Identification of c-kit-positive cells in the mouse ureter: the interstitial cells of Cajal of the urinary tract

Michael A. Pezzone1, Simon C. Watkins2, Sean M. Alber2, William E. King1, William C. de Groat3, Michael B. Chancellor4, and Matthew O. Fraser5

1 Division of Gastroenterology, Hepatology, and Nutrition, Department of Medicine, and Departments of 2 Cell Biology and Physiology, 3 Pharmacology, and 4 Urology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15213; and 5 Division of Urology, Department of Surgery, Duke University, Durham, North Carolina 27705


    ABSTRACT
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ABSTRACT
INTRODUCTION
MATERIALS AND METHODS
RESULTS
DISCUSSION
REFERENCES

The existence of a pacemaker system in the urinary tract capable of orchestrating the movement of filtrated urine from the ureteral pelvis to the distal ureter and lower urinary tract seems intuitive. The coordinated activity necessary for such movement or "peristalsis" would likely require an intricate network of cells with pacemaker-like activity, as is the case with the interstitial cells of Cajal (ICC) of the gut. We investigated whether these putative pacemaker cells of the urinary tract are antigenically similar to ICC of the gut by using immunofluorescence staining for c-kit, a cell-surface marker specific for ICC. Ureteral, urinary bladder, and urethral tissues were harvested from female mice of the WBB6F1 strain, and fixed sections were prepared and stained for c-kit. Cell networks composed of stellate-appearing, c-kit-positive, ICC-like cells were found in the lamina propria and at the interface of the inner longitudinal and outer circular muscle layers of the ureteral pelvis but not in the urinary bladder or urethra. Thus, like in the gut, c-kit-positive, ICC-like cells are present in the urinary tract but appear to be restricted to the proximal ureter of this murine species.

urine; urethral tissue; pacemaker; motility


    INTRODUCTION
TOP
ABSTRACT
INTRODUCTION
MATERIALS AND METHODS
RESULTS
DISCUSSION
REFERENCES

THE EXISTENCE OF a pacemaker network capable of coordinating smooth muscle activity in the urinary tract has been previously proposed. The ureter, responsible for the movement of urine from the kidney to the bladder, is thought to contain pacemakers located in the renal pelvis that propagate electrical activity distally giving rise to ureteral peristalsis (6, 16, 17, 32, 47, 50, 60). Although electrical recordings from the ureter demonstrate origination of the pacemaker activity primarily from the proximal renal pelvis, pacemaker potentials have been recorded from the upper, middle, and lower third of the human ureter (49). Further implicating a direct relationship between smooth muscle contraction and electrical pacing, the action potentials following these pacemaker potentials were associated with intraureteral pressure increases.

Although myogenic and neurogenic mechanisms have been invoked for the generation and propagation of ureteral peristalsis, specialized cells with both smooth muscle and neural properties may be involved. With the use of histological techniques designed to identify such cells, Gosling and Dixon (16, 17) were the first to recognize specialized "atypical" smooth muscle cells confined to the upper urinary tract. These "atypical" smooth muscle cells closely apposed each other and typical smooth muscle cells and were thought to be the reputed pacemaker cells. Klemm and Lang (30) found this histologically defined, possible pacemaker-like network in the ureter present throughout the muscle layers, diminishing in cell numbers distally along the ureter. Moreover, they found that the cells comprising this pacemaker network were morphologically similar to those previously described in the gut.

The selective identification and localization of interstitial cells of Cajal (ICC), the pacemaker cells of the gut, have been greatly facilitated by the discovery of their expression of the c-kit receptor. Specific antibodies to the c-kit receptor have been used to identify ICC in both animals (3, 26, 28, 39, 55, 58) and in humans (27, 57). Local decreases in or lack of c-kit immunoreactivity in the gut has been detected in human motility disorders such as Hirschsprungs's disease (57, 61) and intestinal pseudoobstruction (27). Mice with spontaneous mutations of the c-kit gene and deficient in ICC lack spontaneous slow waves in the small intestine and have uncoordinated peristalsis (7). Similarly, the frequency and regularity of colonic peristaltic contractions were altered in such mice (39).

