This work describes, analyzes and compares the wood anatomy of Alseis pickelii from two distinct sites in Tropical Dry Forest. One site is an exploited forest that was disturbed by deforestation whereas the other site is preserved and has not been logged since selective logging in the 1960's. For the evaluation of wood anatomy, plant material was processed following standard techniques for light microscopy and histochemical tests. The results indicated that A. pickelii did not vary qualitatively between the two sites. The histochemical tests indicated the presence of prismatic crystals and starch in radial parenchyma of samples from both sites. Some quantitative parameters differed significantly between the two sites including: vessel frequency; vessel length and lumina area; intervessel pits; diameter, lumina, length and wall thickness of fibres; and radial parenchyma width. In general, these quantitative parameters had higher values in the samples from the exploited site, suggesting an adjustment to the more severe drought conditions there. Quantitative anatomical differences in the samples from the two sites show the influence that environmental conditions can have on wood anatomy. The observed anatomical characteristics may also be useful for taxonomic and ecological studies of this species and genus.

Fagopyrum esculentum Moench, common buckwheat (2n = 2x = 16), is a sporophytic self‐incompatible species with dimorphic flowers, which is resistant to seed shattering, a trait often lost in interspecific crosses. The objective of this study was to determine the inheritance of seed shattering in interspecific crosses with the shattering species F. homotropicum Ohnishi [=F. esculentum var. homotropicum (Ohnishi) Q‐F. Chen] (2n = 2x = 16) to use this species in buckwheat improvement. Four interspecific crosses between F. homotropicum and F. esculentum were made by means of ovule culture. Eight F2 populations derived from F1 single plants were developed and 28 F3 lines from F2 shattering plants were used for progeny testing. The F1 interspecific hybrids expressed seed shattering, indicating that shattering is dominant to nonshattering. The F2 populations from individual F1 plants segregated in the ratios of 3:1, 9:7, and 27:37, supporting the control of shattering by three complementary dominant genes, the first report of multiple gene control in buckwheat. The F3 progeny testing confirmed the F2 segregation patterns. The different segregation ratios in the F2 populations may have been caused by heterogeneity of F. esculentum because of cross‐pollination. The proposed genetic model describes the genotype of F. homotropicum as homozygous dominant to explain the absence of nonshattering genotypes. Fagopyrum esculentum genotypes are homozygous recessive at a minimum of one locus to explain the absence of shattering genotypes. This model provides an explanation for the occurrence of shattering phenotypes from crosses between two nonshattering parents and nonshattering phenotype from crosses between, or selfing of, shattering plants.

Abstract. Five canine cutaneous histiocytomas were studied by electron microscopy and esterase cytochemistry. The tumor cells contained irregular nuclei, characteristic lysosomal granules, and perinuclear microfilaments. The cells showed activity with anaphthyl acetate esterase stains. These characteristics are evidence that this tumor originates from the mononuclear phagocyte system. Canine cutaneous histiocytoma is considered to be a distinct morphologic entity, distinguishable from other neoplasms of the skin [lo, 113. The biologic and light-microscopic characteristics of this clinically benign tumor have been described [15]. Although it is considered to be of histiocytic origin, one ultrastructural study [5] found that the cells were compatible with histiocytes but did not definitely establish their origin from the mononuclear phagocyte system. Materials and MethodsCutaneous tumors from five dogs were surgically removed. Fresh tissue was used to make impression smears. Sections stained with hematoxylin and eosin (HE) were prepared in the routine manner.For electron microscopy, tissue fragments were fixed in 2% glutaraldehyde in Tyrode's buffer at pH 7.3 [7, 141, then in Millonig's phosphate buffered osmium tetroxide [6]. The tissues were stained en bloc with 0.5% uranyl acetate, dehydrated in a graded ethanol series and propylene oxide, and embedded in araldite. Ultra-thin sections were cut on an LKB ultratome, stained with uranyl acetate and lead citrate [13], and examined with a Philips EM 200 electron microscope.Impression smears were stained for esterase by the method described [18].

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Poncirus trifoliata var. monstrosa (T. Ito) Swingle is a rootstock used in Brazilian citriculture for its potential to induce dwarfism and the viability of densified crops. Its recommendation is still restricted due to lack of research on the performance and compatibility of different types of scion under specific conditions of soil and climate. The aim of this study was to correlate plant size and productive efficiency with anatomical indicators of dwarfism or graft incompatibility between citrus scion cultivars and the ‘Flying Dragon’ trifoliate orange (FD) and ‘Rangpur Lime’ (RL) as rootstocks. The experimental design was of randomised blocks with split plots, with the experiment conducted in an orchard from the fourth to the sixth year of cultivation, under localised irrigation. The treatments consisted of two rootstocks (FD and RL) in the plots and five scion cultivars (Tahiti acid lime, and Natal, Navel, Lima Sorocaba and Pera oranges) in the sub-plots, with four replications per treatment. The agronomic performance of the plants was evaluated, together with the characteristics of samples containing the cambial zone and secondary xylem below, above and within the graft region. The FD rootstock gives the smallest size and greatest productive efficiency. The ‘Navel’ orange has good anatomical plasticity, adjusting itself more efficiently to the rootstocks. Visual symptoms of incompatibility between the ‘Pera’ orange grafted onto the FD can be seen at 64 months after planting. Vessel size and frequency, as well as the size and disposition of the cambial zone, are related to dwarfism and graft incompatibility.