The distribution of type IV collagen alpha chains in the mouse ovary and its correlation with follicular development

Relationship between Amino Acid Metabolism and Bovine In Vitro Follicle Activation and Growth

The amino acid metabolism of bovine follicles during in vitro growth (IVG) was evaluated to identify potential indicators of health during culture. The bovine ovarian cortex was sliced, prepared as strips, and cultured for 6 days. Tissue samples were examined histologically before and after 6 days of culture, and the degree of follicle activation was classified as either high or low based on the number of growing secondary follicles present (high: 7~11; low: 0~1). In a separate experiment, secondary follicles (diameter range: 100~200 μm) were manually isolated and cultured, and their growth was monitored for 6 days. Cultured follicles were classified as growth or degenerate based on diameter change during culture (growth: +60.5~74.1 μm; degenerate: -28~15.2 μm). Free amino acids and their metabolites were measured in the spent culture medium from each group. In cultured ovarian cortical strips, the concentration of α-aminoadipic acid was significantly higher in the low activation group than in the high group (p < 0.05), while those of methionine, lysine, and arginine were higher in the high activation group. In cultured isolated secondary follicles, concentrations of methionine, tyrosine, histidine, and hydroxyproline were higher in the degenerate group (p ≤ 0.05). In conclusion, amino acid metabolism has the potential to serve as an indicator of primordial follicle activation and subsequent growth rate during bovine IVG.

Squeezing the eggs to grow: The mechanobiology of mammalian folliculogenesis

The formation of functional eggs (oocyte) in ovarian follicles is arguably one of the most important events in early mammalian development since the oocytes provide the bulk genetic and cytoplasmic materials for successful reproduction. While past studies have identified many genes that are critical to normal ovarian development and function, recent studies have highlighted the role of mechanical force in shaping folliculogenesis. In this review, we discuss the underlying mechanobiological principles and the force-generating cellular structures and extracellular matrix that control the various stages of follicle development. We also highlight emerging techniques that allow for the quantification of mechanical interactions and follicular dynamics during development, and propose new directions for future studies in the field. We hope this review will provide a timely and useful framework for future understanding of mechano-signalling pathways in reproductive biology and diseases.

Main and Minor Types of Collagens in the Articular Cartilage: The Role of Collagens in Repair Tissue Evaluation in Chondral Defects

Several collagen subtypes have been identified in hyaline articular cartilage. The main and most abundant collagens are type II, IX and XI collagens. The minor and less abundant collagens are type III, IV, V, VI, X, XII, XIV, XVI, XXII, and XXVII collagens. All these collagens have been found to play a key role in healthy cartilage, regardless of whether they are more or less abundant. Additionally, an exhaustive evaluation of collagen fibrils in a repaired cartilage tissue after a chondral lesion is necessary to determine the quality of the repaired tissue and even whether or not this repaired tissue is considered hyaline cartilage. Therefore, this review aims to describe in depth all the collagen types found in the normal articular cartilage structure, and based on this, establish the parameters that allow one to consider a repaired cartilage tissue as a hyaline cartilage.

Type IV collagen α6 chain is a regulator of keratin 10 in keratinization of oral mucosal epithelium

Keratinized mucosa is of fundamental importance to maintain healthy gingival tissue, and understanding the mechanisms of oral mucosa keratinization is crucial to successfully manage healthy gingiva. Previous studies have shown a strong involvement of the basement membrane in the proliferation and differentiation of epithelial cells. Therefore, first, to identify the keratinized mucosa-specific basement membrane components, immunohistochemical analysis for the six alpha chains of type IV collagen was performed in 8-week-old mice. No difference in the expression pattern of type IV collagen α1(IV) and α2(IV) chains was observed in the keratinized and non-keratinized mucosa. Interestingly, however, type IV collagen α5(IV) and α6(IV) chains specifically were strongly detected in the keratinized mucosa. To analyze the functional roles of the type IV collagen isoform α6(IV) in oral mucosa keratinization, we analyzed Col4a6-knockout mice. Epithelial developmental delay and low levels of KRT10 were observed in new-born Col4a6-knockout mice. Additionally, in vitro experiments with loss-of function analysis using human gingival epithelial cells confirmed the important role of α6(IV) chain in epithelial keratinization. These findings indicate that α112:α556 (IV) network, which is the only network that includes the α6(IV) chain, is one regulator of KRT10 expression in keratinization of oral mucosal epithelium.

