Ricerche al Microscopio Ottico ed Elettronico Sulla Struttura del Nucleolo di Cellule Meristematiche di Alcune Piante e Considerazioni Critiche Sulla Teoria del «Nucleolonema»

Fine Structure ofPsilotum NudumCells During Division

“…The fine structure of most interphase nucleoli of the sporocytes of Psilotum is similar to nucleoli of the root tip cells of Vicia faba (LAFONTAINE and CHOUINARD 1963 ), root tip cells of Allium cepa (PORTER 1960) and to the nucleoli of microspore mother cells of several orchids ( CHARDARD 1962) as well as to nucleoli already reported for shoot apex cells of Psilotum by FABBRI ( 1963 ). Basically this consists of a central compact mass of fibrils surrounded by a cortex of 18 mp.…”

“…As FABBRI (1960FABBRI ( , 1963 has pointed out, the nucleoli of Psilotum are unique in that some of the 4 to 6 nucleoli present in a nucleus persist during the later stages of mitosis. All persistent nucleoli become detached from the chromosomes during prometaphase and appear to be excluded from the mitotic apparatus.…”

“…Light microscopic investigations of dividing cells in Psilotum nudum (L.) Beauv. have been carried out by KARSTEN ( 1893) and PAMPALONI ( 1904) and more recently with both the light and electron microscope by FABBRI (1960FABBRI ( , 1963. This plant, commonly called the «whisk fern», is a member of the Psilopsida, considered the most ancient taxon of vascular plants extent.…”

Vacuoles in the Nucleoli ofZea MaysRoot Apices and their Possible Significance in Nucleolar Physiology

“…The volume of the nucleolar vacuoles in the root apex of lea mays is similar to that given by FABBRI (1963) for root apices of Phaseolus vulgaris, Ricinus communis and Lupinus luteus, but is smaller than the volume of nucleolar vacuoles in tobacco cells in culture given by JoHNSON and JoNES (1967). The size and number of vacuoles probably vary from species to species.…”

Mitocondri Aggregati inPsilotum Nudum(L.) Beauv.

“…(FABBRI 1963), in cellule profonde del caule, a circa un centimetro dall'apice vegetativo, furono notate strutture vescicolose che fino dal primo esame apparvero come aggregati di mitocondri.…”