Qualitative hydrological and land-use planning tool for the Israel Coastal aquifer.

Due to a variety of past and present land-usages on the aquifer ground surface, appropriate groundwater management should consider anthropogenic activities on the ground surface and the potential of unsaturated zone media to convey water and pollutants to the aquifer. The objective of this paper is to present an approach which generates guidelines and recommendations which can lead to sustainable development. This method assesses the lithological characteristics of the aquifer's vadose zone, indicating potential rechargeability, while weighting factors leading to potential groundwater pollution resulting from some land-use. Recommendations regarding land-use planning and aquifer recharge can then provide a qualitative ecological tool towards sustainable groundwater management. Owing to its location, its critical significance to the country's fresh water supply, and its available field data, Israel's Coastal aquifer is employed here as the study area for implementation of this approach.

Histological changes in TSH-dependent tumours of the thyroid gland during serial transplantation in Fischer 344 rats.

Transplantable tumours were induced in the thyroids of Fischer 344 rats fed thiouracil (TU) in a moderately low iodine diet for 8-13 months. Pieces of hyperplastic thyroid were implanted subcutaneously into rats fed a TU containing diet. Almost all implants gave rise to very small vascularized transplants but there were three significantly larger, pieces of which were transplanted again and gave rise to the tumour lines. From the third transplantation generation on, pieces of tumours were implanted into rats treated to have elevated circulating thyrotropin and a group fed a high iodine diet. With some exceptions, the implants grew only in rats fed the TU or a low iodine diet and yielded TSH-dependent tumours. Almost all the tumours observed initially were papillary, and most of the remainder had colloid-filled follicles bounded by columnar cells. One line of tumours was of the latter type for eight generations. The others had more complex histories, in which there were sublines that were papillary for eight or nine generations, whereas, others became progressively more cellular or follicular, and more heterogeneous with respect to histological types present per section at rates that varied with the subline. The large number of population doublings necessary to make a one gram tumour from a single original tumour cell indicates that the cells of dependent papillary tumours were immortalized.

Summary of observations on transplantable tumors of the rat thyroid gland.

Transplantable tumors of the thyroid gland have been produced by feeding of thiouracil (TU) to inbred Fischer 344 rats followed by the transplantation, initially, of pieces of hyperplastic thyroid gland, and in later generations, of pieces of transplanted tissue into similar rats or into rats fed a high iodine diet. In early generations, transplants grew only in the rats fed the TU diet, and this tissue was called dependent, whereas if the tissue grew in rats fed the high iodine diet in the absence of TU, it was called independent. Dependent tumors were, initially, either papillary or of follicles distended with colloid. Later generations of some sublines were cellular or microfollicular in pattern and some became progressively more heterogeneous with later generations. Independent tumors began to appear by the third transplant generation. They were, initially, relatively uniform in pattern, and some tended to remain so, whereas other sublines exhibited some heterogeneity. Tumors had patterns that were cellular, or microfollicular, or follicular or had open follicles, etc.; there was one cellular ascites tumor subline. Other observations were made of vascular patterns, connective tissue, necrosis, and metastases.

Kinetics of equilibration of radioiodide in individual mouse thyroid follicles in vivo.

Microdensitometric measurements were made on autoradiographs of radioiodide localized in mouse thyroids subjected to various degrees of stimulation, in which the formation of organic radioiodide was acutely blocked. Estimates were made of the relative concentrations of radioiodide in lumens and cells of follicles and in the nearby blood vessels. Simple models were introduced to interpret the data. Analysis of the ratio of radioiodide concentrations in the lumen and cells of follicles as a function of follicles size and time after injection indicated that smaller follicles equilibrated faster than larger follicles, that the equilibration was faster the more active the gland was, and that the release of radioiodide from follicles in the less active glands must be characterized by a time-dependent exit rate constant. Analysis of the relative concentration of luminal radioiodide as a function of follicle size at short time intervals and in the steady state indicated that the transport properties of the average epithelial cell were generally independent of follicle size.

Histologic changes in tissue components of the hyperplastic thyroid gland during its involution in the rat.