Development of the follicular basement membrane during human gametogenesis and early folliculogenesis

Background

In society, there is a clear need to improve the success rate of techniques to restore fertility. Therefore a deeper knowledge of the dynamics of the complex molecular environment that regulates human gametogenesis and (early) folliculogenesis in vivo is necessary. Here, we have studied these processes focusing on the formation of the follicular basement membrane (BM) in vivo.

Results

The distribution of the main components of the extracellular matrix (ECM) collagen IV, laminin and fibronectin by week 10 of gestation (W10) in the ovarian cortex revealed the existence of ovarian cords and of a distinct mesenchymal compartment, resembling the organization in the male gonads. By W17, the first primordial follicles were assembled individually in that (cortical) mesenchymal compartment and were already encapsulated by a BM of collagen IV and laminin, but not fibronectin. In adults, in the primary and secondary follicles, collagen IV, laminin and to a lesser extent fibronectin were prominent in the follicular BM.

Conclusions

The ECM-molecular niche compartimentalizes the female gonads from the time of germ cell colonization until adulthood. This knowledge may contribute to improve methods to recreate the environment needed for successful folliculogenesis in vitro and that would benefit a large number of infertility patients.

Electronic supplementary material

The online version of this article (doi:10.1186/s12861-015-0054-0) contains supplementary material, which is available to authorized users.

Identifying a novel role for X-prolyl aminopeptidase (Xpnpep) 2 in CrVI-induced adverse effects on germ cell nest breakdown and follicle development in rats

Environmental exposure to endocrine-disrupting chemicals (EDCs) is one cause of premature ovarian failure (POF). Hexavalent chromium (CrVI) is a heavy metal EDC widely used in more than 50 industries, including chrome plating, welding, wood processing, and tanneries. Recent data from U.S. Environmental Protection Agency indicate increased levels of Cr in drinking water from several American cities, which potentially predispose residents to various health problems. Recently, we demonstrated that gestational exposure to CrVI caused POF in F1 offspring. The current study was performed to identify the molecular mechanism behind CrVI-induced POF. Pregnant rats were treated with 25 ppm of potassium dichromate from Gestational Day (GD) 9.5 to GD 14.5 through drinking water, and the fetuses were exposed to CrVI through transplacental transfer. Ovaries were removed from the fetuses or pups on Embryonic Day (ED) 15.5, ED 17.5, Postnatal Day (PND) 1, PND 4, or PND 25, and various analyses were performed. Results showed that gestational exposure to CrVI: 1) increased germ cell/oocyte apoptosis and advanced germ cell nest (GCN) breakdown; 2) increased X-prolyl aminopeptidase (Xpnpep) 2, a POF marker in humans, during GCN breakdown; 3) decreased Xpnpep2 during postnatal follicle development; and 4) increased colocalization of Xpnpep2 with Col3 and Col4. We also found that Xpnpep2 inversely regulated the expression of Col1, Col3, and Col4 in all the developmental stages studied. Thus, CrVI advanced GCN breakdown and increased follicle atresia in F1 female progeny by targeting Xpnpep2.