In this study, the presence of ICC-like cell networks that may be responsible for the generation of pacemaker activity in the urinary tract was investigated in mice using c-kit receptor immunofluorescence. Identification of the pacemaker system in the urinary tract and its implications for our present understanding of the neurophysiology of the urinary tract would be profound and may provide further insight into a variety of important urological conditions.


    MATERIALS AND METHODS
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ABSTRACT
INTRODUCTION
MATERIALS AND METHODS
RESULTS
DISCUSSION
REFERENCES

Animals. Female WBB6F1 mice (Jackson Labs, Bar Harbor, ME), weighing 20-25 g and 12-20 wk old, were housed in standard polypropylene cages with ad libitum access to food and water in the University of Pittsburgh's Central Animal Facility. All studies were approved by the University of Pittsburgh's Institutional Animal Care and Use Committee and found to meet the standards for humane animal care and use as set by the Animal Welfare Act and the National Institutes of Health Guide for the Care and Use of Laboratory Animals.

Tissue processing. Mice were anesthetized with isoflurane (4%), and the ureters, urinary bladders, and urethras were harvested and immediately placed in 2% buffered paraformaldehyde for 1 h, cryoprotected in 30% sucrose in PBS overnight, and flash-frozen in liquid nitrogen-cooled isopentane. Tissues were cut in 8-µm frozen sections, mounted on polylysine-coated slides, and kept frozen (-20°C) until immunocytochemical processing.

Immunocytochemistry. Tissue sections were rehydrated in KPBS at room temperature for 20 min, blocked with 10% normal goat serum for 20 min, and incubated overnight at 4°C with the primary antiserum, a rabbit polyclonal IgG antibody to the human c-kit protein (Oncogene Research Products, Cambridge, MA), diluted 1:100 in KPBS, 0.05% goat serum and 0.1% Triton X-100. The following day, slides were rinsed with KPBS three times (10 min each) and then incubated with a Cy3-conjugated goat anti-rabbit IgG secondary antibody (Jackson ImmunoResearch, West Grove, PA) at room temperature for 2 h at a dilution of 1:800 in KPBS, 0.05% goat serum, and 0.1% Triton X-100. Because mast cells also contain the c-kit receptor and hence stain positive with c-kit antibodies, dual staining with fluorescein- avidin DCS (Vector Laboratories, Burlingame, CA) diluted 1:200 for 2 h was used to specifically identify mast cell staining. Slides were again washed three times (10 min each) with KPBS and coverslipped. Slides were imaged using an Olympus Fluoview 500 scanning confocal microscope in the Center for Biological Imaging at the University of Pittsburgh.

Controls for the specificity of the antisera consisted of incubation of the tissue with normal rabbit serum substituted for the primary antiserum. With the use of this procedure, no nonspecific staining was seen. The antibody concentrations and the optimal tissue preparation used for immunofluorescence staining of c-kit in this murine species had been previously determined in the intestine (39). Optimal antibody concentrations used in the urinary tract were determined by serial dilutions and are documented above.


    RESULTS
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ABSTRACT
INTRODUCTION
MATERIALS AND METHODS
RESULTS
DISCUSSION
REFERENCES

In Fig. 1, a confocal slice with differential interference contrast and fluorescence overlay depicts dual immunofluorescence staining of a section of proximal mouse ureter. In the lamina propria, note the network of red fluorescent, stellate-appearing cells that are c-kit positive. These c-kit-positive cells resembled ICC (ICC-like) and were negative for mast cell markers (FITC-avidin immunofluorescence). With the use of maximum-intensity projection of the confocal stack, the c-kit-positive, ICC-like cells were magnified and are depicted in Fig. 1B.


