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PubMed1988

Development of the blood-testis barrier and changes in vascular permeability at puberty in rats.

The effectiveness of the blood-testis barrier to water-soluble substances was assessed in rats of various ages by measuring the volumes of distribution of Cr-EDTA and albumin, and estimating the proportion of the testis made up by interstitial tissue and tubular lumen by morphometric techniques on cryostat sections of frozen tissue. The interstitial tissue volume fell from 15 days to reach adult values at about 30 days of age. A lumen was present in some animals at 15 days, and it enlarged progressively to reach adult levels at about 45 days of age. The 1-h Cr-EDTA space began to fall after 25 days, and reached adult values by 33 days; in rats aged 25 and 30 days, the Cr-EDTA space was almost twice the measured interstitial tissue volume, but even in the older rats, the Cr-EDTA space remained appreciably greater than the interstitial tissue volume. The 20-h albumin space did not begin to fall until after 33 days, and had still not reached adult values in rats aged 44 days. Thus, the functional barrier to water-soluble markers develops later and more gradually than the barrier to electron-opaque markers as used by previous authors, and its appearance correlates more closely with enlargement of the tubular lumen than with formation of the inter-Sertoli cell junctions. The rate at which the albumin space approached its final value was used to calculate the vascular permeability to albumin. This rose to a maximum between 25 days and 33 days of age, and then fell again, although adult values had still not been reached by 44 days of age.

Animals↗
PubMed1994

Developmental and cell type specificity of LINE-1 expression in mouse testis: implications for transposition.

The LINE-1, or L1, family of interspersed repeated DNA constitutes roughly 10% of the mammalian genome. Its abundance is due to duplicative transposition via an RNA intermediate, L1-encoded proteins, and reverse transcription. Although, in principle, transposition may occur in any cell type, expression and transposition of a full-length functional element in the germ line are necessary to explain the evolutionary genetics of L1. We have found differential expression of L1 protein and RNA in germ and somatic cells of the mouse testis during development. Of particular interest is the coexpression of full-length, sense-strand L1 RNA and L1-encoded protein in leptotene and zygotene spermatocytes at postnatal day 14 of development. Expression in meiotic prophase precedes the strand breakage that occurs during chromosomal recombination; this offers an avenue for L1 insertion into new locations in chromosomal DNA in a cell type that ensures L1 propagation in future generations.

Aging↗
PubMed2005

Heterogeneity of growth hormone immunoreactivity in lymphoid tissues and changes during ontogeny in domestic fowl.

Growth hormone (GH) expression is not confined to the pituitary and occurs in many extrapituitary tissues. Here, we describe the presence of GH-like moieties in chicken lymphoid tissues and particularly in the bursa of Fabricius. GH-immunoreactivity (GH-IR), determined by ELISA, was found in thymus, spleen, and in bursa of young chickens, but at concentrations <1% of those in the pituitary gland. Although the GH concentration in the spleen and bursa was approximately 0.82 and 0.23% of that in the pituitary at 9-weeks of age, because of their greater mass, the total GH content in the spleen, bursa, and in thymus were 236, 5.18, and 31.5%, respectively, of that in the pituitary gland. This GH-IR was associated with several proteins of different molecular size, as in the pituitary gland, when analyzed by SDS-PAGE under reducing conditions. While most of the GH-IR in the pituitary was associated with the 26 kDa monomer (40%), the putatively glycosylated 29 kDa variant (16%), the 52 kDa dimer (14%) and the 15 kDa submonomeric isoform (16%), GH-IR in the lymphoid tissues was primarily associated (27-36%) with a 17 kDa moiety, although bands of 14, 26, 29, 32, 37, 40, and 52 kDa were also identified in these tissues. The heterogeneity pattern and relative abundance of bursal GH-IR bands were determined during development between embryonic day 13 (ED13) and 9-weeks of age. The relative proportion of the 17 kDa GH-like band was higher (45-58%) in posthatched birds than in the 15 and 18-day old embryos (21 and 19%, respectively). The 26 kDa isoform was minimally present in embryos (<4% of total GH-IR) but in posthatched chicks it increased to 12-20%. Conversely, while GH-IR of 37, 40, and 45 kDa were abundantly present in embryonic bursa ( approximately 30% at ED13 and approximately 52-55% at ED15 and ED18, respectively), in neonatal chicks and juveniles they accounted for less than 5%. These ontogenic changes were comparable to those previously reported for similar GH-IR proteins in the chicken testis during development. In summary, these results demonstrate age-related and tissue-specific changes in the content and composition of GH in immune tissues of the chicken, in which GH is likely to be an autocrine or paracrine regulator.