Slit2 promotes tumor growth and invasion in chemically induced skin carcinogenesis

Slit, a neuronal guidance cue, binds to Roundabout (Robo) receptors to modulate neuronal, leukocytic, and endothelial migration. Slit has been reported to have an important effect on tumor growth and metastasis. In the current study, we evaluated the role of Slit2 in skin tumor growth and invasion in mice using a two-step chemical carcinogenesis protocol. We found that Slit2 expression correlated with the loss of basement membrane in the samples of human skin squamous cell carcinoma at different stages of disease progression. Slit2-Tg mice developed significantly more skin tumors than wild-type mice. Furthermore, the skin tumors that occurred in Slit2-Tg mice were significantly larger than those in the wild-type mice 10 weeks after 7,12-dimethylbenz[a]anthracene initiation until the end of the experiment. We also found that pathological development of the wild-type mice was delayed compared with that of Slit2-Tg mice. To further investigate the mechanism of increasing tumors in Slit2-Tg mice, we analyzed the expression of 5-bromo-2'-deoxyuridine (BrdU) in mouse skin lesions and found that the number of BrdU-positive cells and microvessel density in skin lesions were significantly higher in Slit2-Tg mice than in wild-type mice. Histological staining of PAS and type IV collagen and the colocalization of Slit2 and type IV collagen demonstrated varying degrees of loss of the basement membrane in the skin lesions from Slit2-Tg mice that were at the stage of carcinoma in situ. However, the basement membrane was well defined in the wild-type mice. In addition, MMP2, but not MMP9, was upregulated in the skin tissue of Slit2-Tg mice. Interruption of Slit2-Robo1 signaling by the antibody R5 significantly repressed the invasive capability of the squamous cell carcinoma cell line A431. Taken together, our findings reveal that Slit2 promotes DMBA/TPA-induced skin tumorigenesis by increasing cell proliferation, microvessel density, and invasive behavior of cutaneous squamous cell carcinoma, along with loss of basement membrane, by upregulation of MMP2 expression.

A new step toward the artificial ovary: survival and proliferation of isolated murine follicles after autologous transplantation in a fibrin scaffold

OBJECTIVE

To create an artificial ovary to provide an alternative way of restoring fertility in patients who cannot benefit from transplantation of cryopreserved ovarian tissue due to the threat of reintroducing malignant cells.

DESIGN

In vivo experimental study.

SETTING

Gynecology research unit in a university hospital.

ANIMAL(S)

Six-week-old female NMRI mice.

INTERVENTION(S)

Autografting of isolated preantral follicles and ovarian cells (OCs) encapsulated in two fibrin matrices containing low concentrations of fibrinogen (F; mg/mL) and thrombin (T; IU/mL): F12.5/T1 and F25/T4.

MAIN OUTCOME MEASURE(S)

Follicular density and development, OC survival and proliferation, inflammatory response, and vascularization.

RESULT(S)

After 1 week, the follicle recovery rate ranged from 30.8% (F25/T4) to 31.8% (F12.5/T1). With both fibrin formulations, all follicles were found to be alive or minimally damaged, as demonstrated by terminal deoxynucleotide transferase-mediated dUTP nick-end labeling assay, and at the growing stage (primary, secondary, and antral follicles), confirmed by Ki67 immunostaining. Isolated OCs also survived and proliferated after grafting, as evidenced by <1% apoptotic cells and a high proportion of Ki67-positive cells. Vessels were found in both fibrin formulations, and the global vascular surface area varied from 1.35% (F25/T4) to 1.88% (F12.5/T1). Numerous CD45-positive cells were also observed in both F25/T4 and F12.5/T1 combinations.

CONCLUSION(S)

The present study is the first to show survival and growth of isolated murine ovarian follicles 1 week after autotransplantation of isolated OCs in a fibrin scaffold. The results indicate that fibrin is a promising candidate as a matrix for the construction of an artificial ovary. Xenotransplantation of isolated human follicles and OCs is the necessary next step to validate these findings.

