Attachment of blastocysts to lens capsule: A model system for trophoblast-epithelial cell interaction on a natural basement membrane

Summary The bovine lens capsule has previously been shown to provide an optimal surface for the examination of epithelial cell interaction with a basement membrane. This native substrate has been used to investigate some initial aspects of attachment of mouse blastocysts and trophoblastic cellular outgrowth. Mouse blastocysts were presented to the cell-free humoral side of the anterior lens capsule, incubated for 72 h, and examined by scanning and transmission electron microscopy. Blastocysts hatch and attach from their zonae pellucidae by 30 h. Trophoblastic cells proliferate rapidly in a coronal direction, display extensive surface microvilli, and advance by the extension of numerous filipodia, many of which terminate with bulbous projections. These projections were shown by transmission electron microscopy to contain numerous vacuoles and polysomes. To simulate further the initial blastocyst-uterine interaction, a suspension of lens epithelial cells was introduced to the capsule and permitted to form a monolayer prior to the addition of the blastocysts. At 72 h the monolayer of lens cells remained intact. We observed that: a) lens cells appear to recede from the advancing trophoblastic cells, and b) trophoblastic cells extend beneath the monolayer of lens cells and thereby dislodge the cells from the lens capsule substrate. No infiltration of the capsule by the advancing trophoblastic cells was observed. The lens capsule appears to offer a promising system for the study of trophoblast-epithelial cell interaction on a natural basement membrane.     

Formation of Basal Bodies in Ciliary Epithelium of Molluscs Buccinum undatum L. and Lymnaea stagnalis L.

Electron microscopic studies of the leg ciliary epithelium was carried out in two mollusks. In the epithelium of the leg of adult animals, the centrioles were mostly formed de novo with participation of deuterosomes during the formation of basal bodies. Transformation of the centriolar cylinder in a mature basal body is accompanied by the cylinder elongation and appearance of pericentriolar structures, such as rootlet system, basal legs, and basal plate. Centriolegenesis proceeds in both ciliate and nonciliate (with microvilli) cells of the epithelium. It has been proposed that the cell with microvilli represent a transitional stage in differentiation of the ciliary cells.     

Epithelial differentiation at the edentulous alveolar ridge in man

Summary The epithelial lining of the mucosa of the edentulous, maxillary alveolar ridge was subjected to an ultrastructural and stereological analysis. Four biopsies collected from the non-inflamed crest, i.e., the center over former tooth sockets, in non-denture-wearing female patients 30 to 55 years of age were processed for light and electron microscopy. At the light-microscopic level, epithelial thickness was determined histometrically. Electron micrographs were sampled at two levels of magnification, from five strata in regions of epithelial ridges and from three strata over connective tissue papillae. Standardized stereological pointcounting techniques were employed to analyze a total of 990 electron micrographs. Observations and data revealed that at the alveolar ridge the oral epithelium is truly keratinizing and comprises four strata including a 40±5 m-thick stratum corneum, which displays the oral keratin pattern. The histoand cytodifferentiation were peculiar: (1) Compared to the neighbouring gingival and hard palate epithelium, that of the alveolar crest was markedly thicker, with elongated rete ridges indicating acanthosis. (2) The cytoarchitecture was identical neither to the gingival nor to the hard palate epithelium but revealed a mixture of features typical for either of these two epithelia. Reasons for this are explained on the basis of factors, possible genetic, inherent in epithelial cells that are possibly derived from both the gingival and the palatal environment.     

Characterisation of the anti-bladder-cancer monoclonal antibody BLCA-8: Identification of its antigen as a neutral glycolipid

A monoclonal antibody, BLCA-8, was raised against the human bladder cancer cell line, UCRU-BL-17CL. By flow cytometry and immunoperoxidase staining, this antibody was found to possess high specificity for bladder tumours, some reactivity with fetal tissues, and no reactivity with normal bladder, or any normal or malignant tissue. This high specificity and the stability of the antigen to the urinary environment suggest that BLCA-8 may have potential for use as an anti-bladder-cancer therapeutic agent. By thin-layer chromatography and autoradiography, BLCA-8 was found to bind four components within the neutral lipid fraction of a bladder cancer cell line, UCRU-BL-17/23. These components hadR _F values of 0.22, 0.16/0.15 (doublet), 0.12 and 0.08, and migrated below globoside, indicating the presence of more than four sugars. By enzyme-linked immunosorbant assay and thin-layer chromatography it was found that the binding of BLCA-8 to the lipid extract was increased by both mild alkaline hydrolysis and enzymatic treatments, indicating that adjacent phospholipids and glycolipids interfere with the accessibility of the antibody-binding site. Full biochemical characterisation of the BLCA-8 antigen is currently underway.     

