Summary
Testicular macrophages and Leydig cells from adult animals are known to be functionally coupled. For example, secreted products from macrophages stimulate testosterone secretion by Leydig cells. In adult rat testes, structural coupling also exists between these cells. This coupling consists of cytoplasmic projections from Leydig cells located within cytoplasmic invaginations of macrophages. Although macrophages are known to exist in the testis in immature animals, it is not known when these digitations develop. The purpose of the present study was to determine whether the time of their development coincides with known maturational events that occur in Leydig cells, particularly during the peripubertal period. Testes from rats at 20, 30 and 40-days-of-age as well as testes from mature rats weighing more than 500 gm were prepared for ultrastructural analysis. It was found that digitations form between 20 and 30-days-of-age. These structures varied from simple tubular projections to complicated branched structures, suggesting that digitations are more than simple invaginations of microvilli into coated vesicles as previously described. Subplasmalemmal linear densities were also observed within macrophages juxtaposed to Leydig cells. Collagen was commonly observed between macrophages and Leydig cells in animals 20 days old. These studies demonstrate that although macrophages are present in the testis in maximal numbers at 20 days-of-age, they do not form junctions with Leydig cells until day 30. This is just prior to the major increase in secretory activity of rat Leydig cells that occurs during puberty.
Similar content being viewed by others
References
Breucker H (1978) Macrophages, a normal component in seasonally involuting testes of the swan, Cygnus olor. Cell Tissue Res 193:463–471
Christensen AK, Gillim SW (1969) The correlation of fine structure and function in steroid-secreting cells, with emphasis on those of the gonads. In: McKerns KW (ed) The Gonads. Appleton-Century-Crofts, New York, pp 415–488
Connell CJ, Christensen AK (1975) The ultrastructure of the canine testicular interstitial tissue. Biol Reprod 12:368–382
Fawcett DW, Dym M (1975) A glycogen-rich segment of the tubuli recti and proximal portion of the rete testis in the guinea pig. J Reprod Fert 42:1–7
Fawcett DW, Neaves WB, Flores MN (1973) Comparative observations on intertubular lymphatics and the organization of the interstitial tissue of the mammalian testis. Biol Reprod 9:500–532
Friess AE (1977) Macrophage-lymphocyte cluster formation in the medullary sinus of lymph node after immunization with sheep red blood cells (SRBS) Cell Tissue Res 180:505–514
Hutson JC (1989) Leydig cell do not have Fc receptors. J Andrology 10:159–165
Hutson JC (1990) Changes in the concentration and size of testicular macrophages during development. Biol Reprod 43:885–890
Hutson JC, Stocco DM (1989) Comparison of cellular and secreted proteins of macrophages from the testis and peritoneum on two-dimensional polyacrylamide gels. Regional Immunol 2:249–253
Karnovsky MJ (1971) Use of ferrocyanide-reduced osmium tetroxide in electron microscopy. J Cell Biol Abstract no 284
Miller SC (1982) Localization of plutonium-241 in the testis. An interspecies comparison using light and electron microscope autoradiography. Int J Radiat Biol 41:633–643
Miller SC, Bowman BM, Rowland HG (1983) Structure, cytochemistry, endocytic activity, and immunoglobulin (Fc) receptors of rat testicular interstitial-tissue macrophages. Am J Anat 168:1–13
Miller SC, Bowman BM, Roberts LK (1984) Identification and characterization of mononuclear phagocytes isolated from rat testicular interstitial tissues. J Leuk Biol 36:679–687
Miyata K and Takaya K (1984) Intercellular junctions between macrophages in the regional lymph node of the rat after injection of large doses of steroids. Cell Tissue Res 236:351–355
Oichi K, Ferrans V, Crystal RG (1980) Subplasmalemmal linear densities on cells of the mononuclear phagocyte system. Am J Path 100:131–144
Raburn DJ, Coquelin A, Hutson JC (1991) Human chorionic gonadotropin increases the concentration of macrophages in neonatal rat testis. Biol Reprod 44:172–177
Russell L, Burguet S (1977) Ultrastructure of Leydig cells as revealed by secondary tissue treatment with a ferrocyanide-osmium mixture. Tissue Cell 9:751–766
Sinha AA, Erickson AW, Seal US (1977) Fine structure of Leydig cells in crabeater, leopard and ross seals. J Reprod Fert 49:51–54
Wei RQ, Yee JB, Straus DC, Hutson JC (1988) Bactericidal activity of testicular macrophages. Biol Reprod 38:830–835
Werb Z, Banda MJ, Jones PA (1980) Degradation of connective tissue matrices by macrophages. I. Proteolysis of elastin glycoproteins, and collagen by proteinases isolated from macrophages. J Exp Med 152:1340–1357
Wing TY, Lin HS (1977) The fine structure of testicular interstitial cells in the adult golden hamster with special reference to seasonal changes. Cell Tissue Res 183:385–393
Yee JB, Hutson JC (1983) Testicular macrophages: isolation, characterization and hormonal responsiveness. Biol Reprod 29:1319–1326
Yee JB, Hutson JC (1985a) In vivo effects of FSH on testicular macrophages. Biol Reprod 32:880–883
Yee JB, Hutson JC (1985b) Biochemical consequences of FSH binding to testicular macrophages in culture. Biol Reprod 32:872–879
Yee JB, Hutson JC (1985c) Effects of testicular macrophage-conditioned medium on Leydig cells in culture. Endocrinology 116:2682–2684
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Hutson, J.C. Development of cytoplasmic digitations between Leydig cells and testicular macrophages of the rat. Cell Tissue Res 267, 385–389 (1992). https://doi.org/10.1007/BF00302977
Received:
Accepted:
Issue Date:
DOI: https://doi.org/10.1007/BF00302977