Retinoic acid induced heparin-binding protein expression and localization during gastrulation,neurulation, and organogenesis

Retinoic acid induced heparin-binding protein (RIHB) is a highly basic, soluble polypeptide of the chick embryonic extracellular matrix. We have examined the expression and localization of RIHB during very early embryogenesis by in situ hybridization and immunohistochemistry. RIHB mRNA is very weakly detectable above background in the blastodiscs of unincubated eggs. The expression increases greatly over the first 24 hours of incubation, and is observed throughout the blastodisc in all three of the germ layers following gastrulation. As neurulation occurs, the expression becomes more restricted to certain areas, notably the ectoderm, the neural folds, and especially the notochord. After the neural tube has formed the expression in the tube itself decreases dramatically, whereas the expression in the head ectoderm and the notochord persists. After 72 hours of incubation expression remains relatively high throughout most of the embryo, with higher levels of expression in regions undergoing organogenesis and lower levels in organs which have already differentiated. RIHB protein is also weakly detectable in unincubated eggs as patches of immunoreactive material between the blastodisc and the vitelline. After 6 hours of incubation small regions of basement membrane are immunoreactive. RIHB is detected in this matrix, apparently before even fibronectin. The amount of RIHB protein increases dramatically over the first 24 hours of incubation. It is found in basement membrane separating the epiblast from the hypoblast, then later in that separating the ectoderm from the mesoderm. It is also detected surrounding individual cells, especially of the ectodermal layer. During neurulation RIHB is observed in the basement membrane surrounding the neural fold and the notochord, and in the lamina separating the ectodermal, mesodermal, and endodermal layers. Later in development, RIHB is detected in the basement membrane under the epidermis, throughout the developing limbs, and in the lamina of various developing organs, such as the eye, the pulmonary bud, the intestine, and the mesonephros. These results demonstrate that RIHB is highly expressed during the early embryonic period, by all three germ layers, and is an important and very early component of the embryonic extracellular matrix. Its very broad expression and localization argue for a more general role in development than its demonstrated weak neurotrophic activity. © 1994 Wiley-Liss, Inc.     

Ascidian embryonic development: An emerging model system for the study of cell fate specification in chordates

The ascidian tadpole larva represents the basic body plan of all chordates in a relatively small number of cells and tissue types. Although it had been considered that ascidians develop largely in a determinative way, whereas vertebrates develop in an inductive way, recent studies at the molecular and cellular levels have uncovered several similarities in the way developmental fates are specified. In this review, we describe ascidian embryogenesis and its cell lineages, introduce several characteristics of ascidian embryos, describe recent advances in understanding of the mechanisms of cell fate specification, and discuss them in the context of what is known in vertebrates and other organisms. Developmental Dynamics 236:1748–1757, 2007. © 2007 Wiley‐Liss, Inc.     

System for inducible expression of cre-recombinase from the Foxa2 locus in endoderm, notochord, and floor plate.

We targeted the reverse tetracycline controlled transactivator (rtTA) to the Foxa2 locus (Foxa2(ITA)) to generate a system for regulating Cre-recombinase activity within Foxa2 expression domains, including the endoderm, notochord, and floor plate of early mouse embryos. The use of an internal ribosomal entry site to obtain rtTA expression preserves Foxa2 function of the targeted allele. Cre activity with this system reflects the level of endogenous Foxa2 activity and is also tightly controlled by doxycycline. The location of Cre activity within the broader Foxa2 expression domain can be restricted by altering the timing of doxycycline administration. Isolated floor plate expression can be obtained in this manner. This system will provide a useful tool for manipulating gene expression in endoderm, notochord, and floor plate, all of which are tissues with important structural and patterning functions during embryogenesis.     

Sensitivity of early mouse embryos to the antifolic drug pyrimethamine

The effect of the antifolic drug pyrimethamine (2,4-diamino-5-p-chlorophenyl-6-ethylpyrimidine) on cleavage of CBA mouse embryos was studied. Pyrimethamine does not affect the development of early mouse embryos in utero but considerably inhibits cleavage of embryos explanted into medium containing the drug. The sensitivity of mouse and rat embryos to pyrimethamine is compared and it is concluded that there are no interspecific differences in their response to the teratogen at the level of the embryonic cells themselves.Department of Embryology, Institute of Experimental Medicine, Academy of Medical Sciences of the USSR, Leningrad. (Presented by Academician of the Academy of Medical Sciences of the USSR A. N. Klimov.) Translated from Byulleten' Éksperimental'noi Biologii i Meditsiny, Vol. 82, No. 10, pp. 1247–1250, October, 1976.     

