On Stereological Estimation of Second-order Characteristics and of the Hard-core Distance of Systems of Sphere Centres

For planar and thin sections of sphere systems integral equations are given which connect second-order quantities of the point process of sphere centres with second-order quantities of the point process of intersection circle centres. For special point process models, which serve as sphere centres, the planar second-order quantities are calculated and discussed. Some simple stereo-logical formulae for the estimation of the hard-core distance are given when the sphere centres form a hard-core process.     

Instillation and Fixation Methods Useful in Mouse Lung Cancer Research

The ability to instill live agents, cells, or chemicals directly into the lung without injuring or killing the mice is an important tool in lung cancer research. Although there are a number of methods that have been published showing how to intubate mice for pulmonary function measurements, none are without potential problems for rapid tracheal instillation in large cohorts of mice. In the present paper, a simple and quick method is described that enables an investigator to carry out such instillations in an efficient manner. The method does not require any special tools or lighting and can be learned with very little practice. It involves anesthetizing a mouse, making a small incision in the neck to visualize the trachea, and then inserting an intravenous catheter directly. The small incision is quickly closed with tissue adhesive, and the mice are allowed to recover. A skilled student or technician can do instillations at an average rate of 2 min/mouse. Once the cancer is established, there is frequently a need for quantitative histologic analysis of the lungs. Traditionally pathologists usually do not bother to standardize lung inflation during fixation, and analyses are often based on a scoring system that can be quite subjective. While this may sometime be sufficiently adequate for gross estimates of the size of a lung tumor, any proper stereological quantification of lung structure or cells requires a reproducible fixation procedure and subsequent lung volume measurement. Here we describe simple reliable procedures for both fixing the lungs under pressure and then accurately measuring the fixed lung volume. The only requirement is a laboratory balance that is accurate over a range of 1 mg–300 g. The procedures presented here thus could greatly improve the ability to create, treat, and analyze lung cancers in mice.     

Quantitative morphological changes of the uterine gland cells in relation to physiological events during a pregnancy cycle in Glossina morsitans morsitans

Secretory cells of the uterine gland were investigated morphometrically during the second pregnancy cycle in Glossina morsitans morsitans. In early pregnancy when an egg was present in the uterus, morphometric parameters of the nucleus, the cytoplasm and its organelles were markedly low coincident with low physiological activity in the gland cells. This is the period when a proportion of the assimilated amino acids from the digested blood meals are converted to triglyceride in the fat body and stored. During the second half of pregnancy, when a larva was present in the uterus, there was a striking increase of the cytoplasmic and organelle volumes as well as of the surface areas of rough and smooth endoplasmic reticulum. There was also a marked augmentation of triglyceride-like inclusions, and later of secretory vesicles which released their content into enlarging extracellular reservoirs. This indicated a markedly high activity in the gland cells concomittant with the period of rapid synthesis of large amounts of proteins and lipoproteins destined for the growing intra-uterine larva. Mitochondrial parameters also increased, probably to generate adequate energy for synthesis, transport and secretion of nutriments for the larva. After larviposition, a marked reduction of cellular parameters was measured, and the volume density of lysosome-like structures had increased, indicating that larviposition is followed by degradation of large amounts of cellular organelles involved in biosynthetic processes. Morphometrical investigation of the uterine gland cells demonstrated a temporal correlation of the cellular dynamics with physiological events involved in producing a fully developed third-instar larva at the end of a pregnancy cycle.     

Use of Low Temperature Scanning Electron Microscopy to Observe Frozen Hydrated Specimens of Nematodes

Frozen hydrated specimens of Pratylenchus agilis and dauer larvae of Steinernema carpocapsae were observed with low-temperature field emission scanning electron microscopy. This new technique provides information about the surface features of nematodes and also allows specimens to be fractured to reveal their internal structure. Furthermore, both halves of fractured specimens can be retained, examined, and photographed either as two-dimensional micrographs or as three-dimensional images for stereo observation (stereology) or quantitative measurements (stereometry). This technique avoids artifacts normally associated with procedures required to prepare nematodes for examination in the transmission and scanning electron microscopes, such as chemical fixation, dehydration, and sectioning or critical point drying.     