Basement membrane components of bronchial epithelium in humans suffering from chronic nonspecific lung diseases

Collagen IV and laminin are important constituents of the basement membrane (BM). By use of immunocytochemistry we examined the occurrence and distribution of these two components in the BM beneath normal, mucoid and metaplastic epithelium of large bronchi in 22 adults suffering from chronic nonspecific lung diseases. Both collagen IV and laminin were expressed as a thin and continuous layer beneath the epithelium in most tissue specimens with normal epithelium. In a few specimens the layer showed interruptions with a patchy distribution of the immunoreactivity. Three patterns of distribution of BM components were found under the metaplastic epithelium. Total absence of immunoreactive collagen IV and laminin was the most common variant. Weak and scarce staining for both proteins in the BM characterized the second pattern. The third variant showed strong collagen IV immunoreactivity but lack of laminin. The BM beneath the mucoid epithelium was characterized by irregular distribution of collagen IV and laminin. We suggest that the occurrence and distributional pattern of the BM components are related to the type of overlying epithelium and connected with an altered synthesis of these components.     

Organotypic growth and differentiation of human mammary gland in sponge-gel matrix supported histoculture

Summary Blocks of breast tissue obtained during radical mastectomies from 23 patients with mammary gland carcinomas were used for cultivation in native-state, gel-supported histocultures. We show that the human mammary gland can be successfully maintained in this system so that normal epithelial breast structures proliferate and undergo differentiation for several weeks and a well-developed system of ducts and lobules is formed. Using antibodies to individual keratins 17 and 8 we have shown for the first time that ducts and alveoles developing in vitro undergo differentiation into the lining epithelium and myoepithelium in the same way as mammary gland epithelium in vivo. Growth of epithelial structures in vitro is also accompanied by the development of continuous basal membrane.     

The goblet cavity matrix in the larval midgut of Hyalophora cecropia

The larval midgut of the silkmoth Hyalophora cecropia was examined using scanning electron microscopy. Goblet cells were observed to contain within their cavities a matrix plug. This matrix material was extruded onto the lumen side of the epithelium when the tissue was stretched. The rôle of this matrix material in maintenance of the capacity of the midgut to transport ions in vivo and in vitro is discussed.     

The seminiferous epithelium in the guinea fowl (Numida meleagris)

Summary Spermiogenesis and cellular associations in the seminiferous epithelium of the guinea fowl were studied and described in sexually active adult birds. PAS stain was found to be useful in the recognition of steps of spermatid differentiation only in the first early stages. Nuclear morphological changes were subsequently found to be more reliable in tracing steps of spermiogenesis. It was observed that haematoxylin-eosin stained tissue can be used in the study of spermiogenesis in the bird. Various stages of the seminiferous epithelium were observed in any cross-section of the seminiferous tubules. Distinct cellular associations were observed, but intermix of adjacent germ cells or heterogenous cellular associations were frequently encountered.     

Ultrastructure of the respiratory epithelium in the lungs of the tortoise,Testudo graeca

The respiratory epithelium in the lungs of the tortoise (Testudo graeca) has been studied by electron microscopy. The epithelium consists of a mosaic of two different cell types (here called "pneumonocytes"). Type I pneumonocytes are roughly squamous and possess attenuated flanges of cytoplasm which extend over the septal capillaries. Localized cytoplasmic expansions are often present near the periphery of these flanges. Most of the organelles are concentrated in the perinuclear region; the most prominent of these are the mitochondria and osmiophilic inclusions. In contrast, type II pneumonocytes are cuboidal and are richly endowed with organelles including large Golgi complexes, extensive endoplasmic reticulum and numerous inclusion bodies. The morphological evidence suggests that type I pneumonocytes are involved in the secretion of osmiophilic material (presumed to be pulmonary surfactant) and in maintaining the integrity of the air-blood barrier. Type II pneumonocytes appear to be concerned solely with the production of surfactant.