HISTOCHEMISTRY OF HUMAN URETHRAL GLANDS
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P. SIRIGU, F. TURNO, M. T. PERRA, E. USAI, and E. S. E. HAFEZ
Human urethral glands were reacted histochemically and immunohistochemically to identify glycoproteins, some androgen metabolic enzymes, and VIP-like immunoreactivity. NeutraVacid mucosubstances were detected mainly in the apical cytoplasm of the principal cells. 3p-, 17p-, and 3whydroxysteroid dehydrogenase, G6PD, and 6PGD reactivity were intense in all the glandular epithelium. Small amounts of VIP-positive fibers were noted around the secretory elements. Key Words: Histochernistry; lrnmunohistochernistry; Urethral glands; Human.
INTRODUCTION The human urethral (LittrC’s) glands are simple or ramified tubulo-alveolar glands numerous mainly in the superior wall of the cavernous urethra. There are also occasional groups of secretory cells interspersed within the epithelial lining of the urethra [ 101. Like Cowper’s glands, they discharge their secretions into the so-called presperm fraction of the human ejaculate, where they mix with the prostatic fluid [8]. Very little is known about the cytology of these glands [ 131. Their only supposed functions are the production of a colloid elaborate containing glycosaminoglycans acting as a protector of the epithelium against urine [7] and the secretion of some components into the first seminal fraction [4, 81. Histochemical analyses of the human urethral glands were conducted to identify some of their components and to ascertain some of their metabolic features. The localization of some androgen metabolic enzymes and the distribution of vasoactive intestinal polypeptide (VIP)like immunoreactivity in these glands was also studied.
MATERIALS AND METHODS Bioptic specimens, normal at histological examination, were obtained from five patients (ages 40-55) undergoing cystectomy and urethrectomy for carcinoma of the urinary bladder. Some pieces were fixed
Received 7/18/90; accepted 7/30/90. From Dipartimento di Citomorfologia (P.S., F.T., M.T.P.), Clinica Urologica, dell’universita’ di Cagliari, Italy (E.U.), Reproductive Health Center, Kiawah Island, South Carolina (E.S.E.H.). Address reprint requests to: Prof. Paola Sirigu, Dipartimento di Citomorfologia, Via Porcell, 2-09124, Cagliari, Italy. ARCHIVES OF ANDROLOGY 26:43-51 (1991) Copyright 0 199I by Hemisphere Publishing Corporation
43
P. Sirigu et al.
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44
FIGURE 1 (A) Hematoxylin-eosin. Human urethral glands are tubuloalveolar glands, but occasional groups of secretory cells are interspersed within urethral epithelium (arrow). Principal cylindrical cells and rare basal cells make up the glandular epithelium. x 95. (B)PAS-hematoxylin. The principal cells show strong PAS positivity in their apical cytoplasm. x 300; x 375 (inset). (C) Alcian blue pH 2.5. A marked reactivity is observed in the apical cytoplasm of the principal cells. x 200; ~ 3 7 5(inset). (D) Toluidine blue. The methachromatic reactivity is confined to the apical cytoplasm. x 150; x 375 (inset).
Urethral Gland Histochemistry
45
TABLE 1 Localization and Identification of Glycoproteins in Human Urethral Glands
Glycoprotein Apical Cytoplasm
Remaining Cytoplasm
PAS D-PAS
P P
M-PAS 90 min at 60°C M-PAS 5 h at 60°C DM-PAS 30 min at 22°C DM-PAS 5 h at 60°C A-PAS 6 h at 22°C DA-PAS AB pH I , AB pH 2.5 S-AB pH 1, S-AB pH 2.5 AB pH1 and AB pH 2.5-PAS AB-CEC below 0.3 M AB-CEC above 0.3 M LID HID LID-AB pH 2.5 HID-AB pH 2.5 TB pH 4
P R
Pi Pi Pi Pi Pi
Syst Biol Reprod Med Downloaded from informahealthcare.com by University of Auckland on 11/12/14 For personal use only.
