Immunolocalization of type IV collagen and laminin during rat gonadal morphogenesis and postnatal development of the testis and epididymis

Transcriptional profiling validates involvement of extracellular matrix and proteinases genes in mouse gonad development

Extracellular matrix (ECM) plays an important scaffolding role in the establishment of organs structure during development. A great number of ECM components and enzymes (proteinases) regulating formation/degradation of ECM during organ remodeling have been identified. In order to study the role of ECM in the mouse gonad development, especially during sexual differentiation of the gonads when the structure of the testis and ovary becomes established, we performed a global analysis of transcriptome in three main cell types of developing gonad (supporting, interstitial/stromal and germ cells) using transgenic mice, cell sorting and microarray. The genes coding for ECM components were mostly expressed in two gonadal cell lines: supporting and interstitial/stromal cells. These two cell lines differed in the expression pattern of ECM components, which suggests that ECM components might be crucial for differentiation of gonad compartments (for example testis cords vs. interstitium in XY gonads). Collagens and proteoglycans coding genes were mainly expressed in the interstitium/stromal cells, while non-collagen glycoproteins and matricellular coding genes were expressed in both cell lines. We also analyzed the expression of genes encoding ECM enzymes that are secreted to the ECM where they remodel the scaffolding of developing organs. We found that the ECM enzyme genes were also mostly expressed in supporting and interstitial/stromal cells. In contrast to the somatic cells, the germ cells expressed only limited number of ECM components and enzymes. This suggests that the germ line cells do not participate, or play only a minor role, in the sculpting of the gonad structure via ECM synthesis and remodeling. Importantly, the supporting cells showed the sex-specific pattern of expression of ECM components. However, the pattern of expression of most ECM enzymes in the somatic and germ cells is independent on the sex of the gonad. Further studies are required to elucidate the exact roles of identified genes in sexual differentiation of the gonads.

Regulation of spermatogenesis by a local functional axis in the testis: role of the basement membrane-derived noncollagenous 1 domain peptide

Spermatogenesis takes place in the epithelium of the seminiferous tubules of the testes, producing millions of spermatozoa per day in an adult male in rodents and humans. Thus, multiple cellular events that are regulated by an array of signaling molecules and pathways are tightly coordinated to support spermatogenesis. Here, we report findings of a local regulatory axis between the basement membrane (BM), the blood-testis barrier (BTB), and the apical ectoplasmic specialization (apical ES; a testis-specific, actin-rich adherens junction at the Sertoli cell-spermatid interface) to coordinate cellular events across the seminiferous epithelium during the epithelial cycle. In short, a biologically active fragment, noncollagenous 1 (NC1) domain that is derived from collagen chains in the BM, was found to modulate cell junction dynamics at the BTB and apical ES. NC1 domain from the collagen α3(IV) chain was cloned into a mammalian expression vector, pCI-neo, with and without a collagen signal peptide. We also prepared a specific Ab against the purified recombinant NC1 domain peptide. These reagents were used to examine whether overexpression of NC1 domain with high transfection efficacy would perturb spermatogenesis, in particular, spermatid adhesion (i.e., inducing apical ES degeneration) and BTB function (i.e., basal ES and tight junction disruption, making the barrier leaky), in the testis in vivo We report our findings that NC1 domain derived from collagen α3(IV) chain-a major structural component of the BM-was capable of inducing BTB remodeling, making the BTB leaky in studies in vivo Furthermore, NC1 domain peptide was transported across the epithelium via a microtubule-dependent mechanism and is capable of inducing apical ES degeneration, which leads to germ cell exfoliation from the seminiferous epithelium. Of more importance, we show that NC1 domain peptide exerted its regulatory effect by disorganizing actin microfilaments and microtubules in Sertoli cells so that they failed to support cell adhesion and transport of germ cells and organelles (e.g., residual bodies, phagosomes) across the seminiferous epithelium. This local regulatory axis between the BM, BTB, and the apical ES thus coordinates cellular events that take place across the seminiferous epithelium during the epithelial cycle of spermatogenesis.-Chen, H., Mruk, D. D., Lee, W. M., Cheng, C. Y. Regulation of spermatogenesis by a local functional axis in the testis: role of the basement membrane-derived noncollagenous 1 domain peptide.