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Fig. 1.   Confocal slice with differential interference contrast and fluorescence overlay of the proximal ureter of a female WBB6F1 mouse. A: network of interstitial cells of Cajal (ICC)-like cells expressing c-kit immunoreactivity is depicted in red fluorescence in the lamina propria. The larger, yellowish-green-appearing granular cells staining positively for both FITC-avidin and c-kit are mast cells. Bar = 20 µm. B: high-power image of ICC-like cells offset from A using maximum-intensity projection of confocal stack. Bar = 10 µm.

Networks of c-kit-positive, ICC-like cells were also localized adjacent to the inner longitudinal muscle fiber bundles and at the interface of the inner longitudinal and outer circular muscle layers (not shown). Furthermore, the c-kit-positive stellate cells were contiguous in serial tissue sections but limited to the ureteral pelvis and proximal ureter. Such cells were not, however, found in either the urinary bladder or urethra.

Larger c-kit-positive cells were also noted in the lamina propria. Unlike the ICC-like cells, these larger cells also stained positively for FITC-avidin and therefore appeared as yellow-green fluorescence as seen in Fig. 1A. These immunohistological characteristics together with their intense granular morphology clearly characterized these cells as mast cells.


    DISCUSSION
TOP
ABSTRACT
INTRODUCTION
MATERIALS AND METHODS
RESULTS
DISCUSSION
REFERENCES

This study is the first to identify c-kit-positive, ICC-like cells in the ureter that may be the putative pacemaker cells responsible for generation of ureteral peristalsis and the consequential movement of urine from the kidney to the urinary bladder. The histological distribution and cellular morphology of these c-kit-positive cells are characteristic of those cells previously identified as the ICC or pacemaker cells in the gastrointestinal tract. These findings further indirectly support the role of these identified cells as mediators and/or initiators of smooth muscle contraction in the tubular components of the upper urinary tract. Recognition of abnormalities of the ICC-like system in the urinary tract may offer insight into a variety of important urological diseases, such as hydroureter and megaloureter, which are congenital and/or acquired conditions thought to be a consequence of a deficiency in ureteral musculature innervation (42).

An extensive review of the literature revealed few studies that evaluated c-kit immunoreactivity in the genital urinary tract, and most have focused on the role of c-kit in gametogenesis in the testes (11, 36, 38, 45). Most recently, Klemm et al. (29) comprehensively evaluated the cells underlying pacemaker activity in the guinea pig upper urinary tract and found cells morphologically similar to ICC cells, but they were not immunoreactive for c-kit, the marker of ICC cells in the gut. Although c-kit-positive cells were present, they were morphologically consistent with mast cells, the only other known c-kit-positive cell. The lack of c-kit-positive ICC cells in Klemm's studies may be related to the species (guinea pig vs. mouse), the c-kit antibody used (murine vs. human), and/or the fixation methods, as we have found that ICC cells are very sensitive to fixation methods.

In a comprehensive evaluation of human tissue, Lammie et al. (31) found scattered c-kit-positive immunoreactivity in transitional epithelial cells of the bladder and in mast cells of the bladder and gastrointestinal tract. Consistent with our results, they found no c-kit immunoreactivity in the urinary bladder smooth muscle, although they did report significant immunocytochemical localization of kit ligand, the endogenous mast cell growth factor that binds to the c-kit receptor, both in the smooth muscle of the bladder and the intestines. This is not surprising, as the role of the bladder is one of storage and intermittent expulsion. The lack of c-kit-positive, ICC-like cells in the mouse bladder stands in contrast to the recent report of McCloskey and Gurney (35) where such cells were identified in the guinea pig bladder. Interestingly, the urinary bladder of the guinea pig also contains intramural autonomic ganglia (15, 19, 62), in contrast to the murine bladder (15, 56). Given the association of ICC in the gut with intrinsic ganglia and given that conditions of hypoganglionosis are also associated with marked reductions in ICC (43), it seems reasonable to propose that the lack of ICC in the mouse bladder is due to a lack of intramural ganglia. With the use of this same line of reasoning, one would predict that the human and cat bladder, which, like the guinea pig, both possess intramural urinary bladder ganglia (40, 52, 53), would likewise possess ICC-like, c-kit-positive pacemaker cells. It has also been suggested that a urinary bladder network of intramural ganglia may contribute functionally as an entity unto itself to both normal and pathological bladder function (9, 52), similarly, but to a lesser degree than the enteric nervous system in the gut.