Acute doxorubicin insult in the mouse ovary is cell- and follicle-type dependent

Primary ovarian insufficiency (POI) is one of the many unintended consequences of chemotherapy faced by the growing number of female cancer survivors. While ovarian repercussions of chemotherapy have long been recognized, the acute insult phase and primary sites of damage are not well-studied, hampering efforts to design effective intervention therapies to protect the ovary. Utilizing doxorubicin (DXR) as a model chemotherapy agent, we defined the acute timeline for drug accumulation, induced DNA damage, and subsequent cellular and follicular demise in the mouse ovary. DXR accumulated first in the core ovarian stroma cells, then redistributed outwards into the cortex and follicles in a time-dependent manner, without further increase in total ovarian drug levels after four hours post-injection. Consistent with early drug accumulation and intimate interactions with the blood supply, stroma cell-enriched populations exhibited an earlier DNA damage response (measurable at 2 hours) than granulosa cells (measurable at 4 hours), as quantified by the comet assay. Granulosa cell-enriched populations were more sensitive however, responding with greater levels of DNA damage. The oocyte DNA damage response was delayed, and not measurable above background until 10-12 hours post-DXR injection. By 8 hours post-DXR injection and prior to the oocyte DNA damage response, the number of primary, secondary, and antral follicles exhibiting TUNEL (terminal deoxynucleotidyl transferase dUTP nick end labeling)-positive granulosa cells plateaued, indicating late-stage apoptosis and suggesting damage to the oocytes is subsequent to somatic cell failure. Primordial follicles accumulate significant DXR by 4 hours post-injection, but do not exhibit TUNEL-positive granulosa cells until 48 hours post-injection, indicating delayed demise. Taken together, the data suggest effective intervention therapies designed to protect the ovary from chemotherapy accumulation and induced insult in the ovary must act almost immediately to prevent acute insult as significant damage was seen in stroma cells within the first two hours.

Expression of extracellular matrix components is disrupted in the immature and adult estrogen receptor β-null mouse ovary

Within the ovary, Estrogen Receptor β (ERβ) is localized to the granulosa cells of growing follicles. 17β-estradiol (E2) acting via ERβ augments the actions of follicle stimulating hormone in granulosa cells, leading to granulosa cell differentiation and formation of a preovulatory follicle. Adult ERβ-null females are subfertile and possess ovaries with reduced numbers of growing follicles and corpora lutea. Because the majority of E2 production by granulosa cells occurs once puberty is reached, a role for ERβ in the ovary prior to puberty has not been well examined. We now provide evidence that lack of ERβ disrupts gene expression as early as post-natal day (PND) 13, and in particular, we identify a number of genes of the extracellular matrix (ECM) that are significantly higher in ERβ-null follicles than in wildtype (WT) follicles. Considerable changes occur to the ECM occur during normal folliculogenesis to allow for the dramatic growth, cellular differentiation, and reorganization of the follicle from the primary to preovulatory stage. Using quantitative PCR and immunofluorescence, we now show that several ECM genes are aberrantly overexpressed in ERβ-null follicles. We find that Collagen11a1, a protein highly expressed in cartilage, is significantly higher in ERβ-null follicles than WT follicles as early as PND 13, and this heightened expression continues through PND 23–29 into adulthood. Similarly, Nidogen 2, a highly conserved basement membrane glycoprotein, is elevated in ERβ-null follicles at PND 13 into adulthood, and is elevated specifically in the ERβ-null focimatrix, a basal lamina-like matrix located between granulosa cells. Focimatrix laminin and Collagen IV expression were also higher in ERβ-null ovaries than in WT ovaries at various ages. Our findings suggest two novel observations: a) that ERβ regulates granulosa cell gene expression ovary prior to puberty, and b) that ERβ regulates expression of ECM components in the mouse ovary.

Co-culturing of follicles with interstitial cells in collagen gel reproduce follicular development accompanied with theca cell layer formation

BACKGROUND

The mechanism of theca cell layer formation in mammalian ovaries has not been elucidated; one reason is that there is no follicle culture system that can reproduce theca cell layer formation in vitro. Therefore, a three-dimensional follicle culture system that can reproduce theca cell layer formation is required.

