INNERVATION CANINE
DAVID DAVID
AREA OF
URINARY BLADDER
M. RAEZER,
STANLEY
OF TRIGONAL
M.D.
H. GREENBERG,
M. JACOBOWITZ,
M.D. PH.D.
GEORGE
S. BENSON,
JOSEPH
N. CORRIERE,
ALAN J. WEIN,
M.D. JR., M.D.
M.D.
From the Division of Urology, Department of Surgery, the Harrison Department of Surgical Research of University of Pennsylvania, and the Philadelphia Veterans Hospital, Philadelphia, Pennsylvania, and the Laboratory of Clinical Science, National Institute of Mental Health, Bethesda, Maryland
ABSTRACT - Adrenergic and cholinergic histochemical staining techniques and in vitro muscle strip responses to adrenergic and cholinergic stimulation and blockade have failed to demonstrate any neuromorphologic or neuropharmacologic differences between the musculature of the canine trigone and that of the underlying detrusor. There is no evidence to suggest that a functional potential could be attributed to the trigone separate from that of the related bladder base.
The trigonal area of the urinary bladder is of fundamental importance to an understanding of the ureterovesical junction and bladder neck. Anatomically and embryologically, the trigone muscle is distinct from the detrusor muscle.“’ The trigone muscle which is continuous with the musculature of the ureter is subepithelial and backed posteriorly by detrusor muscle (Fig. 1).
Therefore, the trigonal area or posterior base contains the anatomically and embryologically distinct trigone and detrusor muscles. In our previous studies the trigone muscle and its underlying detrusor muscle taken together reacted identically to the rest of the bladder basee3 Neuromorphologically and pharmacologically, the bladder was found to be more appropriately divided between its base and body than between its trigone and detrusor muscles. To further investigate this conclusion, the trigone muscle and the underlying detrusor muscle were separated anatomically and studied individually by in vitro pharmacologic studies and histochemical stains. Material
and Methods
In vitro muscle bath studies
TRUSOR MUSCLE ERLYINO TRIOONE
FIGURE 1.
UROLOGY
Bladder anatomy and nomenclature.
/ APRIL 1976 / VOLUME
VII, NUMBER 4
The urinary bladders of 3 female and 2 male mongrel dogs were removed under light sodium pentobarbital anesthesia and placed in iced Tyrode’s solution in preparation for dissection after the descriptions of Woodburne’ and was then Tanagho and Pugh. 2 Each bladder opened through an anterior midline incision and
369
&ureter !% +;:..j ;::::,I..
::ZY,tycosol Incision
“intravesical”
ureteral orifice
i adherent
C
mucoso
FIGURE 2. (A and B) Dog urinary bladder removed in preparation for dissection as described in meth ods. (C and D) Left ureter brought intravesically to establish level of dissection.
the trigonal area identified. The detrusor muscle was incised about the trigonal area leaving a l-cm. cuK(Fig. 2A and B). Several centimeters of distal ureter were also left intact. The vesical mucosa above the left ureteral orifice was then incised (Fig. 2C and D), and the submucosal and intravesical portions of the ureters were separated from their surrounding structures. The left ureter was then pulled through the wall of the detrusor muscle, making the ureter intravesical. The same was accomplished with the right ureter. Using the ureters as points for traction, the trigone muscle was dissected and elevated from its underlying detrusor muscle (Fig. 3). Muscle strips, measuring approximately 1 by 0.5 cm. from the trigone muscle and underlying detrusor muscle were placed in 35-ml. chambers filled with Tyrode’s solution kept at a constant temperature of 37°C. After placing an initial tension of 500 mg., the muscle strip was allowed to equilibrate with a gas mixture of 95 per cent oxygen and 5 per cent carbon dioxide for at least one-half hour. Each strip was exposed to increasing concentrations (0.01 to 10 micrograms per
370
cubic centimeter) of bethanechol chloride (Urecholine), a parasympathomimetic agent; ACh (acetylcholine), the cholinergic transmitter; epinephrine, an alpha and beta stimulator; norepinephrine (levarterenol bitartrate), an alpha and beta stimulator; and isoproterenol hydrochloride, a beta stimulator. Each muscle strip was triply washed with Tyrode’s solution before administering a different substance. Propranolol, a beta blocker, was added to the bath in a concentration of 10 micrograms per cubic centimeter, and after ten minutes the muscle response to norepinephrine was again tested. After several rinses with Tyrode’s solution the same procedure was carried out after pretreatment with phentolamine mesylate (Regitine), an alpha blocker, in a concentration of 10 micrograms per cubic centimeter. The muscle strip was then stimulated with ACh after a fifteen-minute treatment with physostigmine salicylate (eserine), an anticholinesterase agent. The contractions were measured isometrically by a force displacement transducer (Grass FT-03) on a four-channel Beckman recorder which was calibrated in grams.
