Embed Size (px)
Citation preview
Scand J Urol Nephrol9: 185-191, 1975
THE LOBES OF THE HUMAN PROSTATE
Lars-Eric Tisell and HBkan Salander
From the Department of Surgery I1 and Department of Pathology 11, University of GBtet.org. Sweden
(Submitted for publication November 6, 1974)
Abstract. A dissection technique for the human prostate has been developed on about one hundred male autopsies, which makes it possible to delimit two dorsal, two lateral and two median lobes, each with separate ducts. It was found that both the dorsal lobes and the lateral lobes join dorsally to the ejaculatory ducts. The median lobes are situated below the medial parts of the seminal vesicles, and are closely apposed both ventrally and dorsally of the ejaculatory ducts. The ability to delimit the prostatic lobes in man may offer new opportunities to study the relation of prostatic diseases to different lobes as well as the hormonal dependency of the separate lobes.
After studies on the hormonal dependency of the canine prostate (Huggins, Masina, Eichelberger & Wharton, 1939; Huggins & Clark, 1940) Huggins and co-workers (Huggins & Hodges, 1941; Hug- gins, Stevens & Hodges, 1941; Huggins, Scott & Hodges, 1941) introduced ablation of the testes and medication with oestrogens in the treatment of men suffering from prostatic carcinoma.
The problems of prostatic diseases in man have stimulated further experimental studies in animals to elucidate the role of hormones in prostatic growth. Such studies have been performed mainly in the rat. The prostatic gland of the rat is composed of discrete lobes, viz. the ventral prostate, the dorsolateral prostate, and the coagulating glands. The histological structure differs in the various lobes of the rat prostate as does the chemical com- position of the lobes and their secretion (Price, 1963). The various lobes also differ in their de- pendency to different hormones (Grayhack, 1963; Grayhack 1965; Tisell & Angervall, 1969; Tisell, 1970; Tisell, 1971; Tisell, 1972 a ) .
When studying step sections from prostates of human embryos, Lowsley (1912) observed that when the ducts of the lobules were traced to their
urethral openings, the prostate could be divided into five lobes: a dorsal or posterior lobe dorsal to the ejaculatory ducts, a median or middle lobe be- tween the ejaculatory ducts and the urethra, a lat- eral lobe on each side of the urethra, and a small ventral or anterior lobe which was generally absent or atrophic in postnatal life.
Several attempts have been msde to correlate prostatic diseases in man to prostatic anatomy (Moore, 1935; Gaynor, 1938; Kahler, 1939; Andrews, 1949; Edwards, Steinthorsson & Nic- holson, 1953; Franks, 1954a, b; Butler, Braun- stein, Freiman & Gall, 1959; Blennerhasset & Vickery, 1966; LiavBg, 1967; Hutch & Rambo, 1970). The prostatic lobes in man have never been defined by dissection (Karube, 1961; Oota, 1961; Price, 1963; LiavBg, 1%7) nor has i t been possible to find any microscopic demarcations postnatally (Johnson, 1920; Karube, 1961; Liav%g, 1967) be- tween the lobes described by Lowsley (1912). It is therefore easily understandable that in the above- mentioned series diverging results with regard to frequency of pathological conditions in different portions of the prostate have been reported. These inconsistencies cannot be resolved unless the anatomical boundaries of the prostatic lobes are defined. If this could be done the possibilities of correlating experimental observations in animals with the conditions in man would also be improved.
The present work was carried out with the purpose of investigating by dissection, whether any anatomical boundaries between the lobes. of the human prostate could be demonstrated.
MATERIAL AND METHODS The material in this study consisted of the prostates from about one hundred autopsies on males ranging in age from
Scand J Urol Nephrol9
Scan
d J
Uro
l Nep
hrol
Dow
nloa
ded
from
info
rmah
ealth
care
.com
by
Uni
vers
ity o
f A
uckl
and
on 1
1/25
/14
For
pers
onal
use
onl
y.