NC1 domain of collagen α3(IV) derived from the basement membrane regulates Sertoli cell blood-testis barrier dynamics

The blood-testis barrier (BTB) is an important ultrastructure for spermatogenesis. Delay in BTB formation in neonatal rats or its irreversible damage in adult rats leads to meiotic arrest and failure of spermatogonial differentiation beyond type A. While hormones, such as testosterone and FSH, are crucial to BTB function, little is known if there is a local regulatory mechanism in the seminiferous epithelium that modulates BTB function. Herein, we report that collagen α3(IV) chain, a component of the basement membrane in the rat testis, could generate a noncollagenous (NC1) domain peptide [Colα3(IV) NC1] via limited proteolysis by matrix metalloproteinase-9 (MMP-9), and that the expression of MMP-9 was upregulated by TNFα. While recombinant Colα3(IV) NC1 protein produced in E. coli failed to perturb Sertoli cell tight junction (TJ)-permeability barrier function, possibly due to the lack of glycosylation, Colα3(IV) NC1 recombinant protein produced in mammalian cells and purified to apparent homogeneity by affinity chromatography was found to reversibly perturb the Sertoli cell TJ-barrier function. Interestingly, Colα3(IV) NC1 recombinant protein did not perturb the steady-state levels of several TJ- (e.g., occludin, CAR, JAM-A, ZO-1) and basal ectoplasmic specialization- (e.g., N-cadherin, α-catenin, β-catenin) proteins at the BTB but induced changes in protein localization and/or distribution at the Sertoli cell-cell interface in which these proteins moved from the cell surface into the cell cytosol, thereby destabilizing the TJ function. These findings illustrate the presence of a local regulatory axis known as the BTB-basement membrane axis that regulates BTB restructuring during spermatogenesis.

Wt1 deficiency causes undifferentiated spermatogonia accumulation and meiotic progression disruption in neonatal mice

Spermatogenesis is a complex process involving the regulation of multiple cell types. As the only somatic cell type in the seminiferous tubules, Sertoli cells are essential for spermatogenesis throughout the spermatogenic cycle. The Wilms tumor gene, Wt1, is specifically expressed in the Sertoli cells of the mouse testes. In this study, we demonstrated that Wt1 is required for germ cell differentiation in the developing mouse testes. At 10 days post partum, Wt1-deficient testes exhibited clear meiotic arrest and undifferentiated spermatogonia accumulation in the seminiferous tubules. In addition, the expression of claudin11, a marker and indispensable component of Sertoli cell integrity, was impaired in Wt1−/flox; Cre-ERTM testes. This observation was confirmed in in vitro testis cultures. However, the basal membrane of the seminiferous tubules in Wt1-deficient testes was not affected. Based on these findings, we propose that Sertoli cells' status is affected in Wt1-deficient mice, resulting in spermatogenesis failure.

Prenatal development of the bovine epididymis: light microscopical, glycohistochemical and immunohistochemical studies

Prenatal development of the epididymis was studied in bovine fetuses ranging from 10 to 90cm crown-rump length (CRL) (75-285 pcd). The studies aimed to apply both glycohistochemistry and immunohistochemistry for the detection of the differentiation of the developing prenatal epididymis. Both conventional histological and histochemical techniques were applied on paraffin sections of the epididymis from different fetal stages. Establishment of the urogenital junction between the extra-testicular rete testis and the mesonephric duct, via the growing efferent ductules (ductuli efferentes) was first evident in fetuses with 10cm CRL. At the fetal age of 110 pcd (24cm CRL), the mesonephric duct began to lengthen and coil forming three distinct regions (caput, corpus and cauda). In addition to the macroscopical modifications in the extra-testicular excurrent duct system, histological differentiation involved both the tubular epithelial and the peritubular mesenchymal cells. The epithelium lining the efferent ductules was differentiated into ciliated and non-ciliated columnar cells. The simple epithelium of the epididymal duct increased in height and developed stereocilia on the apical surface. Additionally, some basal cells first appeared at 185 pcd (56cm CRL), within the epithelium lining the cauda only. Lectin histochemistry (WGA, PNA, GSA-I) showed early immunostaining in epithelium of the efferent ductules and in peritubular mesenchymal structures. Immunoreactivity for different proteins (S-100, fibroblast growth factor-1 and factor-2, angiotensin converting enzyme, laminin, alpha-smooth muscle actin) was evident, both in the epithelial and in the peritubular mesenchymal cells as early as at 75 pcd. On the basis of our histochemical observations, we conclude that both glycohistochemistry and immunohistochemistry are useful tools to demonstrate that the differentiation in the peritubular structures and efferent ductular epithelium begins earlier than other components.