Reaction
S-TB pH 4
P R R B
B+ BP B -
Pi =
Pi
B-
Pi -
B
B
Me Me +
PAS, periodic acid Schiff; D, diastase; M, methylation; DM, demethylation; A, acetylation; DA, deacetylation; AB, alcian blue; S, sulfation; CEC, MgCI, molarity; LID, low iron diamine; HID, high iron diamine; TB. toluidine blue; + , intense staining; - , weak staining; P, purple; R , red; Pi, pink; B, blue; Me, metachromasia; Or, orthochromasia; = , no staining. in Lillie’s buffered formol for 24-48 h, dehydrated with ethanol, passed through toluol, and embedded in paraffin. Microtome sections (5-6 pm) were then processed for the localization and identification of the glycoproteins according to methods described by Pearse [ 1 11. Other pieces were immediately frozen and, after a few hours, cryostat sections (10 pm) were cut. Groups of slides were then incubated for the localization of enzymatic activities: 30-hydroxysteroid dehydrogenase (30-HSD; E.C. 1.1.1.5 I ) , using dehydroepiandrosterone as specific substrate and nitroBT as electron acceptor [20]. Other slides were used for the demonstration of the 170-hydroxysteroid dehydrogenase (17P-HSD; E . C . 1.1.1.63), using testosterone as substrate [ 121. Slides were also treated for the demonstration of 3a-hydroxysteroid dehydrogenase (3a-HSD; E.C. 1.1.1.50). using androsterone as substrate [I]. Other sections were treated for the demonstration of the glucose-6-phosphate dehydrogenase (G6PD; E.C. 1 . 1 . I .49) and 6phosphogluconate dehydrogenase (6PGD; E.C. 1.1.1.43) with glucose-6-phosphate disodium salt and 6phosphogluconate Ba salt, respectively, as substrates [ 181. In each experiment, control sections were incubated with a substrate-free medium. Samples were fixed in 4 % buffered paraformaldehyde and cut in a cryostat. Sections collected on coated slides were processed by the indirect immunofluorescence technique [3], using a rabbit anti-VIP serum (Immunonuclear) followed by a FITC-conjugated anti-rabbit serum. VIP antiserum pretreated with excess of VIP was used for control preparations. After fluorescence microscopic observation/ photography, slides were stained with hematoxylin-eosin and subjected to histological examination.
46
P. Sirigu et al.
Syst Biol Reprod Med Downloaded from informahealthcare.com by University of Auckland on 11/12/14 For personal use only.
RESULTSlDISCUSSION Some of the urethral glands are simple outpocketings of the urethral mucosa formed by clear cells; others are larger and formed by a globular secretory portion connected with the urethra by a short duct (Fig. 1). Histologically, the glandular epithelium consists of principal cylindrical cells and rare basal cells. The identification of glycoproteins is shown in Table 1. The principal cells showed strong PAS positivity in their apical cytoplasm (Fig. 1B). This same zone appeared alcianophilic (Fig. 1C) and metachromatic (Fig. lD), whereas the remaining cytoplasm was unreactive and orthochromatic. The PAS reactivity is not abolished after treatment with diastase. Methylating for 90 min at 60°C did not block the reaction, whereas prolonged methylation (5 h) led to reduction of the stain. The demethylation, however, restored the PAS reactivity. Prior acetylation completely blocked the PAS staining, whereas saponification following acetylation led to strong staining. After high iron-diamine or low iron-diamine methods, the cytoplasm of the secretory cells was unreactive, but if Alcian blue staining was superadded only the apical portion of the cytoplasm appeared blue (Fig. 2A). In the same zone the alcianophilia at molarity of MgC1, (CEC) was only in the presence of low concentrations (below 0.3 M) of electrolytes (Fig. 2B). All epithelial cells exhibited 3/3-HSD, 17P-HSD (Fig. 3A, B), and 3a-HSD (Fig. 4). G6PD (Fig. 5) and 6PGD appeared widely distributed in the glands, all the secretory cells being uniformly stained. VIP-like immunoreactivity showed a small amount of VIP-positive fibers, mainly distributed around the secretory elements (Fig. 6A, B). These findings were in all samples examined and control sections were completely negative.
