Apical cytoplasm

About: Apical cytoplasm is a research topic. Over the lifetime, 1080 publications have been published within this topic receiving 36131 citations.

Ultrastructural and Histochemical Observations on Serous Ovarian Cystadenomas

Abstract: One hundred and twelve serous ovarian cystadenomas (46 benign, 33 tumours of borderline malignancy and 33 malignant tumours) were investigated with histological and mucin histochemical methods. Electron microscopy was applied to 9 benign, 6 borderline and 5 malignant tumours. The epithelium of the benign serous cystadenomas contained ciliated and nonciliated columnar cells, which sometimes were edematous ("pale cells"), and smaller basal cells. The large Golgi apparatus with small secretory vesicles and occasional larger secretory granules was located in the apical cytoplasm. There were numerous pinocytotic vesicles at the basal plasma membrane. The extracellular mucin in the cystic lumen and the mucin on the apical epithelial border consisted of material with vic-glycols (1.2-hydroxyl groups) mixed with sulpho- and carboxymucin. With increasing degree of malignancy the number of ciliated cells diminished and were not found in the malignant epithelium. The number of nucleoli and the amount of carboxymucin with sialic acid residues increased with increasing degree of malignancy. However, there were no single consistent ultrastructural feature which could be considered as a reliable criterion for malignancy of these tumours in the absence of invasive growth. The findings support the view that serous ovarian cystadenomas are of coelomic origin.

Discovery of three novel coccidian parasites infecting California sea lions (Zalophus californianus), with evidence of sexual replication and interspecies pathogenicity.

Abstract: Enteric protozoal infection was identified in 5 stranded California sea lions (Zalophus californianus). Microscopically, the apical cytoplasm of distal jejunal enterocytes contained multiple stages of coccidian parasites, including schizonts with merozoites and spherical gametocytes, which were morphologically similar to coccidians. By histopathology, organisms appeared to be confined to the intestine and accompanied by only mild enteritis. Using electron microscopy, both sexual (microgametocytes, macrogamonts) and asexual (schizonts, merozoites) coccidian stages were identified in enterocytes within parasitophorous vacuoles, consistent with apicomplexan development in a definitive host. Serology was negative for tissue cyst-forming coccidians, and immunohistochemistry for Toxoplasma gondii was inconclusive and negative for Neospora caninum and Sarcocystis neurona. Analysis of ITS-1 gene sequences amplified from frozen or formalin-fixed paraffin-embedded intestinal sections identified DNA seque...

Immunocytochemical localization of vitamin A in the retina and pineal organ of the frog, Rana esculenta.

Abstract: Vitamin A immunoreactive sites were studied in the retina and pineal organ of the frog, Rana esculenta, by the peroxidase antiperoxidase, avidin-biotinperoxidase and immunogold methods. In dark-adapted material, strong immunoreaction was found in the outer and inner segments of the photoreceptor cells of both retina and pineal organ, as well as in the pigment epithelium, retinal Muller cells and pineal ependymal cells. In light-adapted retina, cones and green (blue-sensitive) rods were immunopositive. At the electron microscopic level, immunogold particles were found on the membranes of the photoreceptor outer segments as well as on the membranes of the endoplasmic reticulum and mitochondria. Individual retinal photorecptor cells exhibited strong immunoreaction in the distal portion of the inner segment, the ciliary connecting piece and the electron-dense material covering the outer segment. In the pigment epithelium, the immunolabeling varied in intensity in the basal and apical cytoplasm and phagocytosed outer segments. The immunocytochemical results indicate that retinoids (retinal, retinol and possibly retinoic acid) are present not only in the photoreceptor cells of the retina but also in those of the pineal organ. The light-dependent differences in the immunoreactivity of vitamin A underlines its essential role in the visual cycle of the photopigments. Our results suggest that the pineal ependyma plays a role comparable to that of the Muller cells and pigment epithelium of the retina with regard to the transport and storage of vitamin A. The presence of a retinoid in nuclei, mitochondria and cytoplasmic membranes suggests an additional role of vitamin A in other metabolic processes.

Ultrastructural characteristics of tuft cells in mouse gallbladder epithelium.

Abstract: Mouse gallbladder was fixed by perfusion or immersion in glutaraldehyde and/or osmium tetroxide for electron microscopy. Besides usual columnar epithelial cells there were infrequent tuft cells in the epithelium. The cells rested on the basal lamina and extended to the gallbladder lumen. The microvilli on the apical cell surface were tall and thick and there was a rich network of microfilaments radiating from the core of the microvilli to the apical and juxta-nuclear cytoplasm. Among the bundles of microfilaments there were vertically oriented microtubules in the apical cytoplasm. Although the function of the tuft cells in the gallbladder epithelium remains unknown, it is proposed that their unique morphology may reflect a specialized resorptive function involving motility of microvilli and other cell organelles.