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Sixteen species of 14 genera of 7 different tribes of the Cinchonoideae (Rubiaceae) were investigated with a scanning electron microscope to examine orbicule presence and morphological diversity. Orbicules are lacking only in Gouldia terminalis (Hook, et Arn.) Hbd. and Simira rubescens (Benth.) Bremek. ex Steyerm. Four orbicule types could be distinguished mainly on the basis of shape and ornamentation characteristics. Spiny orbicules (type I) we found only in the Catesbaeeae (sensu Delprete). Augusta longifolia (Spreng.) Rehd. has microrugulate orbicules (type II). Smooth and spherical orbicules smaller than 0.5 μm (type III) are most widespread in our sample of the Cinchonoideae. In Burttdavya nyasica Hoyle, they are irregular and folded (type IV). For each species a description is given of the orbicule and of the sexine morphology, to allow comparison. Species with spiny orbicules always have microspines on the pollen sexine. For the other orbicule types no such resemblance could be observed. Transmission electron microscope observations of four species are included to comment on ultrastructural differences between orbicule types. From this preliminary survey, we suggest that orbicule features in Cinchonoideae may be systematically useful on generic and tribal levels. Key words: Ubisch bodies, Rubiaceae, Cinchonoideae, orbicule ultrastructure, tapetum.

Our results and those we review indicate that the exine has a great capacity for modifications that enable nutrients to pass through from the anther loculus to the microspore cytoplasm. Avenues of passage include strands, some of which are viscin threads, from the tapetum to microspores in, for example, Betula, Fuchsia, and Epilobium. Micro channels in Lopezia, Gaura, and Gelsemium extend through the ectexine, endexine, and intine to the cytoplasm. The bulge regions in Epilobium represent portions of the endexine that become very greatly enlarged, forming conducting channels that transport materials into the microspore cytoplasm. Results with tracers such as colloidal iron and lanthanum have also shown that exines of microspores are permeable across areas lacking obvious channels.Key words: Betula, Epilobium, exine, Fuchsia, Gaura, Gelsemium, Lopezia, microchannels, pollen, tapetum, tufts, viscin threads.

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Pollen wall ontogeny of RONDELETIA: odorata was studied with transmission electron microscopy (TEM) and scanning electron microscopy (SEM) from tetrad stage until maturity. The ontogenetic sequence of wall development in RONDELETIA: follows, to some extent, the basic scheme in the angiosperms, i.e., development starts centripetally with the pro-columellae in a plasmalemma surface coating (primexine) at the early tetrad stage when the microspores are still enveloped by callose, until intine formation in young pollen grains. The main ontogenetical features of Rondeletia odorata pollen are (1) the very thin irregular foot layer, (2) development of a continuous layer of radially oriented membranous granular material under the thick endexine, (3) initiation of intine before first mitosis with characteristic radial plasmalemma invaginations, and (4) a strong stretching force upon engorgement just prior to dehiscence, which leads to reduction in thickness of all wall layers. The possible function of Golgi vesicles in the considerable increase in surface area of the plasmalemma at intine initiation is discussed. The endocingulum observed on acetolyzed and sectioned mature grains is explained ultrastructurally.

The external morphology, internal structure and stainability for protein of orbicules in Betitla pertdula are examined by SEM and TEM. The pollen and the orbicule walls stain moderately for protein. The protein is localized mainly at the pollen aperture, in a thin layer betneen the exine and the intine and in the core and on the surface of the orbicules. The nitrocellulose membrane test indicates possible allergenicity of the orbicules as well as of the pollen. Since the orbicules of Befirla peiidula are 2-4 pm in diameter, they can pass through the bronchiole of the lungs and cause bronchial asthma. Orbicules have been recognized since 1865 by Rosanoff, who described a membrane with granules around the pollinia in the Mimosaceae. Ubisch (1927) and Kosmath (1927) published lists of different species that contain tapetal cells with orbicules on their surface. These early studies were followed by several others which were based solely on light microscopy investigations (for detailed review, see Banerjee 1967 andRaj &.Later studies using SEM andTEM were published on the morphology and ontogeny of orbicules (Ubisch bodies), e.g., Rowley (1962Rowley ( , 1963 To our knowledge, there is no information published on the morphology, ontogeny and histochemistry of orbicules in Befirla.The allergenicity of Befirla pollen is well documented (Wihl et al. 1988. However the possible allergenic effects of the orbicules in Betrrla have not yet been investigated. Takahashi et a1 (1991, 1995) demonstrated the presence of small particles with Cry j allergen activity together with intact, airborne Cryptoiseria japonica pollen *grains during the pollen season. The sites of C r y j I were found to be on the pollen exine and on the orbicule walls (MikiHirosige et al. 1994 andTakahashi et al. 1992).In the present study we describe the morphology and ultrastructure of orbicules in Betrrla pendirln. The allergenic effects of Betirla pollen and orbicules are also tested by the immunoblotting method. MATERIAL AND METHODSThe material for this study was collected during the period 1989-1993 from a Berula tree growing close to the Palynological Laboratory, Stockholm.For SEM preparations, fresh anthers mere dehydrated in an acetone series. Anthers were opened longitudinally and mounted on a stub. They were coated with gold for 3 minutes and examined with a Jeol JSM 6300 microscope.For TEhl preparations, anthers \\ere futed in 2% glutaraldehyde (GA) in 0.05 M Nacacodylate buffer, pH 7.4 at room temp. for 24 hours, postfixed with 0~01, then dehydrated in an acetone series, embedded in Spurr's medium (Spurr 1969) and sectioned. Ultrathin sections were stained with 1% aqueous uranyl acetate for 5 min, washed with distilled water, and floated on lead citrate stain for 5 minutes in order to improve the general contrast. Stain for protein: Sections on gold grids were stained with 5% phosphotungstic acid (FTA) in 10% acetone for 15min (Benedetti & Bertolini 1963, Marinozzi 1968. Aeroallergen immunoblotting procedureSamples collected on Burkard tapes w...

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