The urethra, which is also comprised by an outer circular and inner longitudinal smooth muscle similar to the ureter (2), was also devoid of ICC-like cells in the present study. This was somewhat surprising to us, as we previously observed peristaltic-like activity in in vitro whole mounted preparations of urethras from the rat (unpublished observations). It is tempting to speculate that either some other mechanism is responsible for pacemaker potential generation in the urethra, such as intrinisic smooth muscle tone responsible for maintaining continence with wave propagation via smooth muscle gap junctions, or that our present histological protocols are, for some unknown reason, not allowing for the identification of ICC-like cells in this organ.

Early studies investigating the neural input to the ureter and the pacemaker-like control of ureteral peristalsis focused on catecholaminergic and cholinergic neural input to the ureter (8, 10, 13, 18, 37, 48). Follow-up studies, however, revealed that the adrenergic axons are preferentially distributed to the arterial vessels that supply the ureter rather than to the smooth muscle itself (16, 59). With the later discovery of rich capsaicin-sensitive afferent input to the ureteral smooth musculature, a role of both substance P (SP) and calcitonin gene-related peptide (CGRP) containing afferent input has been implicated (12, 14, 23, 24, 46, 51, 54) with the latter neuropeptide found to be more extensively represented (1, 46). These findings are also reflected in the subepithelial plexus of the ureter with ~90% of its axons being capsaicin-sensitive afferents (25, 46). Because the majority of the sensory fibers supplying the ureter are not activated by physiological stimuli, they most likely signal noxious stimuli (5) and may also regulate vascular and smooth muscle responses (22) to noxious stimuli by local efferent-like actions. On the other hand, direct physiological evidence implicating a role of CGRP containing afferent neurons in the modulation of ureteral peristalsis is apparent in studies which showed that motility changes induced by electrical field stimulation are mainly mediated by CGRP (33, 34). Taken together, these findings suggest that CGRP in primary sensory axons of the ureter may play a role in modulation of ureteral smooth muscle activity and/or putative ureteral pacemaker cells rather than acting as the pacemaker system itself.

Additional evidence supporting a relationship between afferent innervation and c-kit expression is apparent in previous studies that showed that kit ligand is a neurotrophic factor for dorsal root ganglia (DRG) neurons, playing a role in neurite outgrowth and guiding axons from the DRG (4, 21). Moreover, further characterization of these c-kit-positive neurons in the DRG revealed that many (44%) contained SP, terminated in spinal cord laminae I and II, and were nerve growth factor responsive, further supporting their role as nociceptive C-fiber afferents (20). The importance and complexity of these interactions between sensory neurons and kit ligand are further evident in the finding that SP can induce production of kit ligand, which, in turn, can upregulate SP receptors of the NK-1 subtype in bone marrow stroma (41).

Follow-up studies would be necessary to determine the functional role of the c-kit-positive, ICC-like cells of the urinary tract. Physiological studies of ureteral peristalsis using techniques such as those recently described by Roshani et al. (44) combined with immunocytochemical techniques in the commercially available c-kit-deficient mice would help define the direct role of these c-kit-positive, pacemaker-like cells in the urinary tract.

In summary, we have identified cells in the proximal tubular components of the urinary tract with morphological and immunological phenotypes similar to ICC pacemaker cells of the gut. We predict an abnormal distribution of these ICC-like cells in the urinary tract may be a useful diagnostic marker of urinary tract diseases that involve the ureter and may be useful in the planning of appropriate surgical or pharmacological interventions. Although the study of the role of ICC-like cells in urinary tract motility is in its infancy, modern technologies should facilitate rapid progress toward delineation of the role of these cells in normal physiology and pathological conditions.


    ACKNOWLEDGEMENTS

Funding for this study was provided by National Institutes of Health Grant DK-02488 to M. A. Pezzone. Portions of this study were previously reported in abstract form at the 1999 annual meeting of the American Urological Association.


