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Identification and characterization of testis- and epididymis-specific genes: cystatin SC and cystatin TE-1.

Differential display-reverse transcriptase-polymerase chain reaction was used to examine Sertoli cell gene expression. As a result, two new members of the mouse cystatin multigene family were isolated and named cystatin SC (cystatin-related gene expressed in Sertoli cells) and cystatin TE-1 (cystatin-related gene highly expressed in testis and epididymis). The full-length cDNA sequence of cystatin SC contains an open reading frame that encodes a putative signal peptide of 20 amino acids and a mature protein of 110 amino acids, whereas that of cystatin TE-1 encodes a 128 amino acid protein with a predicted signal peptide of 21 amino acids. Both of the deduced amino acid sequences contain four highly conserved cysteine residues in precise alignment with other cystatin family members. The derived cystatin SC and TE-1 amino acid sequences lack some of the specific, highly conserved motifs believed to be necessary for cysteine proteinase inhibition activity. Northern blot analysis revealed that cystatin SC mRNA was detected only in the testis, whereas the cystatin TE-1 gene was highly expressed in testis and epididymis with very low expression in ovary and prostate. In situ hybridization showed that cystatin SC mRNA was localized mainly to Sertoli cells with an obvious stage-dependent expression, and that cystatin TE-1 mRNA was predominantly expressed in Sertoli cells without apparent stage-dependent expression. Cystatin TE-1 mRNA, as displayed by in situ hybridization, was expressed only in the epithelial cells of the proximal caput region of the epididymis. The unusual amino acid sequence and highly restricted expression suggests that cystatins SC and TE-1 play a very specialized role in the testis and epididymis.

Amino Acid Sequence↗

Cellular location and hormonal regulation of ghrelin expression in rat testis.

Ghrelin, the endogenous ligand for the growth hormone-secretagogue receptor, is a recently cloned 28-amino acid peptide, expressed primarily in the stomach and hypothalamus, with the ability to stimulate growth hormone (GH) release and food intake. However, the possibility of additional, as yet unknown biological actions of ghrelin has been suggested. As a continuation of our recent findings on the expression and functional role of ghrelin in rat testis, we report here the pattern of cellular expression of ghrelin peptide in rat testis during postnatal development and after selective Leydig cell elimination, and we assess hormonal regulation of testicular ghrelin expression, at the mRNA and/or protein levels, in different experimental models. Immunohistochemical analyses along postnatal development demonstrated selective location of ghrelin peptide within rat testis in mature fetal- and adult-type Leydig cells. In good agreement, ghrelin protein appeared undetectable in testicular interstitium after selective Leydig cell withdrawal. In terms of hormonal regulation, testicular ghrelin mRNA and protein expression decreased to negligible levels after long-term hypophysectomy, whereas replacement with human chorionic gonadotropin (CG) (as superagonist of LH) partially restored ghrelin mRNA and peptide expression. Furthermore, acute administration of human CG (25 IU) to intact rats resulted in a transient increase in testicular ghrelin mRNA levels, with peak values 4 h after injection, an effect that was not mimicked by FSH (12.5 IU/rat). In contrast, testicular expression of ghrelin mRNA remained unaltered in GH-deficient rats, under hyper- and hypothyroidism conditions, as well as in adrenalectomized animals. In conclusion, our results demonstrate that mature Leydig cells are the source of ghrelin expression in rat testis, the protein being expressed in both fetal- and adult-type Leydig cells. In addition, our data indicate that testicular expression of ghrelin is hormonally regulated and is at least partially dependent on pituitary LH.

Adrenalectomy↗

Type II and type IX collagen transcript isoforms are expressed during mouse testis development.

