The cell adhesion molecule E-cadherin mediates the compaction process of mouse preimplantation embryos and is important for the maintenance and function of epithelial cell layers. To determine precisely the role of E-cadherin in epithelial biogenesis we monitored the developmental potential of embryos homozygously negative for E-cadherin that were derived from E-cadherin heterozygous transgenic mice. The homozygous negative embryos died around the time of implantation, although they did undergo compaction like their littermate controls, largely due to the presence of residual maternal E-cadherin. At the blastocyst stage, E-cadherin-negative embryos failed to form a trophectodermal epithelium or a biastocyst cavity. These results demonstrate the pivotal role of E-cadherin in one of the most basic morphogenetic events in the development of multicellular organisms, the biogenesis of an epithelium.Mouse preimplantation embryos represent a unique model for studying the biogenesis of an epithelium from a nonpolarized cell, the fertilized egg (1, 2). During preimplantation development, loosely attached blastomeres maximize their cell-cell contacts and form a compact morula as a prerequisite for the generation of two distinct cell types, those of the trophectoderm epithelium and those of the inner cell mass (ICM). The first morphological changes in spherical blastomeres occur at the 8-cell stage and result in cytocortical asymmetry, including apical membrane microvilli and polar-

Myoglobin may serve a variety of functions in muscular oxygen supply, such as O 2 storage, facilitated O 2 diffusion, and myoglobin-mediated oxidative phosphorylation. We studied the functional consequences of a myoglobin deficiency on cardiac function by producing myoglobinknockout (myo ؊͞؊ ) mice. )]. These data demonstrate that disruption of myoglobin results in the activation of multiple compensatory mechanisms that steepen the pO 2 gradient and reduce the diffusion path length for O 2 between capillary and the mitochondria; this suggests that myoglobin normally is important for the delivery of oxygen.

Abstract-For the specific analysis of endothelial NO synthase (eNOS) function in the coronary vasculature, we generated a mouse homozygous for a defective eNOS gene (eNOSϪ/Ϫ). Western blot as well as immunohistochemical staining revealed the absence of eNOS protein in eNOSϪ/Ϫ mice. Aortic endothelial cells derived from eNOSϪ/Ϫ mice displayed only background levels of NO x formation compared with wild-type (WT) cells (88 versus 1990 pmol). eNOSϪ/Ϫ mice were hypertensive (mean arterial pressure, 135Ϯ15 versus 107Ϯ8 mm Hg in WT) without the development of cardiac hypertrophy. Coronary hemodynamics, analyzed in Langendorff-perfused hearts, showed no differences either in basal coronary flow or in maximal and repayment flow of reactive hyperemia. Acute NOS inhibition with N -nitro-L-arginine methyl ester (L-NAME) in WT hearts substantially reduced basal flow and reactive hyperemia. The coronary response to acetylcholine (ACh) (500 nmol/L) was biphasic: An initial vasoconstriction (flow, Ϫ35%) in WT hearts was followed by sustained vasodilation (ϩ190%). L-NAME significantly reduced vasodilation in WT hearts (ϩ125%) but did not alter the initial vasoconstriction. In eNOSϪ/Ϫ hearts, the initial vasoconstriction was augmented (Ϫ70%), whereas the ACh-induced vasodilation was not affected. Inhibition of cyclooxygenase with diclofenac converted the ACh-induced vasodilation into vasoconstriction (Ϫ49% decrease of basal flow). This effect was even more pronounced in eNOSϪ/Ϫ hearts (Ϫ71%). Our results demonstrate that (1) acute inhibition of eNOS reveals a role for NO in setting the basal coronary vascular tone as well as participation in reactive hyperemia and the response to ACh; (2) chronic inhibition of NO formation in eNOSϪ/Ϫ mutant mice induces no changes in basal coronary flow and reactive hyperemia, suggesting the activation of important compensatory mechanisms; and (3) Key Words: heart Ⅲ gene targeting Ⅲ reactive hyperemia Ⅲ coronary flow Ⅲ blood pressure E ndothelial NO synthase, also called type III NO synthase, is the major NOS isoenzyme that is widely expressed in endothelial cells throughout the vascular bed. It is generally accepted that endothelium-derived NO is an important factor in the control of basal vascular tone.1 NO is also involved in receptor-mediated vasodilation in response to various agonists such as ACh, ATP, thrombin, bradykinin, and others. Through experiments using NOS inhibitors 2,3 but also by use of genetically modified animals, 4,5 it has been demonstrated that functional inactivation of eNOS activity results in hypertension. In addition to the control of vascular tone, NO inhibits platelet aggregation and leukocyte adhesion to the vessel wall as well as proliferation and migration of smooth muscle cells. Thus, eNOS is considered to play an important role in maintaining the antiatherogenic surface of the vessel wall. 6In the heart, eNOS is expressed primarily in the coronary and endocardial endothelia. In addition, eNOS has been localized to cardiac myocytes and the specialized cells of s...

The Drosophila fat facets (faf) gene is a ubiquitin-specific protease necessary for the normal development of the eye and of the syncytial stage embryo in the fly. Using a gene trap approach in embryonic stem cells we have isolated a murine gene with extensive sequence similarity to the Drosophila faf gene and called it Fam (fat facets in mouse). The putative mouse protein shows colinearity and a high degree of sequence identity to the Drosophila protein over almost its entire length of 2554 amino acids. The two enzymatic sites characteristic of ubiquitin-specific proteases are very highly conserved between mice and Drosophila and this conservation extends to yeast. Fam is expressed in a complex pattern during postimplantation development. In situ hybridisation detected Fam transcripts in the rapidly expanding cell populations of gastrulating and neurulating embryos, in post-mitotic cells of the CNS as well as in the apoptotic regions between the digits, indicating that it is not associated with a single developmental or cellular event. The strong sequence similarity to faf and the developmentally regulated expression pattern suggest that Fam and the ubiquitin pathway may play a role in determining cell fate in mammals, as has been established for Drosophila.

Aim The aim of this official guideline published by the German Society of Gynecology and Obstetrics (DGGG) and coordinated with the German Society of Urology (DGU) and the German Society of Reproductive Medicine (DGRM) is to provide consensus-based recommendations, obtained by evaluating the relevant literature, on counseling and fertility preservation for prepubertal girls and boys as well as patients of reproductive age. Statements and recommendations for girls and women are presented below. Statements or recommendations for boys and men are not the focus of this guideline. Methods This S2k guideline was developed at the suggestion of the guideline commission of the DGGG, DGU and DGRM and represents the structured consensus of representative members from various professional associations (n = 40). Recommendations The guideline provides recommendations on counseling and fertility preservation for women and girls which take account of the patientʼs personal circumstances, the planned oncologic therapy and the individual risk profile as well as the preferred approach for selected tumor entities.