Animals↗
PubMed1983

Maturation of the hypothalamic--pituitary--gonadal axis in the male lamb: a review.

We have studied the activity of the hypothalamic--pituitary--gonadal (HPG) axis in the male ovine fetus and newborn lamb. Circulating levels of gonadotropins, prolactin, cortisol (F), testosterone (T), dehydroepiandrosterone sulfate and delta 4androstenedione (delta 4A) were measured in fetal plasma in the third trimester of gestation and the testicular response to hCG was studied in ovine fetuses at 95 - 141 days. Ultradian variations of LH, FSH and testosterone and the testicular response to hCG also were assessed from 1 to 28 days postnatally. The data indicate that (1) fetal plasma LH, FSH, delta 4A and T levels are low from 95 days of gestation to term, while F levels increase in the last 10 days. Postnatally, F decreases rapidly. Spontaneous T peaks may occur as early as 36 hr of life. (2) Spontaneous LH and concomitant or subsequent T secretory peaks are observed by 3 days of age. (3) hCG can induce an increase in T production by interstitial cells in vitro and can increase the T testicular content and its release in the plasma from 95 days of intrauterine life. Desensitization to hCG also can be observed throughout the last trimester of gestation. We conclude that the HPG axis of the male lamb is active ty 36 - 72 hr of postnatal life and that the steroidogenic capacity of the ovine testis is developed several weeks prenatally. Consequently, the relative quiescence of the axis prenatally and in the first 24 hr of life seems to result from relatively low LH secretion and release, related to an undefined endogenous control, together with decreased Leydig cell sensitivity and relatively low enzyme activity limiting T release.

Animals↗
PubMed2005

The relaxin gene-knockout mouse: a model of progressive fibrosis.

Relaxin is well known for its actions on collagen remodeling. To improve our understanding of the physiologic role(s) of relaxin, the relaxin gene-knockout (RLX-KO) mouse was established by our group and subsequently phenotyped. Pregnant RLX-KO mice underwent inadequate development of the pubic symphysis as well as the mammary glands and nipples compared to wild-type mice, thus preventing lactation. Later studies showed that these deficiencies were associated with increased collagen, primarily in the nipple and vagina. Analysis of male RLX-KO mice also demonstrated inadequate reproductive tract development. The testis, epididymis, and prostate of RLX-KO mice showed delayed tissue maturation and growth associated with increased collagen deposition. In nonreproductive tissues, an age-related increase in interstitial collagen (fibrosis) was also detected in the lung, heart, and kidneys of RLX-KO mice and was associated with organ dysfunction. From 6-9 months of age and onwards, all organs of RLX-KO mice, particularly male mice, underwent progressive increases in tissue weight and collagen content (all P < .05) compared with wild-type animals. The increased fibrosis contributed to bronchiole epithelium thickening and alveolar congestion (lung), atrial hypertrophy and increased ventricular chamber stiffness (heart) in addition to glomerulosclerosis (kidney). Treatment of RLX-KO mice with recombinant human relaxin in early and developed stages of fibrosis caused the reversal of collagen deposition in the lung, heart, and kidneys. Together, these findings suggest that relaxin is a naturally occurring inhibitor of collagen deposition during normal development, aging, and pregnancy and can be used to prevent the progression of fibrosis.

Aging↗
PubMed2003

Interactions of proteases, protease inhibitors, and the beta1 integrin/laminin gamma3 protein complex in the regulation of ectoplasmic specialization dynamics in the rat testis.

