Scanning electron microscopy of human endometrium

Hydrodynamic instability and flow reduction in polymer brush coated channels

A polymer brush is a passive medium. At equilibrium the knowledge of its chemical composition and thickness is enough for a full system characterization. However, when the brush is exposed to fluid flow it reveals a much more intriguing nature, in which filamentous protrusions and the way they interact among themselves and with the surrounding fluid are of outmost importance. Here we investigate such a rich behavior via numerical simulations. We focus on the brush hydrodynamic response at low Reynolds numbers, observing a significant fluid flow reduction inside a polymer-brush coated channel. We find that the reduction of the flow inside the channel is significantly larger than what would happen if the brush effect consisted only in reducing the effective channel width. This amplified reduction is understood as being due to the morphological instability of the brush-liquid interface which is shown to have an elastic origin: the mechanical stress acting on the brush due to the imposed flow is partially released by the interface modulation. In turn, this modulation dissipates more energy than a flat interface in the surrounding fluid, causing a reduction of flow velocity. Our results and interpretations provide an explanation for recent experimental measurements.

General method for classification of fiber families in fiber-reinforced materials: application to in-vivo human skin images

Fiber structures play a major role for the function of fiber-reinforced materials such as biological tissue. An objective classification of the fiber orientations into fiber families is crucial to understand its mechanical properties. We introduce the Fiber Image Network Evaluation Algorithm (FINE algorithm) to classify and quantify the number of fiber families in scientific images. Each fiber family is characterized by an amplitude, a mean orientation, and a dispersion. A new alignment index giving the averaged fraction of aligned fibers is defined. The FINE algorithm is validated by realistic grayscale Monte-Carlo fiber images. We apply the algorithm to an in-vivo depth scan of second harmonic generation images of dermal collagen in human skin. The derived alignment index exhibits a crossover at a critical depth where two fiber families with a perpendicular orientation around the main tension line arise. This strongly suggests the presence of a transition from the papillary to the reticular dermis. Hence, the FINE algorithm provides a valuable tool for a reliable classification and a meaningful interpretation of in-vivo collagen fiber networks and general fiber reinforced materials.

Ultrastructure of endometrial epithelial cells in a three-dimensional cell culture system for human implantation studies

PURPOSE

A three-dimensional cell culture system imitating normal uterine endometrium has previously been established. To what degree do cultured epithelial cells retain their morphological characteristics as compared to in vivo material obtained simultaneously from the same tissue donor.

RESULTS

We found a high degree of similarity between the in vivo and in vitro situations. The present culture system furthermore imitates the day-to-day morphology of the cycle.

CONCLUSIONS

This indicates, that a correct timing of the biopsy tissue is important for future human implantation studies.

The effects of steroids on the fine structure of the endometrium

This brief review illustrates the lack of ultrastructural studies on human endometrium, particularly on well-dated material from normal, fertile women. The glandular epithelium, with its triad of unusual organelles in the early luteal phase, poses fascinating problems in cell biology and, probably for this reason, has attracted the most work. Many problems in reproductive biology, in uterine pathology and in the study of unexplained infertility are crying out for detailed study of the luminal epithelium, the stroma and the blood vessels. If this review, by highlighting the gaps in our knowledge, stimulates research into these areas, it will have been successful.

Scanning electron microscopy of human preimplantation endometrium in normal and clomiphene/human chorionic gonadotropin-stimulated cycles

Embryo transfer after in vitro fertilization of oocytes obtained from unstimulated or stimulated women is usually carried out earlier than when an embryo developed in vivo reaches the womb. The possible asynchrony between the developmental stage of the embryo and that of the endometrium at transfer might reduce the prospects for implantation; so also might any secondary effect of stimulation. Preimplantation endometrium dated by plasma hormone analyses of 17 beta-estradiol and progesterone in five unstimulated and eight stimulated women was surveyed. Three features were examined, namely, the frequency, distribution, and appearance of ciliated cells, nonciliated cells, and apical protrusion. Wide regional variations were observed, but no continuous or consistent changes or differences were found from ovulation to the time for implantation in unstimulated and stimulated cycles. Therefore, from the morphologic point of view, the surface might be ready to accept a transferred embryo at any time within a range of days after ovulation.

Ultrastructural changes in human endometrium with copper and nonmedicated IUDs in utero

Scanning and transmission electron microscopy were used for a study of the surface and glandular ultrastructure of human endometrium in the presence of different types of IUDs at comparable phases of the menstrual cycle. The aim of the study was to compare the effect of the nonmedicated with the copper and multiload copper devices to further explain the differences in their contraceptive potencies and their mechanism of action. The endometrium was evaluated at and away from the IUD; emphasis was put on the ultrastructure of endometrial gland openings, secretory activity, cellular glycogen content, ciliated cells, microvillous pattern, and kinocilia. The changes of the surface ultrastructure of the endometrium in the presence of copper IUDs were more extensive in this study than those previously reported. There seems to be a direct relationship between the amount of copper incorporated in the device, the degree of ultrastructure changes, and the area of endometrium involved. Copper devices affect the endometrial cells away from the IUD. The altered secretory function with disturbed macroapocrine secretion, the abnormality of ciliated cells, and the defective microvillous growth seem to interfere with the physiologic and functional integrity of the endometrium, reducing the chances of contraception in the presence of copper IUDs.

Surface ultrastructure of human endometrium. Effect of hormonal status and neoplastic progression

The structure, size and number of uterine endometrial surface epithelial cells and specialized structures, cilia and microvilli were analyzed by light microscopy, transmission and scanning electron microscopy. The purpose was to further our understanding of the biological, morphological and prognostical implications of change in hormonal status and neoplastic progression. The results of this study showed that the quantitative and qualitative alterations followed a similar pattern: the cilia and microvilli were minimally developed in atrophic endometrium, and gradually progressed in size and number in relation to oped in atrophic endometrium, and gradually progressed in size and number in relation to the hormonal cycle and hyperplastic endometrium, unless associated with cellular atypia. Lesions with atypical adenomatous hyperplasia showed irregular and disorganized surface structure, progressively more apparent in specimens from adenocarcinomas. Decreasing degree of differentiation of the tumor and radiation treatment caused a reduction in number and size, as well as derangement in the structure of cilia and microvilli. The results showed the sensitivity of the uterine lining to hormonal changes, the distinction between different types of edometrial hyperplasia and the close interrelationship between atypical adenomatous hyperplasia and early adenocarcinoma, as well as the extent and severity of different clinical entities, including radiation treatment.

On the function of cilia in the female reproductive tract

A recently discovered syndrome is characterized by congenital immotility of the cilia. It consists of chronic infections in the respiratory system, male infertility, and, in about one-half of the cases, situs inversus. The syndrome thus includes Kartagener's syndrome. The syndrome provides a unique opportunity to gain insight into the role of the cilia in the human body. Five women evidently suffering from this syndrome were examined. They had no gynecologic disorders. Three of the five women had tried to become pregnant and two have suceeded. A review of the literature indicates that men with Kartagener's syndrome are usually infertile, whereas the women are not. This fact and the data presented herein constitute strong evidence that ciliary motility is not essential for female fertility. More conclusive proof could be obtained if any of the affected women would consent to ultrastructural investigation of the oviductal cilia.