Urinary bladder of rat: fine structure of normal and hypertrophic musculature

Abstract

The fine structure of the muscle of the urinary bladder in female rats is similar to that of other visceral muscles, although it is arranged in bundles of variable length, cross-section and orientation, forming a meshwork. When distended, the musculature is 100-120 microns thick, with some variation and occasional discontinuity. Extended areas of cell-to-cell apposition with uniform intercellular space occur between muscle cells, whereas attachment plaques for mechanical coupling are less common than in other visceral muscles. There are no gap junctions between muscle cells. Many bundles of microfilaments and small elastic fibres run between the muscle cells. After chronic partial obstruction of the urethra, the bladder enlarges and is about 15 times heavier, but has the same shape as in controls; the growth is mainly accounted for by muscle hypertrophy. The outer surface of the hypertrophic bladder is increased 6-fold over the controls; the muscle is increased 3-fold in thickness, and is more compact. Mitoses are not found, but there is a massive increase in muscle cell size. There is a modest decrease in percentage volume of mitochondria, an increase in sarcoplasmic reticulum, and no appreciable change in the pattern of myofilaments. Gap junctions between hypertrophic muscle cells are virtually absent. Intramuscular nerve fibres and vesicle-containing varicosities appear as common in the hypertrophic muscle as in controls. There is no infiltration of the muscle by connective tissue and no significant occurrence of muscle cell death.

COMBINED USE OF Α-Adrenergic AND MUSCARINIC ANTAGONISTS FOR THE TREATMENT OF VOIDING DYSFUNCTION

“…Bilateral removal of the major pelvic ganglia in rats denervates the bladder since, unlike in other mammalian species, the rat bladder does not contain intramural ganglia. 39 Antagonist affinities in denervated bladders is intermediate between that reported for M 2 and M 3 receptors, while in control bladders all affinities are consistent with M 3 mediated contraction. After denervation there is a 60% increase in M 2 receptor density with no change in M 3 receptor density.…”

Immunohistochemical characteristics and distribution of neurons in the intramural ganglia supplying the urinary bladder in the male pig

“…They are numerous in the guinea-pig (Gabella 1990) and less numerous in the cat (Feher et al 1979) ferret, rabbit (Gabella 1990), horse (Prieto et al 1989) and female pig (Pidsudko 2004). No, or very few, UB-IG have been found in the mouse (Grozdanovic et al 1992) and rat (Gabella and Uvelius 1990).…”

Conscious voiding during bladder obstruction in guinea pigs correlates with contractile activity of isolated bladders

“…This difference between rats and guinea pigs could be due to species, sex differences or to the amount of damage to the bladder neck area during surgery, which would affect the degree of obstruction. Bladder outlet obstruction caused patchy denervation in the guinea pig bladder but not in rats (Gabella and Uvelius, 1990;de Jongh et al, 2009). In present study, cholinergic EFS-induced contractions were reduced in four weeks obstructed guinea pigs but were up-regulated in rats (Banks et al, 2005).…”