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L1 and laminin : their expression during rathypophysis ontogenesis and in adult neurohemal areas
Author(s) -
Berardi M.,
Hindelang C.,
Félix J.M.,
Stoeckel M.E.
Publication year - 1999
Publication title -
international journal of developmental neuroscience
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.761
H-Index - 88
eISSN - 1873-474X
pISSN - 0736-5748
DOI - 10.1016/s0736-5748(98)00067-7
Subject(s) - laminin , biology , neurite , synaptogenesis , basal lamina , microbiology and biotechnology , growth cone , anatomy , pathology , axon , ultrastructure , extracellular matrix , in vitro , biochemistry , medicine
L1 is a murine multidomain glycoprotein implicated in cell aggregation, fasciculation,neurite outgrowth and synaptogenesis. Laminin, a trimeric polypeptide, is implicated in neuronalsurvival, growth cone guidance, neurite outgrowth and cell differentiation. Laminin can alsointeract with the cell adhesion molecule L1. Their expressions were investigated from embryonicday 15 (E15) to adult in the rat hypophysis, and in adult neurohemal zones. Detected in the neural lobe from E17, the L1 immunoreactivity increased during prenataldevelopment and persisted in adulthood mainly related to the neuropeptidergic fibers. Pituicyteswere only labelled on the plasmalemma apposed to axons. In the intermediate lobe, L1 appearedat birth on folliculo‐stellate cells extensions, constituting a network which densified duringpostnatal development. L1 is also expressed in all neurohemal areas on neuronal profiles. Laminin was clearly detectable in the hypophysis at E15 before the first blood vesselspenetrate the Rathke pouch. At E20, all the basal membranes of the blood vessels were stained. Inthe intermediate lobe, a spotted laminin immunoreactivity was detected at E21. At this stage, weobserved the staining of intercellular spaces and the intracellular labelling of melanotrophs,concerning reticulum or vesicles. The staining of melanotrophs seemed to maintain duringadulthood. In contrast with blood vessels of the adult cerebral tissue, adult capillaries of the neurallobe and the others neuro‐hemal zones were intensely labelled with the anti‐laminin antibody. These results suggest that neurite outgrowth and neurite guidance could be promoted byL1 and laminin in the neurointermediate lobe. The intercellular tunnels could also be an importantguidance cue for migrating cells in the intermediate lobe. These data also demonstrate thatmelanotrophic cells, secreting the laminin, have a role in the ontogenesis of the gland. Finally, wesuggest that L1 and laminin can collaborate to reinforce neurons‐capillaries interactions inneurohemal zones.