Different patterns of anti‐Müllerian hormone expression, as related to DMRT1, SF‐1, WT1, GATA‐4, Wnt‐4, and Lhx9 expression, in the chick differentiating gonads

Abstract

In mammals, anti-Mü llerian hormone (AMH) is produced by Sertoli cells from the onset of testicular differentiation and by granulosa cells after birth. In birds, AMH starts to be expressed in indifferent gonads of both sexes at a similar level and is later upregulated in males. We previously demonstrated that, unlike in mammals, the onset of AMH expression occurs in chick embryo in the absence of SOX9. We looked for potential factors that might be involved in regulating AMH expression at different stages of chick gonad differentiation by comparing its expression pattern in embryos and young chicken with that of DMRT1, SF-1, WT1, GATA-4, Wnt-4, and

Isolation of chicken homolog of the FOXL2 gene and comparison of its expression patterns with those of aromatase during ovarian development

“…These investigations revealed that cFoxL2 protein distribution was restricted to the medullar part of the ovary during early development. The same region of expression has been reported for aromatase transcripts Nakabayashi et al, 1998;Nishikimi et al, 2000;Oreal et al, 2002) and for the aromatase protein (Smith et al, 2003). The double immunolocalization of cFoxL2 and aromatase proteins to the sections of the left female gonad at E14 in our study demonstrated that cFoxL2 and aromatase proteins are expressed in the same cells.…”

“…Two other transcriptional factors (Wnt4 and DAX1), which are considered to be suppressive factors of the male pathway in mammalian sex differentiation, do not seem to play the same role in the chicken. WNT4 expression in chickens is not dimorphic as in mammals during gonad differentiation (Oreal et al, 2002), and DAX1 is only slightly up-regulated in female compared with male differentiating gonads (Smith et al, 1999).…”

“…However, cFoxL2 transcripts and protein were both detected in the theca cell layer of the adult chicken ovary, but the levels of cFoxL2 expression in theca cells were considerably lower than that in granulosa cells. In chicken, it has been shown previously that aromatase transcripts were present only in analogs of theca cells of developing follicles (Oreal et al, 2002) and in the theca externa of maturing follicles (Kato et al, 1995). They were never detected in granulosa cells, which are known to be a site of specific aromatase expression in mammals.…”

“…Although the regulatory mechanisms of testis differentiation in birds remain unclear, it is known that this process is associated with the successive activation of doublesex mab-3-related transcription factor DMRT1, anti-mü llerian hormone, and high mobility group box protein Sox9 expression leading to the formation of testicular cords and the regression of mü llerian ducts (Oreal et al, 2002). Less is known about the control of ovarian differentiation.…”

Characterization of early molecular sex differentiation in rainbow trout, Oncorhynchus mykiss

“…In trout, both amh and sox9a2 were detected in female embryonic gonads by ISH, despite a higher level of expression in the differentiating testis. Such an incomplete sexually dimorphic expression pattern has already been described for sox9 genes in some fish (Zhou et al, 2003;Nakamoto et al, 2005), and for Amh in birds (Oreal et al, 1998(Oreal et al, , 2002. In trout, it is currently difficult to draw any conclusions about the implication of sox9 genes as we were unable to investigate the cellular localization of sox9a1 by ISH, but its temporal expression profile seems to be sexually dimorphic earlier than those of sox9a2 and amh.…”