UROLOGY
i
APRIL 1976 !
VOLU.ME VII, NUMBER 4
detrusor muscle underlying trigone
FIGURE3. (A and B) lntravesical ureters used to establish plane by which trigone is separated from its underlying detrusor muscle. (C and D) Demonstrates posterior sulfate of trigone and detrusor muscle underlying this.
Histochemical
studies
The dissection of the trigone was accomplished in situ on 1 male and 1 female mongrel dog under light sodium pentobarbital anesthesia. Sections were taken from the trigone area after the trigone muscle and underlying detrusor muscle had been reapproximated. Sections were also taken from the anterior base (Fig. 1). These sections were stained for cholinergic and adrenergic nerves. The muscle strips to be studied for cholinergic innervation were immediately frozen with solid carbon dioxide on removal from the animal. Sections of 15 microns were cut with a cryostat at -15’C., placed on slides, and stained for AChE (acetylcholinesterase) by the thiocholine method of Koelle.4 The slides were placed in the appropriate preincubation solutions for thirty minutes at 37”C., after which they were incubated for one hour at 37°C. Butyrocholinesterase was selectively inhibited by preincubation with lo-’ M DFP (diisoprophylfluorophosphate). All slides were counterstained with eosin.
UROLOGY
/ APRIL 1976
/ VOLUME
VII,
NUMBER
4
Visualization of adrenergic nerves was made according to the method of Falck.5 Muscle strips from the two regions were frozen in isopentane cooled with liquid nitrogen. The tissue was freeze-dried for four to five days at minus 30°C. The dried tissue was exposed to dry stock formaldehyde fumes at 80°C. for one hour and embedded in par&n in a vacuum oven at 60°C. for thirty minutes. Paraffin blocks were cut at 14 microns. All sections were mounted in xylene and observed under a fluorescence microscope by means of a BG-3 exciting filter and a Zeiss 47 barrier filter. Results In vitro muscle
bath studies
Only two of the five specimens of trigone showed good spontaneous activity in the muscle bath, while three of five pieces of trigonal area detrusor exhibited spontaneous contractions, but all muscle strips tested responded vigorously to
371
FIGURE 4. (A) Posteriw base contains mucosal surface (M), trigone (T), and underlying detrusor muscle CD). This muscle is stained for cholinergic nerves and demonstrates rich cholinergic innervation throughout post erior base. (B) A blow up of trigone taken from figure A. (C) This section taken from anterior base demonstrates rich cholinergic innervation which is similar to that of posterior base.
