 or Snai1 resulted in bilateral PE development. These data provide novel insight into the molecular control of asymmetric morphogenesis suggesting that also the right side harbors an instructive signaling pathway that is involved in the control of PE development. This pathway might be of general relevance for setting up L-R asymmetries at the venous pole of the heart.     

Prenatal craniofacial morphogenesis: four-dimensional visualization of morphogenetic processes

Author – Radlanski RJ Objectives – Basic research concerning craniofacial development presently runs along two pathways, namely the molecular and the morphometric. This gap needs to be bridged. Design – Using histological serial sections of human fetuses computer‐aided three‐dimensional reconstructions were made (Software Analysis, SIS) with special focus given to all anatomical structures of the orofacial region of the growing head. Results – All reconstructions can be viewed from any rotation and they are available for virtual dissection according to anatomical rules. As an example, the prenatal development of the human mandible with the formation of the mental foramen therein is described. Furthermore, the spatial arrangement of bone, cartilage and nerves is presented in three dimensions in different developmental stages. The interaction of tissues with possible morphogenetic interaction is discussed. Conclusions – This work serves as a reference system for prenatal development in comparison with pathological development.     

Control of embryonic lung branching morphogenesis by the Rho activator,cytotoxic necrotizing factor 1

BACKGROUND: Lung development is sensitive to physiological stresses, and its development may be impaired by physical distortion, as in patients with congenital diaphragmatic hernia. Yet, little is known about how mechanical forces can influence lung morphogenesis. Studies with cultured cells suggest that cytoskeletal tension may play a key role in growth control. Since the small GTPase Rho plays an important role in the control of cell tension generation, we carried out studies to test the hypothesis that changes in Rho-mediated cell tension may influence branching morphogenesis. METHODS: Embryonic lung buds from timed pregnant Swiss Webster mice were microdissected on Embryonic Day 12 (E12), and whole organs were cultured in serum-free medium in the presence of the Rho activator cytotoxic necrotizing factor 1 (CNF-1) for 48 h. Serial measurements of the degree of epithelial branch formation and tissue maturation were performed using light microscopy and computerized image analysis. RESULTS: At 48 h, embryonic lungs treated with 2 ng/ml CNF-1 increased their terminal bud count by 236 +/- 18% (P = 0.01) compared with 132 +/- 2% for untreated controls. However, dose-response experiments revealed biphasic behavior: at a higher dose of CNF-1 (200 ng/ml), bud number was actually decreased relative to controls (43 +/- 1%, P < 0.001). Histological analysis revealed that individual glands appeared to be more highly developed at low-dose CNF-1, whereas the high dose produced gland contraction. CONCLUSIONS: These data support a potential role for Rho and cytoskeletal tension in control of epithelial pattern formation during lung development.     

Developmental timing of hair follicle and dorsal skin innervation in mice

The innervation of hair follicles offers an intriguing, yet hardly studied model for the dissection of the stepwise innervation during cutaneous morphogenesis. We have used immunofluorescence and a panel of neuronal markers to characterize the developmental choreography of C57BL/6 mouse backskin innervation. The development of murine skin innervation occurs in successive waves. The first cutaneous nerve fibers appeared before any morphological evidence of hair follicle development at embryonic day 15 (E15). Stage 1 and 2 developing hair follicles were already associated with nerve fibers at E16. These fibers approached a location where later in development the follicular (neural) network A (FNA) is located on fully developed pelage hair follicles. Prior to birth (E18), some nerve fibers had penetrated the epidermis, and an additional set of perifollicular nerve fibers arranged itself around the isthmus and bulge region of stage 5 hair follicles, to develop into the follicular (neural) network B (FNB). By the day of birth (P1), the neuropeptides substance P and calcitonin gene-related peptide became detectable in subcutaneous and dermal nerve fibers first. Newly formed hair follicles on E18 and P1 displayed the same innervation pattern seen in the first wave of hair follicle development. Just prior to epidermal penetration of hair shafts (P5), peptide histidine methionine-IR nerve fibers became detectable and epidermal innervation peaked; such innervation decreased after penetration (P7- P17). Last, tyrosine hydroxylase-IR and neuropeptide Y-IR became readily detectable. This sequence of developing innervation consistently correlates with hair follicle development, indicating a close interdependence of neuronal and epithelial morphogenesis.     

Defective sexual development in an infant with 46, XY, der(9)t(8;9)(q23.1;p23)mat

We report on a male infant with ambiguous genitalia (scrotal hypospadias, sinus urogenitalis) trisomic for 8q23-ter and monosomic for 9p23-ter, who shared craniofacial and other abnormalities with either phenotype. Gonadal histology was nearly normal for age. Normal endocrinological findings and exclusion of mutations in SRY, androgen receptor and alpha-reductase genes point to supplementary gene(s) located in 9p2305-ter, haplo-insufficiency (by deletion) of which is expected to cause defective male morphogenesis. Conclusion This observation lends further support to the hypothesis that genetic factors are located at 9p23-ter which are involved in normal sex determination. Received: 26 February 1998 / Accepted: 28 May 1998     

Myoepithelial Cells in the Control of Mammary Development and Tumorigenesis: Data From Genetically Modified Mice

Until recently, myoepithelial cells—the second major cell population in the mammary epithelium—were not considered to play an important role in the morphogenetic events during gland development. Mouse mutants with changes in the gene expression pattern characteristic of the basal myoepithelial cell layer have been generated and used to show that these cells influence the proliferation, survival and differentiation of luminal cells, modulate stromal–epithelial interactions and actively participate in mammary morphogenesis. Various cellular and molecular mechanisms may underlie the observed phenotypes. These include an unbalanced expression of matrix degrading metalloproteinases (MMPs) and their inhibitors, leading to changes in the composition and organization of the (extracellular matrix) ECM, the production of soluble growth factors affecting stromal and epithelial cell growth and differentiation and direct signaling through cell–cell contacts between the myoepithelial and luminal cell layers.