186 L.-E. Tisell and H . Salander
18 to 87 years at the Departments of Pathology (11) and Forensic Medicine, University of Goteborg, Sweden. The corpses were kept at a temperature of 44°C. and the autopsy was usually performed I to 3 days after death. At autopsy the rectum, urinary bladder, proximal urethra, prostate and seminal vesicles were taken out en bloc. The prostate with the seminal vesicles was carefully dissected free from the surrounding tissue. The dissection of the prostatic lobes was then performed with the aid of a magnifying glass. During the dissection the prostate with attached seminal vesicles was kept moist with physiologi- cal saline. The anatomical relations between the indi- vidual prostatic lobes and their relationship to the urethra as well as the ejaculatory ducts were noted. During the period when the dissection technique was developed, histological examination of sections from the prostatic lobes and the adhering tissues was performed in order to help to demarcate the prostatic lobes. The tissues were fixed in 10% formalin solution and after dehydration they were embedded in paraffin and cut into 5 F m sections which were stained according to Weigert-van Gieson or with PAS-staining (McManus, 1948).
After the dissection technique had been developed and perfected, prostates from autopsy cases between 20 and 40 years of age were selected. In this series only cases with- out history or gross signs of prostatic diseases were in- cluded. The prostates were photographed at various stages of the dissection.
Technique of dissection and anatomical relations of the prostatic lobes
A technique for the dissection of the prostatic lobes has been developed and used in morphological studies in rats. With this technique reliable and reproducible results were obtained even when the prostatic lobes were small (Tisell, 1972 6 ) . A similar technique was applied for study- ing the possible lobation of the adult human prostate. After the dissection of about fifteen human prostates it became obvious that there is a lobation of the adult human prostate. From these first dissections, it was evident that not only the dorsal lobes but also the lateral lobes join dorsally to the ejaculatory ducts.
The first dissections were very laborious and the time required for the dissection of one prostate amounted to 15-20 hours. With improvement of technique and knowledge of the anatomy the dissection time was re- duced to 2-3 hours in the last 20 cases in the series.
Viewing the prostate and the seminal vesicles from the dorsal aspect the prostatic vessels are found to reach the prostatic gland at its upper lateral corners (Fig. I). Here the dorsal, lateral and median lobes on each side are in close proximity to each other, the knowledge of which is of fundamental importance for the dissection (Fig. 2 a , 6 ) .
When viewed from the lateral aspect, the prostate is seen to be flattened antero-posteriorly (Fig. 3 a , 6 ) with most of its parenchyma located dorsal to the urethra (Fig. 4).
On viewing the prostate from the anterior aspect, the urethra is seen in the centre, surrounded by an abundance of penurethral tissue (Fig. 5a, 6 ) .
The dissection generally started with the dorsal lobes. No demarcations between the dorsal and lateral lobes can
be seen on the surface of the prostate. By palpation of the prostate along its lateral borders, the boundaries between these lobes could be felt as a groove. A s the dorsal lobes are firmly adherent to the lateral lobes and to the prostatic capsule peripherally, the cleavage between the lobes may be difficult to find. Stretching of the prostate from its upper lateral corner, where the blood vessels enter, can facilitate the dissection laterally. The cranial edge of the dorsal lobes cannot be distinguished from the lateral lobes by palpation. Sometimes the cleavage can be found in this site but because of the small amount of glandular tissue here there is a high risk of faulty dissection with this approach. Once the cleavage between the lobes has been entered at one point the lobes are readily separated (Figs. 6 and 7). There are two dorsal lobes which are joined together in the dorsal midline (Figs. 8 and 9). Each of these lobes has some 6 to 8 ducts opening into the urethra distal to and at the level of the seminal colliculus (Figs. 7 and 10 a , 6).
In most cases the dorsal lobes form the entire dorsal surface of the prostate. In some cases the median lobes form the upper medial part of the dorsal surface. In these cases the median lobes can be distinguished from the dorsal lobes by their paler colour (Fig. I I a , 6 ) . In a few cases, when viewed from behind, even the lateral lobes have been observed to be uncovered by the dorsal lobes i n the upper midline.
The dorsal lobes also form some of the lateral surfaces of the prostate and distally they reach the lower part of an anterior commissure which consists of connective tissue and smooth muscle cells and connects the lobes on each side. Hence the dorsal lobes form the apex of the prostatic gland (Fig. 3 a , 6 ) .
The dissection of the lateral lobes starts at the upper dorso-lateral corner of the prostate. The lateral lobes are more firmly adherent to the median lobes than to the dorsal lobes. The lateral and median lobes can be disting- uished by palpation because the median lobes have a firmer consistency. There are two lateral lobes which are joined together dorsally to the ejaculatory ducts. In some cases there is no glandular tissue from half a centimetre up to 1 cm from the midline and in these cases the two lateral lobes are bound together by a layer of fibrous tissue in which the main ducts run to reach the urethra. The ducts of the lateral lobes enter the urethra lateral to those of the dorsal lobes, but the openings of the most distal ducts of the dorsal lobes are located more caudally (Figs. 12, 13, 14, 15 and 16). In most cases the lateral lobes, being situated between
the dorsal and the median lobes. only reach the surface of the gland laterally. The free border of the lateral lobe extends from the upper lateral corner of the prostate downwards and anteriorly to reach the lateral edge of the anterior commissure. This portion of the lateral lobe forms the anterior part of the lateral surface of the prostate (Fig. 3 a, 6 ) .