stimulation with bethanechol chloride at a concentration of 1 to 10 micrograms per cubic centimeter. The response was noteworthy for a marked increase in baseline tension. The response to acetylcholine was a rapid increase in baseline tension with essentially no change in frequency or amplitude of spontaneous contraction. The threshold contraction of ACh was decreased by a factor of 10 to 100 when the muscle
372
was pretreated with physostigmine. Two specimens of detrusor did not react at all to ACh at the 10 microgram per cubic centimeter level, yet they showed marked response to this concentration of the drug after fifteen minutes’ exposure to physostigmine. All the muscle strips responded with increased baseline tension on exposure to both norepinephrine and epinephrine at concentrations of 1 to 10
UROLOGY
/
APRIL 1976
/
VOLUME
VII,
NUMBER
4
I. Responses of trigone and underlying detrusor muscle to pharmacologic stimulation
TABLE
TRIGONE
ARFNT
OETRUSOR MfURsCLE UNDWYING IGONE
Bsthonrchol*
++ lo +++
++ to +++
Acrtylcholine
+ to ++t
0 10 t+t
Phyrortigminr** followrd by Acrfylcholine
tttt
tttt
Norrpinrphrinr
t lo ttt
+ lo ttt
Epmrphrmr
+ lo tt+
t
lo +tt
lsoproterrnol
- lo --
0
lo -
Propronolol** followed by Norrpinsphrlne
tt
Phrntolomine** followed by Norwinrohrine
lo ttt
+t
0
lo t+t
0
s All drugs 01 LO-;0 &g/cc concmlro(ion unless otherwise noted ** Prrtrrotmrnt for IO-15 minutes 0 = no rr¶ponrr ; t = contraction; - = inhibition; + or - *minimal; tt = mild; ttt = strong; tt+t = mprkad; -- = mold.
micrograms per cubic centimeter. The response to norepinephrine was slightly increased by pretreatment with propranolol while it was completely abolished by phentolamine. The trigone muscle exhibited decreased baseline tension and, in specimens with spontaneous activity, decreased frequency and amplitude of contraction on the addition of isoproterenol to the bath; however, only one specimen of detrusor responded in a similar manner, the remainder of the muscle strips apparently being unaffected by isoproterenol. These results are summarized in Table I. Histochemical
studies
The muscle from the posterior base contained an abundant number of cholinergic nerves (Fig. 4A). Both the trigone and the underlying detrusor muscle were richly innervated. In addition, intensely stained choline&c ganglion cell bodies and nerve trunks were observed in the connective tissue septa in proximity to the muscles. The trigonal area (Fig. 4B) had a similar innervation to that of the anterior base (Fig. 4C). The muscle of the posterior base also contained an abundant number of adrenergic nerve fibers (Fig. 5). The deep longitudinal muscle layer (Fig. 6A) contained a somewhat greater number of
UROLOGY
/ APRIL1976 / VOLUMEVII,
NUMBER4
nerves than the subepithelial muscle layer - the trigone muscle. Numerous blood vessels were noted particularly in the connective tissue regions. The arteries were well innervated and the large veins contained a few fibers. The muscle of the anterior base (Fig. 6B) also contained a somewhat greater number of nerves to the deep muscle when compared with the subepithelial muscle layer (Fig. 6C). The subepithelial muscle of both the anterior base and posterior base were similarly innervated. Comment By the use of histochemical stains and in vitro muscle bath studies, the trigone muscle and the detrusor muscle of the base are neuromomhologically and pharmacologically similar. Thi trigone and detrusor muscle of the base do not demonstrate any differences that might be predicted on the basis of anatomy and embryology. The trigone and detrusor muscle of the base are indistinguishable in their anatomic innervation. This conclusion is in direct conflict with Elbadawi and Schenk’a’ who, using similar histochemical stains, concluded that the innervation of the trigone muscle “be it cholinergic or adrenergic is less prominent than that of the related bladder base.“’ The trigone and detrusor muscle of the base are also indistinguishable in their response to cholinergic and adrenergic stimulation. We originally described a lack of “a consistent contractile response of detrusor strips to acetylcholine in strips taken from the trigone or.posterior lateral base.“* The reason for the apparent lack of consistency is due to the presence of both the neuronal and membrane acetylcholinesterase in the urinary bladder.3 By its peripheral location, neuronal acetylcholinesterase appears to inactivate exogenous acetylcholine before it reaches the receptors on the muscle cell. It is suggested that membrane acetylcholinesterase acts at the membrane after activation of the receptor. The base of the bladd r is rich in neuronal acetylcholinesterase whi f 6 the body has an abundance of membrane acetylcholinesterase.3 Therefore, we now believe that the trigonal area, like the rest of the bladder, is cholinergically innervated and has an abundance of cholinergic receptor sites. The trigone, the subepithelial muscle of the neuroposterior base, is indistinguishable morphologically from the subepithelial muscle of the rest of the bladder base. That is to say, the subepithelial muscle of the base is uniform in its
37-3
?? D
*D
base which is stained for FIGURE 5. Posterior adrenergic nerves and contains mucosal sulfate (M), trigone (T), and underlying detrusor muscle (D). Area of posterior base demonstrates variable adrenergic innervation.
