Development of cytoplasmic digitations between Leydig cells and testicular macrophages of the rat

Abstract

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.

Single Subcutaneous Administration of Chorionic Gonadotropin to Rats Induces a Rapid and Transient Increase in Testicular Expression of Pro-Inflammatory Cytokines

“…Our immunohistochemical examination confirms previous observations (15,25) of an intimate spatial relationship between macrophages and Leydig cells in the testis. Our detection of IL-1␤ in macrophages only, but not in Leydig cells, after administration of hCG, indicates that Leydig cells may emit juxtacrine signals which activate adjacent macrophages to begin production of pro-inflammatory cytokines.…”

Morphology of the Interstitial Tissue of Active and Resting Testis of the Guinea Fowl

“…Few fibroblasts were found in both groups. Macrophages may represent as much as 25 % of the interstitial cell population in adult mice and rats (Hutson, 1992). But the macrophages were not noticed in sexually active testis, however few macrophages were found in sexually resting testis between blood vessels and Interstitial cells (Fig.…”

Macrophages in the embryo and beyond: Much more than just giant phagocytes

“…Interestingly, many of those defects appear to stem from the disregulation of hypothalamic-pituitary interactions, attributed to the defects in microglial function during development (Cohen et al, 1999). In the testis, macrophages make up to 25% of the interstitial cell population, and are well known to establish close intercellular contacts of a very specialized type with steroidogenic Leydig cells in both in vivo and in vitro conditions (Giannessi et al, 2005;Hutson, 1992;Niemi et al, 1986). Similar to the testis, in the ovary macrophages are present in the interstitial tissue and are recruited to the theca layers just before ovulation, probably by the CSF-1 produced by the granulosa cells (Cohen et al, 1997).…”