Mutations in the transcription factor SOX9 give rise to campomelic dysplasia, a syndrome characterized by skeletal abnormalities and XY sex reversal. Sox9 is expressed at sites of chondrogenesis and in the developing testis, and, thus, it plays a role in two overtly different pathways of differentiation. Previous studies have identified the gene for type II collagen, Col2a1, as a target of Sox9 in mouse chondrocytes and implicated Col9a3 as a Sox9 target in testis. Using differential expression analysis combined with reverse transcription-polymerase chain reaction and whole-mount in situ hybridization, we have identified nonchondrocytic collagen transcript isoforms that are expressed in the early male mouse gonad. Male-specific, gonadal expression of nonchondrocytic Col2a1 was first seen at 11.5 days postcoitum (dpc) and was undetectable by 13.5 dpc. This was accompanied by increasing expression of nonchondrocytic Col9a1, Col9a2, and Col9a3, first detected at 11.5 dpc. Expression was analyzed in testes that had been depleted of germ cells by the cytotoxic drug busulfan. These studies showed Col9a3 and Col2a1 to be expressed in Sertoli cells within the developing testis cords. Nonchondrocytic type II collagen contains a cysteine-rich domain that has been shown to bind members of the transforming growth factor beta superfamily of signaling molecules. Thus, this interaction may play a role in the morphogenesis and differentiation of the testis.

Alkylating Agents↗

INSL3 ligand-receptor system in the equine testis.

We employed molecular and immunological techniques to investigate the expression of INSL3, a member of the insulin-like superfamily, in prepubertal testis, postpubertal testes exhibiting normal and disturbed spermatogenesis, and cryptorchid testes of male horses. In addition, the partial cDNA coding sequences of the equine homologue of the human relaxin/INSL3-receptor Lgr8 were determined. Nonradioactive in-situ hybridization with a cRNA probe for equine Insl3 and immunohistochemistry with a specific rabbit INSL3 antiserum localized Insl3 transcripts and immunoreactive INSL3 ligand to Leydig cells in all types of testes investigated. Quantitative polymerase chain reaction analysis revealed a down-regulation of Insl3 and an up-regulation of the relaxin/INSL3-receptor expression in unilateral cryptorchid versus descended testes. Western blot analysis of protein extracts from adult normal and cryptorchid testes and prepubertal testes showed a single immunoreactive band at 14.5 kDa, which correlates with the predicted size of equine proINSL3. Densitometric analysis of Western blot data of adult normal testes revealed significantly stronger expression of immunoreactive proINSL3 as compared to extracts derived from cryptorchid or prepubertal testes. Thus, decreased expression of immunoreactive INSL3 in cryptorchid and prepubertal equine testis is transcriptionally regulated. The detection of transcripts for equine Lgr8 in the testis has identified the testis as a potential target of INSL3.

Animals↗

Prenatal exposure to estrogenic compounds alters the expression pattern of platelet-derived growth factor receptors alpha and beta in neonatal rat testis: identification of gonocytes as targets of estrogen exposure.

We examined the effects of maternal exposure to estrogens on platelet-derived growth factor (PDGF) receptor (PDGFR) expression in newborn rat testis. Pregnant rats were treated from gestation Day 14 to birth with corn oil containing diethylstilbestrol, bisphenol A, genistein, or coumestrol by gavage or subcutaneous injection. These treatments induced a dose-dependent increase in the expression of PDGFR alpha and beta mRNAs, determined by semiquantitative reverse transcription polymerase chain reaction, though diethylstilbestrol had a biphasic effect on both mRNAs. In situ hybridization analysis showed that PDGFRalpha mRNA increased mostly in the interstitium, while PDGFRbeta mRNA increased both in the interstitium and seminiferous cords. Immunohistochemical studies of PDGFRalpha and beta proteins revealed that both receptors were present in testis before and after birth and that they were upregulated upon treatment with estrogens in 3-day-old rats, with PDGFRbeta increasing dramatically in gonocytes. PDGFRalpha and beta mRNAs and proteins were also found in purified gonocytes. Our previous finding that PDGF and 17beta-estradiol induce gonocyte proliferation in vitro, together with the present finding that in vivo exposure to estrogens upregulates PDGF receptors in testis, suggest that PDGF pathway is a target of estrogens in testis. In addition, these data identify PDGFRbeta in gonocytes as a major target of gestational estrogen exposure, suggesting that estrogen may have a physiological interaction with PDGF during gonocyte development. These results, however, do not exclude the possibility that the effects of the compounds examined in this study might be due to estrogen receptor-independent action(s).

