The developmental changes of the "paraclaustral reservoir" of migrating cells in the rat brain: A study using morphometric and in situ DNA end labeling techniques

A distinct group of small cells lying in the ventral part of the external c apsule in the rat brain is clearly visible at birth. On the basis of its lo cation (medially to the prepiriform claustrum) and probably its function (a s a source of neurons for adjacent structures), we define this nucleus as t he "paraclaustral reservoir". The present study reveals the cellular change s of the paraclaustral reservoir during postnatal development of the rat br ain using unbiased morphometry and in situ DNA end labeling. During the fir st 4 days after birth the density and total number of cells in the paraclau stral reservoir were stable; after this period a decrease of these paramete rs was observed until the complete disappearance of this structure at the e nd of first postnatal week. The rather low number of TUNEL (TdT mediated dU TP nick end labeling of fragmented DNA) positive nuclei in the paraclaustra l reservoir suggests that apoptosis is not a crucial mechanism leading to d ecay of this structure, (C) 1999 Elsevier Science Inc.