Sexually dimorphic and laterally asymmetric development of the embryonic duck syrinx: Effect of estrogen on in vitro cell proliferation and chondrogenesis

Abstract

The syrinx, the vocal organ in birds, shows sexual dimorphism in the duck, Anas platyrhynchos. At the cellular level, to examine the role of estrogen in sexually dimorphic and laterally asymmetric development of duck syrinx, cells dissociated from the right and left halves of sexually monomorphic and primitive masculine syrinxes from 10 2 3-day embryos of male and female ducks were cultured by the micromass culture method, with or without estrogen. In the absence of estrogen, primary cell cultures from either side of male syrinx revealed identical abilities in both cell proliferation and chondrogenesis. In the female cell cultures, the right- and left-side cells proliferated equally but the right-side cells accumulated a larger amount of sulfated proteoglycans than the left-side cells did. Both proliferation and chondrogenesis in the male cell cultures were more active than those in the female cell cultures. Estradiol inhibited significantly cell proliferation as well as chondrogenesis in cell cultures from either side of female syrinx. Cultures from right-side cells of male syrinx were less inhibited by estradiol in cell proliferation and especially in chondrogenesis than the other three cultures. Generally, in both sexes the left-side cells of syrinx were more responsive to estrogen than the right-side cells in diminishing proliferation and chondrogenesis. The present results suggest that estrogen inhibits both cell proliferation and chondrogenesis in the female syrinx and that this process may contribute to the development of sexual dimorphism in the duck syrinx. © 1987.