Male Fischer rats were fed a low-iodine diet containing thiouracil for 21 days to produce hyperplastic thyroid glands, and then fed a high-iodine diet for various time intervals, from 5 hr to 180 days, in order to study the morphological changes that occur during involution. Thyroids were fixed by perfusion fixation and embedded in Epon. Sections were examined by light microscopy. Initially at 0 days of involution (at the time of the change to the high-iodine diet), follicular lumens were very narrow and capillary lumens were very wide. The capsule was thick and infiltrated with mononuclear leukocytes. No obvious changes occurred for 1 day after the change in diet, but shortly thereafter capillary lumens began to narrow. By 4 days, most capillary lumens were close to normal size; capillaries formed a more or less normal bed except that many were embedded in a relatively thick or wide interfollicular matrix. This matrix was largely gone by 21 days. Between 1 and 21 days, follicular lumens dilated progressively as colloid accumulated. The density of staining of the accumulated colloid varied from follicle to follicle, and this variation was also observed in older controls. Inflammatory cells gradually disappeared from the capsule and most were gone by 15 days. Starting at approximately 15 days and continuing to 180 days, one or more disintegrating cells were found in some lumen profiles. Colloid goiters were not observed in these rats even after several months of involution. Some lumens were rather large, however, and small fractions of the follicles, both small and large, were bounded by flat cells and resembled "cold" follicles morphologically.

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.

Comparison of a special class of epithelial cells in hyperplastic thyroids undergoing involution and in thyroids in hypophysectomized rats.

In male Fischer rats, a class of follicles with flat epithelium is present as a minor component of thyroid glands in which most of the follicles have cuboidal epithelium. These follicles occur in thyroids that have been made hyperplastic by feeding the rats thiouracil for 21 days and then allowing involution for 21 days or more. They also occur in older control rats. The follicles resemble in morphology, at the light-microscope level, the so-called "cold" follicles that occur in aged mice. We have examined the ultrastructure of the flat cells in these follicles and compared it with that of the flat cells occurring in the thyroid follicles of hypophysectomized rats. The cells in involution have abundant rough endoplasmic reticulum (RER) and few lysosomes and, in these respects, differ markedly from cells in hypophysectomized rats. The follicles with flat cells are surrounded by a normal incidence of blood capillaries, so that the cells do not appear to be deprived of access to an adequate supply of materials necessary to satisfy their metabolic requirements. Their abundant RER suggests that they have thyroid-stimulating hormone (TSH) receptors, so that the flat cell may be the result of some process occurring at a step distal to receptor coupling with TSH. Their occurrence in young rats after the induction of hyperplasia may be a consequence of cell multiplication producing a clone of neighboring abnormal cells that have an abnormally small cell height.

Cell polarity and water transport in thyroid epithelial cells in separated follicles in suspension culture.

Separated thyroid follicles maintained in suspension culture can be used to study the properties of thyroid epithelium in the virtual absence of other cell types and to study the effect of extracellular materials on the follicles. They can be prepared by enzymatic separation of thyroid into single cells followed by reaggregation of the epithelial cells and also by collagenase treatment of thyroids to release follicles and sheets of epithelia that can be separated from other materials by differential filtration. The follicles can exist with normal orientation or inverted (inside out). The follicles are inverted in the presence of high serum concentrations (5%) but can have normal orientation when embedded in a type I collagen gel, even at high serum concentrations. When normally oriented follicles invert, the polarity of the epithelial cells reverses while they are connected to neighbors. During inversion, bipolar cells are observed having microvilli-bearing surfaces at both lumen and medium. Inverted follicles can revert to normal orientation when embedded in collagen gel. Various functional properties of normally oriented follicles are similar to those of follicles in vitro. However, inverted follicles do not concentrate iodide, although they synthesize thyroglobulin and secrete it into the medium. Mutants are available in established cell lines. They have functional and organizational properties that differ from those of normal cells and demonstrate a lack of coupling between functional properties and organization.(ABSTRACT TRUNCATED AT 250 WORDS)

Change of inverted thyroid follicle into a spheroid after embedding in a collagen gel.

