Distribution of the α1 to α6 Chains of Type IV Collagen in Bovine Follicles1

Abstract

During follicular development the proliferative and differentiated state of the epithelioid granulosa cells changes, and the movement of fluid across the follicular basal lamina enables the formation of an antrum. Type IV collagen is an important component of many basal laminae. Each molecule is composed of three alpha chains; however, six different type IV collagen chains have been identified. It is not known which of these chains are present in the follicular basal lamina and whether the type IV collagen composition of the basal lamina changes during follicular development. Therefore, we immunolocalized each of the six chains in bovine ovaries using antibodies directed to the nonconserved non-collagenous (NC) domains. Additionally, dissected follicles were digested with collagenase to release the NC domains, and the NC1 domains were then detected by standard Western immunoblot methods. The follicular basal lamina of almost all primordial and preantral follicles was positive for all type IV collagen alpha chains. Colocalization of type IV collagen and factor VIII-related antigen allowed for discrimination between the follicular and endothelial basal laminae. Type IV collagen alpha1, alpha2, alpha3, alpha4, and alpha5 chains were present within the follicular basal lamina of only a proportion of antral follicles (17 of 22, 20 of 21, 15 of 18, 14 of 28, and 12 of 23, respectively), and staining was less intense than in the preantral follicles. Staining for the alpha1 and alpha2 chains was diffusely distributed throughout the theca in regions not associated with recognized basal laminae. The specificity of this immunostaining for alpha1 and alpha2 chains of type IV collagen was confirmed by Western immunoblots. As well as being detected in the basal lamina of approximately half of the antral follicles examined, type IV collagen alpha4 also colocalized with 3beta-hydroxysteroid dehydrogenase-immunopositive cells in the theca interna. Type IV collagen alpha6 was detected in the basal lamina of only one of the 16 antral follicles examined. Thus, the follicular basal lamina changes in composition during follicular development, with immunostaining levels being reduced for all type IV collagen chains and immunoreactivity for type IV collagen alpha6 being lost as follicle size increases. Additionally, immunoreactivity for alpha1 and alpha2 appears in the extracellular matrix of the theca as it develops.

Distribution of extracellular matrix proteins type I collagen, type IV collagen, fibronectin, and laminin in mouse folliculogenesis

“…Collagen IV presented in the theca layer of the follicle, with more intense staining detected in later stage follicles and older ovaries. These observations are consistent with staining in the rat (Bortolussi et al 1989;Frojdman et al 1998) and bovine (Zhao and Luck 1995;Rodgers et al 1998;IrvingRodgers et al 2002). Laminin also stains the basal lamina in the pig and rabbit (Lee et al 1996) and type IV collagen was found in the theca of human ovaries (Iwahashi et al 2000).…”

“…In the bovine, ECM composition varies during growth ) and changes during atresia (Irving-Rodgers et al 2002). The ECM in the ovary has been characterized for several species, such as bovine (Zhao and Luck 1995;Rodgers et al 1998;McArthur et al 2000;Rodgers et al 2001), human (Yamada et al 1999;Iwahashi et al 2000), rat (Rajah et al 1994;Frojdman et al 1998), ovine (Huet et al 2001;Le Bellego et al 2002), and equine (Gentry et al 1996), with type I collagen, type IV collagen, fibronectin, and laminin the most commonly examined ECM proteins (Bortolussi et al 1989;Rajah et al 1994;Figueiredo et al 1995;Zhao and Luck 1995;Huet et al 1997). The mouse has been a widely used model to examine folliculogenesis in vivo (Matzuk 2000) and in vitro (Cortvrindt and Smith 1998;Spears et al 1998;O'Brien et al 2003;Kreeger et al 2005;Kreeger et al 2006), yet the mouse ovarian ECM has not been well described relative to other species.…”

Permselectivity of blood follicle barriers in mouse ovaries of the mifepristone-induced polycystic ovary model revealed by in vivo cryotechnique

“…5, some collagen type IV a-chains were immunohistochemically examined to reveal any changes in the major components of the basement membranes (Rodgers et al 1998, Nakano et al 2007). However, no apparent differences in the collagen a-chains were observed in the antral follicles between the PCO model and control mice (Fig.…”

Effect of copper and thiomolybdates on bovine theca cell differentiation in vitro

“…This is not surprising as dramatic changes and remodelling of the extracellular matrix occur during ovarian follicle development (Rodgers et al 1998). The ECM is also considered as an active regulator of cell migration, division, differentiation, death and anchorage.…”

“…Thiomolybdates have also previously been shown to affect lysyl oxidase and subsequent collagen and elastin formation, often observed as symptoms of clinical copper deficiency which include cardiac problems, bone weakness and joint abnormalities (Underwood 1981). The ECM is also considered as an active regulator of cell migration, division, differentiation, death and anchorage with significant and dramatic changes in the remodelling of the extracellular matrix occurring during ovarian follicle development (Rodgers et al 1998). Collagen type IV, laminin and fibronectin are thought to be present in lamina-like material in the theca matrix and this basal lamina seems to be constantly remodelled as the follicle matures (Rodgers et al 1999).…”