Posthatching development of Alligator mississippiensis ovary and testis

We investigated ovary and testis development of Alligator mississippiensis during the first 5 months posthatch. To better describe follicle assembly and seminiferous cord development, we used histochemical techniques to detect carbohydrate-rich extracellular matrix components in 1-week, 1-month, 3-month, and 5-month-old gonads. We found profound morphological changes in both ovary and testis. During this time, oogenesis progressed up to diplotene arrest and meiotic germ cells increasingly interacted with follicular cells. Concomitant with follicles becoming invested with full complements of granulosa cells, a periodic acid Schiff's (PAS)-positive basement membrane formed. As follicles enlarged and thecal layers were observed, basement membranes and thecal compartments gained periodic acid-methionine silver (PAMS)-reactive fibers. The ovarian medulla increased first PAS- and then PAMS reactivity as it fragmented into wide lacunae lined with low cuboidal to squamous epithelia. During this same period, testicular germ cells found along the tubule margins were observed progressing from spermatogonia to round spermatids located within the center of tubules. Accompanying this meiotic development, interstitial Leydig cell clusters become more visible and testicular capsules thickened. During the observed testis development, the thickening tunica albuginea and widening interstitial tissues showed increasing PAS- and PAMS reactivity. We observed putative intersex structures in both ovary and testis. On the coelomic aspect of testes were cell clusters with germ cell morphology and at the posterior end of ovaries, we observed "medullary rests" resembling immature testis cords. We hypothesize laboratory conditions accelerated gonad maturation due to optimum conditions, including nutrients and temperature. Laboratory alligators grew more rapidly and with increased body conditions compared with previous measured, field-caught animals. Additionally, we predict the morphological maturation observed in these gonads is concomitant with increased endocrine activities.

Comparative expression of laminin and smooth muscle actin in the testis and epididymis of poultry and rabbit

The present investigation was conducted to demonstrate laminin and alpha smooth muscle actin (alphaSMA) in the testis and epididymis of adult chickens, Sudani ducks, pigeons, and rabbits. This study may represent the first indication for the presence of laminin in the male reproductive organs of birds and rabbits and might therefore serve as a milestone for further reports. In the testis of chicken, Sudani duck, pigeon, and rabbit, the laminin was localized in the basal lamina of the seminiferous tubules and of the peritubular myoid cells, in the testicular capsule and to a small extent in the vicinity of Leydig cells. The testicular vasculature also exhibited intense laminin immunostaining. Weak laminin staining was additionally seen in the cytoplasm of the duck Sertoli cells. In the epididymis, the basal lamina of the epididymal epithelium showed a distinctly positive reaction in all birds and rabbit. The basal lamina of the periductal myoid cells also showed a positive reaction. In the interductal tissue, laminin immunostaining was particularly observed in chicken, duck and pigeon. Laminin positive reaction was also seen in the epididymal vasculatures of all birds and rabbit. Interestingly, weak to moderate laminin staining was observed in the apical surface of the ciliated cells of the proximal and distal efferent ductules in chicken, duck and pigeon. alphaSMA positive reaction was seen in the testicular capsule and in the peritubular myoid cells of all birds and rabbit. In the testicular capsule, alphaSMA staining was either observed in the inner portion (chicken) or throughout the tunica albuginea (Sudani duck and pigeon), or in the outer aspect (rabbit). Distinct alphaSMA reaction was additionally observed in the testicular vasculature. In the epididymis of all birds and rabbit, the alphaSMA was particularly seen in the periductal and interductal myoid cells as well as in the epididymal vasculatures. No alphaSMA specific staining was however detected in the epididymal epithelium, fibrous lamina propria, and luminal spermatozoa of all birds and rabbits. In conclusion, the distribution of laminin and alphaSMA in the testis and epididymis might point out to their roles in the male reproduction.

Characterization and distribution of hyaluronan and the proteoglycans decorin, biglycan and perlecan in the developing embryonic mouse gonad

The morphogenesis of tissues and organs requires dynamic changes in cells and in extracellular matrix components. It is known that various extracellular matrix molecules are of fundamental importance for gonad differentiation and growth. In the adult testis, the extracellular matrix represents an important component of the interstitium, participating in the transport of biologically active substances needed for the communication between different cellular components, as well as for the regulation of spermatogenesis and hormone production. The present study was designed in order to identify the proteoglycans biglycan, decorin and perlecan, as well as the glycosaminoglycan hyaluronan, during testis development in mouse embryos. Our data profile the chronology of testis differentiation, as well as the distribution of these extracellular matrix components during testis development in mice. We show that these extracellular matrix molecules are present early in the development of the gonads, suggesting that they play a role in gonad development. In addition, we found no decorin in the testicular cords. Furthermore, of the proteoglycans analysed, only biglycan was seen surrounding immature Sertoli cells and Leydig cell precursors in the testicular cords. This indicates that specific sets of extracellular matrix molecules are required in the various compartments of the developing gonad.