FIGURE 2 (A) LID-AB. The apical portion of the cytoplasm appears blue. x 150; ~ 3 7 (inset). 5 (B) AB-CEC; nuclei contrasted with neutral red. Only the apical portion of the principal cells are stained. x 150; x 375 (inset).
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Urethral Gland Histochemistry
47
FIGURE 3 (A) 3&HSD and (B) 17fl-HSD. A marked reactivity is observed in all epithelial cells. x 300.
In a histochemical study of the human urethral glands, Halbhuber [6] indicated that their secretion consists of sialoproteins. However, his findings do not indicate where these substances are localized in the cells or the true composition of this material. Treatment with PAS, Alcian blue, Toluidine blue but mainly the alcianophilia at molarity of MgC1, and HID or LID methods, indicated that glycoproteic material containing carboxyl groups, but not sulphated mucosubstances, is concentrated only in the apical cytoplasm of glandular epithelium tracts. Riva et al. [13] in an ultrastructural study showed that the apical cytoplasm of the principal cells of human LittrC’s glands are filled with many secretory vacuoles originating from a prominent Golgi complex. It would appear that these secretory droplets correspond to those with acid glycoproteic material detected in this study. Since no evidence has been hitherto provided of any functional or morphologic distinction within the principal cells, probably the apical positivity, observed in epithelial tracts, could represent a particular functional stage of the principal cells in which the production and, perhaps, the secretion of this glycoproteic material occurs. The LNAase-activity, in the apical cytoplasm of the secretory elements of
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P. Sirigu et al.
FIGURE 4 3cr-HSD. The epithelium shows a strong reactivity. x 300.
these glands [4], may represent one component of the proteinaceous material secreted by these cells. The presence of 3P-HSD, 17P-HSD, and 3a-HSD chiefly indicates that the human urethral glands can metabolize male sex hormones. In a histochemical study [17] we have obtained identical results in the other human male accessory glands, whereas in the human salivary or ceruminous glands we have found only the 3P-HSD and the 17P-HSD [15, 161. The histochemically detectable 3a-HSD indicates that the human Littri’s glands normally are sites of significant androgen activation [2]. The presence of intense glucose-6-phosphate dehydrogenase and 6-phosphogluconic dehydrogenase activities suggests that the pentose phosphate shunt may be functioning. G6PD and 6PGD catalyze the first two steps of the pentose phosphate shunt, which represents an important source of NADPH. This metabolic process seems to be controlled by the sex hormones in
Syst Biol Reprod Med Downloaded from informahealthcare.com by University of Auckland on 11/12/14 For personal use only.
Urethral Gland Histochemistry
49
FIGURE 5 G6PD. The epithelial cells are intensely stained. x 200.
FIGURE 6 VIP-like imrnunoreactivity. The immunoreactivity is localized in isolated fibers around secretory acini. x 300.
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P. Sirigu et al.
some nongenital tissues such as salivary glands and liver [9, 181. In all androgen target tissues, a possible role of the pentose shunt would be the production of NADPH required for androgen activation. However, the complex interaction between androgens and pentose metabolism in target organs needs to be clarified. The distribution of vasoactive intestinal polypeptide (VIP)-like immunoreactivity has been demonstrated in some human genital organs [5, 191. The abundance and distribution patterns of these peptide-containing nerves indicate that they may play an important role in male reproductive physiology. Morphological/experimental data suggest that VIP plays a part in the regulation of smooth muscle tone, blood flow, and secretion [ 141. Although the functional significance of VIP-ergic innervation in the human urethral glands remains to be established, the most probable hypothesis appears that VIP has a role in the secretion of these glands. In fact, a small amount of VIP-positive fibers were found around secretory acini and in a few cases in association with ducts and blood vessels.