METHODS

A collagen gel was used in the follicle culture system. To determine the optimum conditions for follicle culture that can reproduce theca cell layer formation, the effects of hormonal treatment and cell types co-cultured with follicles were examined. In addition, immunohistochemistry was used to examine the properties of the cell layers formed in the outermost part of follicles.

RESULTS

Follicles maintained a three-dimensional shape and grew in collagen gel. By adding follicle-stimulating hormone (FSH) and co-culturing with interstitial cells, the follicles grew well, and cell layers were formed in the outermost part of follicles. Immunohistochemistry confirmed that the cells forming the outermost layers of the follicles were theca cells.

CONCLUSION

In this study, follicle culture system that can reproduce theca cell layer formation in vitro was established. In our opinion, this system is suitable for the analysis of theca cell layer formation and contributes to our understanding of the mechanisms of folliculogenesis.

Glycomic analyses of ovarian follicles during development and atresia

To examine the detailed composition of glycosaminoglycans during bovine ovarian follicular development and atresia, the specialized stromal theca layers were separated from the stratified epithelial granulosa cells of healthy (n = 6) and atretic (n = 6) follicles in each of three size ranges: small (3–5 mm), medium (6-9 mm) and large (10 mm or more) (n = 29 animals). Fluorophore-assisted carbohydrate electrophoresis analyses (on a per cell basis) and immunohistochemistry (n = 14) were undertaken. We identified the major disaccharides in thecal layers and the membrana granulosa as chondroitin sulfate-derived ∆uronic acid with 4-sulfated N-acetylgalactosamine and ∆uronic acid with 6-sulfated N-acetylgalactosamine and the heparan sulfate-derived Δuronic acid with N-acetlyglucosamine, with elevated levels in the thecal layers. Increasing follicle size and atresia was associated with increased levels of some disaccharides. We concluded that versican contains 4-sulfated N-acetylgalactosamine and it is the predominant 4-sulfated N-acetylgalactosamine proteoglycan in antral follicles. At least one other non- or 6-sulfated N-acetylgalactosamine proteoglycan(s), which is not decorin or an inter-α-trypsin inhibitor family member, is present in bovine antral follicles and associated with hitherto unknown groups of cells around some larger blood vessels. These areas stained positively for chondroitin/dermatan sulfate epitopes [antibodies 7D4, 3C5, and 4C3], similar to stem cell niches observed in other tissues. The sulfation pattern of heparan sulfate glycosaminoglycans appears uniform across follicles of different sizes and in healthy and atretic follicles. The heparan sulfate products detected in the follicles are likely to be associated with perlecan, collagen XVIII or betaglycan.

Distribution of α(IV) collagen chains in the ocular anterior segments of adult mice

The distribution of the collagen chains from α1(IV) to α6(IV) could serve as a basis for the characterization of type IV collagen. In this study, immunohistochemistry of the ocular anterior segment of adult mice was performed using specific monoclonal antibodies against each chain in the series from α1(IV) to α6(IV). The results show that the components of type IV collagen in vascular basement membranes are α1(IV) and α2(IV) with or without α5(IV) and α6(IV) chains and those in epithelium and muscle basement membranes are α1(IV), α2(IV), α5(IV), and α6(IV) chains. In corneal endothelium, pigmented epithelium of iris and ciliary body, and trabecular meshwork, α3(IV) and α4(IV) chains are also expressed in addition to α1(IV), α2(IV), α5(IV), and α6(IV) chains. Moreover, we investigated the change in molecular composition in ciliary body during postnatal development. α3(IV) and α4(IV) chains were also expressed in addition to α1(IV), α2(IV), α5(IV), and α6(IV) chains in ciliary pigmented epithelium basement membrane from 7 days after birth. This result suggests that the basement membranes gradually change their biochemical features owing to temporal regulation. Taken together, these findings suggest that the different distribution and the developmental expression of α1(IV) to α6(IV) chains are associated with the tissue-specific function of type IV collagen in basement membranes.