Laminin alpha 3 forms a complex with beta3 and gamma3 chains that serves as the ligand for alpha 6beta1-integrin at the apical ectoplasmic specialization in adult rat testes

Apical ectoplasmic specialization (ES) is a testis-specific hybrid cell/cell actin-based adherens junction and cell/matrix focal contact anchoring junction type restricted to the interface between Sertoli cells and developing spermatids. Recent studies have shown that laminin gamma3, restricted to elongating spermatids, is a putative binding partner of alpha 6beta 1-integrin localized in Sertoli cells at the apical ES. However, the identity of the alpha and beta chains, which constitute a functional laminin ligand with the gamma3 chain at the apical ES, is not known. Using reverse transcription-PCR and immunoblotting to survey all laminin chains in cells of the seminiferous epithelium, it was noted that alpha 2, alpha 3, beta1, beta2, beta3, and gamma3 chains were found in germ cells, whereas alpha 1, alpha 2, alpha 4, alpha 5, beta1, beta2, gamma1, gamma2, and gamma3 chains were found in Sertoli cells, implying that alpha 3 and beta3 are the plausible laminin chains restricted to germ cells that may be the bona fide partners of gamma3. To verify this postulate, recombinant proteins based on domain G of alpha 3 and domain I of beta3 and gamma3 chains were produced and used to obtain the corresponding specific polyclonal antibodies. Additional studies have demonstrated that the laminin alpha 3, beta3, and gamma3 chains indeed are restricted to germ cells at the apical ES, co-localizing with each other and with beta1-integrin. Furthermore, co-immunoprecipitation studies have confirmed the interactions among laminin alpha 3, beta3, and gamma3, as well as beta1-integrin. When the functional laminin ligand at the apical ES was disrupted via blocking antibodies, such as using anti-laminin alpha 3 or gamma3 IgG, this treatment perturbed adhesion between Sertoli and germ cells (mostly spermatids), leading to germ cell loss from the epithelium. More important, a transient disruption of the blood-testis barrier was also detected.

Expression pattern of alphavbeta3 and alphavbeta5 integrin mRNA in mouse fetal gonads

The alphavbeta3 and alphavbeta5 integrins are known as transmembrane receptors capable of binding to the RGD amino acid peptide sequence. In mouse early gonadogenesis, some proteins containing the RGD sequence are deposited into extracellular space and participate in morphogenesis. We analyzed the expression patterns of the alphavbeta3 and alphavbeta5 integrins in mouse developing gonads (10.5-13.5 days post coitum) using whole-mount in situ hybridization. The alphav integrin mRNA was homogenously expressed in developing gonadal regions. On the other hand, the beta3 integrin mRNA was found only in large and round cells (presumptive germ cells), whereas beta5 integrin was localized in gonadal somatic cells, with the exception of coelomic epithelial cells. The beta3 integrin-expressed cells were determined to be primordial germ cells because the number of these cells was drastically reduced in busulfan-treated gonads. In this study, we demonstrated that the alphavbeta3 and alphavbeta5 integrins are widely localized in the mouse developing gonads and discussed their presumptive functions on mouse gonadogenesis.

Dysplastic Development of Seminiferous Tubules and Interstitial Tissue in Rat Hypogonadic (hgn/hgn) Testes1

The hypogonadic rat is characterized by male sterility, reduced female fertility, and renal hypoplasia controlled by a single recessive allele (hgn) on chromosome 10. Plasma testosterone is low and levels of gonadotropins are high in adult male hgn/hgn rats, indicating that the cause of hypogonadism lies within the testis itself. We found that the postnatal growth of the seminiferous tubules was severely affected. Here we describe the details of postnatal testicular pathogenesis of the hgn/ hgn rats. In these rats, gonadal sex determination and initial differentiation of each type of testicular cell occur, but proliferation, differentiation, and maturation of these cells during postnatal testicular development is severely affected. Postnatal pathological changes include reduced proliferation and apoptotic cell death of Sertoli cells, abnormal mitosis and cell death of gonocytes, reduced deposition of extracellular matrix proteins into the basal lamina, lack of the formation of an outer basal lamina, formation of multiple layers of undifferentiated peritubular cells, and the delayed appearance and islet conformation of adult-type Leydig cells. Apoptotic cell death of Sertoli cells and disappearance of FSH receptor mRNA expression indicate that this mutant rat is a useful model for Sertoli cell dysfunction. The abnormalities listed above might be caused by defective interactions between Sertoli cells and other types of testicular cells. Because the results presented here strongly indicate that a normal allele for hgn encodes a factor playing a critical role in testicular development, the determination of the gene responsible for hgn and the analysis of early alterations of gene expression caused by mutations in this gene would provide important information on the mechanisms of testicular development.

