The testicular position and descent in developing human

AimThe present study aimed at reevaluating and providing a more comprehensive knowledge of position and descent of the testis.Materials and methodsThe position and descent of testis was studied on 104 male formalin fixed human fetuses in the Department of Anatomy, RIMS, Imphal. The fetuses were dissected and the location of the testes and the extent of the gubernaculum were noted. Special staining was done using Weigert's iron hematoxylin and Van Gieson's stain.ResultsThe testes were located, in the earliest specimen of the present series, retroperitoneally in the lower abdomen at L3–4 level. Left testis was usually at a lower level than the right. Testicular descent was observed earliest at 24 weeks of intra-uterine life (IUL) and 100% successful complete bilateral descent by 36 weeks IUL. Descent through the inguinal canal was rapid and no case of undescended testis was encountered. The testicular descent was symmetrical in majority of the cases except in 7 where the descent was asymmetrical with the left descending earlier. Structural changes in gubernaculum but not its contraction played a role in testicular descent.ConclusionThus, a comprehensive and thorough knowledge of the testicular descent will assist in management of cases related with testis, especially the undescended and ectopic testis.     

Screening of testicular descent in older boys is worthwhile: an observational study

Background

Testicular descent in boys is now routinely screened only once, at 6–8 weeks of age. Early surgery for undescended testes is recommended.

Aim

To assess the value of screening for testicular descent at 6–8 weeks, 8–9 months, and 39–42 months of age.

Design of study

Observational study.

Setting

Royal Hospital for Sick Children, Glasgow and the Scottish community-based Child Health Surveillance Programme.

Method

Screening data for boys undergoing surgery for abnormal testicular descent between April 2006 and September 2007 was reviewed. The main outcome measure was median age at first operation for abnormal testicular descent comparing attendance at screening with non-attendance.

Results

Boys who attended screening underwent surgery at a significantly younger median age than boys who did not attend screening at 6–8 weeks (2.7 versus 7.7 years; P<0.001); 8–9 months (4.5 versus 9.7 years; P<0.001); and 39–42 months (7.8 versus 10.8 years; P = 0.014). A new diagnosis was made in 33% (42 of 128 boys) at 6–8 weeks, 28% (21/74) at 8–9 months, and 39% (15/38) at 39–42 months. Detection on screening did not always trigger referral. Referral was triggered by screening in 48% (62/128) of cases, and by incidental examinations in 27% (34/128).

Conclusion

The previous screening regimen was effective, but checks at 8–9 months and 39–42 months have recently been abolished. Reinstatement of screening for testicular descent in older boys is advocated because screened boys underwent surgery at a younger age. Doctors should be encouraged to check testicular descent in boys throughout childhood, and refer promptly when there is any concern.     

Ultrastructural study of the gubernacular-scrotal interface during testicular descent in the newborn rat

The gubernaculum has been described as the “rudder” that guides the testis into the scrotum. Prior to inguinoscrotal testicular descent, the gubernaculum rests in the groin and does not attach to the scrotum. Subsequently, it migrates and attaches to the scrotum under control of the genitofemoral nerve. This study evaluates, with electron microscopy, the relationship of the gubernaculum with the developing scrotum during normal testicular descent. Male rats were sacrificed at 0, 2, 4, 7, 10, 14, and 18 days (n = 2 for each group) and sagittal sections through the gubernacular-scrotal interface evaluated with transmission electron microscopy. We observed the following with increasing animal age: (1) gubernacular cremaster muscle matured and nuclei shifted to the periphery of cells as connective tissue surrounding myofibers decreased, (2) scrotal fibroblasts initially showed high activity with dilated endoplasmic reticulum, but activity and number subsequently decreased, (3) scrotal collagen increased and organized into defined fibers and bundles, (4) a well-delineated band of collagen developed along the gubernaculum and advanced towards the inferior scrotum, and (5) nerve fibers appeared between the layers of cremaster muscle, increased in number with increasing age, and became myelinated at age 14 days. Gubernacular migration is intimately associated with scrotal development and testicular descent. Knowledge of cellular and intracellular differentiation during migration in the normal animal can further understanding of abnormal development and lead to improvements in treatment for common surgical problems such as cryptorchidism. © 1993 Wiley-Liss, Inc.     

