The influence of history and contemporary stream hydrology on the evolution of genetic diversity within species: an examination of microsatellite DNA variation in bull trout, Salvelinus confluentus (Pisces: Salmonidae).

An understanding of the relative roles of historical and contemporary factors in structuring genetic variation is a fundamental, but understudied aspect of geographic variation. We examined geographic variation in microsatellite DNA allele frequencies in bull trout (Salvelinus confluentus, Salmonidae) to test hypotheses concerning the relative roles of postglacial dispersal (historical) and current landscape features (contemporary) in structuring genetic variability and population differentiation. Bull trout exhibit relatively low intrapopulation microsatellite variation (average of 1.9 alleles per locus, average He = 0.24), but high levels of interpopulation divergence (F(ST) = 0.39). We found evidence of historical influences on microsatellite variation in the form of a decrease in the number of alleles and heterozygosities in populations on the periphery of the range relative to populations closer to putative glacial refugia. In addition, one region of British Columbia that was colonized later during deglaciation and by more indirect watershed connections showed less developed and more variable patterns of isolation by distance than a similar region colonized earlier and more directly from refugia. Current spatial and drainage interconnectedness among sites and the presence of migration barriers (falls and cascades) within individual streams were found to be important contemporary factors influencing historical patterns of genetic variability and interpopulation divergence. Our work illustrates the limited utility of equilibrium models to delineate population structure and patterns of genetic diversity in recently founded populations or those inhabiting highly heterogeneous environments, and it highlights the need for approaches incorporating a landscape context for population divergence. Substantial microsatellite DNA divergence among bull trout populations may also signal divergence in traits important to population persistence in specific environments.

Malignant haemangioendothelioma involving the liver.

The features of four cases of malignant haemangioendothelioma involving the liver and other organs are described. Two cases were associated with a microangiopathic haemolytic anaemia. The nature of the tumours and possible pathogenesis for the anaemias are discussed.

Enzyme histochemical patterns in the normal human amnion: amniotic histochemical patterns.

The histochemical distribution of 14 enzymes in the human amnion at term are described. Adenosine triphosphatase, 5'-nucleotidase, acid phosphatase and nonspecific esterase show continuous gradations of enzyme activity. Cells with intense activity are prominent in acid phosphatase and nonspecific esterase preparations. A distinct subpopulation of amniotic cells can be defined by their alkaline phosphatase activity. The possible correlations with morphological studies are discussed.

Scanning electron microscopic appearances in the amnion in polyhydramnios and oligohydramnios.

The appearances of the amnion from two patients with polyhydramnios and two patients with oligohydramnios are described. In polyhydramnios the amnion showed a normal incidence of all the four patterns found in normal amnion at term and no abnormal features were noted. In oligohydramnios, two of four normal patterns predominated and intercellular canals were sparse.

Scanning electron microscope appearances of normal human amnion and umbilical cord at term.

The surface morphology of normal term amnion was studied by scanning electron microscopy. Four patterns were observed. Two of the patterns showed distinctive minority populations of cells. In one, there were cells surrounded by intracellular channels; in the other, there were large flat cells. The microvilli in all four patterns showed variable morphology in different samples. Possible functional implications of the findings are discussed.

Endometrial washings histological and cytological assessment of material obtained with an intrauterine jet washing device.

The histological and cytological assessment of material obtained with an intrauterine jet washing device from 138 patients with postmenopausal bleeding, abnormal premenopausal bleeding or infertility is presented. In the first part of the study 55 washings were examined by histological techniques and the findings compared with those in material subsequently obtained by curettage or endometrial biopsy. Only 32 (58 per cent) of the washings were satisfactory for evaluation of the endometrium compared with 46 (84 per cent) of the curettings. When, in the second part of the study the washings in 83 cases were examined by both histological and cytological methods, 76 (92 per cent) were satisfactory compared with 59 (71 per cent) of the curettings. Cytological examination of the washings in the postmenopausal women provided a significantly higher proportion of satisfactory specimens than histological examination alone or evaluation of the curettings. In the whole study, three cases of endometrial carcinoma were diagnosed by endometrial washings and by curettage, while in six cases of endometrial hyperplasia one false negative was obtained by histological examination of the washings and one by examination of the curettings. This study shows that endometrial samples obtained with the intrauterine jet washer provide information about the endometrium which is comparable with that obtained by conventional curettage, and also that in postmenopausal women endometrial lavage may be more reliable than curettage.