Subtractive hybridisation screen identifies sexually dimorphic gene expression in the embryonic mouse gonad

The sex of most mammals is determined by the action of SRY. Its presence initiates testis formation resulting in male differentiation, its absence results in ovary formation and female differentiation. We have used suppression subtraction hybridisation between 12.0-12.5 days postcoitum (dpc) mouse testes and ovaries to identify genes that potentially lie within the Sry pathway. Normalised urogenital ridge libraries comprising 8,352 clones were differentially screened with subtracted probes. A total of 272 candidate cDNAs were tested for qualitative differential expression and localisation by whole mount in situ hybridisation; germ cell-dependent or -independent expression was further resolved using busulfan. Fifty-four genes were identified that showed higher expression in the testis than the ovary. One novel gene may be a candidate for interactions with WT1, based on its localisation to Sertoli cells and map position (16q24.3).

Reticulin fibres in the tunica albuginea and peritubular tissue of seminiferous tubules of adult male Wistar rats

Reticulin fibres are fine fibres that contain primarily collagen type III and are found in soft blood-forming or blood-processing tissues, and are supportive elements in kidney, liver and thymus. This study demonstrates for the first time the presence of reticulin fibres in the tunica albuginea and peritubular tissue of seminiferous tubules of adult rat testes after staining with the metallic silver impregnation method. Reticulin fibres of peritubular tissues may provide a supportive framework for germinal epithelium of seminiferous tubules to allow the periphery-to-centre progression of spermatozoa during spermatogenesis. The presence of fibres in all stages of the spermatogenic cycle suggests that they have structural functions.

Relationship of interstitial edema with L-cysteine-induced sperm granulomas in the pubertal rat epididymis

Although the pathogenesis of sperm granulomas is complicated, the leakage of spermatozoa into extraluminal tissues is regarded as a crucial event. It has been previously shown that pubertal rats injected with L-cysteine develop interstitial edema followed by sperm granulomas in the epididymis. In this study we investigated the relationships between these two lesions in 6-week old rats given daily intraperitoneal injections of L-cysteine (1,000 mg/kg body weight) for 4 weeks. Rats were examined during weeks 0, 1, 2, 3 and 4 after the first injection. Interstitial edema (moderate or severe) and sperm granulomas were seen in the corpus and cauda epididymis of L-cysteine-treated rats in study weeks 2, 3, and 4. There was no marked alteration of basement membrane of the epididymal ducts in the edematous tissues as shown by immunohistochemistry with an antilaminin antibody. However, the extravasation of Evans blue dye given I hour before necropsy suggested that the severe interstitial edema was due to increased vascular permeability. In addition, a small number of neutrophils were seen in the edematous tissues, suggesting that they might play a role in the increased vascular permeability and leakage of epididymal fluid. Interestingly, slight interstitial edema was observed in the caput epididymis in both control and L-cysteine-treated rats in early study weeks 0, 1, and 2. It is speculated that this change was related to the leakage of epididymal fluid due to increased intraluminal pressure depending on rat epididymal maturation. Taken together, these findings suggest that the severe interstitial edema results from increased vascular permeability. This, along with increased intraluminal pressure, might be the trigger for duct rupture, the prerequisite for sperm granuloma formation associated with excessive doses of L-cysteine.

Post-natal development of the rat testis: steroid hormone receptor distribution and extracellular matrix deposition

The control of testicular development and differentiation depends on hormones and a variety of cell-cell interactions mediated mainly by paracrine factors. In the second and third weeks of post-natal development important changes take place in the rat testis, e.g. the tubular lumen starts to open on post-natal day 10, the blood-testis barrier starts to form on day 15, and Sertoli cell proliferation ceases on day 15. In the present study the expression in different testicular compartments of the androgen receptor (AR), progesterone receptor (PR), and extracellular matrix proteins such as laminin, entactin-1 (nidogen-1) and fibronectin, during post-natal development was examined using immunohistochemistry and semiquantitative image analysis. An intratubular AR peak on days 14-17, an increase in intratubular PR expression on days 14-16, and an increase in peritubular entactin-1 expression during the second and third weeks post-partum are demonstrated. These results suggest that a variety of changes occur at the cellular level during this period when certain milestones of testicular development occur, substantiating the hypothesis of a particular role for paracrine interactions during the development of the rat testis.