人类睾丸下降的胚胎学研究及隐睾病因探索

目的：从解剖学角度探讨人类胚胎睾丸下降机理以及隐睾的发生原因。方法：解剖２２周以上流产死胎１５具以及成人尸体标本１４具,观察鞘突、鞘膜囊开放、充盈状态,测量内环口与腹股沟韧带、耻骨结节之间的距离和角度,对照２０例隐睾手术时的测量数据进行统计学处理。结果：发现胚胎期睾丸鞘膜囊均为积水大状态,鞘突开放,内环口全部位于腹膜腔生理性积水之下,隐睾病人的内环位置偏高或偏内,与胚胎和尸检相比有明显差异（Ｐ〈     

Familial male pseudohermaphroditism and testicular descent in the racoon dog (Nyctereutes)

Sexual differentiation was investigated in familial male pseudohermaphroditism in Nyctereutes procyonoides (Canidae). In intersex males, development of external genital organs and prostate glandular tissue was severely disturbed; Wolffian (mesonephric) duct derivatives developed prepubertally but were absent in some adults. Müllerian (paramesonephric) duct regression was complete. Testicular descent was undisturbed. Male/female sex differences in plasma testosterone, 5 alpha-dihydrotestosterone, and luteinizing hormone concentrations were present. Intersex plasma hormone concentrations were within the normal male range. The concentration of androgen receptors in pubic skin was similar in male, female, and intersex animals and no significant differences in affinity for the ligand were detected. It was concluded that in intersex animals androgen-dependent virilisation was deficient despite the presence of androgens and androgen receptors and that this condition had not affected gubernaculum development and testicular descent.     

Absence of mutations involving the INSL3 gene in human idiopathic cryptorchidism

The aetiology of cryptorchidism is for the most part unknown and appears to be multifactorial. Recently, a product of Leydig cells termed Leydig insulin-like hormone (INSL3) has been proposed as a putative trophic hormone of the first part of descent. Absence of Insl3 in male mice results in bilateral cryptorchidism and mutations involving this gene may be a cause of cryptorchidism in man. We sequenced both exons of the human INSL3 gene in 31 men who presented with idiopathic unilateral or bilateral cryptorchidism. The only sequence variant was an amino acid substitution in the C-peptide of the molecule. This change was also found in a control group of normal fertile men indicating that it is a polymorphism unrelated to the phenotype. These results suggest that mutations involving the human INSL3 gene are not a common cause of cryptorchidism in man.     

Hand development and sequence of ossification in the forelimb of the European shrew Crocidura russula (Soricidae) and comparisons across therian mammals

Hand development in the European shrew Crocidura russula is described, based on the examination of a cleared and double-stained ontogenetic series and histological sections of a c. 20-day-old embryo and a neonate. In the embryo all carpal elements are still mesenchymal condensations, and there are three more elements than in the adult stage: the 'lunatum', which fuses with the scaphoid around birth; a centrale, which either fuses with another carpal element or just disappears later in ontogeny; and the anlage of an element that later fuses with the radius. Carpal arrangement in the neonate and the adult is the same. In order to compare the relative timing of the onset of ossification in forelimb bones in C. russula with that of other therians, we built up two matrices of events based on two sets of data and used the event-pair method. In the first analysis, ossification of forelimb elements in general was examined, including that of the humerus, radius, ulna, the first carpal and metacarpal to ossify, and the phalanges of the third digit. The second analysis included each carpal, humerus, radius, ulna, the first metacarpal and the first phalanx to ossify. Some characters (= event-pairs) provide synapomorphies for some clades examined. There have been some shifts in the timing of ossification apparently not caused by ecological and/or environmental influences. In two species (Oryctolagus and Myotis), there is a tendency to start the ossification of the carpals relatively earlier than in all other species examined, the sauropsid outgroups included.     