The median lobes form the central part and most of the base of the prostate. The medial parts of the seminal vesicles are bound to the median lobes (Figs. 17, 18 and 19). In most cases the median lobes are covered dorsally and laterally by the lateral lobes and only in a few cases do they reach the dorsal surface of the prostate and form the
Scand J Urol Nephrol9
Scan
d J
Uro
l Nep
hrol
Dow
nloa
ded
from
info
rmah
ealth
care
.com
by
Uni
vers
ity o
f A
uckl
and
on 1
1/25
/14
For
pers
onal
use
onl
y.
Lobes of the human prostate 187
Fig. I . Dorsal view of intact prostate with seminal vesicles and deferential ducts with ampullae. Note the prostatic vessels reach- ing the prostatic gland at its upper lateral corners.
Fig. 2a and b. Dorsal view of prostate with seminal vesicles where the dorsal and lateral lobes partly have b e n freed from each other a t the right upper corner to demonstrate the close proximity of the lobes to each other at this site. Key: DL, dorsal lobe; LL, lateral lobe; ML, median lobe; SV, seminal vesicle; UR, urethra.
Fig. 3a and b. Left lateral aspect of the prostate where the borderline between the Fig. 4 . Left lateral aspect of intact pros- dorsal and lateral lobes has been accentuated through dissection. Note that the tate with seminal vesicles. Remnants of dorsal lobe forms a considerable part of the lateral surface of the prostate and the bladder-neck mucosa can be seen that it caudally reaches the lateral edge of the anterior commissure. ventro-cranially to the prostate and part Key: DL, dorsal lobe; LL, lateral lobe; SV, seminal vesicle; UR, urethm, VASC, of the urethra caudally to it. The figure vascular pedicle. illustrates that most of the prostate is
situated dorsally to the urethra.
- -
Fig. 5 a and b. Anterior view of intact prostate with seminal vesicles. The figure demonstrates the abundant periurethral tissue and in front of this the low anterior commissure. Some of the external sphincter muscle remains caudally around the urethra. wards. Key: AC, anterior commissure; DD, deferential duct with ampulla; ES, external sphincter; PR, prostate; PU, periurethral tissue; SV, seminal vesicle; UR, urethra.
Fig. 6. View from behind. The upper parts of the lateral lobes are exposed by re- tracting the mobilized dorsal lobes down-
Fig. 7 . View from behind. The dorsal lobes Fig. 8. The isolated dorsal lobes viewed Fig. 9. Anterior view of the same isolated have been mobilized and turned down- from behind. The lobes are covered by a dorsal lobes as in fig. 8. The two lobes wards exposing the dorsal surfaces of the thin capsule and are united in the midline. have separate ducts coming from the peri- lateral lobes. Ducts from the dorsal lobes pheral parts of the lobes and going cen- can be seen penetrating between the two trally where the two lobes are connected. lateral lobes to reach the urethra near the midline.
13 - 752913 Scand J Urol Nephrol 9
Scan
d J
Uro
l Nep
hrol
Dow
nloa
ded
from
info
rmah
ealth
care
.com
by
Uni
vers
ity o
f A
uckl
and
on 1
1/25
/14
For
pers
onal
use
onl
y.
188 L.-E. Tisell and H. Sallander
r\
Fig. IOa and b. Left lateral view of a sagittal section through the prostate just to the right of the midline. Note the ejaculatory duct opening on the seminal colli- culus. A thin section of the lateral lobe can be seen cranial and dorsal to the ejaculatory duct and ventral to the dorsal lobe. The ducts of the dorsal lobe can be seen to approach the urethra at the level of and distal to the seminal colliculus. In front and cranial to the ejaculatory duct the median lobe can be seen. The lateral parts of the median lobe and the seminal vesicle are displaced somewhat ventrally by the underneath layer. There is no prostatic tissue anterior to the urethra in the midline. Key: DL, dorsal lobe: ED, ejaculatory duct; LL, lateral lobe; ML, median lobe; SV, seminal vesicle: UR, urethra.