Gonadal development in mammals at the cellular and molecular levels

In mammals, although sex is determined chromosomally, gonads in both sexes begin development as similar structures. Until recently it was widely held that female development constituted a "default" pathway of development, which would occur in the absence of a testis-determining gene. This master gene on the Y chromosome, SRY in the human and Sry in the mouse, is thought to act in a cell-autonomous fashion to determine that cells in the gonadal somatic population develop as pre-Sertoli cells. Triggering of somatic cell differentiation along the Sertoli cell pathway is therefore a key event; it was thought that further steps in gonadal differentiation would follow in a developmental cascade. In the absence of Sertoli cells, the lack of anti-Mullerian hormone would allow development of the female Mullerian duct and absence of Leydig cells would prevent maintenance of the Wolffian duct. Recent findings that female signals not only maintain the Mullerian duct and repress the Wolffian duct but also suppress the development of Leydig cells and maintain meiotic germ cells, together with the finding that an X-linked gene is required for ovarian development and must be silenced in the male, have shown that the female default pathway model is an oversimplification. Morphological steps in gonadal differentiation can be correlated with emerging evidence of molecular mechanisms; growth factors, cell adhesion, and signaling molecules interact together, often acting within short time windows via reciprocal control relationships.

Sex-specific localization of laminin alpha 5 chain in the differentiating rat testis and ovary

The localization of laminin (Ln) alpha 5, beta 1 and beta 2 chains in the differentiating rat testis and ovary was studied by immunolabeling light and electron microscopy. The initial formation of the male and female gonadal blastemas included an emergence of Ln alpha 5 and beta 1 chains, but not of Ln beta 2 chain. The sexual differentiation of the embryonic male gonadal cords included rapid sex-specific disappearance of the incipient Ln alpha 5 chain. The rete testis cords, in contrast, remained positive for Ln alpha 5 chain. In the postnatal testis, the Ln alpha 5 chain reappeared in Ln beta 1 chain-positive cord basement membranes, which also became positive for Ln beta 2 chain. The differentiating myoid cells also gradually became positive for both Ln alpha 5 and Ln beta 1 chains. In the ovary Ln alpha 5 chain persisted in BMs of the cords throughout the fetal phase. Small and newly formed follicles in the early postnatal rat ovary were also positive for Ln alpha 5 chain, whereas growing and large follicles were negative. During the early postnatal phase, Ln beta 1-chain positive follicular BMs became also positive for the Ln beta 2 chain. Basement membranes of testicular and ovarian surface epithelia contained the Ln alpha 5 chain throughout the study. The blood vessels of the male and female gonad showed differentiation-dependent variation in their reactivity for the Ln alpha 5 and beta 2 chains. The present results show that the Ln alpha 5 chain is an early molecular marker for sexual differentiation, which therefore may be regulated by the testis-determining factors. The results also show that in the early postnatal rat ovary, the follicular basement membranes are heterogeneous in their Ln content, which may offer a means to distinguish different follicular populations from each other and to identify the different stages of follicular growth.

Differential distribution of type IV collagen chains in the developing rat testis and ovary

The localization of type IV collagen alpha 1-alpha 5 chains in the differentiating rat testis and ovary was studied by immunocytochemistry. The initial formation of the testis and ovary included the appearance of collagen alpha 1/alpha 2(IV) chains in the gonadal blastemas. Upon further differentiation of the epithelia of the gonads alpha 1/alpha 2(IV) chains became localized in all of the respective basement membranes (BMs). The alpha 3, alpha 4 and alpha 5 chains of type IV collagen were not detectable in the prenatal rat testis and ovary. With the postnatal differentiation of the rat testis the alpha 3-alpha 5(IV) chains gradually appeared, and were localized in BMs of the testicular cords and seminiferous tubules, rete cords, myoid cells, surface epithelium, Leydig cells, and in some blood vessels. In the postnatal rat ovary, the alpha 3(IV) chain appeared in the BMs of small cortical follicles whereas the BMs of secondary and more deeply localized follicles were devoid of this chain. The alpha 1/alpha 2(IV) chains were abundant in the theca. A reaction for alpha 3-alpha 5(IV) chains also appeared in the BM of the ovarian surface epithelium and of some blood vessels after birth. The present results show that the alpha 3-alpha 5(IV) chains are not only less widely distributed than the alpha 1/alpha 2(IV) chains but are also synthesized much later in development. The late appearance of the alpha 3-alpha 5(IV) chains shows that the development of the mature testicular and ovarian BMs is a long process and that the time schedule for the synthesis of these chains is different from that of many other extracellular matrix proteins. A careful analysis of the expression of alpha 3(IV) chain may be useful in the further study of the kinetics and regulation of ovarian follicular growth.

