Ultrastructure of the tracheal muscle in developing, adult and ageing guinea-pigs

Abstract

The musculature of the trachea of adult guinea-pigs is ultrastructurally similar to other visceral muscles. However, tracheal muscle cells have irregular outlines, large accumulations of glycogen, a small number of gap junctions, and many small elastic fibres and collagen fibrils (50 nm in diameter). Fibroblasts, mast cells, Schwann cells and axons are found within the muscle, but no interstitial cells. Capillaries run in the connective tissue septa. The tracheal muscle is well differentiated at the end of the fetal life. At this time, muscle cells have an appearance similar to that of a mature muscle. However, the cells are smaller, especially in length, and their orientation is less regular. There are no undifferentiated cells; a few muscle cells are seen in mitosis. There is a limited amount of stroma, mainly small collagen fibrils not exceeding 30 nm in diameter. Within the muscle there are many nerves, but no fibroblasts or mast cells. Many structural contacts link together the muscle cells, but there are no gap junctions. Gap junctions develop in the first few days after birth and are distinct in 5-day-old animals. In ageing guinea-pigs (30-36 months old) the muscle cells are slightly larger than in the young adult. They display deep invaginations of the cell membrane and a very irregular profile. There is an increase in the number of glycogen granule clusters, and the basal lamina is particularly prominent. The amount of stroma has increased, and is made of large elastic fibres and collagen fibrils up to 105 nm in diameter.

Ovine middle cerebral artery characterization and quantification of ultrastructure and other features: changes with development

“…In rat aortas, the basal lamina is relatively scant at birth (4,17). Basal lamina thickening has also been noted in developing guinea pig tracheal muscle (5,9). In the present study, SMC basal lamina thickness increased 114% from 140 GD to the adult ( Table 2).…”

“…Several workers have described the architecture of the arterial wall (3), as well as the ultrastructure of SMCs per se (9). Nonetheless, surprisingly few reports have described the ontogeny of SMC development in a particular vascular bed.…”

Morphology of aging lung in F344/N rat: Alveolar size, connective tissue, and smooth muscle cell markers

“…In rodents, it has been reported that elastin content and hydroxyproline content per dry tissue weight did not change in BALB/c mice and SAMR1 rats during aging (Takubo et al, 1999). Furthermore, morphological alteration of smooth muscle cells (SMCs) in the aging airway was also reported in guinea pig trachea (Gabella, 1991). In 30-to 36-month-old guinea pigs, deep invagination and irregular profiles of the cellular membrane were demonstrated in SMCs.…”

Connective Tissue Framework of the Hepatic Ligaments in the Human Liver

“…They suggested a correlation between the distribution of the fibrils, biochemical conditions and the functional loading of the tissue. Different diameters of collagen fibrils have been reported in various tissues including cartilage [19][20][21], subepithelial connective tissue of oral mucosa [22,23], eye [24,25], peripheral nerve [26,27], skeletal muscle [28,29] and tendon [30][31][32]. From studying these works, it seems that collagen fibers generally have a large diameter in tendons and sclera, where they are exposed to substantial mechanical stress.…”