Fig. I l a and b. Dorsal view of intact prostate demonstrating that the dorsal lobes Fig. 12. The prostate viewed from behind not always form all of the dorsal surface of the mostate. The median lobes can be after the dorsal lobes have been removed seen below the medial parts of the seminal vesicles. so that the lateral lobes are exposed. Key: DL, dorsal lobe: ML, median lobe; SV, seminal vesicle; UR, urethra. Distally in the midline a damage of the
surface can be seen where the ducts of the dorsal lobes have pierced to reach the urethra.
Fig. 13. Left dorsolateral aspect of the Fig. 14. View from behind after the lateral Fig. 15. View from behind of the isolated prostate after the dorsal lobes have been lobes have been freed peripherally and lateral lobes. The defect seen in the upper removed exposing the lateral lobes. Some retracted downwards exposing the upper midline of the thin capsule covering the ducts of the left lateral lobe are seen to parts of the median lobes. lobes was caused through the dissection. reach the urethra dorsally and laterally. Some ducts can be seen coming from the
periphery of the lobes going centrally where the two lobes are connected.
Fig. 16. Anterior view of the same isolated lateral lobes as in fig. 15.
Fig. 17. View from behind after the dorsal and lateral lobes have been totally re- moved. The dorsal surface of the median lobes, not yet dissected free from the peri- urethral tissue below, is exposed. Note that the seminal vesicles are bound to the median lobes.
Scand J Urol Neplrrol9
Scan
d J
Uro
l Nep
hrol
Dow
nloa
ded
from
info
rmah
ealth
care
.com
by
Uni
vers
ity o
f A
uckl
and
on 1
1/25
/14
For
pers
onal
use
onl
y.
Lobes of the human prostate 189
Fig. 18. Anterior view of the prostate and Fig. 19. Anterior view of the same pros- seminal vesicles. Centrally the urethra tate as in fig. 18 after the dorsal and withperiurethral tissue is seen. The median lateral lobes have been removed. lobes surround the urethra dorsolaterally. Lateral and posterior to the median lobes the freed lateral lobes can be seen.
Fig. 20a and b. The median lobes viewed from behind. On the right side the border between the median lobe and the periurethral tissue can be seen as well as a main duct reaching the urethra dorso-laterally. On the left side the periurethral tissue has been removed. In the midline between the two median lobes the ejaculatory ducts appear. Key: DD, deferential duct with ampulla; M D , duct of median lobe; ED, ejaculatory ducts; ML, median lobe; PU, periurethral tissue; SV, seminal vesicle; UR, urethra.
Fig. 21. Compared to fig. 19 the urethra with periurethral tissue has been removed. The seminal colliculus has been left in place for the purpose of orientation.
Fig. 22. The median lobes viewed from behind after they have been dissected free from the seminal vesicles. This figure illustrates that although the two median lobes are in close contact to each other both dorsally and ventrally to the ejacu- latory ducts they are two independent structures.
Fig. 23. Anterior view of the prostate Fig. 24. The same prostate as in fig. 23. demonstrating “the onion” arrangement The lateral and median lobes are turned of the lobes. The median lobe is turned anteriorly and the anterior surface of the anteriorly demonstrating the anterior sur- dorsal lobe can be seen. face of the lateral lobe.
Fig. 25. Right lateral aspect of the prostate. In the periphery the three lobes have been freed to demonstrate their relations to each other. Note how the median lobe is attached to the lower border of the semi- nal vesicle.
Srand J Urol Nephrol9
Scan
d J
Uro
l Nep
hrol
Dow
nloa
ded
from
info
rmah
ealth
care
.com
by
Uni
vers
ity o
f A
uckl
and
on 1
1/25
/14
For
pers
onal
use
onl
y.
190 L.-E. Tisell and H . Salunder
upper medial part of its dorsal surface (Fig. 11 a, b). To human prostate cannot be defined simply as dorsal, expose the anterior surface of the median lobes the blad- der neck mucosa has to be removed. The median lobes surround the proximal urethra dorso-laterally and are firmly adherent to the periurethral tissue from which they can be separated by dissection. The two median lobes are bound together by connective tissue both dorsally and ventrally of the ejaculatory ducts (Figs. 17, 18, 19,20 a, b and 21). The two median lobes can always be separated in the midline both ventrally and dorsally (Fig. 22). Dorsally each median lobe has a main duct running distally and opening into the urethra at the level of the seminal col- liculus (Figs. 20 a, b , and 22). There also seem to be some ventral short ducts emptying more proximally. The adhesions between the median lobes and the periurethral tissue renders the dissection here difficult and further studies are needed for clear separation of these structures. No anterior prostatic lobe has been found in any dissec- tion. The dissection revealed that the prostatic lobes were arranged in an ‘onion pattern’ with the median lobes in the centre almost enclosing the ejaculatory ducts and the lat- eral and dorsal lobes forming the outer layers (Figs. 23.24 and 25).