REFERENCES I . Balogh K (1966): Histochemical demonstration of 3a-hydroxysteroid dehydrogenase activity. J Histochem Cytochem 14:77-83 2. Coffey DS (1988): Androgen action and the sex accessory tissues. In: The Physiology of Reproduction. Knobil E, Neil1 JD (Eds). New York: Raven Press, pp 1081-1 119 3. Coons AH, Kaplan MH (1950): Localization of antigens in tissue cells. 11. Improvements in a method for the detection of antigen by means of fluorescent antibody. J Exp Med 9 1: 1-9 4. Cossu M, Lantini MS, Perra MT, Usai E, Sirigu P (1988): Histochemistry of L-leucyl 0-naphthylamidase activity in genital tract of man. Arch Androl 21: 163-168 5 . Gu J, Polak JM, Probert L, et al. (1983): Peptidergic innervation of human male genital tract. J Urol 130:38639 1 6. Halbhuber KJ (1969): Histochemischemische Untersuchungen am Sekret der Urethraldrusen bei Mensch und einigen Saugern. Acta Histochem 33:331-346 7. Krstic RV (1984): Illustrated Encyclopedia of Human Histology. Berlin: Springer-Verlag, p 436 8. Mann T, Lutwak-Mann C (1981): Male Reproductive Function and Semen. Berlin: Springer-Verlag, pp 269-336 9. Nakamura T, Fujii M, Kaiho M, Kumegawa M (1974): Sex difference in glucose-6-phosphate dehydrogenase activity in the submandibular gland of mice. Biochim Biophys Acta 362:llO-120 10. Narbaitz R (1974): Embriology, anatomy, and histology of the male sex accessory glands. In: Male Accessory Sex Organs. Brandes D (Ed). London: Academic Press, p 15 11. Pearse AGE (1985): Histochemistry, Theoretical and Applied. London: Churchill 12. Pearson B, Grose F (1959): Histochemical demonstration of 17(3-hydroxysteroid dehydrogenase by use of tetrazolium salt. Proc SOCExp Biol Med 100:636-638 13. Riva A, Usai E, Scarpa R, Lantini MS, Valentino L, Testa-Riva F (1989): The human urethral glands: An EM study. Fourth International Congress of Andrology, Florence, pp 33 1-335 14. Said SI, Giachetti A, Nicosia S (1980): VIP: Possible function as a neural peptide. In: Neural Peptides and Neuronal Communication. Costa E, Trabucchi M (Eds). New York: Raven Press, pp 75-82 15. Sirigu P, Cossu M, Perra MT, Puxeddu P (1982): Histochemistry of the 3P-hydroxysteroid, 170-hydroxysteroid and 3a-hydroxysteroid dehydrogenases in human salivary glands. Arch Oral Biol 27:547-551 16. Sirigu P, Cossu M, Puxeddu P, Marchisio AM, Perra MT (1983): Human ceruminous glands: A histochemical study. Basic Appl Histochem 2 7 3 7 - 2 6 5 17. Sirigu P, Cossu M, Scarpa R, Pinna A (1981): Histochemistry of some steroid dehydrogenases in epithelia of human seminal vesicle, deferential ampulla and prostate gland. Arch Androl 7:9-13
Urethral Gland Histochemistry
51
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18. Teutsch HF, Rieder H (1979): NADP-dependent dehydrogenases in rat liver parenchyma patterns with particular reference to sex differences. Histochemistry 60:43-52 19. Vaalasti A, Tainio H, Pelto-Huikko M, Hervonen A (1986): Light and electron microscope demonstration of VIPand enkephalin-immunoreactive nerves in the human male genitourinary tract. Anat Rec 215:21-27 20. Wattenberg LW (1958): Microscopic histochemical demonstration of steroid-36-01 dehydrogenase in tissue secretions. J Histochem Cytochem 6:225-232
Syst Biol Reprod Med Downloaded from informahealthcare.com by University of Auckland on 11/12/14 For personal use only.