FIGURE 6. (A) This section of muscle taken from deep posterior base or, as it has been phrased, detrusor muscle underlying trigone and demonstrates abundance of adrenergic nerves. (B) Deep anterior base demonstrates similar nerves to detrusor abundance of adrenergic muscle underlying trigone in posterior base. (C) Somewhat lesser number of adrenergic nerves than section from deep anterior base and is similar to that of trigone.
374
UROLOGY
/ APRIL 1976 / VOLUME
VII, NUMBER 4
adrenergic innervation. Interestingly, in the earlier work of Elbadawi and Schenk,gJO they stated that the trigone could not be distinguished by histochemical stains from the rest of the bladder base. The base is richly innervated by both adrenergic and cholinergic nerves. The body has only a scant to modest innervation.3,g,10 Adrenergic stimulation of the body demonstrates primarily beta inhibitory activity while cholinergic stimulation produces a consistent cholinergic contraction.3 Therefore, large and predictable differences exist between the body and base rather than the detrusor and the trigone. It is difficult to imagine that the trigone could function separately from the detrusor muscle of the base. The base appears to be the functional unit. There is no evidence to suggest that a functional potential could be attributed to the trigone alone. Theories that give the trigone functional responsibilities separate from the bladder base must be questioned. 1 Children’s Center 34th Street and Civic Center Boulevard, Philadelphia, Pennsylvania 19104 (DR. RAEZER)
UROLOGY
/
APRIL 1976 /
VOLUME VII, NUMBER 4
References 1. WOODBURNE, R. T.: Anatomy of the bladder and bladder outlet, J. Urol. 100: 474 (1968). 2. TANAGHO, E. A., and PUGH, R. C. B.: The anatomy and function of the ureterovesical junction, Br. J. Urol. 35: 151 (1963). 3. RAEZER, D. M., WEIN, A. J., JACOBOWITZ, D., and CORRIERE, J. N.: The autonomic innervation of the canine urinary bladder, Urology 2: 211 (1973). 4. KOELLE, G. B.: The histochemical identification of acetylcholinesterase in cholinergic, adrenergic and sensory neurons, J. Pharmacol. Exp. Ther. 103: 153 (1955). 5. FALCK, B.: Observations on the possibilities of the cellular localization of monoamines by a fluorescence method, Acta Physiol. Stand. 56: (Suppl. 197) 1 (1962). 6. ELBADAWI, A., and SCHENK, E. A.: A new theory of the innervation of the urinary bladder musculature. II. The innervation apparatus of the ureterovesical junction, J. Urol. 105: 368 (1971). 7. ELBADAWI, A.: Bladder innervation, Urology 2: 331 (1973). 8. ROHNER, T. J., RAEZER, D. M., WEIN, A. J., and SCHOENBERG, H. W.: Contractile responses of dog bladder muscle to adrenergic drugs. J. Urol. 105: 657 (1971). Dual innervation of 9. ELBADAWI, A., and SCHENK, E.: the mammalian urinary bladder, Am. J. Anat. 119: 405 (1966). 10. IDEM: A new theory of the innervation of bladder musculature. I. Morphology of the intrinsic vesical innervation apparatus, J. Urol. 99: 585 (1968).