During spermatogenesis, developing germ cells migrate progressively across the seminiferous epithelium. This event requires extensive restructuring of cell-cell actin-based adherens junctions (AJs), such as the ectoplasmic specialization (ES, a testis-specific AJ type), between Sertoli cells and elongating/elongate spermatids. It was postulated that proteases and protease inhibitors worked in a yin-yang relationship to regulate these events. If this is true, then it is anticipated that both proteases and protease inhibitors are found at the ES. Indeed, matrix metalloprotease (MMP)-2, membrane-type 1 (MT1)-MMP and their inhibitor, tissue-inhibitor of metalloproteases (TIMP)-2, were shown to localize at the apical ES. In order to identify the putative MMP substrate as well as the unknown binding ligand for alpha6beta1 integrin in the ES, immunofluorescent microscopy coupled with immunoprecipitation techniques were used to demonstrate that laminin gamma3, largely a germ cell product, was present at the apical ES and could form a bona fide complex with beta1-integrin. Furthermore, the structural interactions of MMP-2 and MT1-MMP with laminin gamma3 and beta1-integrin, but not with N-cadherin or nectin-3, have implicated the crucial role of MMP-2/MT1-MMP in the regulation of integrin/laminin-based ES dynamics. Using an in vivo model to study AJ dynamics where adult rats were treated with 1-(2,4-dichlorobenzyl)-indazole-3-carbohydrazide (AF-2364) to disrupt Sertoli-germ cell adhesive function, an induction of active MMP-2, active MT1-MMP and TIMP-2 but not active MMP-9 was detected between 0.5 and 8 h after AF-2364 treatment. This time frame coincided with the depletion of elongating/elongate spermatids from the epithelium, illustrating the synergistic relationships between MMP-2, MT1-MMP, and TIMP-2 in AJ disassembly. Perhaps the most important of all, the use of a specific MMP-2 and MMP-9 inhibitor, (2R)-2-[(4-biphenylylsulfonyl)amino]-3-phenylpropionic acid, could effectively delay the AF-2364-induced elongating/elongate spermatid loss from the epithelium, demonstrating the pivotal role of MMP-2 activation in ES disassembly. Collectively, these studies illustrate that the beta1-integrin/laminin gamma3 complex is a putative ES-structural protein complex, which is regulated, at least in part, by the activation of MMP-2 involving MT1-MMP and TIMP-2 at the apical ES. The net result of this interaction likely regulates germ cell movement in the seminiferous epithelium.

Adherens Junctions↗
PubMed2005

The testis histology of artificially maturated European eel (Anguilla anguilla L.) at the end of sexual maturation, and spermatozoa ultrastructure in freshwater rearing. Short communication.

The artificial induction of sexual maturation of European eel males was carried out by using weekly hCG administrations. Histological pictures showed that the testis tissues developed and regressed naturally and no pathological changes took place under the conditions of artificial rearing in freshwater. According to light and electron microscopic investigations the morphology and motility of the spermatozoa of males kept in freshwater proved to be similar to those in seawater. The authors suppose that freshwater rearing of males is not a barrier factor in the artificial propagation of European eels.

Anguilla↗
PubMed2000

Transforming growth factor-beta2 mediates mesenchymal-epithelial interactions of testicular somatic cells.

Transforming growth factor-beta2 (TGFbeta2) is an important mediator of growth and differentiation. We here describe for the first time the complete sequence of the TGFbeta2 complementary DNA derived from peritubular myoid cells of the rat testis. The size of the rat TGFbeta2 complementary DNA was 1245 bp, and the deduced protein sequence contained 414 amino acids. Sequence comparison with the human and mouse amino acid sequences demonstrated 96.4% and 97.9% sequence identities, respectively. To elucidate the functional role of TGFbeta2 in testicular somatic cells, we studied its secretion in vitro in monocultures and cocultures of mesenchymal peritubular and epithelial Sertoli cells. The highest amounts of TGFbeta2 protein were secreted in the cocultures and by peritubular cells, whereas Sertoli cells secreted only minor amounts. Stimulation experiments with FSH revealed a reduced secretion of TGFbeta2 in cocultures, probably mediated by a paracrine interaction of the FSH-responsive Sertoli cells. In contrast, TGFbeta2 secretion by peritubular cells was increased after stimulation with glucocorticoids and after addition of recombinant TGFbeta2, indicating an autoregulation of TGFbeta2. Furthermore, application of recombinant TGFbeta2 to cocultures resulted in an enhanced aggregation and cell clustering of Sertoli cells, pointing to an important role of TGFbeta2 in the paracrine interaction of peritubular and Sertoli cells of the developing rat testis.

Amino Acid Sequence↗
PubMed2005

Magnetic resonance angiography for the nonpalpable testis: a cost and cancer risk analysis.