    FOOTNOTES

Address for reprint requests and other correspondence: M. A. Pezzone, Division of Gastroenterology, Hepatology, and Nutrition, Univ. of Pittsburgh School of Medicine, 200 Lothrop St., Pittsburgh, PA 15213.

The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

First published January 21, 2003;10.1152/ajprenal.00138.2002

Received 12 April 2002; accepted in final form 21 January 2003.


    REFERENCES
TOP
ABSTRACT
INTRODUCTION
MATERIALS AND METHODS
RESULTS
DISCUSSION
REFERENCES

1.   Amann, R, Skofitsch G, and Lembeck F. Species-related differences in the capsaicin-sensitive innervation of the rat and guinea-pig ureter. Naunyn Schmiedebergs Arch Pharmacol 338: 407-410, 1988[ISI][Medline].

2.   Brading, AF. The physiology of the mammalian urinary outflow tract. Exp Physiol 84: 215-221, 1999[Abstract].

3.   Burns, AJ, Lomax AEJ, Torihashi S, Sanders KM, and Ward SM. Interstitial cells of Cajal mediate inhibitory neurotransmission in the stomach. Proc Natl Acad Sci USA 93: 12008-12013, 1996[Abstract/Free Full Text].

4.   Carnahan, JF, Patel DR, and Miller JA. Stem cell factor is a neurotrophic factor for neural crest-derived chick sensory neurons. J Neurosci 14: 1433-1440, 1994[Abstract].

5.   Cervero, F, and Sann H. Mechanically evoked responses of afferent fibres innervating the guinea-pig's ureter: an in vitro study. J Physiol 412: 245-266, 1989[Abstract].

6.   Constantinou, CE. Renal pelvic pacemaker control of ureteral peristaltic rate. Am J Physiol 226: 1413-1419, 1974[Free Full Text].

7.   Der-Silaphet, T, Malysz J, Hagel S, Larry Arsenault A, and Huizinga JD. Interstitial cells of cajal direct normal propulsive contractile activity in the mouse small intestine. Gastroenterology 114: 724-736, 1998[ISI][Medline].

8.   Dixon, JS, and Gosling JA. Histochemical and electron microscopic observations on the innervation of the upper segment of the mammalian ureter. J Anat 110: 57-66, 1971[ISI][Medline].

9.   Drake, MJ, Mills IW, and Gillespie JI. Model of peripheral autonomous modules and a myovesical plexus in normal and overactive bladder function. Lancet 358: 401-403, 2001[ISI][Medline].

10.   Duarte-Escalente, O, Labay P, and Boyarsky S. The neurohistochemistry of mammalian ureter: a new combination of histochemical procedures to demonstrate adrenergic, cholinergic, and chromaffin structures in ureter. J Urol 101: 803-811, 1969[ISI][Medline].

11.   Dym, M, Jia MC, Dirami G, Price JM, Rabin SJ, Mocchetti I, and Ravindranath N. Expression of c-kit receptor and its autophosphorylation in immature rat type A spermatogonia. Biol Reprod 52: 8-19, 1995[Abstract].

12.   Edyvane, KA, Smet PJ, Trussell DC, Jonavicius J, and Marshall VR. Patterns of neuronal colocalisation of tyrosine hydroxylase, neuropeptide Y, vasoactive intestinal polypeptide, calcitonin gene-related peptide and substance P in human ureter. J Auton Nerv Syst 48: 241-255, 1994[ISI][Medline].

13.   Elbadawi, A, and Schenk EA. Innervation of the abdominopelvic ureter in the cat. Am J Anat 126: 103-120, 1969[ISI][Medline].

14.   Franco-Cereceda, A, Henke H, Lundberg JM, Petermann JB, Hokfelt TH, and Fischer JA. Calcitonin gene-related peptide (CGRP) in capsaicin-sensitive substance P-immunoreactive sensory neurons in animals and man: distribution and release by capsaicin. Peptides 8: 399-410, 1987[ISI][Medline].