375
DAVID DAVID
AREA OF
URINARY BLADDER
M. RAEZER,
STANLEY
OF TRIGONAL
M.D.
H. GREENBERG,
M. JACOBOWITZ,
M.D. PH.D.
GEORGE
S. BENSON,
JOSEPH
N. CORRIERE,
ALAN J. WEIN,
M.D. JR., M.D.
M.D.
From the Division of Urology, Department of Surgery, the Harrison Department of Surgical Research of University of Pennsylvania, and the Philadelphia Veterans Hospital, Philadelphia, Pennsylvania, and the Laboratory of Clinical Science, National Institute of Mental Health, Bethesda, Maryland
ABSTRACT - Adrenergic and cholinergic histochemical staining techniques and in vitro muscle strip responses to adrenergic and cholinergic stimulation and blockade have failed to demonstrate any neuromorphologic or neuropharmacologic differences between the musculature of the canine trigone and that of the underlying detrusor. There is no evidence to suggest that a functional potential could be attributed to the trigone separate from that of the related bladder base.
The trigonal area of the urinary bladder is of fundamental importance to an understanding of the ureterovesical junction and bladder neck. Anatomically and embryologically, the trigone muscle is distinct from the detrusor muscle.“’ The trigone muscle which is continuous with the musculature of the ureter is subepithelial and backed posteriorly by detrusor muscle (Fig. 1).
Therefore, the trigonal area or posterior base contains the anatomically and embryologically distinct trigone and detrusor muscles. In our previous studies the trigone muscle and its underlying detrusor muscle taken together reacted identically to the rest of the bladder basee3 Neuromorphologically and pharmacologically, the bladder was found to be more appropriately divided between its base and body than between its trigone and detrusor muscles. To further investigate this conclusion, the trigone muscle and the underlying detrusor muscle were separated anatomically and studied individually by in vitro pharmacologic studies and histochemical stains. Material
and Methods
In vitro muscle bath studies
TRUSOR MUSCLE ERLYINO TRIOONE
FIGURE 1.
UROLOGY
Bladder anatomy and nomenclature.
/ APRIL 1976 / VOLUME
VII, NUMBER 4
The urinary bladders of 3 female and 2 male mongrel dogs were removed under light sodium pentobarbital anesthesia and placed in iced Tyrode’s solution in preparation for dissection after the descriptions of Woodburne’ and was then Tanagho and Pugh. 2 Each bladder opened through an anterior midline incision and
369
&ureter !% +;:..j ;::::,I..
::ZY,tycosol Incision
“intravesical”
ureteral orifice
i adherent
C
mucoso
FIGURE 2. (A and B) Dog urinary bladder removed in preparation for dissection as described in meth ods. (C and D) Left ureter brought intravesically to establish level of dissection.
the trigonal area identified. The detrusor muscle was incised about the trigonal area leaving a l-cm. cuK(Fig. 2A and B). Several centimeters of distal ureter were also left intact. The vesical mucosa above the left ureteral orifice was then incised (Fig. 2C and D), and the submucosal and intravesical portions of the ureters were separated from their surrounding structures. The left ureter was then pulled through the wall of the detrusor muscle, making the ureter intravesical. The same was accomplished with the right ureter. Using the ureters as points for traction, the trigone muscle was dissected and elevated from its underlying detrusor muscle (Fig. 3). Muscle strips, measuring approximately 1 by 0.5 cm. from the trigone muscle and underlying detrusor muscle were placed in 35-ml. chambers filled with Tyrode’s solution kept at a constant temperature of 37°C. After placing an initial tension of 500 mg., the muscle strip was allowed to equilibrate with a gas mixture of 95 per cent oxygen and 5 per cent carbon dioxide for at least one-half hour. Each strip was exposed to increasing concentrations (0.01 to 10 micrograms per
370
cubic centimeter) of bethanechol chloride (Urecholine), a parasympathomimetic agent; ACh (acetylcholine), the cholinergic transmitter; epinephrine, an alpha and beta stimulator; norepinephrine (levarterenol bitartrate), an alpha and beta stimulator; and isoproterenol hydrochloride, a beta stimulator. Each muscle strip was triply washed with Tyrode’s solution before administering a different substance. Propranolol, a beta blocker, was added to the bath in a concentration of 10 micrograms per cubic centimeter, and after ten minutes the muscle response to norepinephrine was again tested. After several rinses with Tyrode’s solution the same procedure was carried out after pretreatment with phentolamine mesylate (Regitine), an alpha blocker, in a concentration of 10 micrograms per cubic centimeter. The muscle strip was then stimulated with ACh after a fifteen-minute treatment with physostigmine salicylate (eserine), an anticholinesterase agent. The contractions were measured isometrically by a force displacement transducer (Grass FT-03) on a four-channel Beckman recorder which was calibrated in grams.