Animals↗

Neonatal hypothyroidism alters the localization of gap junctional protein connexin 43 in the testis and messenger RNA levels in the epididymis of the rat.

The objectives of this study were to determine the effects of propylthiouracil (PTU)-induced neonatal hypothyroidism on the gap junctional protein Cx43 in rat testis and epididymis. PTU (0.02%) was administered via lactation from birth to Day 30, and the rats were sampled at 14, 18, 22, 26, 30, and 91 days of age. Testicular Cx43 was localized along the plasma membranes and cytoplasm of Sertoli cells until Day 22. At Day 30, the immunostaining was localized exclusively along the plasma membrane of Sertoli cells. In PTU-treated rats, Cx43 did not localize to the plasma membrane and was still cytoplasmic at 30 days of age. Occludin was present in tubules of treated rats, but was not localized to the blood-testis barrier in 30-day-old rats, as in controls. There were no differences in Cx43 immunostaining in the adult testis. In the proximal epididymis (initial segment, caput, corpus), Cx43 mRNA levels were lower in PTU-treated rats at 14, 18, and 22 days of age, but no differences were observed in the distal (cauda) epididymis at these ages. In 22- and 30-day-old rats, Cx43 was localized along the plasma membrane between principal and basal cells throughout the epididymis. In PTU-treated rats, Cx43 was not detectable in initial segment, caput, or corpus epididymidis. In the cauda epididymidis, however, Cx43 immunostaining in PTU-treated rats was similar to controls. These data suggest that thyroid hormones regulate Cx43-dependent gap junctional communication in the testis and epididymis.

Animals↗

Chemotactic role of neurotropin 3 in the embryonic testis that facilitates male sex determination.

The first morphological event after initiation of male sex determination is seminiferous cord formation in the embryonic testis. Cord formation requires migration of pre-peritubular myoid cells from the adjacent mesonephros. The embryonic Sertoli cells are the first testicular cells to differentiate and have been shown to express neurotropin-3 (NT3), which can act on high-affinity trkC receptors expressed on migrating mesonephros cells. NT3 expression is elevated in the embryonic testis during the time of seminiferous cord formation. A trkC receptor tyrophostin inhibitor, AG879, was found to inhibit seminiferous cord formation and mesonephros cell migration. Beads containing NT3 were found to directly promote mesonephros cell migration into the gonad. Beads containing other growth factors such as epidermal growth factor (EGF) did not influence cell migration. At male sex determination the SRY gene promotes testis development and the expression of downstream sex differentiation genes such as SOX-9. Inhibition of NT3 actions caused a reduction in the expression of SOX-9. Combined observations suggest that when male sex determination is initiated, the developing Sertoli cells express NT3 as a chemotactic agent for migrating mesonephros cells, which are essential to promote embryonic testis cord formation and influence downstream male sex differentiation.

Animals↗

Hormonal regulation and functional role of vascular endothelial growth factor a in the rat testis.

Vascular endothelial cell growth factor (VEGF-A) is synthesized in the testis but its role and regulation in this organ have not been examined. VEGF and its receptors (VEGF-R) were quantified using reverse transcription-polymerase chain reaction and Western blot. VEGF, VEGF-R1, and VEGF-R2 mRNAs and VEGF protein were increased after treatment with 50 IU hCG. Injection of 100 ng human recombinant VEGF 165 into the testis caused an increase in endothelial cell proliferation, but only a moderate increase in testicular interstitial fluid volume. In contrast with systemic hCG treatment, local VEGF injection did not increase the permeability to intravenously injected colloidal carbon particles. However, if VEGF was given locally in the testes of animals pretreated with hCG 4 or 8 h earlier, VEGF acted in synergy with hCG to increase vascular carbon leakage by forming interendothelial cell gaps. Testicular blood flow was unaffected by local VEGF 165 injection. Treatment with a specific VEGF-R2 tyrosine kinase inhibitor blocked the hCG-induced increase in endothelial cell proliferation but did not affect the hCG-induced accumulation of polymorphonuclear leukocytes in testicular blood vessels or the increase in the testicular interstitial space. The present study demonstrated that testicular VEGF secretion is increased by hormonal stimulation of Leydig cells and that VEGF, through effects mediated via VEGF-R2, regulates endothelial cell proliferation in the rat testis. VEGF does not appear to regulate testicular blood flow and it is not involved in inducing the hCG-induced inflammation-like response in the testicular microvasculature. The permeability-increasing effect of VEGF is low in the testis under basal conditions but is apparently up-regulated by hCG treatment.