15.   Gabella, G. Intramural neurons in the urinary bladder of the guinea-pig. Cell Tissue Res 261: 231-237, 1990[ISI][Medline].

16.   Gosling, JA, and Dixon JS. Species variation in the location of upper urinary tract pacemaker cells. Investig Urol (Berl) 11: 418-423, 1974.

17.   Gosling, JA, and Dixon JS. Structural evidence in support of an urinary tract pacemaker. Br J Urol 44: 550-560, 1972[Medline].

18.   Gosling, JA, and Dixon JS. The effect of 6-hydroxydopamine on nerves in the rat upper urinary tract. J Cell Sci 10: 197-209, 1972[ISI][Medline].

19.   Hanani, M, and Maudlej N. Intracellular recordings from intramural neurons in the guinea pig urinary bladder. J Neurophysiol 74: 2358-2365, 1995[Abstract/Free Full Text].

20.   Hirata, T, Kasugai T, Morii E, Hirota S, Nomura S, Fujisawa H, and Kitamura Y. Characterization of c-kit-positive neurons in the dorsal root ganglion of the mouse. Dev Brain Res 85: 201-211, 1995[ISI][Medline].

21.   Hirata, T, Morii E, Morimoto M, Kasugai T, Tsujimura T, Hirota S, Kanakura Y, Nomura S, and Kitamura Y. Stem cell factor induces outgrowth of c-kit-positive neurites and supports the survival of c-kit-positive neurons in dorsal root ganglia of mouse embryos. Development 119: 49-56, 1993[Abstract/Free Full Text].

22.   Holzer, P. Capsaicin: cellular targets, mechanisms of action, and selectivity for thin sensory neurons. Pharmacol Rev 43: 143-201, 1991[ISI][Medline].

23.   Holzer, P, Bucsics A, and Lembeck F. Distribution of capsaicin-sensitive nerve fibres containing immunoreactive substance P in cutaneous and visceral tissues of the rat. Neurosci Lett 31: 253-257, 1982[ISI][Medline].

24.   Hoyes, AD. Fine structure and response to capsaicin of primary afferent nociceptive axons in the rat and guinea-pig ureter. In: Sensory Receptor Mechanisms, edited by Hamann W, and Iggo A.. Singapore: World Scientific, 1984, p. 25-34.

25.   Hoyes, AD, and Barber P. Degeneration of axons in the ureteric and duodenal nerve plexuses of the adult rat following in vivo treatment with capsaicin. Neurosci Lett 25: 19-24, 1981[ISI][Medline].

26.   Huizinga, JD, Thuneberg L, Kluppel M, Malysz J, Mikkelsen HB, and Bernstein A. W/Kit gene required for interstitial cells of Cajal and for intestinal pacemaker activity. Nature 373: 347-349, 1995[ISI][Medline].

27.   Isozaki, K, Hirota S, Miyagawa JI, Taniguchi M, Shinomura Y, and Matsuzawa Y. Deficiency of c-kit cells in patients with a myopathic form of chronic idiopathic intestinal pseudo-obstruction. Am J Gastroenterol 92: 332-334, 1997[ISI][Medline].

28.   Isozaki, K, Hirota S, Nakama A, Miyagawa JI, Sinomura Y, Xu Z, Nomura S, and Kitamura Y. Disturbed intestinal movement, bile reflux to the stomach and deficiency of c-kit-expressing cells in Ws/Ws mutant rats. Gastroenterology 109: 456-464, 1995[ISI][Medline].

29.   Klemm, MF, Exintaris B, and Lang RJ. Identification of the cells underlying pacemaker activity in the guinea-pig upper urinary tract. J Physiol 519: 867-884, 1999[Abstract/Free Full Text].

30.   Klemm, MF, and Lang RJ. Morphological characterization of guinea pig upper urinary tract (Abstract). Proc Aust Neurosci Soc 9: 87, 1998.