Sequences 5' of the basement membrane laminin beta 1 chain gene (LAMB1) direct the expression of beta-galactosidase during development of the mouse testis and ovary

The murine LAMB1 gene encoding laminin beta 1 is expressed in the developing male and female gonads and mesonephros. To identify the cis-acting elements regulating the expression of LAMB1, murine transgenic lines were generated by fusing regions of the LAMB1 gene to the Eschericia coli lacZ gene. The p3.9LAM beta gal construct contained approximately 4 kb of 5' flanking sequence and directed beta-galactosidase expression in many different organs including the kidney, mammary gland, and the male and female genital systems, the focus of this report. In male embryos, between gestational ages E 14.5 and birth beta-galactosidase was transiently expressed in the prospermatogonia cells of the testis and in the differentiating epithelial cells in the ductus deferens, ductus epididymis, and seminal vesicles. In female embryos, beta-galactosidase was not detected in the ovary until about 1 week after birth; at this time, beta-galactosidase was expressed by oocytes of primary and secondary follicles. In contrast, transgenic mice carrying the first 0.7 kb of LAMB1 fused to the lacZ gene expressed beta-galactosidase only in the prospermatogonia cells of the testis. Thus, the cis-acting element(s) necessary for the expression of the LAMB1 gene in prospermatogonia cells are located in the first 0.7 kb of LAMB1 5' flanking sequence; element(s) required for expression of the LAMB1 gene in oocytes and epithelial cells of the mesonephric ducts, mesonephric tubules, the ductus deferens, ductus epididymis, and seminal vesicles are located with 4 kb 5' of the transcription initiation site.

Optimizing collagen antigen unmasking in paraffin-embedded tissues

In order to optimize collagen antigen unmasking in paraffin-embedded tissue sections, the effects of various fixatives and duration of fixation in relation to enzyme pretreatment and microwave irradiation for collagen antigen unmasking were studied. A streptavidin-biotin-peroxidase complex method was used for the immunolocalization of type III and IV collagen antigens. Fixatives and fixation time had significant adverse effects on the immunoreactivity of the antigens. Enzyme pretreatment was found to be superior to microwave irradiation for collagen antigen unmasking. Fixation with paraformaldehyde required shorter enzyme pretreatment and yielded a more enhanced reaction than treatment with formalin and Bouin's fluid. The optimum conditions for type III and IV collagen unmasking were found to be fixation with 4% paraformaldehyde in 0.01 M phosphate-buffered saline, pH 7.4, for up to 3 weeks followed by enzyme pretreatment with 1 mg ml-1 pepsin in 0.01 N hydrochloric acid, pH 2.0, for 30 min (human tissues) or 60 min (rat tissues) at 37 degrees C. It is concluded that collagen antigen unmasking by enzyme pretreatment in tissue sections fixed for a long period of time can be successful if appropriate enzyme(s) and incubation time(s) are employed with regard to the antigen under study and fixative and fixation time used for tissue preparation.

Basement membrane proteins in synovial membrane: distribution in rheumatoid arthritis and synthesis by fibroblast-like cells

Rheumatoid arthritis is a complex disease of unknown origin. In consequence of some immunological reactions, proliferative invading synovial tissue leads to destruction of normal joint architecture. The aim of this study was to investigate qualitative changes in extracellular matrix distribution of proliferating rheumatoid synovium and their cellular origin. Synovial tissues from 57 clinically indicated arthrotomies were investigated with immunofluorescence, using specific antibodies against extracellular matrix proteins in tissue slides and cultured cells, which were also studied for collagen biosynthesis. Results indicated that synovial fibroblast-like cells synthesize and secrete basement membrane proteins laminin and collagen type IV as e.g. endothelial cells or organogenic fibroblasts. Laminin and collagen type IV were specifically demonstrated pericellularly in the hyperplastic lining layer of active rheumatoid synovitis. These findings are discussed with respect to the possible implication of altered cell-matrix interactions in rheumatoid synovial proliferation.

Lectin-binding carbohydrates in sexual differentiation of rat male and female gonads

Development and sexual differentiation of the mammalian gonad involve changes in the type and distribution of different proteins and glycoproteins in and around the epithelial gonadal cords, the future seminiferous tubules in the testis, and follicles in the ovary. To study changes in cellular carbohydrate-containing compounds in the sex-specific morphogenesis of rat gonads, sections from embryonic, fetal and early postnatal gonads were labelled with seven different fluorescein isothiocyanate (FITC)-conjugated plant lectins of various carbohydrate-binding specificities. Double labelling of laminin with tetramethylrhodamine isothiocyanate (TRITC)-conjugated antibodies was used to outline the epithelial tissues. From the results we conclude that the abundance and similar distribution of carbohydrates in the early gonads of both sexes supports their sexually indifferent nature. Furthermore, the basement membranes of the differentiating gonadal cords in both sexes have common features, which differ, however, from those of the other developing urogenital organs. Changes in carbohydrate composition appear with the sexual differentiation of the gonads; the similarity of the changes in lectin binding to the gonadal cords of embryonic and fetal male, and to postnatal female, suggests similar mechanisms of cell-cell interactions in both sexes although activated at different developmental stages. These carbohydrate specificities at the tissue level should be taken into account together with cell-type specific changes, e.g. in the formation of the zona pellucida, when the phenomenon of polymorphic expression of different compounds is integrated into theories of epithelial differentiation.