UROLOGY
i
APRIL 1976 !
VOLU.ME VII, NUMBER 4
detrusor muscle underlying trigone
FIGURE3. (A and B) lntravesical ureters used to establish plane by which trigone is separated from its underlying detrusor muscle. (C and D) Demonstrates posterior sulfate of trigone and detrusor muscle underlying this.
Histochemical
studies
The dissection of the trigone was accomplished in situ on 1 male and 1 female mongrel dog under light sodium pentobarbital anesthesia. Sections were taken from the trigone area after the trigone muscle and underlying detrusor muscle had been reapproximated. Sections were also taken from the anterior base (Fig. 1). These sections were stained for cholinergic and adrenergic nerves. The muscle strips to be studied for cholinergic innervation were immediately frozen with solid carbon dioxide on removal from the animal. Sections of 15 microns were cut with a cryostat at -15’C., placed on slides, and stained for AChE (acetylcholinesterase) by the thiocholine method of Koelle.4 The slides were placed in the appropriate preincubation solutions for thirty minutes at 37”C., after which they were incubated for one hour at 37°C. Butyrocholinesterase was selectively inhibited by preincubation with lo-’ M DFP (diisoprophylfluorophosphate). All slides were counterstained with eosin.
UROLOGY
/ APRIL 1976
/ VOLUME
VII,
NUMBER
4
Visualization of adrenergic nerves was made according to the method of Falck.5 Muscle strips from the two regions were frozen in isopentane cooled with liquid nitrogen. The tissue was freeze-dried for four to five days at minus 30°C. The dried tissue was exposed to dry stock formaldehyde fumes at 80°C. for one hour and embedded in par&n in a vacuum oven at 60°C. for thirty minutes. Paraffin blocks were cut at 14 microns. All sections were mounted in xylene and observed under a fluorescence microscope by means of a BG-3 exciting filter and a Zeiss 47 barrier filter. Results In vitro muscle
bath studies
Only two of the five specimens of trigone showed good spontaneous activity in the muscle bath, while three of five pieces of trigonal area detrusor exhibited spontaneous contractions, but all muscle strips tested responded vigorously to
371
FIGURE 4. (A) Posteriw base contains mucosal surface (M), trigone (T), and underlying detrusor muscle CD). This muscle is stained for cholinergic nerves and demonstrates rich cholinergic innervation throughout post erior base. (B) A blow up of trigone taken from figure A. (C) This section taken from anterior base demonstrates rich cholinergic innervation which is similar to that of posterior base.
