Ultrastructure of the human endometrial glandular cell during the menstrual cycle

Human endometrium ultrastructure during the implantation window: a new perspective of the epithelium cell types

The human endometrium is a hormonally regulated tissue that cyclically growths and differentiates in order to become a structure adequate for implantation. Molecular studies have shown some contradicting results and thus a reappraisal of the endometrium ultrastructure is warranted. In our study, endometrium biopsies were taken during the implantation window of 10 healthy women of reproductive age and analyzed using electron microscopy. Our results showed that during implantation window, the endometrial epithelium encompassed 4 cell types: microvilli-rich cells, pinopode cells, vesiculated cells, and ciliated cells. These cells showed signs of active communication with their external environment and neighboring cells, such as endocytosis, transcytosis and exocytosis. We highlighted important differences between surface and glandular epitheliums and characterized apocrine and holocrine secretion. It is likely that the features described reflect distinct functions in endometrium physiology that should be taken into account in the evaluation of the endometrium during the implantation window.

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.

Differences in lectin binding patterns of normal human endometrium between proliferative and secretory phases

Lectin binding patterns in normal human endometrium were examined by light and electron microscopy using seven different lectins (ConA, WGA, RCA, PNA, UEA-1, DBA, and SBA). For light microscopic observations, criteria based on the incidence and intensity of cells positive for the lectin staining were adopted to evaluate the different staining patterns of the proliferative and secretory endometria obtained by the avidin-biotin-peroxidase complex (ABC) technique. At the light microscopic level, ConA, WGA, and RCA stained endometrial glandular cells in both phases. The number of PNA-positive cells with the binding sites entirely limited to the apical surface tended to be reduced slightly in the secretory phase. UEA-1 weakly stained the apical surface of glandular cells in the proliferative phase but not in the secretory phase. Among the lectins used in this study, DBA and SBA displayed remarkable changes between the phases. That is, in the proliferative phase they produced only a faint or slight positive stain at the apical surface, but the incidence and intensity of DBA- and the SBA-positive glandular cells increased in the secretory phase. By electron microscopy, the reaction product of ConA was observed in the plasma membrane, endoplasmic reticulum, nuclear envelope, and the Golgi apparatus, and the binding sites of RCA and DBA were observed in the plasma and Golgi membranes. Between both phases, the reactivity of ConA and RCA showed almost no change. However, the secretory endometrial cells containing the DBA-positive Golgi apparatus were markedly increased in number compared with the proliferative ones bearing the lectin-positive organelles.(ABSTRACT TRUNCATED AT 250 WORDS)

The annulate lamellae--from obscurity to spotlight

This review aims to provide a comprehensive and in-depth survey of a cell organelle, the annulate lamellae, that is widely distributed and especially prevalent in both female and male sex cells as well as tumor and cancer cells. The organelle is also present in many somatic cells and plant cells. Emphasis is placed on the contributions that electron microscopy and associated experimental approaches have made in providing information about the distribution, ultrastructure, morphogenesis and relationships of annulate lamellae to other cellular organelles, especially the nuclear envelope and endoplasmic reticulum, as well as cell product. An increasing number of experimental manipulations have recently been shown to alter, either increase or decrease, the amount of annulate lamellae and these studies are explored in depth. Information about the origin and morphogenesis of annulate lamellae in different cells is summarized and extensive coverage is given to several hypotheses about possible annulate lamellae function. A detailed bibliography provides a thorough compilation of research dealing with annulate lamellae. A major goal of this extensive review is to generate increased awareness of, and interest in, this cell organelle for students and investigators of the cell who, by bringing current techniques in cell and molecular biology to bear, might focus and intensify studies on the function of an organelle whose precise role in the cell is presently enigmatic.

Ultrastructural study of a female adnexal tumor of probable wolffian origin

A broad-ligament tumor, of probable wolffian origin, is presented. The ultrastructural features of this histologically benign tumor have not been previously described. The fine structure of this tumor is compared with normal structures and tumors derived from wolffian and müllerian anlage. The findings are consistent with derivation from wolffian duct.

Müllerian adenosarcoma of the uterus: literature review, case report, and ultrastructural observations

This is a report of a transmission and scanning electron microscopic examination of a müllerian adenosarcoma. The neoplasm had the characteristic pattern of benign neoplastic glands with focal squamous metaplasia and a sarcomatous stroma. Ultrastructurally, both mesenchymal and epithelial elements were identified. The mesenchymal components were ultrastructurally identical to those present in endometrial stromal sarcomas, including active collagen synthesis. The epithelial component resembled bening endometrial glands, and there was significant secretory activity as evidenced by prominent cytoplasmic glycogen collections.