DISCUSSION
In the present study of anatomical dissection of about one hundred cases, it was possible to dif- ferentiate two dorsal, two lateral and two median lobes of the adult human prostate. These lobes were found to have their own ducts opening into the urethra. The present findings differ from those of Lowsley (1912) who studied the prostate of human embryos by a step section technique. The dorsal and median as well as the lateral portions of the prostate were found to be paired lobes. The dorsal lobes form not only the dorsal surface but also a considerable part of the lateral surfaces of the prostate. The lateral lobes are joined together dor- sally to the ejaculatory ducts. The median lobes are in close proximity to each other and to the ejac- ulatory ducts not only ventrally but also dorsal- ly. In some cases the median and lateral lobes form part of the upper dorsal surface of the prostate. Lowsley (1930) reported that in 2 specimens of 93 adult prostates he was able to demonstrate a per- sistent anterior lobe. In the present study no pros- tatic lobe anterior to the urethra could be demon- strated.
I t was found that the seminal vesicles in man are bound to the median lobes of the prostate just as the seminal vesicles in rat are bound to the coagulating glands. This may strengthen the assumption of Price (1%3) that the median lobes in man and the coagulating glands in rat are homologous.
The anatomical relation of the lobes of the adult
lateral and median according to their position vis- h-vis the ejaculatory ducts. When the cleavages between the prostatic lobes were searched along the ejaculatory ducts the parenchyma of the lobes were invariably entered. Instead it was found that the prostatic lobes were arranged in an ‘onion pattern’ with the median lobes in the centre almost enclosing the ejaculatory ducts and the lateral and dorsal lobes forming the outer layers. For simplicity we have kept the generally accepted nomenclature.
It was earlier claimed that it is impossible to define the lobes of the human prostate by dissection (Andrews, 1951; Edwards et al., 1953; Oota, 1961; Karube, 1961; Liavag, 1967) or by microscopic ex- amination postnatally (Johnson, 1920; Karube, 1961; Liavig, 1967) and that there is only an embryological lobation (Bengmark, 1958).
The current concept of the anatomy of the adult prostate is based on Lowsley’s (1912) embryo studies and this may be one of the reasons for previous failures in dissection.
The ability to delimit the prostatic lobes in man may open up new possibilities to study the relation of prostatic diseases to different lobes as well as the hormonal dependency of the separate lobes.
ACKNOWLEDGEMENTS This study was supported by grants from the Swedish Medical Research Council (B74-I2X-7 19-09B). The skilful technical assistance of Miss Karin Karlsson is highly appreciated.
REFERENCES Andrews. G. S. 1949. Latent carcinoma of the prostate. J
Clin Pathol2. 197. Bengmark, S . 1958. The prostatic urethra and prostatic
glands. Thesis. C. W. K. Gleerup, Lund. Blennerhasset. J . B. & Vickery, A. L. 1966. Carcinomaof
the prostate gland. An anatomical study of tumor loca- tion. Cancer 19, 980.
Butler, J . , Braunstein, H.. Freiman, D. G. & Gall, E. A. 1959. Incidence, distribution, and enzymatic activity of carcinoma of the prostate gland. Arch Pathol 68, 243.
Edwards, C. N., Steinthorsson, E. & Nicholson, D. 1953. An autopsy study of latent prostatic cancer. Cancer 6 , 531.
Franks. L. M. 1954 a . Latent carcinoma of the pr0state.J Pathol Bact 68. 603.
- 1954 b. Benign nodular hyperplasia of the prostate: A review. Ann R Coil Surg Engi 14. 92.
Gaynor, E. P. 1938. Zur Frage des Prostatakrebses. Vir- chon. Arch Puth Anur 301. 602.
Scrrnd J U r d Nephrol 9
Scan
d J
Uro
l Nep
hrol
Dow
nloa
ded
from
info
rmah
ealth
care
.com
by
Uni
vers
ity o
f A
uckl
and
on 1
1/25
/14
For
pers
onal
use
onl
y.
