Autometallographic enhancement of the Golgi-Cox staining enables high resolution visualization of dendrites and spines

We present a method for autometallographic (AMG) enhancement of the Golgi-Cox staining enabling high resolution visualization of dendrites and spines. The method is cheaper and more flexible than conventional enhancement procedures performed with commercial photographic developers. The staining procedure is thoroughly described and we demonstrate with qualitative and quantitative data, how histological tissue sectioning, Golgi-Cox immersion time and different AMG enhancement length may influence the staining of dendrites and spines in the rat hippocampus. The described method will be of value for future behavioural-anatomical studies, examining changes in dendrite branching and spine density caused by brain diseases and their subsequent treatment.     

Respiration rate, heart rate, and body temperature values in cynomolgus monkeys (Macaca fascicularis) during barbiturate anesthesia

Respiration rate, heart rate, and body temperature values were obtained from 14 cynomolgus monkeys (Macaca fascicularis) during neurosurgery under barbiturate anesthesia. Vital sign values markedly declined below baseline during the early stages of surgery, steadily increased as surgery progressed and neared completion, and finally returned to baseline by the end of the postsurgical recovery period. There was considerable variability among the 14 monkeys, but the ranking of each monkey relative to the others remained constant across the period of observation. The findings suggested that the cynomolgus monkey may be more sensitive to barbiturates than the rhesus monkey, and cynomolgus monkeys may exhibit considerable individual differences in their sensitivity to barbiturates.     

Age and sex biases in the preservation of human skeletal remains

Inaccuracies introduced through biases in preservation are a major source of error in paleodemographic reconstructions. Although it is generally assumed that such biases exist, little is known about their magnitude. To investigate this problem, we studied age and sex differences in the preservation of skeletal remains from Mission La Purisima and a prehistoric cemetery (Ca-Ven-110). Comparison of mortality profiles obtained through analysis of skeletal remains and burial records from the mission indicates that biases in preservation can be very significant in poorly preserved skeletal collections. The Purisima burial records show that most of the people interred in the cemetery were either infants or elderly adults. The skeletal remains, in contrast, are predominantly those of young adults. The burial records and skeletal collection produced comparable sex ratios. These results show that age biases in preservation are much more important than sex biases. This conclusion is supported by data on the completeness of the skeletons from La Purisima and Ca-Ven-110. At both sites, the remains of young adults were better preserved than those of children or elderly adults, and the completeness of male and female skeletons was comparable.     

Visualization of interstitial cells of Cajal in the mouse colon by vital staining

Interstitial cells of Cajal (ICCs) are believed to be a major element in generating the spontaneous rhythm of the gastrointestinal tract. A prominent problem in the study of these cells has been the difficulty in observing them in intact tissues. We used the lipophilic dye DiI to stain ICCs in the submucosal-circular muscle border of freshly dissected mouse colon. The placement of small DiI crystals in this area resulted in the labeling of ICC-like cells. Two main morphological cell types, viz., bipolar and multipolar, were noted. Bipolar cells had two primary processes emerging from the poles of an elongated soma. The mean length of these processes was 78.7 μm. These cells constituted 42.3% of the sample (n=105). Multipolar cells (54.3% of total) had a less elongated soma and extended 3–6 main processes whose mean length was 56.3 μm. These processes showed no preferred direction. The length of the primary processes of bipolar cells was 40% greater than that of multipolar cells (P<0.02). Three cells (2.9%) had only one primary process. The DiI stain could be converted into a stable electron-opaque product. Electron-microscopic observations showed that these cells had the typical appearance of ICCs reported in previous studies. This staining method should be useful for physiological investigations of ICCs in gastrointestinal tissues. Received: 16 September 1997 / Accepted: 11 November 1997     

The effect of spatial pattern on community dynamics; a comparison of simulated and field data

The effect of the spatial limits of dispersal and competition on plant community dynamics was studied using Monte-Carlo simulation. The model generates community point patterns, using life-table data, dispersion parameters and radii of competitive effects. These data have been estimated in a field situation, for the 11 most abundant weed species growing on the refuse soil dumps of a strip coal mine. In a simulation experiment, the patterns produced by two versions of the model were compared. The first was based on the field situation as much as possible; the other used the same input parameters except for dispersal, which was randomized in this case. We found considerable differences regarding the temporal changes of species abundances, the realized competitive abilities and the spatial patterns generated by the two versions. An important conclusion of this comparison is that the realized competitive effect (both intra-and interspecific) of a species is dependent not only on constant competition parameters, but on the abundance relations and on the spatial patterns of the competing populations as well. It is concluded that the spatial limits of dispersal and competition may result in the increased persistence of weak competitors, moderate the realized competitive effects of strong species, and shape the spatial coalition structure of the community.