A three-dimensional study of endometrial mitochondria during the menstrual cycle

Three-dimensional reconstruction of endometrial mitochondria during the menstrual cycle in the woman has produced three mitochondrial populations. These populations are seen to change in size, in number, and in complexity of structure as the menstrual cycle progresses. Through reconstruction and statistical analysis, morphologic data seem to support histochemical data relating to anaerobic and aerobic metabolism in endometrial gland cells.

Müllerian adenosarcoma of the uterus: an ultrastructural study of four cases

Four cases of uterine müllerian adenosarcoma, a distinctive form of mixed müllerian tumor, were studied by light and electron microscopy. All tumors showed the characteristic histologic pattern of benign neoplastic glands within sarcomatous stroma. Ultrastructurally, both mesenchymal and epithelial cells were seen. The mesenchymal cells showed some features of endometrial stromal cells, including the presence of intracytoplasmic collagen fibers. The epithelial cells formed glands, which resembled benign endometrial glands and were separated from the stroma by a well-defined basal lamina. No transitional cells between the epithelial and mesenchymal cells were seen. The ultrastructural features of these tumors suggest that the sarcomatous portion is of endometrial stromal origin. The glandular portion may arise, along with the stroma, from multipotential stem cells, or the glands may be non-neoplastic entrapped endometrial glands stimulated by the stroma and thus appearing to form an integral part of the tumor.

Atrophy and apoptosis in the cyclical human endometrium

Electron microscopy of human cyclical endometrium indicates that there is considerable loss of gland epithelial cells with formation of apoptotic bodies in the late secretory, premenstrual and menstrual phases, but also to a lesser extent in the proliferative phase. Apoptotic bodies containing nuclear fragments may be recognised on light microscopy as basophilic or Feulgen positive granules. These granules accumulate in greatest numbers towards the end of the cycle and may be used as an additional aid in dating curettings.

Ultrastructural studies on the endometrium of women wearing TCu-200 intrauterine devices by means of transmission and scanning electron microscopy and x-ray dispersive analysis

Endometrial biopsies obtained from 12 young women wearing TCu-200 intrauterine contraceptive devices from six to 12 months were studied by means of transmission and scanning electron microscopes as well as with the use of rubeanic acid stains and x-ray dispersive analysis. Six biopsies were taken at Day 10 and six were taken at Day 20 of the menstrual cycle. The aim was to investigate epithelial and stromal changes possibly related to copper deposition. The main changes were located in the cell organelles at Day 10 of the cycle. The mitochondria disclosed vacuolization of the matrix and myelin figure formation in 70 to 80% of the epithelial cells. There were also increased numbers of lysosomes. There were similar alterations of secretory endometrium in only a few cases. Instead, there was an increased number of mitochondria, and most of them were dividing. Rubeanic acid stains as well as energy-dispersive x-ray analysis failed to reveal significant amounts of copper in the various cell organelles studied. The above observations seem to indicate that there is a definite alteration of the mitochondria of epithelial cells which may result in impairment of respiratory mechanisms and energy production, rendering the endometrial environment inhospitable to the fertilized egg. These changes are thought to be reversible. The absence of copper is explained on the basis of a rapid turnover of the endometrium or to a problem in sampling common to this methodology.

The ultrastructural response of human endometrium to medroxyprogesterone acetate

Medroxyprogesterone acetate is a steroid compound similar to progesterone in structure and function. Thirty women were given 150 mg. of medroxyprogesterone intramuscularly, and samples of the endometrium were examined by light and electron microscopy. The initial response of normal human endometrium was maturation and then inhibition. By 50 days after injection, the atrophic changes began to reverse, and by Day 90, after injection the tissue resembled normal proliferative endometrium. A previously undescribed nuclear inclusion body is present; however, its significance is unclear at this time. On the basis of ultrastructural changes, medroxyprogesterone appeared not to exert a significant influence on the endometrium past 90 days at this dosage.

Human endometrial fluid kinetics as observed by scanning electron microscopy

Segments of human endometrium, obtained during different stages of the menstrual cycle, were fixed in glutaraldehyde, processed by critical point drying, coated with carbon and gold, than observed with a scanning electron microscope under magnifications varying from 20 to 200,000. The endometrium was basically made of two different types of cells: secretory nonciliated cells and ciliated cells. Different types of secretory cells at different stages of secretory cycles were observed. The endometrial secretion is apocrine: the apical cell membrane of the endometrial cell ruptures, releasing secretory material. The rupture of cells within a given segment of the endometrium is asynchronous. Development of aptical microvilli, synthesis, storage, and release of endometrial secretory granules, and ciliogenesis are hormone dependent. The response of the ciliated and secretory cells of the endometrium varies throughout the menstrual cycle. This is particularly noted in cell specialization, the development of apical microcilli, and ciliogenesis.