Cytokinins play an important role in plant development. We investigated the possibility that the nopaline Ti plasmid gene (tzs) from Agrobacterium tumefaciens could encode a protein able to participate in plant cytokinin production and lead to alterations in plant phenotype as a result of the expression of endogenous tzs. tzs was placed under the control of a heat‐inducible promoter from the Zea mays hsp70 gene. The expression of this fused gene was examined in transgenic Brassica napus plants. The tzs gene, which encodes the enzyme dimethylallyl transferase, was used as a cytokinin biosynthetic gene. The expression of the tzs gene was monitored by RNA hybridization and analysis of cytokinin content. Overproduction of cytokinin was observed even when the plants had not been heat‐shocked, and the plants displayed a reduced root system, increased height and branching, and delayed flowering. In addition, a significant increase in seed yield was observed in the transgenic plants, accounted for by increased number of seeds per silique and seed weight. The results suggest that increased levels of cytokinins, through the expression of tzs, are correlated with growth rather than with differentiation processes.

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__~-_ ~y~ RESUME Des v~sicules de secr(~tions apocrines ont 6t(~ observees dans la lumiere de nombreux tissus du tractus g~nital m&le. Longtemps considerees comme des artefacts de fixation des tissus, elles sont maintenant reconnues comme des elements b part enti6re qui jouent des r61es physiologiques dans la maturation des gametes m~les. L'objet de cette revue est de presenter les diff6rentes structures vdsiculaires qui ont ete decrites chez les mammiferes tant sur les plans de leurs organisations, contenus et fonctions potentielles. ABSTRACT Apocrine secretions in the male genital tract: putative roles in sperm maturationHanae REJRAJI, Jo~l R. DREVET Apocrine secretory vesicles have been observed in the lumen of several ducts of the male genital tract, namely the epididymis and vas deferens. Initially considered to be tissue-fixation artefacts, they are now recognized as genuine elements, which might play physiological roles in terms of sperm maturation. The aim of this review is to present these vesicles observed in various mammalian species and to describe their respective organization, content and putative roles.