Development of the caput epididymidis studied by expressed proteins (a glutamate transporter, a lipocalin and ?-galactosidase) in the c-ros knockout and wild-type mice with prepubertally ligated efferent ducts

Abstract

Expression of a glutamate transporter (EAAC1), a lipocalin (MEP17) and beta-galactosidase (beta-Gal) in histological sections was used to monitor post-natal development of the murine epididymis. Three epithelia in the adult caput of wild-type mice were distinguished: I, the initial segment; II, the proximal caput; and III, the distal caput. The regions in which epithelia I, II and III were situated were called regions I, II and III, respectively. Regions I, II and III developed from a precursor epithelium present on day 14; from day 16, a presumptive region I epithelium was evident and, by day 21, epithelia characteristic of future regions II and III appeared. The relationship between the c-ros gene and the initial segment was studied by investigating the development of the caput epididymidis in transgenic homozygous c-ros knockout (-/-) mice that lack the initial segment, heterozygous (+/-) males and wild-type males in which the efferent ducts had been ligated prepubertally so that the initial segment failed to develop. In mice with prepubertally ligated efferent ducts, regions II and III developed normally but region I was missing in the adult and expression of c-ros was partially decreased. In (-/-) mice, the precursor epithelium was present, differentiation of epithelium II was delayed until day 32 and epithelium I never developed. Thus, caput region I develops before c-ros expression, high testosterone secretion and differentiation of regions II and III but not if the organ is deprived of the oncogene c-ros or testicular exocrine secretions. The caput of the knockout male lacks solely the initial segment so that the efferent ducts are in continuity with the post-initial segment, proximal caput region. The ligand for c-ros may be present in testicular fluid and both ligand and receptor may be necessary for differentiation of epithelia I and II.

Why are epididymal tumours so rare?

“…79 b-galactosidase (b-Gal) with neutral pH activity is constitutively expressed in the caput and corpus epididymidal epithelium of young adult rats and mice. 81 It is located in the supranuclear region of principal cells in the initial segment, but not in adjacent caput regions, 82 and in the corpus. 42 It is not known if this b-Gal is identical to SABG in oncogene-induced senescence.…”

Expression pattern of the orphan receptor LGR4/GPR48 gene in the mouse

“…The beta-galactosidase signal in Leydig regions of epididymis head as described in Avram and Cooper 2004. g, h In situ hybridization of epididymis with LGR4 ectodomain antisense probe (g) and negative control with corresponding sense probe (h) Original magnification x400 (a-d) and x25 (e-h) x25 (a,b), x200 (c-e) and x160 (f) cells is only due to endogenous activity. Beta-galactosidase activity is known to be normally present in the head of the epididymis in zona I (Avram and Cooper 2004;Fig. 8f).…”

Regulation of the initial segment of the murine epididymis by dihydrotestosterone and testicular exocrine secretions studied by expression of specific proteins and gene expression

“…There are few sperm in the lumen, because of a reduced luminal size (Abe et al 1983). The lumen is lined by a tall, actively secretory epithelium, with principal cells bearing stereocilia; it has a rich vasculature (Suzuki 1982) consisting of fenestrated capillaries (Abe et al 1984), exhibits a more active metabolism than other regions (Elliott 1965), displays a number a specific genes (Kirchhoff 1999;Cornwall et al 2002; and begins differentiation from a precursor epithelium before puberty (Avram and Cooper 2004). The importance of the initial segment for sperm maturation has been demonstrated by study of the c-ros receptor tyrosine kinase knockout mouse in which the initial segment does not develop during puberty and males are infertile (Sonnenberg-Riethmacher et al 1996).…”