Journal of Andrology, Vol 12, Issue 5 288-294, Copyright © 1991 by The American Society of Andrology

JOURNAL ARTICLE

Endocytosis of androgen-binding protein, clusterin, and transferrin in the efferent ducts and epididymis of the ram

D. N. Veeramachaneni and R. P. Amann
Animal Reproduction and Biotechnology Laboratory, Colorado State University, Fort Collins.

The amount of androgen-binding protein (ABP) in luminal fluid from the central caput epididymidis of the ram, on a per sperm basis, remains the same as that in rete testis fluid (RTF) entering the ductuli efferentes, although greater than 85% of the testicular protein is absorbed in proximal sites. To determine if ABP is spared from endocytosis in proximal sites and if proteins are differentially and selectively absorbed at specific sites in the excurrent ducts, we studied the endocytosis of ABP, clusterin, transferrin, and a 26/35-kd dimer isolated from ovine RTF. Each protein was labeled with colloidal gold and microinjected into the lumen of a ductulus efferens and five specific sites in the ductus epididymidis; uptake was quantified by electron microscopy. Endocytosis of each protein, including ABP, was substantially greater in the ductuli efferentes than in any site in the ductus epididymidis. More ABP was endocytosed in proximal regions of the epididymis than any other protein studied. Endocytosis of the 26/35-kd dimer, like ABP, was greater in proximal sites of the epididymis, whereas endocytosis of clusterin and transferrin was greater in distal sites. Thus, there was a differential absorption, since proteins were endocytosed in one or another specific region of the epididymis, depending on the protein. ABP was endocytosed in the ductuli efferentes and caput epididymidis in amounts similar to or greater than other major testicular proteins, and was not spared from endocytosis in the proximal excurrent ducts.(ABSTRACT TRUNCATED AT 250 WORDS)

This article has been cited by other articles:

				Y. Li, C. A. Putnam-Lawson, H. Knapp-Hoch, P. J. Friel, D. Mitchell, R. Hively, and M. D. Griswold Immunolocalization and Regulation of Cystatin 12 in Mouse Testis and Epididymis Biol Reprod, November 1, 2005; 73(5): 872 - 880. [Abstract] [Full Text] [PDF]

				Y. Li, P. J. Friel, D. J. McLean, and M. D. Griswold Cystatin E1 and E2, New Members of Male Reproductive Tract Subgroup Within Cystatin Type 2 Family Biol Reprod, August 1, 2003; 69(2): 489 - 500. [Abstract] [Full Text] [PDF]

				S. Fouchecourt, G. Charpigny, P. Reinaud, P. Dumont, and J.-L. Dacheux Mammalian Lipocalin-Type Prostaglandin D2 Synthase in the Fluids of the Male Genital Tract: Putative Biochemical and Physiological Functions Biol Reprod, February 1, 2002; 66(2): 458 - 467. [Abstract] [Full Text] [PDF]

				N. M. Ibrahim, L. G. Young, and O. Frohlich Epididymal Specificity and Androgen Regulation of Rat EP2 Biol Reprod, August 1, 2001; 65(2): 575 - 580. [Abstract] [Full Text] [PDF]

				S. Fouchécourt, S. Métayer, A. Locatelli, F. Dacheux, and J.-L. Dacheux Stallion Epididymal Fluid Proteome: Qualitative and Quantitative Characterization; Secretion and Dynamic Changes of Major Proteins Biol Reprod, June 1, 2000; 62(6): 1790 - 1803. [Abstract] [Full Text]