stimulation with bethanechol chloride at a concentration of 1 to 10 micrograms per cubic centimeter. The response was noteworthy for a marked increase in baseline tension. The response to acetylcholine was a rapid increase in baseline tension with essentially no change in frequency or amplitude of spontaneous contraction. The threshold contraction of ACh was decreased by a factor of 10 to 100 when the muscle
372
was pretreated with physostigmine. Two specimens of detrusor did not react at all to ACh at the 10 microgram per cubic centimeter level, yet they showed marked response to this concentration of the drug after fifteen minutes’ exposure to physostigmine. All the muscle strips responded with increased baseline tension on exposure to both norepinephrine and epinephrine at concentrations of 1 to 10
UROLOGY
/
APRIL 1976
/
VOLUME
VII,
NUMBER
4
I. Responses of trigone and underlying detrusor muscle to pharmacologic stimulation
TABLE
TRIGONE
ARFNT
OETRUSOR MfURsCLE UNDWYING IGONE
Bsthonrchol*
++ lo +++
++ to +++
Acrtylcholine
+ to ++t
0 10 t+t
Phyrortigminr** followrd by Acrfylcholine
tttt
tttt
Norrpinrphrinr
t lo ttt
+ lo ttt
Epmrphrmr
+ lo tt+
t
lo +tt
lsoproterrnol
- lo --
0
lo -
Propronolol** followed by Norrpinsphrlne
tt
Phrntolomine** followed by Norwinrohrine
lo ttt
+t
0
lo t+t
0
s All drugs 01 LO-;0 &g/cc concmlro(ion unless otherwise noted ** Prrtrrotmrnt for IO-15 minutes 0 = no rr¶ponrr ; t = contraction; - = inhibition; + or - *minimal; tt = mild; ttt = strong; tt+t = mprkad; -- = mold.
micrograms per cubic centimeter. The response to norepinephrine was slightly increased by pretreatment with propranolol while it was completely abolished by phentolamine. The trigone muscle exhibited decreased baseline tension and, in specimens with spontaneous activity, decreased frequency and amplitude of contraction on the addition of isoproterenol to the bath; however, only one specimen of detrusor responded in a similar manner, the remainder of the muscle strips apparently being unaffected by isoproterenol. These results are summarized in Table I. Histochemical
studies
The muscle from the posterior base contained an abundant number of cholinergic nerves (Fig. 4A). Both the trigone and the underlying detrusor muscle were richly innervated. In addition, intensely stained choline&c ganglion cell bodies and nerve trunks were observed in the connective tissue septa in proximity to the muscles. The trigonal area (Fig. 4B) had a similar innervation to that of the anterior base (Fig. 4C). The muscle of the posterior base also contained an abundant number of adrenergic nerve fibers (Fig. 5). The deep longitudinal muscle layer (Fig. 6A) contained a somewhat greater number of
UROLOGY
/ APRIL1976 / VOLUMEVII,
NUMBER4
nerves than the subepithelial muscle layer - the trigone muscle. Numerous blood vessels were noted particularly in the connective tissue regions. The arteries were well innervated and the large veins contained a few fibers. The muscle of the anterior base (Fig. 6B) also contained a somewhat greater number of nerves to the deep muscle when compared with the subepithelial muscle layer (Fig. 6C). The subepithelial muscle of both the anterior base and posterior base were similarly innervated. Comment By the use of histochemical stains and in vitro muscle bath studies, the trigone muscle and the detrusor muscle of the base are neuromomhologically and pharmacologically similar. Thi trigone and detrusor muscle of the base do not demonstrate any differences that might be predicted on the basis of anatomy and embryology. The trigone and detrusor muscle of the base are indistinguishable in their anatomic innervation. This conclusion is in direct conflict with Elbadawi and Schenk’a’ who, using similar histochemical stains, concluded that the innervation of the trigone muscle “be it cholinergic or adrenergic is less prominent than that of the related bladder base.“’ The trigone and detrusor muscle of the base are also indistinguishable in their response to cholinergic and adrenergic stimulation. We originally described a lack of “a consistent contractile response of detrusor strips to acetylcholine in strips taken from the trigone or.posterior lateral base.“* The reason for the apparent lack of consistency is due to the presence of both the neuronal and membrane acetylcholinesterase in the urinary bladder.3 By its peripheral location, neuronal acetylcholinesterase appears to inactivate exogenous acetylcholine before it reaches the receptors on the muscle cell. It is suggested that membrane acetylcholinesterase acts at the membrane after activation of the receptor. The base of the bladd r is rich in neuronal acetylcholinesterase whi f 6 the body has an abundance of membrane acetylcholinesterase.3 Therefore, we now believe that the trigonal area, like the rest of the bladder, is cholinergically innervated and has an abundance of cholinergic receptor sites. The trigone, the subepithelial muscle of the neuroposterior base, is indistinguishable morphologically from the subepithelial muscle of the rest of the bladder base. That is to say, the subepithelial muscle of the base is uniform in its
37-3
?? D
*D
base which is stained for FIGURE 5. Posterior adrenergic nerves and contains mucosal sulfate (M), trigone (T), and underlying detrusor muscle (D). Area of posterior base demonstrates variable adrenergic innervation.
