Ultrastructure of erythrophagocytosis and red blood cell fission by thyroid epithelial cells in vivo

Fine-needle aspiration of subacute granulomatous thyroiditis (De Quervain's thyroiditis): a clinico-cytologic review of 36 cases

Although subacute granulomatous thyroiditis (SGT) is usually diagnose clinically, there are other thyroid conditions that must be ruled out. This task is achieved by means of fine-needle aspiration (FNA). In retrospect, the clinical and cytologic findings seen in 36 SGT cases are reassessed with a view to deciding which findings are most reliable for reaching a confident cytologic diagnosis. These are: the simultaneous presence in the same aspirate of the following cells: 1) follicular cells with intravacuolar granules and/or plump transformed follicular cells; 2) epithelioid granulomas; 3) multinucleated giant cells; 4) an acute and chronic inflammatory dirty background; 5) the absence of the following cells: fire-flare cells, hypertrophic follicular cells, oncocytic cells, and transformed lymphocytes. The absence of one or more of these requirements does not exclude SGT but does increase the number of thyroid conditions that come into the differential diagnosis. In these cases, it is essential to review clinical data carefully and to submit the patient to a close clinical and FNA follow-up.

Erythrophagocytosis by cultured skin fibroblasts from patients with hereditary metabolic disorders

Phagocytosis of native allogenic red blood cells was observed in cultures of skin fibroblasts obtained from patients with neuronal ceroid-lipofuscinosis, Niemann-Pick disease type C and morbus Fabry. Occasional phagocytizing cells were observed in 9 other syndromes. Cells from three normal donors did not phagocytize.

Ultrastructural changes in thyroid epithelium during involution of the hyperplastic thyroid gland

The ultrastructure of the thyroid epithelial cell was examined at various time intervals after induction of involution of the hyperplastic thyroid gland. Thyroids were made hyperplastic by the feeding of thiouracil in a Remington low-iodine diet to male Fischer rats for 3 weeks. Involution was induced by replacing the thiouracil-containing diet with Purina Laboratory Chow, a high-iodine diet. During involution, organelles that play a role in the synthesis and secretion of thyroglobulin, such as the rough endoplasmic reticulum, Golgi apparatus, and apical vesicles, were well preserved and prominent features of the epithelial cell. The apical plasma membrane of many cells was highly irregular for approximately 2 weeks with signs suggesting rapid discharge of apical-vesical contents into the lumen of the follicle. Pseudopods and colloid droplets were present but were not very prominent features of the cell. No signs of extensive autophagy or obvious increased incidence of lysosomes were present, although there was an elevation in the incidence of small dense bodies starting about day 8, and prominent by 15 days. Some of these may be phagosomes formed from luminal debris. The observations indicate that involution of the hyperplastic thyroid in which there is maintenance of the protein synthetic apparatus and little sign of autophagy or death of the epithelial cells is remarkably different from phenomena occurring during involution of prostate or mammary glands.

Three-dimensional aspects of blood vessels in thyroids from normal, low iodine diet-treated, TSH-treated, and PTU-treated rats

Three-dimensional images of blood vessels in thyroid glands from normal, low iodine diet-treated, thyroid-stimulating hormone (TSH)-treated and propylthiouracil (PTU)-treated rats were investigated by use of the corrosion-cast method. The vascular casts made by the injection of methacrylate resin were observed with the scanning electron microscope. In normal animals, each follicle is surrounded by a clearly defined basket-like capillary network, which is generally independent of adjacent networks, though a few anastomoses or common capillaries are sometimes seen. In low iodine diet-treated or TSH-treated animals, the capillaries in the basket-like network become markedly dilated and fuse with one another. Though the vascular casts of PTU-treated animals are similar to those of low iodine diet-treated or TSH-treated ones in some aspects, most basket-like networks become distorted and irregular in shape, and the capillaries are heterogeneously dilated and show many buds, branches and anastomoses. We consider that these peculiar changes in the thyroid of the PTU-treated animals are due not only to the elevation of serum TSH but also to other unknown factors. It is clear that the distribution and morphology of the thyroid capillaries are extremely affected and changed by functional states of the gland.

Fine structural aspects of phagocytotic activity in inverted follicle cells of cultured porcine thyroids

Inversion of thyroid follicles took place when they were isolated by collagenase and trypsin and cultured in suspension in Eagle's medium supplemented with 10% fetal calf serum without TSH. The apical surface facing the culture medium contained numerous microvilli and a central cilium, while the luminal surface became flattened. Phagocytotic activity by pseudopods was promoted after addition of TSH to the culture medium. When the inverted follicles were incubated in culture medium containing TSH (50 mU/ml) and human red blood cells, or TSH and polystyrene latex beads (2.02 micron in diameter) for 1-3 h, numerous red blood cells or latex beads respectively were observed to be taken up by the epithelial follicle cells by scanning electron microscopy, as well as conventional thin-section electron microscopy. These results show that the apical surface (culture medium side) of the epithelial cell of the cultured thyroid follicle whose polarity is reversed phagocytoses red blood cells and latex beads.

Engulfment of erythrocytes by intestinocytes of the rat ileum

The innervation of ileal mucosa of normal, unanaesthetized male Wistar rats was investigated electronmicroscopically. The presence of RBC inside intestinocytes was a secondary, but frequent observation in 4 of 20 rats. No sign of hemorrhage or trauma of the tissue was noted, and the rats had not been exposed to any known toxic agent. The study demonstrates that also intestinocytes have the capacity to engulf RBC, as many other types of epithelial cells. However, previous demonstration of RBC phagocytosis of epithelia was performed in tissues where hemorrhage had occurred for various reasons. In contrast, the rats of the present study were considered normal, although the influence of unknown agents cannot be ruled out.

New models of cellular control: membrane cytoskeletons, membrane curvature potential, and possible interactions

The concepts of "membrane cytoskeletons" (proteins attached to the cytoplasmic face of the membrane to give rigidity and control of lateral protein diffusion) and of membrane curvature potential are briefly reviewed. Possible modes of attachment of the membrane cytoskeleton to the bilayer are discussed, and a detailed calculation of possible sources of membrane curvature potential in the red cell is made. The 2 control systems are then used to illustrate possible mechanisms for some cellular processes, such as vesicle formation and release, pseudopod formation, and red cell aging. It is concluded that combination of these concepts allows control mechanisms which appear to act at a distance, or have other unusual systems properties.

Erythrocytes within pancreatic B-cells of corticosteroid-treated mice

An ultrastructural study of the endocrine pancreas of female ICR mice that received 21 daily injections of the synthetic glucocorticoid, Triamcinolone diacetate (8 mg/kg b.wt) revealed some examples of microhaemorrhage within islets of Langerhans, extravasation of erythrocytes, and the presence of erythrocytes within B-cells, where they undergo degradation to form myelin-like configurations.

Spheroidal filamentous inclusion body cells in von Recklinghausen's disease

Cells with spheroidal filamentous cytoplasmic bodies, distinctive by both light and electron microscopy, were found in a neoplasm arising from the sciatic nerve of a patient with von Recklinghausen's disease. Tissue fixed with formalin and embedded in paraffin for three years was deparaffinized, reprocessed, and examined with the electron microscope. The morphology of the spheroidal body cells, the close resemblance to erythrophagocytosis, and the possible significance of the changes are discussed.