P. SIRIGU, F. TURNO, M. T. PERRA, E. USAI, and E. S. E. HAFEZ
Human urethral glands were reacted histochemically and immunohistochemically to identify glycoproteins, some androgen metabolic enzymes, and VIP-like immunoreactivity. NeutraVacid mucosubstances were detected mainly in the apical cytoplasm of the principal cells. 3p-, 17p-, and 3whydroxysteroid dehydrogenase, G6PD, and 6PGD reactivity were intense in all the glandular epithelium. Small amounts of VIP-positive fibers were noted around the secretory elements. Key Words: Histochernistry; lrnmunohistochernistry; Urethral glands; Human.
INTRODUCTION The human urethral (LittrC’s) glands are simple or ramified tubulo-alveolar glands numerous mainly in the superior wall of the cavernous urethra. There are also occasional groups of secretory cells interspersed within the epithelial lining of the urethra [ 101. Like Cowper’s glands, they discharge their secretions into the so-called presperm fraction of the human ejaculate, where they mix with the prostatic fluid [8]. Very little is known about the cytology of these glands [ 131. Their only supposed functions are the production of a colloid elaborate containing glycosaminoglycans acting as a protector of the epithelium against urine [7] and the secretion of some components into the first seminal fraction [4, 81. Histochemical analyses of the human urethral glands were conducted to identify some of their components and to ascertain some of their metabolic features. The localization of some androgen metabolic enzymes and the distribution of vasoactive intestinal polypeptide (VIP)like immunoreactivity in these glands was also studied.
MATERIALS AND METHODS Bioptic specimens, normal at histological examination, were obtained from five patients (ages 40-55) undergoing cystectomy and urethrectomy for carcinoma of the urinary bladder. Some pieces were fixed
Received 7/18/90; accepted 7/30/90. From Dipartimento di Citomorfologia (P.S., F.T., M.T.P.), Clinica Urologica, dell’universita’ di Cagliari, Italy (E.U.), Reproductive Health Center, Kiawah Island, South Carolina (E.S.E.H.). Address reprint requests to: Prof. Paola Sirigu, Dipartimento di Citomorfologia, Via Porcell, 2-09124, Cagliari, Italy. ARCHIVES OF ANDROLOGY 26:43-51 (1991) Copyright 0 199I by Hemisphere Publishing Corporation
43
P. Sirigu et al.
Syst Biol Reprod Med Downloaded from informahealthcare.com by University of Auckland on 11/12/14 For personal use only.
44
FIGURE 1 (A) Hematoxylin-eosin. Human urethral glands are tubuloalveolar glands, but occasional groups of secretory cells are interspersed within urethral epithelium (arrow). Principal cylindrical cells and rare basal cells make up the glandular epithelium. x 95. (B)PAS-hematoxylin. The principal cells show strong PAS positivity in their apical cytoplasm. x 300; x 375 (inset). (C) Alcian blue pH 2.5. A marked reactivity is observed in the apical cytoplasm of the principal cells. x 200; ~ 3 7 5(inset). (D) Toluidine blue. The methachromatic reactivity is confined to the apical cytoplasm. x 150; x 375 (inset).
