The International Stem Cell Initiative characterized 59 human embryonic stem cell lines from 17 laboratories worldwide. Despite diverse genotypes and different techniques used for derivation and maintenance, all lines exhibited similar expression patterns for several markers of human embryonic stem cells. They expressed the glycolipid antigens SSEA3 and SSEA4, the keratan sulfate antigens TRA-1-60, TRA-1-81, GCTM2 and GCT343, and the protein antigens CD9, Thy1 (also known as CD90), tissue-nonspecific alkaline phosphatase and class 1 HLA, as well as the strongly developmentally regulated genes NANOG, POU5F1 (formerly known as OCT4), TDGF1, DNMT3B, GABRB3 and GDF3. Nevertheless, the lines were not identical: differences in expression of several lineage markers were evident, and several imprinted genes showed generally similar allele-specific expression patterns, but some gene-dependent variation was observed. Also, some female lines expressed readily detectable levels of XIST whereas others did not. No significant contamination of the lines with mycoplasma, bacteria or cytopathic viruses was detected.

The hypothalamoneurohypophyseal system (HNS) consists of the large peptidergic magnocellular neurons of the supraoptic hypothalamic nucleus (SON) and the paraventricular hypothalamic nucleus (PVN), the axons of which course through the internal zone of the median eminence and terminate at blood capillaries of the posterior lobe of the pituitary gland. The HNS is a specialized brain neurosecretory apparatus responsible for the production of the antidiuretic peptide hormone vasopressin (VP). VP maintains water balance by promoting water conservation at the level of the kidney. Dehydration evokes a massive increase in the regulated release of VP from magnocellular neuron axon terminals in the posterior pituitary, which is accompanied by a plethora of changes in the morphology, electrophysiological properties, and biosynthetic and secretory activity of the HNS. We wish to understand this functional plasticity in terms of the differential expression of genes. We have therefore used microarrays to comprehensively catalog the genes expressed in the PVN, the SON and the neurointermediate lobe of the pituitary gland of control and dehydrated rats. Comparison of these gene lists has enabled us to identify transcripts that are regulated as a consequence of dehydration as well as RNAs that are enriched in the PVN or the SON. We suggest that these differentially expressed genes represent candidate regulators and effectors of HNS activity and remodeling.T he hypothalamoneurohypophyseal system (HNS) consists of the large peptidergic magnocellular neurons (MCNs) (cell body diameter, 20-40 m) of the supraoptic hypothalamic nuclei (SON) and paraventricular hypothalamic nuclei (PVN), the axons of which course through the internal zone of the median eminence and terminate at blood capillaries of the posterior (neural) lobe of the pituitary gland (1). The SON is a homogenous collection of MCNs, whereas the PVN is divided into a lateral and more medial subdivision of magnocellular and parvocellular neurons respectively. Parvocellular neurons have smaller cells bodies (10-15 m) whose axons project to the external zone of the median eminence (2) and to the brainstem and spinal cord (3). Additional structural and functional components of the HNS include the associated glia (mainly astrocytes with oligodendrocytes and microglia seen rarely), blood vessels, interneurons, and afferent terminals synapsing on MCN somata and dendrites, all of which are intimately associated with MCNs and with each other.The PVN and SON are important integrative structures that regulate coordinated responses to perturbations in cardiovascular homeostasis. Through descending projections from parvocellular neurons to the brainstem, notably the rostral ventrolateral medulla, and intermediolateral cell column of the spinal cord (3), the PVN regulates changes in sympathetic nerve activity involved in blood pressure and blood volume regulation (3). Endocrine responses are mediated through the axonal projections from SON and PVN MCNs to the posterior pituitary. The e...