FIGURE 6. (A) This section of muscle taken from deep posterior base or, as it has been phrased, detrusor muscle underlying trigone and demonstrates abundance of adrenergic nerves. (B) Deep anterior base demonstrates similar nerves to detrusor abundance of adrenergic muscle underlying trigone in posterior base. (C) Somewhat lesser number of adrenergic nerves than section from deep anterior base and is similar to that of trigone.
374
UROLOGY
/ APRIL 1976 / VOLUME
VII, NUMBER 4
adrenergic innervation. Interestingly, in the earlier work of Elbadawi and Schenk,gJO they stated that the trigone could not be distinguished by histochemical stains from the rest of the bladder base. The base is richly innervated by both adrenergic and cholinergic nerves. The body has only a scant to modest innervation.3,g,10 Adrenergic stimulation of the body demonstrates primarily beta inhibitory activity while cholinergic stimulation produces a consistent cholinergic contraction.3 Therefore, large and predictable differences exist between the body and base rather than the detrusor and the trigone. It is difficult to imagine that the trigone could function separately from the detrusor muscle of the base. The base appears to be the functional unit. There is no evidence to suggest that a functional potential could be attributed to the trigone alone. Theories that give the trigone functional responsibilities separate from the bladder base must be questioned. 1 Children’s Center 34th Street and Civic Center Boulevard, Philadelphia, Pennsylvania 19104 (DR. RAEZER)
UROLOGY
/
APRIL 1976 /
VOLUME VII, NUMBER 4
References 1. WOODBURNE, R. T.: Anatomy of the bladder and bladder outlet, J. Urol. 100: 474 (1968). 2. TANAGHO, E. A., and PUGH, R. C. B.: The anatomy and function of the ureterovesical junction, Br. J. Urol. 35: 151 (1963). 3. RAEZER, D. M., WEIN, A. J., JACOBOWITZ, D., and CORRIERE, J. N.: The autonomic innervation of the canine urinary bladder, Urology 2: 211 (1973). 4. KOELLE, G. B.: The histochemical identification of acetylcholinesterase in cholinergic, adrenergic and sensory neurons, J. Pharmacol. Exp. Ther. 103: 153 (1955). 5. FALCK, B.: Observations on the possibilities of the cellular localization of monoamines by a fluorescence method, Acta Physiol. Stand. 56: (Suppl. 197) 1 (1962). 6. ELBADAWI, A., and SCHENK, E. A.: A new theory of the innervation of the urinary bladder musculature. II. The innervation apparatus of the ureterovesical junction, J. Urol. 105: 368 (1971). 7. ELBADAWI, A.: Bladder innervation, Urology 2: 331 (1973). 8. ROHNER, T. J., RAEZER, D. M., WEIN, A. J., and SCHOENBERG, H. W.: Contractile responses of dog bladder muscle to adrenergic drugs. J. Urol. 105: 657 (1971). Dual innervation of 9. ELBADAWI, A., and SCHENK, E.: the mammalian urinary bladder, Am. J. Anat. 119: 405 (1966). 10. IDEM: A new theory of the innervation of bladder musculature. I. Morphology of the intrinsic vesical innervation apparatus, J. Urol. 99: 585 (1968).
375