Urethral Gland Histochemistry
45
TABLE 1 Localization and Identification of Glycoproteins in Human Urethral Glands
Glycoprotein Apical Cytoplasm
Remaining Cytoplasm
PAS D-PAS
P P
M-PAS 90 min at 60°C M-PAS 5 h at 60°C DM-PAS 30 min at 22°C DM-PAS 5 h at 60°C A-PAS 6 h at 22°C DA-PAS AB pH I , AB pH 2.5 S-AB pH 1, S-AB pH 2.5 AB pH1 and AB pH 2.5-PAS AB-CEC below 0.3 M AB-CEC above 0.3 M LID HID LID-AB pH 2.5 HID-AB pH 2.5 TB pH 4
P R
Pi Pi Pi Pi Pi
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Reaction
S-TB pH 4
P R R B
B+ BP B -
Pi =
Pi
B-
Pi -
B
B
Me Me +
PAS, periodic acid Schiff; D, diastase; M, methylation; DM, demethylation; A, acetylation; DA, deacetylation; AB, alcian blue; S, sulfation; CEC, MgCI, molarity; LID, low iron diamine; HID, high iron diamine; TB. toluidine blue; + , intense staining; - , weak staining; P, purple; R , red; Pi, pink; B, blue; Me, metachromasia; Or, orthochromasia; = , no staining. in Lillie’s buffered formol for 24-48 h, dehydrated with ethanol, passed through toluol, and embedded in paraffin. Microtome sections (5-6 pm) were then processed for the localization and identification of the glycoproteins according to methods described by Pearse [ 1 11. Other pieces were immediately frozen and, after a few hours, cryostat sections (10 pm) were cut. Groups of slides were then incubated for the localization of enzymatic activities: 30-hydroxysteroid dehydrogenase (30-HSD; E.C. 1.1.1.5 I ) , using dehydroepiandrosterone as specific substrate and nitroBT as electron acceptor [20]. Other slides were used for the demonstration of the 170-hydroxysteroid dehydrogenase (17P-HSD; E . C . 1.1.1.63), using testosterone as substrate [ 121. Slides were also treated for the demonstration of 3a-hydroxysteroid dehydrogenase (3a-HSD; E.C. 1.1.1.50). using androsterone as substrate [I]. Other sections were treated for the demonstration of the glucose-6-phosphate dehydrogenase (G6PD; E.C. 1 . 1 . I .49) and 6phosphogluconate dehydrogenase (6PGD; E.C. 1.1.1.43) with glucose-6-phosphate disodium salt and 6phosphogluconate Ba salt, respectively, as substrates [ 181. In each experiment, control sections were incubated with a substrate-free medium. Samples were fixed in 4 % buffered paraformaldehyde and cut in a cryostat. Sections collected on coated slides were processed by the indirect immunofluorescence technique [3], using a rabbit anti-VIP serum (Immunonuclear) followed by a FITC-conjugated anti-rabbit serum. VIP antiserum pretreated with excess of VIP was used for control preparations. After fluorescence microscopic observation/ photography, slides were stained with hematoxylin-eosin and subjected to histological examination.
46
P. Sirigu et al.
Syst Biol Reprod Med Downloaded from informahealthcare.com by University of Auckland on 11/12/14 For personal use only.
RESULTSlDISCUSSION Some of the urethral glands are simple outpocketings of the urethral mucosa formed by clear cells; others are larger and formed by a globular secretory portion connected with the urethra by a short duct (Fig. 1). Histologically, the glandular epithelium consists of principal cylindrical cells and rare basal cells. The identification of glycoproteins is shown in Table 1. The principal cells showed strong PAS positivity in their apical cytoplasm (Fig. 1B). This same zone appeared alcianophilic (Fig. 1C) and metachromatic (Fig. lD), whereas the remaining cytoplasm was unreactive and orthochromatic. The PAS reactivity is not abolished after treatment with diastase. Methylating for 90 min at 60°C did not block the reaction, whereas prolonged methylation (5 h) led to reduction of the stain. The demethylation, however, restored the PAS reactivity. Prior acetylation completely blocked the PAS staining, whereas saponification following acetylation led to strong staining. After high iron-diamine or low iron-diamine methods, the cytoplasm of the secretory cells was unreactive, but if Alcian blue staining was superadded only the apical portion of the cytoplasm appeared blue (Fig. 2A). In the same zone the alcianophilia at molarity of MgC1, (CEC) was only in the presence of low concentrations (below 0.3 M) of electrolytes (Fig. 2B). All epithelial cells exhibited 3/3-HSD, 17P-HSD (Fig. 3A, B), and 3a-HSD (Fig. 4). G6PD (Fig. 5) and 6PGD appeared widely distributed in the glands, all the secretory cells being uniformly stained. VIP-like immunoreactivity showed a small amount of VIP-positive fibers, mainly distributed around the secretory elements (Fig. 6A, B). These findings were in all samples examined and control sections were completely negative.