When inverted thyroid follicles in suspension culture are embedded in a collagen gel, there is extensive reorganization of the follicle. To identify intermediate stages in the reorganization, a suspension of inverted follicles was mixed with a cold solution of collagen (0.1 mg/ml) in culture medium and the resultant was warmed and allowed to gel. Prior to embedding, the epithelial cells bounding the lumens formed a monolayer of attenuated cells with their microvilli-bearing surface in contact with the medium. The first change noted was a shrinkage of the lumen in many follicles by 18 h. The cells became cuboidal to columnar. Some of the cells had long sheet-like processes extending into the lumen in contact with those of other cells. In late stages of the reorganization, 48 h, the cells were arranged in a compact spheroid. The spheroids contained two different kinds of colloid-filled lumens, possibly of different origins, one a spherical microlumen, the other very long and narrow in section. The peripheral cells of the spheroid had a smooth plasma membrane (without microvilli) in contact with collagen. Although most of the cells in a section had a microvilli-bearing surface forming part of the boundary of a lumen, it is not certain that all cells were in contact with a lumen.

Sudden volume changes of the lumen of inverted thyroid follicles in suspension cultures. Use in estimation of rates of water flux through thyroid epithelium.

Inverted thyroid follicles in suspension culture were observed using dark-field illumination and time-lapse video enhancement techniques. The lumens of many follicles undergo episodes of rapid shrinkage followed by relatively slow dilation. The extent of shrinkage ranged from 10 to 40% of the initial diameter. The decrease in lumen diameter is accompanied by loss of luminal fluid. The rate of efflux of fluid amounted to from 1 to 90 microns3/micron2 of luminal surface/min. This was followed after several minutes by a slow and generally linear increase in lumen diameter with time that could be accounted for by an influx of fluid of the order of 0.5 micron3/micron2/min. It is possible that this phenomenon is due to a continued influx of fluid into the lumen until a junction opens between cells allowing a sudden loss of luminal fluid. The junction reseals and fluid begins to accumulate in the lumen. The phenomenon may be a three-dimensional analogue of the behavior of domes.

Honeycomb structure of the apical surface of thyroid epithelium during involution of the hyperplastic thyroid gland.

A heretofore undescribed feature consisting of closely packed pits 0.5-1 micron in diameter was observed on the apical surface of thyroid epithelial cells. The walls of the pits were generally smooth, except at the base where there was a high incidence of irregularities looking like sites of recent fusion of apical vesicles with the pits. The matrix of the partition between pits was similar to the matrix of pseudopods in these cells in being free of membrane-bounded organelles and containing a low concentration of ribosomes. The pits were observed early in the involution of the hyperplastic gland, most prominently between 14 h and 8 days of involution. This is a time when thyroglobulin is accumulating in follicular lumens and the apical end of the epithelial cells usually contains a high concentration of apical vesicles ordinarily considered to be exocytic in character. It is important to recognize the existence of this feature to avoid confusing profiles of it with structures involved in macropinocytosis.

Embedding in a collagen gel stabilizes the polarity of epithelial cells in thyroid follicles in suspension culture.

Separated thyroid follicles are stable in suspension culture in Coon's modified Ham's F12 medium containing 0.5% calf serum. They resemble follicles in vivo except for the absence of a basal lamina. However, the epithelial cells reverse polarity and the follicles invert when the serum concentration is raised to 5%. A number of substances, especially components of extracellular matrix, were added to the medium to ascertain if they could stabilize the follicles against inversion in 5% serum. Cellular and plasma fibronectin, gelatin, heat-denatured collagen, methylcellulose and laminin did not stabilize. The addition to the medium of as little as 50 micrograms/ml of acid-soluble collagen prepared from calf skin or rat tail tendons resulted in the formation of small clouds of gel. Follicles embedded within the gel were stabilized. Follicles in the same dish but not embedded in the gel inverted. Stabilization was not specific for collagen, since follicles embedded in a plasma clot were also stabilized. A gel was not sufficient for stabilization, since embedding in an agarose gel did not stabilize. Ultrastructural studies indicate that adherence to a limited number of gelled fibers of collagen covering only a small fraction of the basal plasma membrane may be sufficient to stabilize and that a basal lamina formed in the presence of laminin but without added collagen does not stabilize.