PURPOSE: For the unilateral nonpalpable testis standard management is open surgical or laparoscopic exploration. An ideal imaging technique would reliably identify testicular nubbins and safely allow children to forgo surgical exploration without compromising future health or fertility. Our goal was to perform a cost and risk analysis of magnetic resonance angiography (MRA) for unilateral nonpalpable cryptorchid testes. MATERIALS AND METHODS: A search of the English medical literature revealed 3 studies addressing the usefulness of MRA for the nonpalpable testicle. We performed a meta-analysis and applied the results to a hypothetical set of patients using historical testicular localization data. Analysis was then performed using 3 different management protocols-MRA with removal of testicular nubbin tissue, MRA with observation of testicular nubbin tissue and diagnostic laparoscopy. A cancer risk and cost analysis was then performed. RESULTS: MRA with observation of testicular nubbin tissue results in 29% of patients avoiding surgery without any increased cost of care. Among the 29% of boys with testicular nubbins left in situ and observed the highest estimated risk was 1 in 300 of cancer developing, and 1 in 5,300 of dying of cancer. CONCLUSIONS: A protocol using MRA with observation of inguinal nubbins results in nearly a third of boys avoiding surgical intervention at a similar cost to standard care without any significant increased risk of development of testis cancer.

Child↗
PubMed2005

Immunolocalization of androgen receptor and estrogen receptors alpha and beta in human fetal testis and epididymis.

PURPOSE: Expression and cellular localization of the androgen receptor (AR) and estrogen receptor (ER) isoforms were determined using antibodies specific to these receptors and to specific cell types. MATERIALS AND METHODS: Gonads and genitourinary structures were removed from 5 human male fetuses 7 to 22 weeks of gestational age. Sections were stained with antibodies to AR, ERalpha and ERbeta, P450 scc and smooth muscle actin. RESULTS: AR was present in undifferentiated gonadal cells, peritubular myoid cells and in some Leydig and stromal cells at 7 weeks of gestation. The number of AR positive peritubular myoid cells remained constant through 22 weeks of gestation but the number of AR positive stromal cells continued to increase through 22 weeks. ERalpha was apparent by 12 weeks of gestation with perinuclear staining of Leydig cells, peaked at 16 weeks and then diminished. ERbeta was first observed at 7 weeks in undifferentiated gonadal cells. By 12 weeks of gestation ERbeta was apparent in germ cells, PTMC and Leydig cells. In the epididymis AR was expressed in the epithelium and stroma of the efferent ductules and the ductus epididymis by 7 weeks of gestation with increased expression by 12 weeks. A similar pattern of staining was observed for ERbeta. By contrast, staining of ERalpha was observed only in the epithelium of the epididymis from 7 weeks of gestation onward with no apparent ERalpha staining in the tail of the epididymis. CONCLUSIONS: These findings are compatible with the well-known roles of androgen signaling in sexual differentiation and spermatogenesis in humans. The role of estrogens in the developing human testis and epididymis remains unknown.

Epididymis↗
PubMed1992

Expression of testis-specific histone genes during the development of rat spermatogenic cells in vitro.

We have used two radiolabeled oligonucleotide probes (TH2B and H1t), Northern blotting, two-dimensional gel electrophoresis, and autoradiography to study the temporal expression of TH2B and H1t testis-specific histone genes during the development of rat spermatogenic cells in vitro. These studies were carried out to determine whether meiotic prophase spermatocytes, known to synthesize in vivo TH2B and H1t histones among other histones, are capable of expressing these testis-specific genes in vitro during an extended period of time. We have found abundant TH2B and H1t mRNA steady state levels as well as newly-synthesized TH2B and H1t histones after 5 days of coculture. Northern blots reprobed with H1t-specific oligonucleotide showed that H1t mRNA remained prominent when TH2B mRNA started to decline after 8-12 days of coculture. Phase-contrast and transmission electron microscopy studies carried out throughout the course of the experiments demonstrated that the number of viable spermatogonia and meiotic prophase spermatocytes was relatively constant during 12 days of coculture. Spermatocytes, in a clone-like arrangement, remained attached to Sertoli cell surfaces and displayed subcellular features consistent with those observed in the intact seminiferous epithelium. Spermatogonia formed long, branching chains of interconnected cells. Results of this study indicate that spermatogenic cells in coculture with Sertoli cells express testis-specific histone genes for an extended period of time. Testis-specific histone gene expression in vitro should facilitate further studies for understanding the role of these histones in chromatin structure, transcription, and genetic recombination during male meiotic prophase.

Animals↗
PubMed1995

The follicle-stimulating hormone (FSH) beta- and common alpha-subunits are expressed in mouse testis, as determined in wild-type mice and those transgenic for the FSH beta-subunit/herpes simplex virus thymidine kinase fusion gene.