FIGURE 2 (A) LID-AB. The apical portion of the cytoplasm appears blue. x 150; ~ 3 7 (inset). 5 (B) AB-CEC; nuclei contrasted with neutral red. Only the apical portion of the principal cells are stained. x 150; x 375 (inset).
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Urethral Gland Histochemistry
47
FIGURE 3 (A) 3&HSD and (B) 17fl-HSD. A marked reactivity is observed in all epithelial cells. x 300.
In a histochemical study of the human urethral glands, Halbhuber [6] indicated that their secretion consists of sialoproteins. However, his findings do not indicate where these substances are localized in the cells or the true composition of this material. Treatment with PAS, Alcian blue, Toluidine blue but mainly the alcianophilia at molarity of MgC1, and HID or LID methods, indicated that glycoproteic material containing carboxyl groups, but not sulphated mucosubstances, is concentrated only in the apical cytoplasm of glandular epithelium tracts. Riva et al. [13] in an ultrastructural study showed that the apical cytoplasm of the principal cells of human LittrC’s glands are filled with many secretory vacuoles originating from a prominent Golgi complex. It would appear that these secretory droplets correspond to those with acid glycoproteic material detected in this study. Since no evidence has been hitherto provided of any functional or morphologic distinction within the principal cells, probably the apical positivity, observed in epithelial tracts, could represent a particular functional stage of the principal cells in which the production and, perhaps, the secretion of this glycoproteic material occurs. The LNAase-activity, in the apical cytoplasm of the secretory elements of
Syst Biol Reprod Med Downloaded from informahealthcare.com by University of Auckland on 11/12/14 For personal use only.
48
P. Sirigu et al.
FIGURE 4 3cr-HSD. The epithelium shows a strong reactivity. x 300.
these glands [4], may represent one component of the proteinaceous material secreted by these cells. The presence of 3P-HSD, 17P-HSD, and 3a-HSD chiefly indicates that the human urethral glands can metabolize male sex hormones. In a histochemical study [17] we have obtained identical results in the other human male accessory glands, whereas in the human salivary or ceruminous glands we have found only the 3P-HSD and the 17P-HSD [15, 161. The histochemically detectable 3a-HSD indicates that the human Littri’s glands normally are sites of significant androgen activation [2]. The presence of intense glucose-6-phosphate dehydrogenase and 6-phosphogluconic dehydrogenase activities suggests that the pentose phosphate shunt may be functioning. G6PD and 6PGD catalyze the first two steps of the pentose phosphate shunt, which represents an important source of NADPH. This metabolic process seems to be controlled by the sex hormones in
Syst Biol Reprod Med Downloaded from informahealthcare.com by University of Auckland on 11/12/14 For personal use only.
Urethral Gland Histochemistry
49
FIGURE 5 G6PD. The epithelial cells are intensely stained. x 200.
FIGURE 6 VIP-like imrnunoreactivity. The immunoreactivity is localized in isolated fibers around secretory acini. x 300.
Syst Biol Reprod Med Downloaded from informahealthcare.com by University of Auckland on 11/12/14 For personal use only.
50
P. Sirigu et al.
some nongenital tissues such as salivary glands and liver [9, 181. In all androgen target tissues, a possible role of the pentose shunt would be the production of NADPH required for androgen activation. However, the complex interaction between androgens and pentose metabolism in target organs needs to be clarified. The distribution of vasoactive intestinal polypeptide (VIP)-like immunoreactivity has been demonstrated in some human genital organs [5, 191. The abundance and distribution patterns of these peptide-containing nerves indicate that they may play an important role in male reproductive physiology. Morphological/experimental data suggest that VIP plays a part in the regulation of smooth muscle tone, blood flow, and secretion [ 141. Although the functional significance of VIP-ergic innervation in the human urethral glands remains to be established, the most probable hypothesis appears that VIP has a role in the secretion of these glands. In fact, a small amount of VIP-positive fibers were found around secretory acini and in a few cases in association with ducts and blood vessels.