Lobes of the human pros ta te 191
Lowsley, 0. S. 1912. The development of the human prostate gland with reference to the development of other structures of the neck of the urinary bladder. Am JAnat 13, 299.
- 1930. Embryology, anatomy and surgery of prostate gland with report of operative results. Am J Surg 8, 526.
McManus, J. F. A. 1948. Histological and histochemical uses of periodic acid. Stain Techno1 23, 99.
Moore, R. A. 1935. Morphology of small prostatic carcinoma. J Urol33, 224.
Oota, K. 1961. Latent carcinoma of the prostate among the Japanese. Acta Un Int Cancr 17, 952.
Price, D. 1963. Comparative aspects of development and structure in the prostate. Nut Cancer Inst Monogr 12, 1.
Tisell, L.-E. 1970. Effect of cortisone on the growth of the ventral prostate, the dorsolateral prostate, the coagulating glands and the seminal vesicles in castrated adrenalectomized and castrated non- adrenalectomized rats. Acta Endocrinol (Kbh) 64,637.
- 1971. The growth of the ventral prostate, the dorsolat- era1 prostate, the coagulating glands and the seminal vesicles in castrated adrenalectomized rats injected with oestradiol and/or cortisone. Acta Endocrinol (Kbh) 68, 485.
- 1972 a . Adrenal effect on the growth of the ventral and dorsolateral prostate in castrated rats injected with oestradiol. Acta Endocrinol (Kbh) 71, 191.
- 1972 6 . Morphological studies of hormonal effects on the ventral and dorsolateral prostate, the coagulating glands and the seminal vesicles in rats. Thesis. Goteborg.
Tisell, L.-E. & Angervall, L. 1969. The growth of the ventral prostate, the dorsolateral prostate, the coagulating glands and the seminal vesicles in castrated male rats injected with ACTH and/or insu- lin. Acta Endocrinol (Kbh) 62, 694.
Grayhack, J. 1%3. Pituitary factors influencing growth of the prostate. Nut Cancer Inst Monogr 12, 189.
- 1965. Effect of testosterone-estradiol administration on the citric acid and fructose content of the rat prostate. Endocrinology 77, 1068.
Huggins, C., Masina, M. H., Eichelberger, L. & Warthon, J. D. 1939. Quantitative studies of prostatic secretion. I. Characteristics of the normal secretion; the influ- ence of thyroid, suprarenal, and testis extirpation and androgen substitution on the prostatic output. J Exp Med 70, 543.
Huggins, C. & Clark, P. J. 1940. Quantitative studies of prostatic secretion. 11. The effect of castration and of estrogen injection on the normal and on the hyperplas- tic prostate glands of dogs. J Exp Med 72, 747.
Huggins, C. & Hodges, C. V. 1941. Studies on prostatic cancer. I. The effect of castration, of estrogen and of androgen injection on serum phosphatases in metasta- tic carcinoma of the prostate. Cancer Res 1 , 293.
Huggins, C., Stevens, R. E. & Hodges, C. V. 1941 a . Studies on prostatic cancer. 11. The effects of castra- tion on advanced carcinoma of the prostate gland. Arch Surg 43, 209.
Huggins, C., Scott, W. W. & Hodges, C. V. 1941 6. Studies on prostatic cancer. 111. The effects of fever, of desoxycorticosterone and of estrogen on clinical patients with metastatic carcinoma of the prostate. J Urol46, 997.
Hutch, J. A. & Rambo, 0. N. 1970. A study of the anatomy of the prostate, prostatic urethra and the urinary sphincter system. J Urol104, 443.
Johnson, F. P. 1920. The later development of the urethra in the male. J Urol4, 447.
Kahler, J. E. 1939. Carcinoma of the prostate gland: A pathologic study. J Urol41, 557.
Karube, K. 1961. Study of latent carcinoma of the prostate in Japanese based on necropsy material. To- hoku J Exp Med 74, 265.
LiavBg, I. 1967. Carcinoma of the prostate. Scandinavian University Books. Universitetsforlaget, Oslo.
Scond J Urol Nephrol9
Scan
d J
Uro
l Nep
hrol
Dow
nloa
ded
from
info
rmah
ealth
care
.com
by
Uni
vers
ity o
f A
uckl
and
on 1
1/25
/14
For
pers
onal
use
onl
y.