Animals↗

Fer kinase/FerT and adherens junction dynamics in the testis: an in vitro and in vivo study.

Fer kinase is a 94-kDa cytoplasmic cell-cell actin-based adherens junction (AJ)-associated nonreceptor protein tyrosine kinase (PTK) found in multiple epithelia including the testis, whereas FerT kinase (51 kDa) is the truncated testis-specific form of Fer kinase, lacking the Fps/Fes/Fer/CIP4 (products of oncogenes identified in avian and feline sarcoma, encoding tyrosine protein kinases) and the three coiled-coil domains versus Fer kinase. Yet the role(s) of Fer kinase in AJ dynamics in the testis remains largely unexplored. We have used an in vitro model of AJ assembly with Sertoli-germ cell cocultures and an in vivo model of AJ disassembly in which adult rats were treated with 1-(2,4-dichlorobenzyl)-indazole-3-carbohydrazide (AF-2364) to study changes in the expression and/or localization of Fer kinase during AJ restructuring. Fer kinase/FerT was expressed by Sertoli and germ cells when cultured in vitro. Using an antibody prepared against a synthetic peptide, NH2-SAPQNCPEEIFTIMMKCWDYK-COOH, corresponding to residues 779-799 of Fer kinase in the rat, which failed to cross-react with FerT kinase, for immunohistochemistry, Fer kinase was detected in the seminiferous epithelium in virtually all stages of the epithelial cycle. At stages XIII-VI, Fer kinase was associated largely with round and elongating spermatids. At stages VII-VIII, Fer kinase associated almost exclusively with round spermatids with very weak staining associated with elongated spermatids. This stage-specific localization of Fer kinase in the epithelium was confirmed by using staged tubules for semiquantitative reverse transcription-polymerase chain reaction. Studies by immunoprecipitation revealed that Fer kinase associated with N-cadherin, gamma-catenin, p120ctn, c-Src (a putative PTK and the product of the transforming, sarcoma-inducing gene of Rous sarcoma virus), Rab 8 (a GTPase), actin, vimentin, but not E-cadherin, afadin, nectin-3, and integrin beta1, suggesting Fer kinase associates not only with the actin-based cell-cell AJ structures, such as the N-cadherin/catenin complex (but not the alpha6beta1 integrin/laminin and the afadin/nectin complex), but also with intermediate filament-based cell-cell desmosomes. An induction in Fer kinase expression was detected during Sertoli-germ cell AJ assembly in vitro but not during AF-2364-induced AJ disruption in vivo. Yet this AF-2364-induced Fer kinase plummeting associated with an induction in N-cadherin, beta-catenin, and p120ctn, particularly at the base of the seminiferous epithelium. In summary, Fer kinase structurally associates with the N-cadherin/catenin protein complex in the testis and can possibly be used to mediate signaling function via the cadherin/catenin protein complex.

Adherens Junctions↗

Seasonal expression of INSL3 and Lgr8/Insl3 receptor transcripts indicates variable differentiation of Leydig cells in the roe deer testis.