REFERENCES I . Balogh K (1966): Histochemical demonstration of 3a-hydroxysteroid dehydrogenase activity. J Histochem Cytochem 14:77-83 2. Coffey DS (1988): Androgen action and the sex accessory tissues. In: The Physiology of Reproduction. Knobil E, Neil1 JD (Eds). New York: Raven Press, pp 1081-1 119 3. Coons AH, Kaplan MH (1950): Localization of antigens in tissue cells. 11. Improvements in a method for the detection of antigen by means of fluorescent antibody. J Exp Med 9 1: 1-9 4. Cossu M, Lantini MS, Perra MT, Usai E, Sirigu P (1988): Histochemistry of L-leucyl 0-naphthylamidase activity in genital tract of man. Arch Androl 21: 163-168 5 . Gu J, Polak JM, Probert L, et al. (1983): Peptidergic innervation of human male genital tract. J Urol 130:38639 1 6. Halbhuber KJ (1969): Histochemischemische Untersuchungen am Sekret der Urethraldrusen bei Mensch und einigen Saugern. Acta Histochem 33:331-346 7. Krstic RV (1984): Illustrated Encyclopedia of Human Histology. Berlin: Springer-Verlag, p 436 8. Mann T, Lutwak-Mann C (1981): Male Reproductive Function and Semen. Berlin: Springer-Verlag, pp 269-336 9. Nakamura T, Fujii M, Kaiho M, Kumegawa M (1974): Sex difference in glucose-6-phosphate dehydrogenase activity in the submandibular gland of mice. Biochim Biophys Acta 362:llO-120 10. Narbaitz R (1974): Embriology, anatomy, and histology of the male sex accessory glands. In: Male Accessory Sex Organs. Brandes D (Ed). London: Academic Press, p 15 11. Pearse AGE (1985): Histochemistry, Theoretical and Applied. London: Churchill 12. Pearson B, Grose F (1959): Histochemical demonstration of 17(3-hydroxysteroid dehydrogenase by use of tetrazolium salt. Proc SOCExp Biol Med 100:636-638 13. Riva A, Usai E, Scarpa R, Lantini MS, Valentino L, Testa-Riva F (1989): The human urethral glands: An EM study. Fourth International Congress of Andrology, Florence, pp 33 1-335 14. Said SI, Giachetti A, Nicosia S (1980): VIP: Possible function as a neural peptide. In: Neural Peptides and Neuronal Communication. Costa E, Trabucchi M (Eds). New York: Raven Press, pp 75-82 15. Sirigu P, Cossu M, Perra MT, Puxeddu P (1982): Histochemistry of the 3P-hydroxysteroid, 170-hydroxysteroid and 3a-hydroxysteroid dehydrogenases in human salivary glands. Arch Oral Biol 27:547-551 16. Sirigu P, Cossu M, Puxeddu P, Marchisio AM, Perra MT (1983): Human ceruminous glands: A histochemical study. Basic Appl Histochem 2 7 3 7 - 2 6 5 17. Sirigu P, Cossu M, Scarpa R, Pinna A (1981): Histochemistry of some steroid dehydrogenases in epithelia of human seminal vesicle, deferential ampulla and prostate gland. Arch Androl 7:9-13
Urethral Gland Histochemistry
51
Syst Biol Reprod Med Downloaded from informahealthcare.com by University of Auckland on 11/12/14 For personal use only.
18. Teutsch HF, Rieder H (1979): NADP-dependent dehydrogenases in rat liver parenchyma patterns with particular reference to sex differences. Histochemistry 60:43-52 19. Vaalasti A, Tainio H, Pelto-Huikko M, Hervonen A (1986): Light and electron microscope demonstration of VIPand enkephalin-immunoreactive nerves in the human male genitourinary tract. Anat Rec 215:21-27 20. Wattenberg LW (1958): Microscopic histochemical demonstration of steroid-36-01 dehydrogenase in tissue secretions. J Histochem Cytochem 6:225-232
