Primary cilia in the developing pig testis

Abstract

In vertebrates, a variety of cell types generate a primary cilium. Cilia are implicated in determination and differentiation of a wide variety of organs and during embryonic development. However, there is little information on the presence or function of primary cilia in the mammalian testis. Therefore, the objective of this study was to characterize expression of primary cilia in the developing pig testis. Testicular tissue from pigs at 2 to 10 weeks of age was analyzed for primary cilia by immunocytochemistry. Expression of primary cilia was also analyzed in testicular tissue formed de novo from a single cell suspension ectopically grafted into a mouse host. Functionality of primary cilia was monitored based on cilia elongation after exposure to lithium. Analysis showed that the primary cilium is present in testis cords as well as in the interstitium of the developing pig testis. Germ cells did not express primary cilia. However, we identified Sertoli cells as one of the somatic cell types that produce a primary cilium within the developing testis. Primary cilium expression was reduced from the second to the third week of pig testis development in situ and during de novo morphogenesis of testis tissue from a single cell suspension after xenotransplantation. In vitro, primary cilia were elongated in response to lithium treatment. These results indicate that primary cilia on Sertoli cells may function during testicular development. De novo morphogenesis of testis tissue from single cell suspensions may provide an accessible platform to study and manipulate expression and function of primary cilia.

Primary cilia on porcine testicular somatic cells and their role in hedgehog signaling and tubular morphogenesis in vitro

“…Sertoli cells at 89.8±2.4% constituted the majority of the population, followed by peritubular myoid cells 6.8±0.2%, Leydig cells 2.6±0.7, and 2.1±1.5 of germ cells (n=5 cell preparations; 500 cells/sample). As described previously (Ou et al, 2014), primary cilia were present on testicular somatic cells but not on germ cells.…”

“…Our group was the first to describe the presence of primary cilia in the testis (Ou et al 2014), and the present study is the first to report a link between primary cilia, tubular morphogenesis and the hedgehog pathway in neonatal testicular somatic cells. As described for other cell types (Corbit et al 2005; Rohatgi et al 2007) Gli-2 was localized at the primary cilium and basal body in testicular somatic cells.…”

“…We demonstrated previously that the temporal pattern of primary cilia formation in the developing postnatal testis is recapitulated in testis tissue formed de novo from isolated cells grafted to mice (Ou et al, 2014). This system could provide a platform to manipulate formation of primary cilia in the testis and serve as a new model for studying cilia function, elucidating reproductive defects in patients with ciliopathies and testing new treatment protocols.…”

“…In males, the sperm flagellum is considered a motile cilium, and the organelles are also described in the efferent ductules (see Ilio & Hess, 1994, Hess, 2002, 2015) where they regulate the continuous uptake of fluid (Reid & Cleland, 1957). Investigations in the role of primary cilia in the testis are relatively recent (Ou et al 2014) but in the last decade the expansion of scientific knowledge surrounding the primary cilium have highlighted this organelle as an important structure in the orchestration of cellular development and homeostasis (Delling et al 2013). …”

“…Our previous work described the presence of primary cilia in the somatic compartment of mammalian testicular cells and their absence in undifferentiated germ cells (Ou et al 2014). We reported that primary cilia are abundant during the first two weeks of age in the porcine testis after which their numbers are reduced.…”