Morphology and morphometry of the normal lung of the adult vervet monkey (Cercopithecus aethiops)

Study of Age-Dependent Structural and Functional Changes of Mitochondria in Skeletal Muscles and Heart of Naked Mole Rats (Heterocephalus glaber)

Morphometric analysis of mitochondria in skeletal muscles and heart of 6- and 60-month-old naked mole rats (Heterocephalus glaber) revealed a significant age-dependent increase in the total area of mitochondrial cross-sections in studied muscle fibers. For 6- and 60-month-old animals, these values were 4.8 ± 0.4 and 12.7 ± 1.8%, respectively. This effect is mainly based on an increase in the number of mitochondria. In 6-month-old naked mole rats, there were 0.23 ± 0.02 mitochondrial cross-sections per µm² of muscle fiber, while in 60-month-old animals this value was 0.47 ± 0.03. The average area of a single mitochondrial cross-section also increased with age in skeletal muscles - from 0.21 ± 0.01 to 0.29 ± 0.03 µm². Thus, naked mole rats show a drastic enlargement of the mitochondrial apparatus in skeletal muscles with age due to an increase in the number of mitochondria and their size. They possess a neotenic type of chondriome accompanied by specific features of mitochondrial functioning in the state of oxidative phosphorylation and a significant decrease in the level of matrix adenine nucleotides.

Morphological analysis of the lung of neonatal yak

Although yaks play an important role as companion or pack and draught animals on Chinese plateaus in alpine and sub-alpine regions, morphological studies and anatomical data on the lung of yak are sparse. To provide anatomical descriptions and morphometric data, 10 one-day-old yaks were examined by means of dissection, light and electron microscopy. The measurements of lung were made on dissected specimens and histological sections. Unequal dichotomous branching was demonstrated in the dissected tracheobronchial tree. The diameters of bronchial airways and height of epithelium were measured, and showed that the variation of diameters in airways was always greater than that of height of epithelium. In addition, the thickness of muscularis, cartilage and adventitia was examined, as well as the number of goblet and Clara cells in airways. Ultrastructural studies showed that the surface epithelium was mainly composed of goblet, ciliated, Clara and basal cells, similar to that in other domestic animals. Under electron microscope, two distinctive types of ciliated cells could be seen in the tracheobronchial epithelium. The first type contained some mitochondria, distended smooth endoplasmic reticulum (SER), little rough endoplasmic reticulum (RER) and numerous vacuoles in electron-lucent cytoplasm. The second type had dense cytoplasm with abundant mitochondria, RER and no vacuoles. Both types were rich of glycogen granules. The goblet cells in neonatal yak lung had the following characteristic features: dentate nucleus in dense cytoplasm, with stacks of RER and numerous dense membrane-bounded mucous droplets, which were round or oval, often with an electron-lucent core. The droplets were not confluent. Glycogen granules were numerous, and Golgi complex was occasionally present. Clara cells were dome-shaped and usually protruded into the airway lumen. Large amounts of SER and many secretory droplets were found within the cytoplasm. Several typical 'clefts' were also found in the cytoplasm.

Alveoli increase in number but not size from birth to adulthood in rhesus monkeys

Postnatal developmental stages of lung parenchyma in rhesus monkeys is about one-third that of humans. Alveoli in humans are reported to be formed up to 8 yr of age. We used design-based stereological methods to estimate the number of alveoli (N(alv)) in male and female rhesus monkeys over the first 7 yr of life. Twenty-six rhesus monkeys (13 males ranging in age from 4 to 1,920 days and lung volumes from 41.7 to 602 cm(3), 13 females ranging in age from 22 to 2,675 days and lung volumes from 43.5 to 380 cm(3)) were necropsied and lungs fixed, isotropically oriented, fractionated, sampled, embedded, and sectioned for alveolar counting. Parenchymal, alveolar, alveolar duct core air, and interalveolar septal tissue volumes increased rapidly during the first 2 yr with slowed growth from 2 to 7 yr. The rate of change was greater in males than females. N(alv) also showed consistent growth throughout the study, with increases in N(alv) best predicted by increases in lung volume. However, mean alveolar volume showed little relationship with age, lung volume, or body weight but was larger in females and showed a greater size distribution than in males. Alveoli increase in number but not volume throughout postnatal development in rhesus monkeys.