Comparison of the phagocytosis of two types of cyclosporin (SDZ OXL 400 and SDZ IMM 125) by alveolar macrophages from hamsters

The aim of this study was to compare two types of cyclosporin (Cs) particles, SDZ OXL 400 and SDZ IMM 125, the latter being more hydrophilic, to understand their uptake by airway macrophages. Alveolar macrophages (AM), harvested by bronchoalveolar lavage (BAL) of hamster lungs, were cultured with two different doses (0.1 mg and 0.5 mg) for 1 h, 6 h, and 24 h. Control incubations without Cs particles or with latex particles were carried out simultaneously. Cell viability, cell activation (i.e., respiratory burst, interleukin-6 (IL-6) synthesis) and mean volume of particles phagocytosed per macrophage were measured. Both types of Cs particles did not modify the AM viability, and failed to induce IL-6 synthesis during phagocytosis but slightly decreased the cell oxidative respiratory burst. The comparison between SDZ OXL 400 and SDZ IMM 125 showed that for the lower dose the mean volume of both Cs types phagocytosed was similar at 1 h and 6 h. At 24 h an increase of the mean volume phagocytosed was seen for SDZ IMM 125 but not for SDZ OXL 400. For the higher dose the mean volume of SDZ IMM 125 phagocytosed was higher than SDZ OXL 400 at 1 h and 6 h and comparable for both types at 24 h. SDZ IMM 125 particles were phagocytosed more rapidly than SDZ OXL 400. The mean volume of phagocytosed latex particles increased with time and dose and was higher than for both Cs particle types. In conclusion, AM were seen to phagocytose particles of different physical properties (i.e., form, size, and shape), chemical properties (i.e., inert or peptidic) and degrees of hydrophilicity in a different manner.     

THE DEVELOPMENT AND POTENTIAL ROLES OF CELL‐WALL TRABECULAE IN CAULERPA MEXICANA (CHLOROPHYTA)1

Siphonous plants represent an alternate scheme to the way most macroscopic plants are constructed. They are single, often large (1–2 m), sometimes morphologically complex, multinucleate (coenocytic) cells where the whole of the cytoplasm is a continuum. Caulerpa mexicana Sond. ex Kütz. is a siphonous tropical marine green alga characterized by four morphologically distinct regions and, as with other members of the genus, by the presence of a dense network of anastomosing cylindrical cell wall in growths called trabeculae. Based on the results of this study, we propose several roles for trabeculae: (i) They are structural components, which likely add some small amount of support in compression but add considerable strength in tension. (ii) As extensions of the cell wall and plasma membrane, they act as diffusion channels from the cell exterior to the interior cytoplasm. It is possible that trabeculae also play a role in determining cell shape through developmental positioning and placement patterns, thus facilitating the diverse shapes found in the morphologically distinct regions of Caulerpa sp.     

Morphological and Histochemical Changes Occurring during the Life-span of Root-tip Galls on Lolium perenne Induced by Longidorus elongatus

The RNA and protein content of perennial ryegrass root-tip galls induced by Longidorus elongatus were measured from transverse sections and the morphology described. Galls progressed through five distinct stages and were viable for only 10-12 days at 18 C, after which they collapsed and became necrotic. In the initial stage hypertrophy occurred and cells contained enlarged nuclei and nucleoli, a greater proportion of cytoplasm, and increased concentrations of protein. This was followed by hyperplasia; cells divided to give two or four daughter cells, accompanied by a proportionate reduction in volumes of cytoplasm, nuclei, and nucleoli and reduced concentrations of RNA and protein. The third stage was secondary hypertrophy with enlarged, amoeboid nuclei and nucleoli and a significant increase in concentration of RNA and protein. In the final two stages, as feeding by L. elongatus progressively removed cell contents, most cells were devoid of inclusions and galls collapsed and were invaded by soil bacteria. This ordered development and exploitation of galls suggests that L. elongatus may have two phases in its feeding.     

Size‐dependent sex allocation in a simultaneous hermaphrodite parasite

Most models of sex allocation distinguish between sequential and simultaneous hermaphrodites, although an intermediate sexual pattern, size‐dependent sex allocation, is widespread in plants. Here we investigated sex allocation in a simultaneous hermaphrodite animal, the tapeworm Schistocephalus solidus, in which adult size is highly variable. Sex allocation was determined using stereological techniques, which allow measuring somatic and reproductive tissues in a common currency, namely volume. We investigated the relationships between individual volume and allocation to different reproductive tissues using an allometric model. One measure of female allocation, yolk gland volume, increased more than proportionally with individual volume. This is in contrast to the measure of male allocation, testis volume, which showed a strong tendency to increase less than proportionally with individual volume. Together these patterns led to sex allocation being strongly related to individual volume, with large individuals being more biased towards female allocation. We discuss these findings in the light of current ideas about size‐dependent sex allocation in, primarily, plants and try to extend them to simultaneous hermaphrodite animals.     

Zur numerischen Auswertung von Schnittflächenverteilungen. III

In this paper the connections between volume and absorption mass of objects resp. volume and absorption mass of segments are studied.