title: The ultrastructure of the developing medial preoptic nucleus in the postnatal rat.
abstract: The postnatal maturation of the medial preoptic area (MPOA) of male and female rats was studied by means of light and electron microscopy. In Golgi-Kopsch preparations, bi- and multipolar cells were present at birth in both sexes; the perikarya of most of these cells, as seen with the electron microscope, exhibited an immature appearance characterized by a sparse organelle content. During the next 5-10 days, an increase in cell size and cytoplasmic differentiation occurred in each sex. By 10 days, many of the MPOA neurons displayed an increased organelle density with the most prominent change being a proliferation of rough endoplasmic reticulum. Further neuronal development was also evidenced by a greater frequency of dendritic spines than seen at either birth or 5 days. Lastly, the number of synapses per unit area increased rapidly in each sex during the first two weeks of postnatal life. Thus, a period of increasing cytological maturation and synaptic organization closely paralleled previously demonstrated stages of functional differentiation of gonadotrophin regulatory mechanisms in the rat brain.
mesh_terms: D000728:Androgens / Q000494:pharmacology; D000818:Animals; D005260:Female; D006056:Golgi Apparatus / Q000648:ultrastructure; D007031:Hypothalamus / Q000254:growth & development*; D008297:Male; D008854:Microscopy, Electron; D009562:Nissl Bodies / Q000648:ultrastructure; D009940:Organoids / Q000648:ultrastructure; D011301:Preoptic Area / Q000187:drug effects / Q000254:growth & development* / Q000648:ultrastructure; D051381:Rats; D012737:Sex Factors; D013569:Synapses / Q000648:ultrastructure
chemical_list: D000728:Androgens