刺五加组织培养与细胞工程进展

综述了国内外对刺五加组织培养与细胞工程研究的现状。分别从体细胞胚胎发生的影响因素外植体的发育程度和类型、培养基、植物生长调节剂的种类和浓度以及作用特点、体细胞胚胎的形态发生过程与解剖学和人工种子的包埋与萌发;茎尖外植体的离体培养与快速繁殖;根癌农杆菌和发根农杆菌对愈伤组织和新生体胚的遗化转化;毛状根培养生产刺五加次生代谢产物的研究现状进行了评述,并进一步分析了其中存在的问题,提出了一些建议。     

Implantation failures in women with infertility associated endometriosis

Abstract

Endometriosis is currently considered as one of the most common diseases associated with infertility. A controversial issue is whether endometriosis per se exerts a detrimental effect on IVF outcomes. Failure of implantation due to endometriosis-associated infertility is a contradictory and widely discussed burden nowadays. The purpose of the study is to assess the quality of embryos and implantation rate in women with infertility associated with endometriosis. The study included infertile reproductive aged women, between 26 and 40 years who underwent IVF and ICSI procedures. The patients were divided into two groups: group I (n?=?70) involved 70 patients with recurrent unilateral endometriomas, II control group (n?=?50) with tubal factor infertility. The quality of the retrieved embryos was assessed according to the generally accepted classification of Gardner, indicating the rate of implantation in each group. Embryo transfer was performed in case of high quality embryos. Assessing the ovarian reserve indicators, in the group I patients with recurrent unilateral endometriomas the serum level of AMH was significantly lower (2.1?±?1.75 vs. 3.2?±?1.4, p?<?.005), as well as the number of retrieved oocytes (8.1?±?3.9 and 10.1?±?6.8, p?<?.005). The analysis of the results demonstrated that the duration of stimulation in the group patients with recurrent unilateral endometriomas was significantly higher in comparison with the group II (12.2?±?1.8 and 10.2?±?1.6 days, p?<?.001). Nevertheless, the number of good quality embryos retrieved was comparable in both groups (2.2?±?1.5 and 2.8?±?1.8). In the group I patients with recurrent unilateral endometriomas, there was a statistically significant decrease of implantation rate (17.1% vs. 24% p?<?.005). The results of the study revealed no statistical difference in embryo quality in the study cohort. However, it is important to note that a statistically significant difference in implantation rate in the group of endometriosis-associated infertility compared was obtained 1.5 times lower than in the control group (15.8% vs. 24.0% p?<?.005). The achieved results demonstrated an adverse IVF outcome in infertile women with recurrent endometrioma compared to the control group.     

During Embryogenesis,Esrp1 Expression Is Restricted to a Subset of Epithelial Cells and Is Associated With Splicing of a Number of Developmentally Important Genes

Background : Development of a mature organism from a single cell requires a series of important morphological changes, which is in part regulated by alternative splicing. In this article, we report the expression of Esrp1 during early mouse embryogenesis, a splicing factor implicated in epithelial to mesenchymal transitions. Results : By qRT‐PCR, we find higher expression of Esrp1 and Esrp2 in placenta compared to the embryos. We also find a correlation between the expression of Esrp1 and alternative splicing of several known target exons. Using in situ RNA hybridization we show that while Esrp1 expression is ubiquitous in embryonic day (E)6.5 mouse embryos, expression becomes restricted to the chorion and definitive endoderm starting at E7.5. Esrp1 expression was consistently restricted to a subset of epithelial cell types in developing embryos from E9.5 to E13.5. Conclusions : Our results suggest that Esrp1 could play an important role in the morphological changes underlying embryogenesis of the placenta and embryo. Developmental Dynamics 242:281–290, 2013. © 2012 Wiley Periodicals, Inc.     

Reverse engineering the mechanical and molecular pathways in stem cell morphogenesis

The formation of relevant biological structures poses a challenge for regenerative medicine. During embryogenesis, embryonic cells differentiate into somatic tissues and undergo morphogenesis to produce three‐dimensional organs. Using stem cells, we can recapitulate this process and create biological constructs for therapeutic transplantation. However, imperfect imitation of nature sometimes results in in vitro artifacts that fail to recapitulate the function of native organs. It has been hypothesized that developing cells may self‐organize into tissue‐specific structures given a correct in vitro environment. This proposition is supported by the generation of neo‐organoids from stem cells. We suggest that morphogenesis may be reverse engineered to uncover its interacting mechanical pathway and molecular circuitry. By harnessing the latent architecture of stem cells, novel tissue‐engineering strategies may be conceptualized for generating self‐organizing transplants. Copyright © 2013 John Wiley & Sons, Ltd.