31.   Lammie, A, Drobnjak M, Gerald W, Saad A, Cote R, and Cordon-Cardo C. Expression of c-kit and kit ligand proteins in normal human tissues. J Histochem Cytochem 42: 1417-1425, 1994[Abstract/Free Full Text].

32.   Lang, RJ, Exintaris B, Teele ME, Harvey J, and Klemm MF. Electrical basis of peristalsis in the mammalian upper urinary tract. Clin Exp Pharmacol Physiol 25: 310-321, 1998[ISI][Medline].

33.   Maggi, CA, and Giuliani S. The neurotransmitter role of calcitonin gene-related peptide in the rat and guinea pig ureter: effect of a calcitonin gene-related peptide antagonist and species-related differences in the action of omega conotoxin on calcitonin gene-related peptide release from primary afferents. Neuroscience 43: 261-268, 1991[ISI][Medline].

34.   Maggi, CA, Santicioli P, Giuliani S, Abelli L, and Meli A. The motor effect of the capsaicin-sensitive inhibitory innervation of the rat ureter. Eur J Pharmacol 126: 333-336, 1986[ISI][Medline].

35.   McCloskey, KD, and Gurney AM. Kit positive cells in the guinea pig bladder. J Urol 168: 832-836, 2002[ISI][Medline].

36.   Munsie, M, Schlatt S, deKretser DM, and Loveland KL. Expression of stem cell factor in the postnatal rat testis. Mol Reprod Dev 47: 19-25, 1997[ISI][Medline].

37.   Ogata, J, Ueno F, Sakata T, and Yamasaki K. Histochemical study of adrenergic and cholinergic nerve fibers in the dog ureter. Kumamoto Med J 26: 113-119, 1973[Medline].

38.   Orth, JM, Jester WF, and Qiu J. Gonocytes in testes of neonatal rats express the c-kit gene. Mol Reprod Dev 45: 123-131, 1996[ISI][Medline].

39.   Pezzone, MA, Fraser MO, VanBibber MM, and de Groat WC. Physiologic evaluation of colonic motility in awake c-kit deficient mice and immunofluorescence evaluation of colonic interstitial cells of Cajal. In: Neurogastroenterology---From the Basics to the Clinics, edited by Krammer HJ, and Singer MV.. London: Kluwer, 2000, p. 461-469.

40.   Pushkarev Iu, P, and Kalganova MA. The functional properties of the intramural bladder neural plexus. Fiziol Zh 76: 1465-1469, 1990.

41.   Rameshwar, P, and Gascon P. Substance P (SP) mediates production of stem cell factor and interleukin-1 in bone marrow stroma: potential autoregulatory role for these cytokines in SP receptor expression and induction. Blood 86: 482-490, 1995[Abstract/Free Full Text].

42.   Robbins, SL, Cotran RS, and Kumar V. The lower urinary tract. In: Pathologic Basis of Disease (3rd ed.), edited by Robbins SL, Cotran RS, and Kumar V.. Philadelphia, PA: Saunders, 1984, p. 1062-1080.

43.   Rolle, U, Piotrowska AP, Nemeth L, and Puri P. Altered distribution of interstitial cells of Cajal in Hirschsprung disease. Arch Pathol Lab Med 126: 928-933, 2002[ISI][Medline].

44.   Roshani, H, Dabhoiwala NF, Tee S, Dijkhuis T, Kurth KH, Ongerboer de Visser BW, de Jong JMBV, and Lamers WH. A study of ureteric peristalsis using a single catheter to record EMG, impedance, and pressure changes. Tech Urol 5: 61-66, 1999[Medline].

45.   Sandlow, JI, Feng HL, and Sandra A. Localization and expression of the c-kit receptor protein in human and rodent testis and sperm. Urology 49: 494-500, 1997[ISI][Medline].

46.   Sann, H, Jancso G, Ambrus A, and Pierau FK. Capsaicin treatment induces selective sensory degeneration and increased sympathetic innervation in the rat ureter. Neuroscience 67: 953-966, 1995[ISI][Medline].