Follicle-stimulating hormone regulation of microRNA expression on progesterone production in cultured rat granulosa cells

MicroRNAs (miRNAs) regulate gene expression post-transcriptionally by interacting with the 3' untranslated regions of their target mRNAs. Previously, miRNAs have been shown to regulate genes involved in cell growth, apoptosis, and differentiation, but their role in ovarian granulosa cell follicle-stimulating hormone (FSH)-stimulated steroidogenesis is unclear. Here we show that expression of 31 miRNAs is altered during FSH-mediated progesterone secretion of cultured granulosa cells. Specifically, 12 h after FSH treatment, miRNAs mir-29a and mir-30d were significantly down-regulated. However, their expression increased after 48 h. Bioinformatic analysis used to predict potential targets of mir-29a and mir-30d revealed a wide array of potential mRNA target genes, including those encoding genes involved in multiple signaling pathways. Taken together, our results pointed to a novel mechanism for the pleiotropic effects of FSH.

Defective gonadotropin-dependent ovarian folliculogenesis and granulosa cell gene expression in inhibin-deficient mice

Inhibin-α knockout (Inha-/-) female mice develop sex cord-stromal ovarian cancer with complete penetrance and previous studies demonstrate that the pituitary gonadotropins (FSH and LH) are influential modifiers of granulosa cell tumor development and progression in inhibin-deficient females. Recent studies have demonstrated that Inha-/- ovarian follicles develop precociously to the early antral stage in prepubertal mice without any increase in serum FSH. These studies suggest that in the absence of inhibins, granulosa cells differentiate abnormally and thus at sexual maturity may undergo an abnormal response to gonadotropin signaling contributing to tumor development. To test this hypothesis, we stimulated immature wild-type and Inha-/- female mice with gonadotropin analogs prior to tumor formation and subsequently examined gonadotropin-induced ovarian follicle development as well as preovulatory and human chorionic gonadotropin-induced gene expression changes in granulosa cells. We find that at 3 wk of age, inhibin-deficient ovaries do not show further antral development or undergo cumulus expansion. In addition, there are widespread alterations in the transcriptome of gonadotropin-treated Inha-/- granulosa cells, with significant changes in genes involved in extracellular matrix and cell-cell communication. These data indicate the gonadotropins initiate an improper program of cell differentiation prior to tumor formation in the absence of inhibins.

Differential expression of focimatrix and steroidogenic enzymes before size deviation during waves of follicular development in bovine ovarian follicles

During the growth of bovine follicles, one emerges from a wave as the largest and dominant follicle. What regulates dominance is not known but candidates include oestradiol, transforming growth factor beta beta1 (TGFB1), and recently CYP11AI (cholesterol side-chain cleavage) and focal intra-epithelial matrix (focimatrix). To examine this, pairs of bovine ovaries with 2 or more follicles of equal size (>5mm) and hence in a wave before deviation, were collected at an abattoir (6.7+/-SEM 0.1mm diameter; n=14 animals, 35 follicles in total). These follicles were dissected and follicular fluid collected to measure progesterone and oestradiol concentrations. A portion of the follicle wall was processed for histological classification of health or atresia and granulosa cells were harvested for quantitative RT-PCR of focimatrix components [COL4A1 (collagen type IV alpha1), LAMB2 (laminin beta2) and HSPG2 (perlecan)], steroidogenic enzymes [CYP11A1 and CYP19A1] and TGFB1. For statistical analyses follicles within each animal were grouped into either the highest (oestradiol, CYP11A1) or lowest (TGFB1) expression (n=14) for comparison with the remaining follicles (n=21). When grouped on oestradiol no other parameters differed significantly, and when grouped on TGFB1 some parameters were different however the levels were also lower, and not higher as expected. When grouped on CYP11A1 other parameters were significantly elevated in the high CYP11A1 group (COL4A1P<0.05; LAMB2P<0.01; HSPG2P<0.01 and CYP19A1P<0.001). This suggests that steroidogenesis and focimatrix might be important in a follicle attaining dominance.