Roe deer are seasonal breeders and show cyclic variation in testicular volume and cellular differentiation within the tubular and interstitial testis compartment. We have employed the roe deer as a model to elucidate the expression of the postpubertal Leydig cell marker INSL3 during seasonal changes in Leydig cell differentiation. Roe deer testis and serum samples were collected bimonthly throughout the complete reproductive cycle. Peak levels of testicular Insl3 mRNA and INSL3 immunoprotein were detected well before the onset of rut in April and coincided with the highest percentage of INSL3-positive cell number/square millimeter of testicular interstitial area. During the winter (December, February), roe deer INSL3 was exclusively detected in a subpopulation of alpha-actin-negative, spindle-shaped peritubular cells. Concordant with the increase in INSL3 production in April and 1 mo after the reported LH peak, a sharp increase in serum testosterone concentrations was observed. High serum testosterone concentrations coincided with the presence of detectable 17alpha-hydroxylase, mRNA and protein, in Leydig cells. Upregulation of INSL3 production in spring appeared to reflect LH-dependent differentiation of Leydig cells. The considerable changes in percentage of INSL3 immunopositive cells within the numerically constant interstitial cell population indicated cyclic seasonal de- and redifferentiation of Leydig cells. A complex functional role of the INSL3/LGR8 ligand-receptor system in the roe deer testis was suggested by the detection of specific hybridization signals for roe deer Lgr8 transcripts in Sertoli cells of the roe deer testis.

Animals↗

LY6A/E (SCA-1) expression in the mouse testis.

Recently, it was found by two research groups that LY6A, known widely in the stem cell community as stem cell antigen-1 or SCA-1, is expressed on testicular side population (SP) cells. Whether these SP cells are spermatogonial stem cells is a point of disagreement and, therefore, the identity of the LY6A-positive cells as well. We studied the expression pattern of LY6A in testis by immunohistochemistry and found it to be expressed in the interstitial tissue on peritubular myoid, endothelial, and spherical-shaped peritubular mesenchymal cells. To address the question whether LY6A has a function in spermatogenesis or testis development, we studied the testis of Ly6a(-/-) mice (allele Ly6a(tm1Pmf)). We found no morphological abnormalities or differences in numbers of spermatogonia, spermatocytes, Leydig cells, or macrophages in relation to the number of Sertoli cells. Therefore, we conclude that LY6A expression does not influence testis development or spermatogenesis and that spermatogonial stem cells are LY6A negative.

Animals↗

Requirement of serum components for the preservation of primordial germ cells in testis cords during early stages of testicular differentiation in vitro in the mouse.

Mouse gonadal primordia were isolated from embryos on the 11th day of gestation and cultured in vitro. They developed into either testes or ovaries after 7 days of culture in Eagle's minimum essential medium (MEM) supplemented with horse serum, whereas they did not differentiate in MEM alone. We studied how serum components are required for testicular development in vitro. When gonadal primordia were cultured in MEM alone for the first 1-3 days and subsequently in MEM supplemented with serum, testis cords developed while germ cells disappeared or only a few remained in the testis cords. In contrast, when serum was present in the medium during the first day of culture and omitted thereafter, germ cells were retained within testis cords. These results suggested that some serum component(s) is specifically required by germ cells independent of testis cord organization. Of more than 10 serum components tested, low and very low density lipoprotein fractions increased the number of germ cells in testicular explants.

Animals↗

Morphological changes in the testis and epididymis of rats treated with cyclophosphamide: a quantitative approach.

