The layers of the human amnion and chorion were examined by light and transmission electron microscopy. Comparisons among different anatomical sites with respect to full-term and prematurely ruptured membranes indicate that (a) the thickness of the membranes is reduced near the rupture point; (b) intercellular canals near the implantation site become dilated and branched; (c) the trophoblast layer of full-term membranes is thinner and with more degenerating cells; and (d) the fibroblast and spongy layers have fewer collagenous fibers and less organization near the rupture site. These findings suggest that, although cellular activity is maintained in prematurely ruptured membranes, the mainly collagenous extracellular matrix undergoes marked disorientation. If this occurs too early in gestation, it may lead to premature rupture.

Punch biopsy specimens from 4 patients with confirmed diagnosis of tinea versicolor were investigated. Hypopigmented, hyperigmented and uninvolved sites from the same subject were compared in relation to ultrastructural alterations as a result of infection with Malassezia furfur, by light, scanning, and transmission electron microscopy. Hyperpigmented skin had thicker stratum corneum than hypopigmented but both were thicker than the uninvolved skin. A large number of tonofilaments were noticed in hyperpigmented sites in stratum granulosum. In hypopigmented skin the melanosomes were individually dispersed and fewer in number than the uninvolved skin. In hyperpigmented skin, the melanosomes were sequestered in most cells suggesting difficulty in the transfer of melanosome granules to keratinocytes. In both cases of pigmentation the most readily affected parts of the cells were cyto-plasmic organelles with a latent effect on the nucleus and nucleolus. We postulate that either stage of pigmentation (hyperpigmentation or hypopigmentation) is an intermediary in nature as a result of M. furfur invasion.

Summary The collagen content and the bursting pressure of human fetal membranes was measured for full term spontaneously ruptured, full term artificially ruptured and prematurely ruptured membranes. The bursting pressure of the prematurely ruptured membranes was significantly higher than the membranes which ruptured spontaneously at term. No significant difference was found in the collagen contents.

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