Ultrastructure of the pineal gland after hypohysectomy

Résumé Nous avons étudié les modifications de l'ultrastructure de la glande pinéale du rat après hypophysectomie et constaté: (a) une atrophie du réticulum endoplasmique, (b) réduction des ribosomes, (c) dépletion du matériel sécrétoire des granules, (d) altération des mitochondries, (e) réduction dans le volume des noyaux et des nucléoles et (f) un agrandissement de l'espace périvasculaire. Il est très probable que l'hypophyse antérieure est nécessaire pour maintenir la structure et la sécrétion de la glande pinéale, mais le mécanisme par quoi s'exerce ce contrôle reste encore inconnu.     

Apoptosis regulation in the mammary gland

Epithelial apoptosis has a key role in the development and function of the mammary gland. It is involved with the formation of ducts during puberty and is required to remove excess epithelial cells after lactation so that the gland can be prepared for future pregnancies. Deregulated apoptosis contributes to malignant progression in the genesis of breast cancer. Since epithelial cell apoptosis in the lactating mammary gland can be synchronised by forced weaning, it has been possible to undertake biochemical analysis of the pathways involved. Together with the targeted overexpression or deletion of candidate genes, these approaches have provided a unique insight into the complex mechanisms of apoptosis regulation in vivo. This review explores what is currently known about the triggers for apoptosis in the normal mammary gland, and how they link with the intrinsic apoptotic machinery.Received 23 September 2003; received after revision 13 February 2004; accepted 3 March 2004     

Ultrastructure of the salivary gland chromosome as revealed by electron microscopy

Zusammenfassung An ultradünnen Schnittpr?paraten von Speicheldrüsenchromosomen (Drosophila melanogaster) und an entsprechenden Quetschpr?paraten (Drosophila virilis) wurde elektronenmikroskopisch festgestellt: Die Chromomeren und Chromonemata bestehen aus Filamenten mit Schraubenwindungen vom ?paran?mischen? Typus. Es ist wahrscheinlich, dass die Windungen der beiden Filamente in der entgegengesetzten Richtung ranken.

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The substance of this article was present in 1956 at the International Genetics Symposia in Tokyo.     

Ultrastructure of neurosecretory granules in the sinus gland of Palaemon serratus Pennant]

Five types secretory granules are distinguished in the sinus gland of Palaemon serratus on the basis of differences in their diameter and their electron density. Variations in the density of the acoplasm and of the granules are observed for three of these granule types.     

Glutathione and gamma-glutamyl cycle enzymes in rat mammary gland

The main enzymes of the gamma-glutamyl cycle during the lactogenic cycle in rat mammary gland were studied. A significant increase was found in all of them with the onset of lactogenesis. The effect of methionine sulfoximine on reduced glutathione concentration was studied in tissue slices of lactating mammary gland. The findings suggest that this compound effects glutathione synthesis by inhibiting gamma-glutamylcysteine synthetase.     

Ultrastructure of a mucous gland cell found in the tube feet of the starfishAsterina stellifera

Resumen Es describida la ultraestrutura de un segundo tipo de célula glandular mucosa que es encontrada en el pié ambulacrario de la estrella del marAsterina stellifera. Los gránulos secretores de esta célula tienen en su interior una ultraestrutura en forma de pequeños puntos densos y delicadas fibrillas, mas faltando una organizatión, principalmente comparada con la organizatión del otro tipo de granulo mucoso, también encontrado en el mismo pié ambulacrario.     

Loss of CD24 expression promotes ductal branching in the murine mammary gland

CD24 is expressed on mammary stem cells and is used as a marker for their isolation, yet its function in the mammary gland still needs to be examined. Here we show that CD24 is expressed throughout the luminal epithelial cell layer, but only weakly in myoepithelial cells. During lactation, CD24 expression was suppressed within alveoli, but upregulated post-lactation, returning to a pre-pregnant spatial distribution. CD24-deficient mice exhibited an accelerated mammary gland ductal extension during puberty and an enhanced branching morphogenesis, resulting in increased furcation in the ductal structure. CD24−/− mammary epithelial cells were able to completely repopulate cleared mammary fat pads and to give rise to fully functional mammary glands. Together, these data suggest that while CD24 is expressed in mammary epithelium compartments thought to contain stem cells, CD24 is not a major regulator of mammary stem/progenitor cell function, but rather plays a role in governing branching morphogenesis.     

Lipid peroxidation,low-level chemiluminescence and regulation of secretion in the mammary gland

In mammary explants of lactating mice, changes in the intensity of chemiluminescence (CL) were observed after the addition to the incubation medium of hormones and mediators that are involved in the regulation of secretion: oxytocin, acetylcholine, epinephrine and norepinephrine. A 15-min period of treatment with oxytocin, epinephrine or norepinephrine changed the level of thiobarbituric acid-reactive substances (TBARS). Two mammary explants, one of which was treated with oxytocin, acetylcholine, epinephrine or norepinephrine, were found to interact even when separated by a quartz glass wall. Analysis of the level of TBARS formation in these two explants showed that the observed interactions might be connected with light emission resulting from lipid peroxidation (LP) processes. The possible role of LP and low-level CL in the regulation of mammary gland secretion is discussed.     

Glutathione andγ -glutamyl cycle enzymes in rat mammary gland

Summary The main enzymes of theγ-glutamyl cycle during the lactogenic cycle in rat mammary gland were studied. A significant increase was found in all of them with the onset of lactogenesis. The effect of methionine sulfoximine on reduced glutathione concentration was studied in tissue slices of lactating mammary gland. The findings suggest that this compound affects glutathione synthesis by inhibitingγ-glutamylcysteine synthetase. This work was supported by grant B1138-8223 from the Servicio de Desarrollo Cientifico, Universidad de Chile.     

Effect of decreased dietary protein upon mammary gland growth in rats

Zusammenfassung Nachweis, dass der gesamte DNS-Gehalt in der Brustdrüse bei Tieren mit proteinfreier oder 5% iger Proteinnahrung im Vergleich zu der Kontroll-gruppe herabgesetzt ist. Wird Protein in der Nahrung um 10–20% erhöht, so bleiben DNS-Gehalt und Körperwachstum konstant.     

Indefinite in vivo life span of serially isografted mouse mammary gland

Zusammenfassung Durch wiederholte Transplantation liess sich Mammagewebe von Mäusen während einer Zeitspanne am Leben erhalten, welche die Lebensdauer von Mäusen wesentlich übertrifft.

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This work was supported by grants from the Jane Coffin Childs Memorial Fund for Medical Research, the Medical Research Council of Canada, and also partly by the National Cancer Institute of Canada. The author is indebted to Mrs.Sharon Griffin for her technical assistance.     

Properties of gamma-glutamyltranspeptidase, and glutathione levels in rat mammary gland

gamma-Glutamyltranspeptidase activity and glutathione levels were studied in rat mammary gland during the lactogenic cycle; both increased during mid-lactation. The enzyme's specific activity with several amino acids showed that glutamine and methionine were the best substrates. Maleate decreased the transpeptidation reaction and increased the hydrolytic activity. These results suggest that gamma-glutamyltranspeptidase from the mammary gland is similar to the enzyme described in other tissues in relation to these properties and the physiological role proposed in amino acids transport.