Cyclophosphamide is a widely used anticancer and immunosuppressive drug that affects fertility in men. In a previous study, we found that chronic, daily treatment of male rats with low doses of cyclophosphamide had no apparent effect on the pituitary-gonadal axis, whereas it had time- and dose-dependent effects on male reproductive organ weights, the hematologic system, and on pregnancy outcome. To determine whether cyclophosphamide induces morphological changes within the male reproductive system, a detailed qualitative and quantitative evaluation of changes in the histology of the testis and epididymis was undertaken. Adult male Sprague-Dawley rats were gavage-fed for 1, 3, 6, and 9 wk with saline (control), 5.1 (low dose) or 6.8 (high dose) mg/kg/day of cyclophosphamide; the testes and epididymides were prepared for light and electron microscopy. At the light microscopic level, the orderly process of spermatogenesis in the seminiferous tubules was not affected at any time point with either dose of the drug. A number of time-dependent drug-induced changes in the histology of the epididymis, however, were apparent: 1) an increase in the relative number and a change in the distribution of halo cells in the caput epididymidis, 2) an increase in the number and size of clear cells in the caput and/or cauda epididymidis, and 3) an increase in the size of clear cells in both the caput and cauda epididymides; these changes were time dependent. At the electron microscopic level, there was a dose-dependent, two- to threefold increase in the number of spermatozoa with abnormal flagellar midpieces in the lumen of both the caput and cauda epididymides. Although the 9 plus 2 axonemal complex and the 9 outer dense fibers were present and appeared normal, the close approximation of these two structures was lost in these abnormal spermatozoa. Such abnormal flagellar midpieces were also found in the testes of control and treated rats. Electron microscopic examination of the testis revealed that both Sertoli and Leydig cells were normal in appearance. The type and timing of the effects of cyclophosphamide on the histology of the testis and epididymis suggest that the drug could be affecting germ cells by 1) inducing changes in the developing spermatozoa in the testis, some of which are seen microscopically in the epididymal lumen, and/or 2) affecting epididymal morphology and function.

Animals↗

Development of the inhibitory guanine nucleotide-binding regulatory protein in the rat testis.

The functional development of the inhibitory guanine nucleotide-binding regulatory protein (Gi) and anti-diuretic hormone (ADH) activity was investigated in rat testes. Adult (90-day-old), adolescent (40-day-old), prepubertal (23-day-old), and fetal (20.5 days of gestation) testis cells were cultured with 100 ng/ml pertussis toxin for 24 h. The cells were then cultured with human chorionic gonadotropin (hCG), the ADH agonist arginine vasotocin (AVT), or a combination of the two. Testis cells from rats 23, 40, and 90 days of age that were incubated with hCG increased testosterone production when compared with controls. Preincubation of the cells from postnatal rats with pertussis toxin significantly increased hCG-stimulated testosterone secretion when compared to cells preincubated in medium only at all three ages. AVT suppressed hCG-stimulated testosterone secretion, but this suppression was partially reversed in cells from all postnatal ages preincubated with pertussis toxin. Fetal testis cells showed no response to preincubation with pertussis toxin, even when levels were increased to 400 ng/ml or when pertussis toxin treatment was continued throughout the culture period. AVT also had no effect on fetal testis cells. These results indicate that the Gi protein and AVT are not functional in fetal testes but are active from prepubertal stages of development through maturity.

Animals↗

Immunolocalization and concentrations of inhibin alpha in the ovine testis and excurrent duct system.

Inhibin was localized in the ovine testis, excurrent ducts, and accessory sex glands by using a rabbit antiserum against a synthetic polypeptide representing the first 30 amino acids of porcine inhibin alpha-subunit. Concentrations of inhibin in fluids entering and leaving the epididymis also were determined in a radioimmunoassay using the same antibody. In the testis, immunostaining of inhibin was conspicuous in the seminiferous epithelium. Leydig cells occasionally were stained and the tunica media of blood vessels always was stained. Intense staining was observed in the epithelia lining the rete testis and ductuli efferentes. Staining also was intense in the epithelium of the initial segment and proximal caput epididymidis, and became less intense along the length of the epididymis. These observations were consistent with concentrations of inhibin in rete testis fluid (8.2 pmol/ml) entering the ductuli efferentes and in cauda epididymal plasma (0.67 pmol/ml) leaving the epididymis. Epithelia of ampullary and vesicular glands and of some prostatic acini were positively stained, but bulbourethral glands were never stained. Adrenal cortex, some proximal convoluted tubules in the kidney, and transitional epithelium of the urethra also were stained. Based on radioimmunoassay data and fluid flow rates for the ram, it was concluded that almost all of the 328 pmol inhibin that enters the ductuli efferentes daily is endocytosed in the proximal parts of the excurrent duct system. The physiological role(s) for inhibin, or inhibin-like peptides, in the excurrent duct system remains speculative.