Formation of the ovarian follicular antrum and follicular fluid

The formation of the follicular antrum and follicular fluid has received scant attention from researchers, yet both are important processes in follicular development. The central hypothesis on follicular fluid formation suggests that production by granulosa cells of hyaluronan and the chondroitin sulfate proteoglycan versican generates an osmotic gradient. This gradient draws in fluid derived from the thecal vasculature. Inter-alpha-trypsin inhibitor is also present in follicular fluid at least in species with large follicles, and inter-alpha-trypsin inhibitor and versican could additionally bind or cross-link with hyaluronan, resulting in the retention of these molecules within the follicular antrum. Barriers to the movement of fluid across the membrana granulosa are apparently minimal, as even relatively large serum proteins are present in follicular fluid. Despite the relative permeability of the follicular wall, aquaporins are present in granulosa cells and could be actively involved in the transport of water into the follicle. The formation of an antrum also requires movement of granulosa cells relative to each other to allow the fluid to accumulate. This presumably involves remodeling of cell-cell junctions and in species with small follicles may involve death of centrally located granulosa cells. Remodeling of the stroma and thecal layers also accompanies growth and expansion of the antrum and presumably involves similar processes that accompany growth of other glands.

Dynamics of extracellular matrix in ovarian follicles and corpora lutea of mice

Despite the mouse being an important laboratory species, little is known about changes in its extracellular matrix (ECM) during follicle and corpora lutea formation and regression. Follicle development was induced in mice (29 days of age/experimental day 0) by injections of pregnant mare’s serum gonadotrophin on days 0 and 1 and ovulation was induced by injection of human chorionic gonadotrophin on day 2. Ovaries were collected for immunohistochemistry (n=10 per group) on days 0, 2 and 5. Another group was mated and ovaries were examined on day 11 (n=7). Collagen type IV α1 and α2, laminin α1, β1 and γ1 chains, nidogens 1 and 2 and perlecan were present in the follicular basal lamina of all developmental stages. Collagen type XVIII was only found in basal lamina of primordial, primary and some preantral follicles, whereas laminin α2 was only detected in some preantral and antral follicles. The focimatrix, a specialised matrix of the membrana granulosa, contained collagen type IV α1 and α2, laminin α1, β1 and γ1 chains, nidogens 1 and 2, perlecan and collagen type XVIII. In the corpora lutea, staining was restricted to capillary sub-endothelial basal laminas containing collagen type IV α1 and α2, laminin α1, β1 and γ1 chains, nidogens 1 and 2, perlecan and collagen type XVIII. Laminins α4 and α5 were not immunolocalised to any structure in the mouse ovary. The ECM composition of the mouse ovary has similarities to, but also major differences from, other species with respect to nidogens 1 and 2 and perlecan.

Type IV collagen alpha chains of the basement membrane in the rat bronchioalveolar transitional segment

In the present study, we have analyzed the alpha(IV) chain distribution in the subepithelial basement membrane (BM) of the rat pulmonary airway from the bronchi to alveoli. We have furthermore analyzed the alpha(IV) chain distribution in the subepithelial BM of the bronchioalveolar duct junction (BADJ) using alpha(IV) chain specific monoclonal antibodies. Our results show that the BM of the bronchial and bronchiolar epithelium contains [alpha1(IV)]2alpha2(IV) and [alpha5(IV)]2alpha6(IV) molecules and confirmed that the alveolar BM consists of [alpha1(IV)]2alpha2(IV) and alpha3(IV) alpha4(IV)alpha5(IV) molecules. There are also small regions in BADJ consisting of only [alpha1(IV)]2alpha2(IV) molecules without alpha3(IV)alpha4(IV)alpha5(IV) and [alpha5(IV)]2alpha6(IV) molecules. Moreover, the bronchioalveolar stem cells (BASCs)-primordial cells for bronchiolar Clara cells and alveolar type II (AT2) cells - lie adjacent to such small regions. These findings suggest that [alpha1(IV)]2 alpha2(IV) may be important for the BASCs to self-renew or to self-maintain themselves and that microenvironments produced by alpha(IV) chains may be important for cell differentiation.

