AUTHOR=Morales-Delgado Nicanor , Merchan Paloma , Bardet Sylvia M., Ferran José L., Puelles Luis , Diaz Carmen 

TITLE=Topography of Somatostatin Gene Expression Relative to Molecular Progenitor Domains during Ontogeny of the Mouse Hypothalamus

JOURNAL=Frontiers in Neuroanatomy

VOLUME=5

YEAR=2011

URL=https://www.frontiersin.org/journals/neuroanatomy/articles/10.3389/fnana.2011.00010

DOI=10.3389/fnana.2011.00010

ISSN=1662-5129

ABSTRACT=<p>The hypothalamus comprises alar, basal, and floor plate developmental compartments. Recent molecular data support a rostrocaudal subdivision into rostral (terminal) and caudal (peduncular) halves. In this context, the distribution of neuronal populations expressing somatostatin (<italic>Sst</italic>) mRNA was analyzed in the developing mouse hypothalamus, comparing with the expression pattern of the genes <italic>Orthopedia</italic> (<italic>Otp</italic>), <italic>Distal-less 5</italic> (<italic>Dlx5</italic>), <italic>Sonic Hedgehog</italic> (<italic>Shh</italic>), and <italic>Nk2 homeobox 1</italic> (<italic>Nkx2.1</italic>). At embryonic day 10.5 (E10.5), <italic>Sst</italic> mRNA was first detectable in the anterobasal nucleus, a <italic>Nkx2.1</italic>-, <italic>Shh</italic>-, and <italic>Otp-</italic>positive basal domain. By E13.5, nascent <italic>Sst</italic> expression was also related to two additional <italic>Otp</italic>-positive domains within the alar plate and one in the basal plate. In the alar plate, <italic>Sst</italic>-positive cells were observed in rostral and caudal ventral subdomains of the <italic>Otp</italic>-positive paraventricular complex. An additional basal <italic>Sst-</italic>expressing cell group was found within a longitudinal <italic>Otp</italic>-positive periretromamillary band that separates the retromamillary area from tuberal areas. Apart of subsequent growth of these initial populations, at E13.5 and E15.5 some <italic>Sst</italic>-positive derivatives migrate tangentially into neighboring regions. A subset of cells produced at the anterobasal nucleus disperses ventralward into the shell of the ventromedial hypothalamic nucleus and the arcuate nucleus. Cells from the rostroventral paraventricular subdomain reach the suboptic nucleus, whereas a caudal contingent migrates radially into lateral paraventricular, perifornical, and entopeduncular nuclei. Our data provide a topologic map of molecularly defined progenitor areas originating a specific neuron type during early hypothalamic development. Identification of four main separate sources helps to understand causally its complex adult organization.</p>