Adrenal Glands↗

Developmental and differential expression of the ornithine decarboxylase gene in rodent testis.

Ornithine decarboxylase (ODCase) is the first and rate-limiting enzyme in the polyamine biosynthetic pathway and it is androgen regulated in the mouse. The expression of ODCase transcripts during testicular development was examined by Northern blot analysis with a mouse ODCase cDNA probe. Total RNA was isolated from the testes of prepubertal mice at 6, 8, 12, 16, 18, 20, 22, and 30 days of age, from enriched populations of germinal cells obtained from the testis of immature (8 days old) and mature (45 days old) mice and from several mouse somatic tissues. The level of the two ODCase transcripts (2.2 and 2.7 kilobases) was low but detectable in the testes of 6- to 16-day-old mice and increased substantially as the first spermatogenic wave proceeded into spermiogenesis. The low ODCase mRNA levels observed in prepubertal mouse testes were confirmed with RNA samples obtained from enriched germ cell populations of type A and type B spermatogonia and interstitial cells obtained from Day 8 mouse testes. In agreement with the developmental studies, ODCase mRNA levels increased substantially in enriched populations of pachytene spermatocytes, round spermatids, and residual bodies/cytoplasts isolated from mature testes. Similar results were obtained by in situ hybridization of sections of rat testes. Reduced levels of ODCase transcripts were detected in RNA obtained from cultured mouse Sertoli cells obtained from the testes of 21-day-old mice and in RNA from liver, brain, heart, spleen, seminal vesicle, and aorta. In contrast, ODCase transcript levels from kidneys of male mice were as high as those detected in testis RNA. Substantial levels of ODCase mRNAs were also found in the epididymis. Analysis of polysome gradients prepared from total testis extracts revealed a distribution of ODCase mRNA in both nonpolysomal and polysomal fractions of the gradient, suggesting that ODCase is translationally regulated in the mouse testis.

Animals↗

Immunocytochemical localization of the epidermal growth factor receptor in mouse testis.

The distribution of the epidermal growth factor receptor (EGFR) in mouse testis was ascertained by immunocytochemical methodology using a polyclonal antibody (RK2) shown previously to recognize the cytoplasmic domain of the human (A431 cells), murine (Swiss 3T3 cells), and chicken (CK 109 cells) EGFR. Initial studies performed to determine the usefulness of this antibody as a probe of the murine EGFR in testis employed two murine cell lines, TM4 and MA10, of Sertoli cell and Leydig cell origin, respectively, in which a physiological response of EGF and specific binding of iodinated EGF has been demonstrated. Western blotting in membrane preparations of TM4 and MA10 revealed only one prominent band at 170 kDa. Immunocytochemical localization in TM4 and MA10 cells illustrated a plasma membrane distribution of the receptor. Western blotting of membrane fractions prepared from testis also revealed a specific band at 170 kDa. In the intact testis, the EGFR was immunolocalized specifically in Leydig cells and Sertoli cells only. These results suggest that the involvement of EGF action in spermatogenesis may occur at the level of the somatic components of the testes, principally in the Leydig and Sertoli cells.

Animals↗

Effects of in utero ultrasound exposure on the development of the fetal mouse testis.

The effect on the developing fetal testis of in utero exposure to 1-MHz, continuous-wave ultrasound in the spatial peak, temporal average intensity range 0.5-10 W/cm2 for durations of 400-30 sec on Day 9, 12, or 15 of gestation was determined. Results show that two subtle, yet potentially deleterious, effects occurred: a reduction in the Sertoli cell population and an apparent delay in the cessation of gonocyte mitosis. An increase was also seen in the number of fetal resorptions and stillborn pups per number of implantation sites in the exposed specimens as compared to the sham and cage controls. Because the reduction in testis weight was proportional to decreased body weight and because there was no difference in Sertoli cell numbers due to day of treatment, the testicular effects may reflect a generalized delay in growth. Whether this effect of ultrasound on fetal testis will be translated into an equal reduction in germ cell numbers in the adult testis remains to be determined.

Animals↗