Retinal twin cones or retinal double cones in fish: misnomer or different morphological forms?

Scanning retinal electronmicroscopy studies demonstrated the presence of both twin cones (two identical cones adhered together) and double cones (two non-identical cones adhered together) in the retinae of the major forms of fish, which included actinopterygi, elasmobranch, and teleosts. The complexity of these visual cells in the retinae of different groups of fishes was revealed for the first time and reflected on the diversities of functions of the fish retina in general.

Effect of oral Tadenan treatment on rabbit bladder structure and function after partial outlet obstruction.

PURPOSE: There is increasing evidence that the progressive dysfunction induced by partial outlet obstruction is mediated by ischemia-reperfusion, and bladder decompensation results from ischemia-reperfusion induced damage to the cellular and subcellular organelle membranes of nerve and smooth muscle, mitochondria and sarcoplasmic reticulum. Tadenan, an extract of Pygeum africanum, is a therapeutic prescribed in Europe to relieve symptoms of obstructive bladder dysfunction secondary to benign prostatic hyperplasia. There is excellent experimental evidence that Tadenan treatment of obstructed rabbits reduces and reverses the progression of bladder decompensation. We determined whether Tadenan therapy can reverse the morphological damage associated with obstructive dysfunction. MATERIAL AND METHODS: A total of 36 male New Zealand White rabbits were separated into 6 groups of 6 each. Rabbits in groups 1 and 2 underwent sham operation. For 3 weeks beginning 2 weeks after sham operation group 1 was treated with vehicle and group 2 was treated with 30 mg./kg. Tadenan daily. Rabbits in groups 3 to 6 underwent partial outlet obstruction surgery. Two weeks after obstruction each rabbit was treated for 3 weeks with vehicle in group 3, and with 1, 10 and 30 mg./kg. Tadenan in groups 4, 5 and 6, respectively. After the completion of treatment cystometry was performed on each rabbit and isolated bladder strips were evaluated for contractile responses to field stimulation, adenosine triphosphate, carbachol and KCl. Separate strips were fixed for electron microscopy to determine the location and severity of cellular and subcellular membrane damage. RESULTS: Partial outlet obstruction resulted in reduced compliance, decreased responses of bladder strips to all forms of stimulation tested, and significant and extensive damage to cellular and subcellular organelle membranes consistent with an ischemia-reperfusion etiology. Daily 1 and 10 mg./kg. Tadenan treatments had little effect on the obstruction induced increase in bladder weight or the deleterious changes in bladder function and structure. However, treating obstructed rabbits with 30 mg./kg. Tadenan daily resulted in reduced bladder hypertrophy, improved compliance, improved contractile responses to nearly normal levels of isolated bladder strips to all stimuli tested and reversal of obstruction induced structural damage to cellular and subcellular organelle membranes. CONCLUSION: Tadenan treatment of obstructed rabbits resulted in a dose dependent improvement in bladder ultrastructure in parallel with improved bladder compliance and contractile responses of isolated strips to stimulation, providing support for the hypothesis that damage to cellular and subcellular organelle membranes mediates the contractile dysfunction induced by partial outlet obstruction.

Correlation between the structure and function of the rabbit urinary bladder following partial outlet obstruction.

PURPOSE: To understand the relationship between contractile and structural changes in the obstructed bladder, rabbit bladder was partially obstructed for up to 70 days and alterations in tension response to field stimulation and carbachol were compared with alterations in ultrastructure and innervation of detrusor smooth muscle (SM). The effect of partial outlet obstruction on the physiological responses to field stimulation (FS) (nerve mediated contraction) and carbachol (receptor mediated contraction) were correlated with the structure and innervation of the detrusor smooth muscle (SM) of the same animal during a 70 day period. MATERIALS AND METHODS: 28 rabbits were subjected to 1 to 70 days of mild partial outlet obstruction. Sham operated rabbits were euthanized at 7, 14, 28, and 70 days post-obstruction. At each time period, isolated strips of bladder body were mounted in individual baths and the contractile response to FS and carbachol determined. Three additional strips from each bladder were fixed for electron microscopy. RESULTS: Bladder mass increased rapidly during the first 7 days after obstruction, was constant for the next 7 days, and then continued to increase gradually. Dysfunction of the contractile response to FS was noted as early as 3 days and progressively increased over the 70-day study period. The decrease in the response to FS increased at a significantly faster rate than the decrease in the contractile response to carbachol. In ultrastructure studies, at 3 and 7 days post-obstruction the majority of SM cells displayed the characteristics of hypertrophy. At 28 days some SM cells displayed loosely packed myofilaments and an irregular distribution of sarcoplasmic dense bodies. At 70 days swollen mitochondria were present in all cell types of the bladder wall. Evidence of axonal degeneration was first observed at 7 days post-obstruction and became more extensive thereafter. No evidence of mitotic figures, nerve growth cones or regenerating SM cells was observed. CONCLUSIONS: Prolonged partial bladder outflow obstruction is accompanied by a progressive decrease in contractility of SM. The present study describes the structural damage that occurs in the bladder wall in response to partial outlet obstruction and correlates these observations with the contractile dysfunction with which it is associated. Furthermore, mitochondrial damage in vessels and fibroblasts is suggestive of bladder wall ischemia.

Ultrastructures of nerve fibers and muscle spindles in adolescent idiopathic scoliosis.

Muscle biopsies were obtained from the erector spinae to investigate ultrastructural changes in nerve fibers and muscle spindles in patients suffering from adolescent idiopathic scoliosis. Membranous bodies are found in myelinated nerve fibers, both within and outside the muscle spindles. Leptofibrils are formed beneath the sarcolemma of the intrafusal muscle fibers. Additionally, in the intrafusal muscle fiber, there are slight increases in the amount of lipid droplets and glycogen particles, and the sarcoplasmic reticulum is slightly dilated. These changes may affect the metabolism of the muscle fiber and the normal balance of the contractile system. The cause-and-effect relationship of the changes in adolescent scoliosis warrants further investigation.

Effects of rheumatic mitral valvular disease and mitral valve replacement on growth and development.

The effects of rheumatic mitral valvular disease and mitral valve replacement on the growth and development of 37 Southern Chinese children were studied. The stature and body weight were measured before and after operation. All the patients had their skeletal maturity and cortical bone growth assessed after operation, but only 10 patients were similarly assessed before operation. At the time of operation the stature and body weight of all patients were generally retarded. The surgery which corrected the haemodynamic abnormality resulted in increases in the growth rates in stature and body weight but there was no evidence of a catch-up growth with subsequent return to normal dimensions. The patients who are skeletally immature had retarded bone ages and impaired growth of cortical bone. The general trend, though less marked, also showed a reduction in cortical bone in the skeletally mature patients. Surgery appears, at least partially, to alleviate the adverse effects of the disease on the growth and development of patients.