Immunoexpression of aquaporin-1 in adolescent varicocele testes: possible significance for fluid reabsorption.
OBJECTIVE
To investigate the immunoexpression of aquaporin-1 (AQP-1), a major transmembrane water channel, in high-grade varicocele testes, which are known to imply an unbalanced transmembrane water flow, in both tubular and extratubular compartments.


METHODS
Light microscopy and AQP-1 immunohistologic examination were carried out on incisional testicular biopsies from 20 adolescent boys, aged 13 to 18 years, with grade 2 or 3 idiopathic varicocele. Testicular tissue from 4 autopsied subjects of matched age were also investigated as parallel controls.


RESULTS
At microscopic examination, the tubular lumina and extracellular matrix were expanded and venular profiles dilated. Cytoplasmic vacuoles were frequent in the Sertoli cells, spermatogonia, and spermatocytes, together with premature sloughing of germ cells and residual cytoplasmic droplets inside the spermatozoa, if present. Diffuse AQP-1 positivity occurred at venular endothelial cell membranes and, unexpectedly, at the cell membranes of the Sertoli cells, diploid germ cells, and haploid cells. In the control testes, focal AQP-1 immunolabeling was confined to the microvessel endothelial cells, without any positive reaction in the tubular or extratubular compartments.


CONCLUSIONS
This is the first report showing AQP-1 cell expression in adolescent varicocele testes in both tubular and extratubular compartments. It was associated with the main histologic features of unbalanced water flow in the tubular and interstitial compartments of the testis. Immunocytochemical patterns revealed AQP-1 as a possible critical reabsorption factor, acting to reduce abnormal fluid retention in endotubular cells and the extracellular matrix and, to a lesser extent, in Leydig cells.
Nicòtina
P A
PA
Department of Human Pathology, University of Messina Medical School, Messina, Italy. pnicotina@unime.it
Romeo
C
C
Arena
S
S
Arena
F
F
Maisano
D
D
Zuccarello
B
B
D000042:Absorption; D000293:Adolescent; D051398:Aquaporin 1; D020346:Aquaporins / Q000032:analysis* / Q000502:physiology; D001789:Blood Group Antigens; D001826:Body Fluids / Q000378:metabolism; D001834:Body Water / Q000378:metabolism; D042783:Endothelial Cells / Q000737:chemistry; D005109:Extracellular Matrix / Q000378:metabolism; D006801:Humans; D007124:Immunoenzyme Techniques; D007985:Leydig Cells / Q000378:metabolism; D008297:Male; D012671:Seminiferous Tubules / Q000737:chemistry; D013737:Testis / Q000737:chemistry* / Q000473:pathology; D014646:Varicocele / Q000378:metabolism* / Q000473:pathology
C496020:AQP1 protein, human; D020346:Aquaporins; D001789:Blood Group Antigens; D051398:Aquaporin 1