Thin and strong! The bioengineering dilemma in the structural and functional design of the blood-gas barrier

In gas exchangers, the tissue barrier, the partition that separates the respiratory media (water/air and hemolymph/blood), is exceptional for its remarkable thinness, striking strength, and vast surface area. These properties formed to meet conflicting roles: thinness was essential for efficient flux of oxygen by passive diffusion, and strength was crucial for maintaining structural integrity. What we have designated as "three-ply" or "laminated tripartite" architecture of the barrier appeared very early in the evolution of the vertebrate gas exchanger. The design is conspicuous in the water-blood barrier of the fish gills through the lungs of air-breathing vertebrates, where the plan first appeared in lungfishes (Dipnoi) some 400 million years ago. The similarity of the structural design of the barrier in respiratory organs of animals that remarkably differ phylogenetically, behaviorally, and ecologically shows that the construction has been highly conserved both vertically and horizontally, i.e., along and across the evolutionary continuum. It is conceivable that the blueprint may have been the only practical construction that could simultaneously grant satisfactory strength and promote gas exchange. In view of the very narrow allometric range of the thickness of the blood-gas barrier in the lungs of different-sized vertebrate groups, the measurement has seemingly been optimized. There is convincing, though indirect, evidence that the extracellular matrix and particularly the type IV collagen in the lamina densa of the basement membrane is the main stress-bearing component of the blood-gas barrier. Under extreme conditions of operation and in some disease states, the barrier fails with serious consequences. The lamina densa which in many parts of the blood-gas barrier is <50 nm thin is a lifeline in the true sense of the word.

A nonhuman primate aerosol deposition model for toxicological and pharmaceutical studies

Nonhuman primates may be used as human surrogates in inhalation exposure studies to assess either the (1) adverse health effects of airborne particulate matter or (2) therapeutic effects of aerosolized drugs and proteins. Mathematical models describing the behavior and fate of inhaled aerosols may be used to complement such laboratory investigations. For example, the optimal conditions, in terms of ventilatory parameters (e.g., breathing frequency and tidal volume) and aerosol characteristics (e.g., geometric size and density), necessary to target drug delivery to specific sites within the respiratory tract may be estimated a priori with models. In this work a mathematical description of the rhesus monkey (Macaca mulatta) lung is presented for use with an aerosol deposition model. Deposition patterns of 0.01- to 5-microm-diameter monodisperse aerosols within lungs were calculated for 3 monkey lung models (using different descriptions of alveolated regions) and compared to human lung results obtained using a previously validated mathematical model of deposition physics. Our findings suggest that there are significant differences between deposition patterns in monkeys and humans. The nonhuman primates had greater exposures to inhaled substances, particularly on the basis of deposition per unit airway surface area. However, the different alveolar volumes in the rhesus monkey models had only minor effects on aerosol dosimetry within those lungs. By being aware of such quantitative differences, investigators can employ the respective primate models (human and nonhuman) to more effectively design and interpret the results of future inhalation exposure experiments.

The origin and pattern of distribution of the posterior intercostal arteries in the baboon (Papio ursinus)

The posterior intercostal arteries of six female and four adult male baboons (Papio ursinus) were investigated by latex injection and subsequent dissection to determine their origin and pattern of distribution. Basic morphological and functional similarities with that of man could provide some base-line data pertinent to future experimental studies in the areas of thoracic aortic aneurysm and aortic atherosclerotic lesion in man. Basic similarities were observed between the baboon and man in the number of intersegmental arteries, the origin of the first two pairs of posterior intercostal arteries, and the anastomosis between the superior intercostal and the third posterior intercostal arteries. However, the baboon showed a craniocaudal sequence of paired orifices giving rise to paired arteries; orifices with incompletely divided septum giving rise to paired arteries; single orifices leading to a common trunk, which finally gives rise to paired arteries; and single orifices opening into single arteries. In addition, there was a craniocaudal decrease in the distance between any given pair of intercostal arteries and an increase in the spacing between adjacent pairs of intercostal arteries. Where a single artery supplied one side of the intercostal space, the contralateral side received a collateral branch, either from the preceding or succeeding intercostal artery. Though the basic organisation of the origin and distribution of the posterior intercostal arteries in the baboon is similar to that of man, the differences observed in the baboon might be attributed to factors such as body size, mode of activity, and even the phylogenetic level of development of the baboon.

An ultrastructural study of the equine lower respiratory tract

The surface features of the lower respiratory tract of 20 clinically normal horses of different ages and types were studied with scanning electron microscopy. Parallel light microscopical and transmission electron microscopical studies were also carried out. The ciliary carpet was virtually complete from the trachea to the lobar bronchi. In small bronchi, ciliation was less complete allowing numerous non-ciliated mucous cells to become obvious. The terminal bronchioles, populated mainly by non-ciliated bronchiolar epithelial cells, had an abrupt junction with alveolar ducts. Interalveolar pores were common particularly in older horses.