47.   Santicioli, P, and Maggi CA. Myogenic and neurogenic factors in the control of pyeloureteral motility and ureteral peristalsis. Pharmacol Rev 50: 683-721, 1998[Abstract/Free Full Text].

48.   Schulman, CC, Duarte-Escalent O, and Boyarsky S. The ureterovesical innervation. A new concept based on a histochemical study. Br J Urol 44: 698-712, 1972[Medline].

49.   Shafik, A. Electroureterogram: human study of the electromechanical activity of the ureter. Urology 48: 696-699, 1996[ISI][Medline].

50.   Shiratori, T, and Kinoshita H. Electromyographic studies on the urinary tract. II. Electromyographic study on the genesis of peristaltic movement of the dog's ureter. Tohoku J Exp Med 73: 103-108, 1961[ISI].

51.   Sikri, KL, Hoyes AD, Barber P, and Jagessar H. Substance P-like immunoreactivity in the intramural nerve plexuses of the guinea-pig ureter: a light and electron microscopical study. J Anat 133: 425-442, 1981[ISI][Medline].

52.   Smet, PJ, Jonaviciius J, Marshall VR, and De Vente J. Distribution of nitric oxide sythase-immunoreactive nerves and identification of the cellular targets of nitric oxide in guinea-pig and human urinary bladder by cGMP immunohistochemistry. Neuroscience 71: 337-348, 1996[ISI][Medline].

53.   Smet, PJ, Moore KH, and Jonavicius J. Distribution and colocalization of calcitonin gene-related peptide, tachykinins, and vasoactive intestinal peptide in normal and idiopathic unstable urinary bladder. Lab Invest 77: 37-49, 1997[ISI][Medline].

54.   Su, HC, Wharton J, Polak JM, Mulderry PK, Ghatei MA, Gibson SJ, Terenght G, Morrison JFB, Ballesta J, and Bloom SR. Calcitonin gene-related peptide immunoreactivity in afferent neurons supplying the urinary tract: combined retrograde tracing and immunohistochemistry. Neurosci Lett 18: 727-747, 1986.

55.   Torihashi, S, Ward SM, Nishikawa S, Nishi K, Kobayashi S, and Sanders KM. C-kit-dependent development of interstitial cells and electrical activity in the murine gastrointestinal tract. Cell Tissue Res 280: 97-111, 1995[ISI][Medline].

56.   Uvelius, B, and Gabella G. Intramural neurones appear in the urinary bladder wall following excision of the pelvic ganglion in the rat. Neuroreport 6: 2213-2216, 1995[ISI][Medline].

57.   Vanderwinden, JM, Rumessen JJ, Liu H, Descamps D, De Laet MH, and Vanderhaeghen JJ. Interstitial cells of Cajal in human colon and in Hirschsprung's disease. Gastroenterology 111: 901-910, 1996[ISI][Medline].

58.   Ward, SM, Burns AJ, Torihashi S, and Sanders KM. Mutation of the proto-oncogene c-kit blocks development of interstitial cells and electrical rhythmicity in murine intestine. J Physiol 480: 91-97, 1994[Abstract].

59.   Wein, AJ, Leoni JV, Schoenberg HW, and Jacobowitz D. A study of the adrenergic nerves in the dog ureter. J Urol 108: 232-233, 1972[ISI][Medline].

60.   Weiss, RM, Wagner ML, and Hoffman BF. Localization of the pacemaker for peristalsis in the intact canine ureter. Investig Urol (Berl) 5: 42-46, 1967.

61.   Yamataka, A, Kato Y, Tibboel D, Murata N, Sueyoshi N, Fujimoto T, Nishiye H, and Miyano T. A lack of intestinal pacemaker (c-kit) in aganglionic bowel of patients with Hirschsprung's Disease. J Pediatr Surg 30: 441-444, 1995[ISI][Medline].

62.   Zhou, Y, and Ling EA. Colocalization of nitric oxide synthase and some neurotransmitters in the intramural ganglia of the guinea pig urinary bladder. J Comp Neurol 394: 496-505, 1998[ISI][Medline].


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