Testicular expression of the endogenous FSH beta-subunit (FSH beta) and common alpha-subunit (C alpha) genes, as well as a Herpes simplex virus type 1 thymidine kinase (tk) transgene, driven by a 2.3-kilobase fragment of the bovine GSH beta promoter, were studied at messenger RNA and protein level in normal and transgenic mice. A major 3.8-kb species of FSH beta messenger RNA was demonstrated i the normal mouse testis by Northern hybridization. This was longer than the main 1.7-kb FSH beta transcript detected in the pituitary gland. Reverse transcription-polymerase chain reaction, followed by Southern hybridization, demonstrated FSH beta and tk expression in the pituitary gland and gonads of adult normal and transgenic mice, respectively. The C alpha expression was detected by reverse transcription-polymerase chain reaction in the pituitary gland and testis. During development, testicular transcription of the FSH beta and tk genes was initiated simultaneously a few days after birth. Immunocytochemistry of adult testes showed stage-specific positive reaction with FSH beta, C alpha, and tk antisera in the pachytene spermatocytes and type B spermatogonia, but not in Sertoli cells. Positive reaction with these antisera was also seen in the interstitial tissue. These results demonstrate testicular expression of the endogenous FSH subunit genes and confirm that the testicular expression of the FSH beta /tk transgene reflects or its subunits play a paracrine or autocrine role in the regulation of testicular function.

Animals↗
PubMed2000

The P450 aromatase (P450 arom) gene is asymmetrically expressed in a critical period for gonadal sexual differentiation in the chick.

Steroid hormones appear to play an important role in gonadal sex differentiation of birds. Here we studied the steady-state level of the P450 arom mRNA by reverse transcriptase polymerase chain reaction (RT-PCR) in the left and the right presumptive ovary and testis of developing chicken embryos. The gonads were evaluated every hour during the undifferentiated period, at 144-156 h of incubation (h/i), and every 24 h after sexual differentiation at 168 and 192 h/i. Activity of P450 arom was determined by estrone production from [3H]androstenedione at 144-192 h/i. Moreover, morphological development of the gonad was also examined by light microscopy. Results show that onset of P450 arom mRNA and its protein activity were simultaneously detected in the left and the right ovaries at 147 h/i. Asymmetric function of P450 arom gene expression was observed at 156 h/i when morphological gonadal differentiation is first recognized. Biotransformation of [3H]androstenedione to estrone was also asymmetrically detected between the left and right gonad at 156 h/i and asymmetry was maintained throughout the analyzed stages. It is proposed that there is a gene in birds that is asymmetrically expressed in the undifferentiated stage of the female and the male gonad. In the female this gene could promote P450 arom gene expression, increasing estrogen production, which in turn could induce ovarian cortex proliferation and expression of other structural estrogen-regulated genes involved in ovarian sexual determination.

Androstenedione↗
PubMed1956

An electron microscope study of spermatid differentiation in the toad, Bufo arenarum Hensel.

The differentiation of the spermatids of Bufo arenarum has been described from a study of electron micrographs of thin sections of testis. The development of the acrosome from the Golgi complex takes place in much the same manner as in mammalian spermatogenesis but no acrosome granule is formed. A perforatorium is described for the first time in this species. It is formed by a convergence of dense filaments that arise between the nuclear membrane and the head cap. During maturation of the spermatid the chromatin undergoes striking physicochemical alterations. Fine chromatin granules uniformly dispersed in the karyoplasm are replaced by larger and larger aggregates and these ultimately coalesce to form a very dense sperm head. Two centrioles of cylindrical form are situated very near the base of the sperm head. The longitudinal fibrils of the tail flagellum take origin from one, and the dense fibrous substance of the undulating membrane is closely related to the other. Phase contrast cinematographic observations on the swimming movements of living toad sperm, when considered in relation to the fine structural components of the tail, suggest that there is a contractile component in the undulating membrane as well as in the axial fibrils. The differences in the structure of mammalian and amphibian sperm tails are discussed in relation to differences in the character of their movements.

Acrosome↗
PubMed1999

Apoptosis and mitosis in gonocytes of the rat testis during foetal and neonatal development.