Developmental distribution of collagen IV isoforms and relevance to ocular diseases

Type IV collagens are the most abundant proteins in basement membranes. Distinct genes encode each of six isoforms, alpha1(IV) through alpha6(IV), which assemble into one of three characteristic heterotrimers. Disease-causing mutations in each of the six genes are identified in humans or mice and frequently include diverse ocular pathogenesis that encompass common congenital and progressive blinding diseases, such as optic nerve hypoplasia, glaucoma, and retinal degeneration. Understanding where and when collagen IV molecules are expressed is important because it defines limits for the location and timing of primary pathogenesis. Although localization of collagen IV isoforms in developed human eyes is known, the spatial and temporal distribution of type IV collagens throughout ocular development has not been determined in humans or in mice. Here, we use isoform-specific monoclonal antibodies to systematically reveal the localization of all six collagen IV isoforms in developing mouse eyes. We found that alpha1(IV) and alpha2(IV) always co-localized and were ubiquitously expressed throughout development. alpha3(IV) and alpha4(IV) also always co-localized but in a much more spatially and temporally specific manner than alpha1(IV) and alpha2(IV). alpha5(IV) co-localized both with alpha3(IV)/alpha4(IV), and with alpha6(IV), consistent with alpha5(IV) involvement in two distinct heterotrimers. alpha5(IV) was present in all basement membranes except those of the vasculature. alpha6(IV) was not detected in vasculature or in Bruch's membrane, indicating that alpha5(IV) in Bruch's membrane is part of the alpha3alpha4alpha5 heterotrimer. This comprehensive analysis defines the spatial and temporal distribution of type IV collagen isoforms in the developing eye, and will contribute to understanding the mechanisms underlying collagen IV-related ocular diseases that collectively lead to blindness in millions of people worldwide.

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

Despite the potential association of polycystic ovary (PCO) syndrome with hemodynamic changes, follicular microenvironment and the involvement of blood follicle barriers (BFB), a histopathological examination has been hampered by artifacts caused by conventional preparation methods. In this study, mouse ovaries of a mifepristone-induced PCO model were morphologically and immunohistochemically examined byin vivocryotechnique (IVCT), which prevents those technical artifacts. Ovarian specimens of PCO model mice were prepared by IVCT or the conventional perfusion fixation after s.c. injection of mifepristone. Their histology and immunolocalization of plasma proteins, including albumin (molecular mass, 69 kDa), immunoglobulin G (IgG, 150 kDa), inter-α-trypsin inhibitor (ITI, 220 kDa), fibrinogen (340 kDa), and IgM (900 kDa), were examined. In the PCO model, enlarged blood vessels with abundant blood flow were observed in addition to cystic follicles with degenerative membrana granulosa. The immunolocalization of albumin and IgM in the PCO model were similar to those in normal mice. Albumin immunolocalized in the blood vessels, interstitium or follicles, and IgM was mostly restricted within the blood vessels. In contrast, immunolocalization of IgG, ITI, and fibrinogen changed in the PCO model. Both IgG and ITI were clearly blocked by follicular basement membranes, and hardly observed in the membrana granulosa, though fibrinogen was mostly observed within blood vessels. These findings suggest that increased blood flow and enhanced selectivity of molecular permeation through the BFB are prominent features in the PCO ovaries, and changes in hemodynamic conditions and permselectivity of BFB are involved in the pathogenesis and pathophysiology of PCO syndrome.