Capillary endothelial cell multiplication in adipose tissue pads on the thyroid during the feeding of thiouracil.

It has been reported that blood capillaries in adipose tissue pads on the upper and lower poles of the thyroid gland enlarge when Fischer rats are fed thiouracil (TU) in a low iodine diet. To test whether the enlargement is accompanied by proliferation of the endothelial cells, [3H]thymidine was injected into rats fed the TU-containing diet, and labeling of the endothelial cells was studied by autoradiography. Nuclear labeling of the capillary endothelial cells was observed in the mixed brown and white adipose tissue (BAT and WAT, respectively) pads on the thyroid. After a single pulse of [3H]thymidine, 10% of the nuclei were labeled at 10 days (the peak labeling), and labeling decreased thereafter. To test whether the adipose tissue was stimulated because of the poor nutritional quality of the low iodine diet, Purina Laboratory Chow (a nutritionally adequate diet) was tested and produced the same result. To test whether TU had a direct effect, 5 micrograms T4/100 g BW were given daily; there was then no response to the TU, suggesting that the effect was due to an elevated circulating concentration of TSH. The effect was generally restricted to the adipose tissue pads on the thyroid. There was no response in interscapular BAT, epididymal WAT, or sc WAT. However, there was a response in small clusters of adipocytes embedded in inguinal sc WAT. The results are consistent with the idea that the effects are directly or indirectly due to elevated circulating TSH levels.

Basal lamina formation on thyroid epithelia in separated follicles in suspension culture.

When thyroid follicles are isolated by collagenase treatment of minced thyroid lobes, the basal lamina around each follicle is removed. The basal lamina does not reform when follicles are cultured in suspension in Coon's modified Ham's F-12 medium containing, in addition, 0.5% calf serum, insulin, transferrin, and thyrotropin. We have added acid soluble collagen and/or laminin to see if they would result in the formation of a basal lamina. An extended basal lamina did not form when follicles were embedded in a gel formed from acid-soluble rat tendon collagen or from calf skin collagen when added at a concentration of 100 micrograms collagen/ml. However, laminin at a concentration of 5.1 micrograms/ml gave rise to short segments of a basal lamina within 30 min. At longer time intervals, the segments lengthened and covered the base of many cells, and were continuous across the gap between cells and across the mouth of a coated pit. Not all basal surfaces were covered, and no exposed apical surfaces with microvilli had a basal lamina. There was no obvious difference in the appearance of the basal lamina if collagen was added in addition to laminin, but collagen, in contact with the plasma membrane when added alone, was lifted off the membrane in the presence of the basal lamina. The basal lamina appeared denser if formed in the presence of 5% serum instead of 0.5%.

Shedding of dense cell fragments into the follicular lumen early in involution of the hyperplastic thyroid gland.

Membrane-bounded fragments of thyroid epithelial cells are found in the lumen of the thyroid follicle at early stages of involution of the hyperplastic gland. To demonstrate this, thyroid glands were made hyperplastic by feeding rats a low iodine diet containing thiouracil for 3 weeks. Involution was induced by the feeding of a high iodine diet. Three types of dense cell fragments were observed in the lumen at its periphery within 5 hours after the change of diet: (1) single, relatively large fragments that contained vesicles occasionally, (2) a cluster of rounded fragments of relatively small size. Some of these had a narrow tail, and (3) elongated narrow fragments in a row parallel to the apical surface of one or more epithelial cells. The fragments are probably derived from the thyroid epithelial cells since no other cell types were generally present. By 14 hours the fragments were distributed randomly throughout the lumen. Fragments were no longer present by 12 days of involution in most follicles. Fragment formation may be a mechanism for disposal of excess plasma membrane deposited by exocytic vesicles during rapid secretion of thyroglobulin into the follicular lumen early in involution.