Electron tomography and computer visualisation of a three-dimensional 'photonic' crystal in a butterfly wing-scale

A combination of transmission electron tomography and computer modelling has been used to determine the three-dimensional structure of the photonic crystals found in the wing-scales of the Kaiser-I-Hind butterfly (Teinopalpus imperialis). These scales presented challenges for electron microscopy because the periodicity of the structure was comparable to the thickness of a section and because of the complex connectivity of the object. The structure obtained has been confirmed by taking slices of the three-dimensional computer model constructed from the tomography and comparing these with transmission electron microscope (TEM) images of microtomed sections of the actual scale. The crystal was found to have chiral tetrahedral repeating units packed in a triclinic lattice.

Expression of glucosamine trisaccharides on the rat uterine surface is altered by clomiphene citrate

We have studied histochemically the effects of clomiphene citrate on the expression of oligosacchrides on the apical plasma membrane of uterine epithelial cells using the lectin Phytolacca americana. Ovariectomized sexually mature rats were given a single injection of either clomiphene in two concentrations or estradiol 17 beta or progesterone and were killed 24 hr later. Uterine tissue was labeled with Phytolacca americana conjugated with avidin and subsequently labeled with biotinalyted ferritin and prepared for transmission electron microscopy. Our results indicate that clomiphene and to a lesser degree progesterone significantly increased lectin binding. However, the increase was not as large as that observed with a single dose of estrodiol 17 beta. When the proportion of lectin positivity in relation to total membrane length was analyzed, treatment with clomiphene and progesterone did not have significantly different effects. Low dose clomiphene did not have a significant effect as compared with controls. Our data show that clomiphene has a dose-dependent adverse effect on lectin binding as compared with ovarian hormones. We suggest that these effects contribute to low pregnancy rates with clomiphene use.

Morphometric comparison of uterine glandular epithelium in the early secretory phase from patients treated with different superovulatory drugs on an in vitro fertilization programme

The glandular structure in the uterine epithelium of three groups of patients on standard superovulatory regimes was studied using a fully automated image analysis system. It was found that one treatment (buserelin stimulation) produced more glandular area than either of the other two. We suggest that buserelin gives the morphometric appearance of the most normal endometrial glands and find that our morphometric analysis is a reliable means to evaluate glandular structure in patients on superovulatory therapy.

Glycerol increases the cytochemical detectability of cholesterol in the apical plasma membrane of uterine epithelial cells

The apical plasma membrane of uterine epithelial cells in the rat has been treated with glycerol before fixation and then examined by freeze-fracture cytochemistry using digitonin and filipin. Many more lesions were produced by both cytochemicals following glycerol treatment than in untreated controls, and we suggest that this indicates an increased detectability of cholesterol. We consider the implications of the findings for the way in which glycerol acts on membranes and propose that glycerol promotes increased binding between cholesterol and the cytochemicals.

Increase in cholesterol in the apical plasma membrane of uterine epithelial cells during early pregnancy in the rat

Freeze-fracture cytochemistry with the cholesterol-binding antibiotic filipin has been used to examine the plasma membrane of uterine epithelial cells at different stages of pregnancy in the rat. We find many more filipin-induced lesions on day 6 of pregnancy than on day 1 and suggest that this indicates a higher cholesterol content at this time. Since day 6 of pregnancy is the time at which blastocysts implant in the rat uterus, we consider the possible significance of an increased cholesterol content for implantation.

Calcium ionophore A23187 as a probe for freeze-fracture studies of membrane changes in the head of human spermatozoa

The membranes of the head of human spermatozoa were examined after incubating the sperm with and without inophore A23187 and calcium ions, using freeze-fracture electron microscopy. After exposure to ionophore and calcium there was a remarkable rearrangement of the intramembraneous particles, especially in the plasma membrane. Buckling of the plasma membrane occurred prior to breaking away from the outer region of the sperm head. The outer acrosomal membrane bubbled and broke down to form vesicles, and blebbing of the inner acrosome membrane also occurred. The nuclear envelope degenerated and often displayed an undulating topography.