Diletto Quattrini

Variazioni del contenuto in acido desossiribonucleco nei nuclei di cellule secernenti

Summary In Papillifera bidens the secreting cells of the Sempers organ have an high degree of polyploidy. Their nuclear amounts of DNA show remarkable variations, which appear cyclical and connected with the secretory cellular cycle.

STRUCTURE AND ULTRASTRUCTURE OF THE MOLLUSCAN PROSTATE

SUMMARY In Aplysia depilans Gmelin an actual and well differentiated prostate does not exist. The functions of this organ are probably accomplished by a large number of secretory cells placed along folds in the wall of the oviducal groove of the large hermaphrodite duct. Cells of the same kind are also contained inside diverticula arising from the external wall of the groove itself. This should be a first indication almost of the formation of a prostate as an organ in itself, placed outside the male gonoduct and independent of them within certain limits. Structure and ultrastructure of the prostatic tissue of the species examined so far by the Author, and represented, besides Aplysia depilans Gmelin, by Milax gagates (Draparnaud), Vaginulus borellianus (Colosi), and Laevicaulis alte (Ferussac), apart from a few differences in details, are quite similar. This tissue appears to be formed everywhere by two different types of epithelial cells: one secretory the other with no secretory activity, usually evenly...

Passaggio di ribonucleoproteine dal citoplasma al nucleo nei neuroni centrali dei Gasteropodi

Summary In centrai neurons of several species of Pulmonata and Pseudopulmonata (Soleolifera) Gastropods, images can be found to be interpreted as passage, at microscopical level, of cytoplasmic materials in the nucleus. These materials are assumed to take in many cases the form and structure of common nucleoles. The significance of such an unusual finding is discussed, as the expression of intense proteic metabolism.

Due partieolarità sulln degenerazione degli cvocili e sulla spermiogenesi nei gasteropodi polmonati

Summary In land-pulmonate gasteropod Papillifera bidens a rather frequent modality of degeneration of the oocytes is characterized by the fact that at first wholly dissolve both cytoplasm and nucleus, while the nucleolus remains to all appearance intact, to degenerate only later on. In the process of spermiogenesis the function of nurse cells sometimes seems to be displayed by oocytes.