Intermediate filaments and epithelial differentiation of male rat embryonic gonad

The presence and distribution of desmin, vimentin, cytokeratin, and laminin in the gonads of developing male rat embryos (11-17 days) were studied by immunocytochemistry. The findings were correlated with morphological changes of the cells and with the formation of basement membranes, as determined by electron microscopy. The surface epithelial and subepithelial cells of the meesonephros in the prospective gonadal region contained desmin. At the onset of gonadal development, vimentin appeared in the somatic cells of the thickening surface epithelium, which formed the gonadal ridge. Desmin disappeared and cytokeratins appeared in the Sertoli precursor cells at the inception of their epithelial differentiation. Simultaneously, the prospective Sertoli cells became polarized during their assembly into epithelial cell aggregates; the aggregates then fused and formed elongated testicular cords. The epithelial cell differentiation was accompanied by a deposition of basement membrane material around the cords and by an increase of desmin in the cells immediately around the cords. With further differentiation of the testicular cords, some cytokeratins from the Sertoli cells, but not from the cells of the rete cords, disappeared. On the other hand, other cytokeratin polypeptides and vimentin remained in the fetal Sertoli cells. The surface cell layer slowly differentiated towards a proper epithelium after the basic formation of the testicular cords and interstitium. Desmin and vimentin persisted in the interstitial cells throughout the entire study period. The early differentiation of the gonad is apparently under a general sex-independent initiation program. The developmental changes in intermediate filaments offer an opportunity for the further analysis of their general role in early organogenesis. In light of the genetic theory of testicular differentiation, the functions of the regulatory factor(s) include specific organization of cord cells, histological organization into looping cords rather than separated follicles, and male development of the interstitium, surface epithelium and tunica albuginea.

Testicular differentiation in mammals under normal and experimental conditions

Gonadal differentiation begins with the establishment of a sexually undifferentiated gonad, in which gonadal cords are formed by condensation of somatic cells and deposition of basal laminar components around the cluster of epithelial-like cells. The first event of sexual differentiation is the invasion of mesenchymal and endothelial cells into the genital ridge in the XY gonad. As a consequence of this event, the gonadal cords become conspicuous, recognized as seminiferous cords (or testis cords). Cytological differentiation of Sertoli cells follows these stromal changes. In the XX gonad, by contrast, the invasion of the mesenchyme is absent and gonadal cords remain associated with the surface epithelium. In the B6.YDOM XY ovotestis, seminiferous cords and ovarian gonadal cords are often enveloped by common basal laminae, confirming that both structures share the embryonic origin. It has been recently reported that seminiferous-like cords are formed after loss of oocytes in the rat XX ovary cultured in the presence of Müllerian inhibiting substance or after long-term culture in the basic medium alone. These results are comparable with our observation on the persistent gonadal cords in the ovary of busulphan-treated rats or W/WV mutant mice, in which oogonia are absent or scarce. Ultrastructural evidence for Sertoli cell differentiation from XX cells has been presented, so far, only in the fetal mouse ovary that has been grafted beneath the kidney capsule of adult male mice. Possible mechanism of gonadal sex determination is discussed based on these morphological studies.

High energy underwater shock wave treatment on implanted urinary bladder cancer in rabbits

The effects of focused high energy shock waves (SW) on the implanted urinary bladder cancer in rabbits were examined. The bladder cancer was exposed to 2000 to 8000 shots of focused SW under ultrasound guidance. Although only focal necrosis of the tumor was seen in the one day SW exposure, wider and deeper tumor necrosis was observed in the tumors following serial SW (2000 to 6000 shots, for two to three days). Eight to 10 day serial SW exposure (6000 to 8000 shots) decreased the tumor growth in comparison with that of the control. Lung metastases examined by periodic chest X-ray after SW treatment revealed that SW did not promote lung metastases. Pathological findings were also in accord with the X-ray examinations. Polyclonal antibody type 4 collagen was used for immunohistochemical staining of vascular wall in bladder cancer. Vascular wall destruction, not found in spontaneous necrotic tumor, were clearly visible in SW induced necrotic area. SW induces vascular damage in the tumor, which may be the primary cause promoting the tumor necrosis.