Immunocytochemical analysis of the expression of gap junction protein connexin 43 in the rat ovary

Abstract

The present immunocytochemical study examines in the rat ovary the pattern of expression of connexin 43 (Cx43), a subunit of gap junctions. Using a well-characterized specific antiserum against rat Cx43, immunoreactivity was not detected in the fetal ovary, i.e., prior to follicular formation. However, in the ovary of 20-day-old, 35-day-old, and adult rats, strong Cx43-immunoreactivity was associated with the cell borders of the follicular epithelium/granulosa cells of all developmental stages (primordial follicles, preantral and antral secondary follicles). In general, immunoreactivity of the granulosa cells of large antral follicles appeared more intense than the one of smaller follicles. Staining was also seen in oocytes (cytoplasmic staining). Theca cells of large antral follicles, but not of small follicles were immunoreactive. Immunoreactive interstitial cells were not seen in ovaries of 20- and 35-day-old animals, but staining in these cells was present in adult rats. In large follicles with signs of atresia, granulosa cells lacked Cx43-immunoreactivity, whereas Cx43-immunoreactivity in their theca interna strikingly increased. Corpora lutea in the cyclic adult rats were heterogeneously stained, with either no detectable immunoreactivity, staining of cell borders of most luteal cells, or with conspicuous staining of only a few cells. In the pregnant animals on gestation days (GD) 12, 14, and 17, all luteal cells stained strongly for Cx43 at the cell surface.(ABSTRACT TRUNCATED AT 250 WORDS)

Expression of connexin 43 and gap junctional intercellular communication in the cumulus–oocyte complex in sheep

“…In the present study, Cx43 was localized between cumulus cells and between the oocyte and cumulus cells, and, in addition some of the staining was localized to the oocyte side of the zona pellucida. Similar to our findings, in most species Cx43 has been localized at the cellular borders of granulosa/cumulus cells and at the interface of the oocyte and the surrounding cumulus cells (Valdimarsson et al 1993, Mayerhofer & Garfield 1995, Simon et al 1997, GrazulBilska et al 1998, Lenhart et al 1998, Johnson et al 1999, Nuttinck et al 2000, Granot & Dekel 2002. Collectively, these findings demonstrate that Cx43 is present Gap junctions in the ovine cumulus-oocyte complex 195 between the oocyte and the adjacent cumulus cells as well as in the oolemma.…”

“…Cx43 has been detected in primordial to preovulatory follicles and its expression has been shown to accompany follicular growth in rats (Mayerhofer & Garfield 1995) and pigs (Lenhart et al 1998). For sheep and cows, an increased Cx43 expression has been reported in large antral follicles as compared with small antral follicles (Grazul-Bilska et al 1998, Johnson et al 1999, Nuttinck et al 2000.…”

“…The expression of Cx43 and the rate of GJIC in COCs seem to depend on the stage of follicular development (Mayerhofer & Garfield 1995, Grazul-Bilska et al 1998, Johnson et al 1999, Melton et al 2001. Cx43 has been detected in primordial to preovulatory follicles and its expression has been shown to accompany follicular growth in rats (Mayerhofer & Garfield 1995) and pigs (Lenhart et al 1998).…”

“…Gap junctions in granulosa/cumulus cells of ovarian follicles may contain several different connexins -including Cx26, Cx32, Cx37, Cx43 and/or Cx45 -depending on the species (Grazul-Bilska et al 1997, Simon et al 1997, Nuttinck et al 2000, Kidder & Mhawi 2002. Cx43 is one of the major gap junctional proteins expressed in the cumulus oocyte complex (COC) and granulosa cells of several species (Valdimarsson et al 1993, Wiesen & Midgley 1993, Mayerhofer & Garfield 1995, Grazul-Bilska et al 1997, Johnson et al 1999, Kidder & Mhawi 2002. Models of targeted mutation of Cx43 clearly demonstrated that gap junctional coupling mediated by Cx43 channels plays an indispensable role in both germ line development and postnatal folliculogenesis (Juneja et al 1999).…”

Estradiol Reduces Connexin43 Gap Junctions in the Uterus during Adenomyosis in Cows

“…A gap junction channel is composed of two hemi-channels (connexons), each of which is composed of six protein subunits (connexins -Cxs) arranged around a pore. Connexin43 (Cx43) and Cx32 are the two most abundant Cxs and are expressed in numerous tissues including the ovary, placenta and decidua in several species, including cattle (Wiesen and Midgley 1993, Mayerhofer and Garfield 1995, Wrenzycki et al 1995, van Engelen et al 2009, Xu et al 2015.…”