This study was undertaken to determine the extent of apoptosis and mitosis in the various testicular cell types throughout rat development from foetal day 14.5 to postnatal days 9-10. Apoptotic activity was studied by detecting DNA fragmentation (TUNEL method) in situ. A TUNEL-positive reaction was detected in gonocytes, while none of the other testicular cells were labelled. The morphology of the TUNEL-positive gonocytes was characteristic of apoptotic cells and was different from that observed in experimentally induced necrosis. The percentage of stained gonocytes peaked on day 15.5-16.5 post-conception (dpc), decreased thereafter and no TUNEL-positive gonocytes were found from foetal day 18.5 onwards. On postnatal day 2, apoptosis resumed and increased to reach a maximum on day 7. Mitosis in the gonocytes, as evaluated by the immunodetection of 5-bromo-2'-deoxyuridine (BrdU) incorporation, was present during the same developmental periods but the ratio of BrdU-positive/TUNEL-positive gonocytes was much greater in the foetal period than in the neonatal period. In an organotypic culture system, the changes in the apoptotic and mitotic activities of the gonocytes in testicular explants from foetuses on days 18.5 and 20.5 or from neonates on day 3, cultured for two days were similar to those observed in vivo. Addition of LH or FSH did not influence either apoptosis or mitosis in the germ cells. These results suggest that both apoptosis and mitosis of gonocytes are independent of gonadotrophins and are mainly controlled by intratesticular factors.

Animals↗
PubMed1998

Sertoli cells of the mouse testis originate from the coelomic epithelium.

During mouse development, the gonad begins to form shortly before 10. 5 days postcoitum (dpc) on the ventromedial side of the mesonephros. The XY gonad consists of germ cells and somatic cells. The origin of the germ cells is clearly established; however, the origin of the somatic cells, especially the epithelial supporting cell lineages, called Sertoli cells, is still unclear. Sertoli cells are the first somatic cell type to differentiate in the testis and are thought to express Sry, the male sex-determining gene, and to play a crucial role in directing testis development. Previous data have suggested that the somatic cells of the gonad may arise from the mesonephric tubules, the mesonephric mesenchyme, or the coelomic epithelium. Immunohistochemical staining of the gonad at 11.5 dpc showed that the basement membrane barrier under the coelomic epithelium is discontinuous, suggesting that cells in the coelomic epithelium at this stage might move inward. To test this possibility directly, cells of the coelomic epithelium were labeled using the fluorescent lipophilic dye, DiI. We show that when labeled at tail somite 15-17 stages, corresponding to 11.2-11.4 dpc, the coelomic epithelial cells of both sexes migrated into the gonad. In XY gonads, the migrating coelomic epithelial cells became Sertoli cells, as well as interstitial cells. This ability of the coelomic epithelium to give rise to Sertoli cells was developmentally regulated. When labeled at tail somite 18-20 stages, corresponding to 11.5-11.7 dpc, the coelomic epithelial cells no longer became Sertoli cells. Instead, cells that migrated into the gonad stayed outside testis cords, in the interstitium. Migration gradually decreased and ceased by tail somite 30 stage, corresponding to 12.5 dpc, after testis cords had formed and the basement membrane layer underlying the coelomic epithelium had thickened to form the tunica albuginea. In XX gonads, coelomic epithelial cells also migrated into the gonad, but there was no obvious fate restriction during the same developmental period. Taken together, our data show that the coelomic epithelium is a source of Sertoli cells as well as other somatic cells of the gonad in the developing mouse testis.

Animals↗
PubMed1999

Sry-negative XX sex reversal in purebred dogs.

The gene responsible for testis induction in normal male mammals is the Y-linked Sry. However, there is increasing evidence that other genes may have testis-determining properties. In XX sex reversal (XXSR), testis tissue develops in the absence of the Y chromosome. Previous polymerase chain reaction (PCR) assays indicated that autosomal recessive XXSR in the American cocker spaniel is Sry-negative. In this study, genomic DNA from the breeding colony of American cocker spaniels and from privately owned purebred dogs were tested by PCR using canine primers for the Sry HMG box and by Southern blots probed with the complete canine Sry coding sequence. Sry was not detected by either method in genomic DNA of affected American cocker spaniels or in the majority (20/21) of affected privately owned purebred dogs. These results confirm that the autosomal recessive form of XXSR in the American cocker spaniel is Sry-negative. In combination with previous studies, this indicates that Sry-negative XXSR occurs in at least 15 dog breeds. The canine disorder may be genetically heterogeneous, potentially with a different mutation in each breed, and may provide several models for human Sry-negative XXSR. A comparative approach to sex determination should be informative in defining the genetic and cellular mechanisms that are common to all mammals.

Amino Acid Sequence↗