Oestrogens and spermatogenesis

Abstract

The role of oestrogens in male reproductive tract physiology has for a long time been a subject of debate. The testis produces significant amounts of oestrogenic hormones, via aromatase, and oestrogen receptors (ERs)alpha (ESR1) and ERbeta (ESR2) are selectively expressed in cells of the testis as well as the epididymal epithelium, depending upon species. This review summarizes the current knowledge concerning the presence and activity of aromatase and ERs in testis and sperm and the potential roles that oestrogens may have in mammalian spermatogenesis. Data show that physiology of the male gonad is in part under the control of a balance of androgens and oestrogens, with aromatase serving as a modulator.

Figure 1.

Age-related changes on the use of P450 aromatase transcripts in rat testis.

Figure 2.

Aromatase immunohistochemical straining in (a) the adult mouse testis and (b) caput epididymis. In testis, staining is intense in elongate spermatids (ES) and spermatozoa in the seminiferous tubule lumen (Sp). All other germ cells and Sertoli cells show weaker staining. Leydig cells (LC) are also positive in the interstitial space. In the epididymal lumen, aromatase is strongly positive in the cytoplasmic droplet of the sperm tail (arrows). The epididymal epithelium (Epid) may also show some weak staining in some cells. Scale bars, (a) 25 µm; (b) 10 µm.

Figure 3.

Localization of aromatase in ejaculated human spermatozoa using confocal microscopy. CD 46 (red): specific marker of inner acrosomal membrane; chromatin is localized with DAPI (blue) and the aromatase is revealed by a polyclonal antibody (green). Adapted from the publisher.

Figure 4.

(a) ERα and (b) ERβ in the adult mouse testis. Immunohistochemical localization of ERα using perfusion fixation with neutral buffered formalin and the NCL-ER-6F11 antibody (Novocastra, Newcastle upon Tyne, UK) gave strong staining in Leydig (Lc), other interstitial cells and peritubular myoid cells (Pc) of the testis. Staining for ERβ was more intense in some spermatocytes (Spc) than other germ cells, but all germ cells, except the elongated spermatids (Es) were positive, including the round spermatids (Rs). Scale bar, 50 µm.

Figure 5.

Wild-type (WT) and neo-ERαKO adult mice testes. (a) WT seminiferous tubules at 90 days of age show normal spermatogenesis with full complement of spermatogenesis. (b) In the ERαKO at 90 days, some tubules are dilated (double arrow) and all seminiferous epithelia are decreased in height. (c) At 180 days of age, total atrophy of all seminiferous tubules can be found in the ERαKO testis, with some tubules showing denuded epithelia. The rete testis (RT) is severely dilated from birth and enlarges into adulthood. (d) Higher magnification of seminiferous tubules from 180 days ERαKO testis showing Sertoli cell (SC)-only tubules. Scale bars, 50 µm.

Figure 6.

(a) ERα (ESR1) colocalized with a Sertoli cell nuclear marker (green) under basal conditions (control) or (b) after incubation with E2 (0.1 nM) for 10 min. Some of the ERα migrates from the nucleus into the Sertoli cell membrane after oestrogen treatment. Scale bar, 30 µm. Adapted from fig. 6 in Lucas et al. (2008).