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The aim of this study was to determine histotopography and age-related changes of immunoreactive substance P (SP-IR) nerve plexus in dog cornea. In this research corneas of three groups of dogs of different age were used: young (2-3 months), adult (1-3 years) and old (8 and more years). Immunohistochemical demonstration of SP was performed on 40 um serial free-floating corneal sections cut parallel to the corneal surface. Results showed that SP-IR nerve plexus of dog cornea was formed by thick (21.9-73 μm diameter), medium (7.3-21.8 μm diameter) and thin (2.19-7.2 um diameter) nerve bundles and varicose or smooth nerve fibers branching into terminals. From limbus SP-IR thick nerve bundles ran radially through superficial and intermediate layers of stroma to the central part of cornea. Thick nerve bundles split into medium ones in central and pericentral parts of cornea. They branched repeatedly forming nerve plexus of stroma. Thin nerve bundles located in subepithelium, superficial and intermediate layers of stroma split from thick and medium bundles. Nerve fibres branched from thin bundles, curved and joined with each other, forming a network of various forms. The highest amount of nerve fibres was observed in corneal epithelium and subepithelium layer. The nerve bundles of young dogs were smaller in diameter than those of adults and old ones. With age the density of nerve fibres and thin bundles decreased in corneal epithelium and subepithelium layer. The density of medium and thick bundles in superficial and intermediate stroma was similar in dogs of all ages. No nerve plexus elements were noticed in stromal deep layer and endothelium in dogs of all ages.
We studied the chronosequence of six Scots pine (Pinus sylvestris L.) plantations (6-, 9-, 11-, 15-, 17-, and 20-years-old) to examine the changes in leaf area index (LAI) over stand age. The study site was located on a mine spoil heap (outer dumping ground) in the Belchatow lignite open-cast mining district (central Poland). The main goal of the study was to analyze LAI changes over stand age in a chronosequence of young Scots pine stands and to test the relationship between LAI estimates derived from a LAI-2000 Plant Canopy Analyzer and site-specific allometric equations. In addition, we tried to determine whether LAI estimated by a LAI-2000 PCA can be used to accurately estimate forest biomass. We hypothesized that LAI-2000 PCA underestimates LAI of the stands, and that stand age (and linked stand parameters) may influence the range of the hypothetical underestimation due to changes in biomass allocation. Our study revealed that LAI was highly dependent upon stand age and tree density (p<0.0001) regardless of the way how LAI was determined. Moreover, we found that LAI estimated by LAI-2000 PCA significantly correlates with stand biomass per area; the highest coefficients of determination were found for total aboveground biomass, aboveground woody biomass, and stem biomass. This means that data obtained by LAI-2000 PCA are good predictors of stand biomass in the young stages of stand development. In contrast to our prior assumption, the results showed that LAI-2000 PCA overestimates leaf area index. The relative differences between the values obtained with LAI-2000 and those calculated on the basis of the site-specific allometric equations increase with age. This may reflect changes in crown architecture over age caused by enlarging tree dimensions and over - crowding of trees leading to deterioration of light conditions inside the canopy.
Background: Oesophagus is a muscular tube that transports food and liquids by coordinated contraction of its muscular lining led by stimuli from the nerve plexus. Its muscularis proper layer consists of muscle cells, connective tissue and myenteric plexus. The aim of our histomorphometric study was to reveal detailed characteristics of this layer, cell number, volume, orientation, properties of myenteric plexus as well as changes related to aging. Materials and methods: Oesophagus tissue samples from 17 male cadavers were taken from the cranial and thoracic parts. Samples were divided in 2 groups: younger (ages 21–45) and older (ages 66–78). The tissue was routinely processed, embedded and serially sectioned. Sections were stained with Masson-Goldner and Cresyl-violet dyes. Digital images were analysed with the image analysis software. Statistics were performed with SPSS software. Results: The average thickness of the cranial part of the oesophageal wall and muscularis proper was 2590 µm and 1197 µm, respectively in the younger and 2453 µm and 1144 µm in the older group. Overall volume of the muscle tissue was slightly larger in the thoracic part, and in the younger group compared to the cranial part and the older group. The average number of the striated muscle cells per 100 µm in the cranial part was 771.5 and 749.7 in the younger and the older group, respectively. Striated cells were significantly less present only in the lower thoracic part of the oesophagus. In the older group, smaller striated muscle cells dominated over the larger ones. In the younger group, majority of the striated muscle cells were mid-sized. The thickness of the circular layer of muscularis proper was more affected by aging than the longitudinal one. Ganglion cells number was lower in the older group, but plexus area was unchanged. Conclusions: Aging affects muscularis proper and myenteric plexus of the oesophagus. Major differences can be observed in the striated muscle cells size, volume of the circular layer and number of the ganglionic cells in the myenteric plexus. (Folia Morphol 2013; 72, 3: 223–229)
In woody perennials, leaf structure and biochemistry vary with tree age under changing environments. However, the related eco-physiological mechanisms have not been elucidated yet. In this study, we investigated agerelated responses of juvenile and mature subalpine fir trees (Abies faxoniana Rehder & E.H. Wilson.) growing at altitudes between 2,500 and 3,500 m in the Wanglang Natural Reserve in southwest China, to study the adaptive strategies of different age trees to suit changing environments. We found that there were distinct age- and altituderelated changes in the structural and biochemical characteristics of leaves. At all altitudes, mature trees exhibited higher area- and mass-based leaf nitrogen content (Narea, Nmass), leaf mass per area (LMA) and stable isotope carbon composition (δ13C), and a lower chlorophyll (Chl) content than those juvenile trees, except for Nmass at 3,000 m as well as LMA at 2,750 m, where the values of Nmass and LMA in mature trees were slightly lower than those in juvenile trees. Furthermore, leaf characteristics showed significant differences in the change rates with altitude between different age groups. Our results indicated that assimilative organs in mature trees do not suffering from nutrient deficiency and that juvenile and mature trees possess different adaptive growth strategies under changing environments, as indicated by higher leaf N content in mature trees and the opposite patterns of LMA and Chl content between two age groups. We also concluded that juvenile could be more sensitive to global warming due to a greater altitudinal influence on the leaf traits in juvenile trees than those in mature trees.
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