Origin and evolution of somatic cell testicular tumours in transgenic mice

Transgenic mice bearing a construct in which the expression of the SV40 oncogene is directed by the AMH promoter (AT mice) develop testicular tumours in adult life. We aimed to study early steps of tumour development and characterize tumours at different ages by histological, morphometric, and immunohistochemical techniques. One‐ to 3‐month‐old AT mice depicted multifocal Leydig cell hyperplasia. The testicular volume occupied by interstitial tissue was significantly higher in 3‐month‐old AT mice in comparison with littermate controls. Between 5 1/2 and 7 months, microscopic interstitial tumours developed that progressively evolved to form large confluent areas of high mitotic index in 7‐ to 14‐month‐old AT mice. Tumour cells had the characteristics and histoarchitecture of Leydig cells, or formed solid cord‐like structures reminiscent of those seen in Sertoli cell tumours. Hyperplastic areas and tumours diffusely expressed 3β‐hydroxysteroid dehydrogenase (3β‐HSD) in Leydig cell areas. AMH expression was negative in Leydig cell conglomerates and tumours and variable in cord‐like tumours. The SV40 T antigen and markers of cell proliferation (PCNA) were intensely positive in hyperplastic cells and tumours. Control mice of similar ages showed neither hyperplasia nor tumours, and SV40 T expression was always negative. In conclusion, transgenic mice develop large testicular tumours that are preceded by interstitial hyperplasia and microtumours. The histological and immunohistochemical phenotype of tumours (Leydig and Sertoli cell differentiation, positive 3β‐HSD, and variable AMH) suggests a mixed differentiation of somatic cells of the specialized gonadal stroma. The finding that an oncogene directed by a promoter specifically active in fetal Sertoli cells has given rise to testicular tumours of mixed differentiation is compatible with a common origin of Leydig and Sertoli cells from the specific stroma of the gonadal ridge, as supported by double labelling experiments in fetal mice showing co‐localization of the transgene with Sertoli and Leydig cell markers. Copyright © 2010 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.     

Origin of anti-tumor immunity failure in mammals and new possibility for immunotherapy

There is now much evidence that tumors can be immunogenic. Tumor cells very often express antigens in a form recognizable by the host immune system, but most frequently without consequences on tumor progression. This has been shown in many experimental models and different experimental conditions. Immediate mechanisms for the escape of tumors from immune response are very similar with mechanisms for the escape of fetoplacental unit (as an allograft) from maternal immune response. Similarity between these two mechanisms is so significant that any randomness is banished. Mechanisms of anti-tumor immunity in mammals are substantially different in comparison with mechanisms of anti-tumor immunity in other classes of vertebrates. Moreover, type of most frequently tumors in non-mammalians vertebrates is also significant different. Incidence of malignant tumors in non-mammalians vertebrates is significantly less than incidence of malignant tumors in mammals. These facts indicate that immune system of mammals during anti-tumor immune response is tricked with similarity between tumor cells and trophoblast or other placental cells. It may be a specific evolutionary approach in rendering of anti-tumor immunity failure in mammals, and new possibility for anti-tumor immunotherapy.     

Origin and distribution of potassium bromate-induced testicular and peritoneal mesotheliomas in rats

Tissue sections were examined from a 2-year bioassay of male Fischer 344 rats treated with potassium bromate administered in drinking water. All animals exhibiting peritoneal mesotheliomas also had mesotheliomas of the tunica vaginalis testis mesorchium (the reverse was not true), and the correlation of these 2 types of mesotheliomas was highly significant (r2 = 0.98). Mapping of the tunica vaginalis tumors at all time points and at all bromate concentrations revealed a pattern of increasing incidence of tumor formation on the mesothelium of the tunica vaginalis testis as a function of proximity to the mesorchial ligament. Thus, the mesorchium appears to be the major mesothelial target site for potassium bromate-mediated carcinogenesis. The frequency of occurrence of mesotheliomas by location was tunica vaginalis testis (25%), mesosplenium (20%), mesentery (10%), mesojejunum/mesocolon (8%), bladder (6.5%), mesogastrium (13%), liver serosa (5%), and kidney, small intestine, and rectum (1% each). A complete cross-section of the rat testis was prepared and used to construct a complete map of the mesothelium. Any attempt to determine the role of local dose and tissue susceptibility for the purpose of interspecies risk extrapolation must take into account the complex anatomy and physiology of this region of the visceral and testicular suspensory apparatus. Improved histologic approaches are needed for adequate assessment of this delicate suspensory system.     

Splice variants of the relaxin and INSL3 receptors reveal unanticipated molecular complexity

LGR7 and LGR8 are G protein-coupled receptors that belong to the leucine-rich repeat-containing G-protein coupled receptor (LGR) family, including the thyroid-stimulating hormone (TSH), LH and FSH receptors. LGR7 and LGR8 stimulate cAMP production upon binding of the cognate ligands, relaxin and insulin-like peptide 3 (INSL3), respectively. We cloned several novel splice variants of both LGR7 and LGR8 and analysed the function of four variants. LGR7.1 is a truncated receptor, including only the N-terminal region of the receptor and two leucine rich repeats. In contrast, LGR7.2, LGR7.10 and LGR 8.1 all contain an intact seven transmembrane domain and most of the extracellular region, lacking only one or two exons in the ectodomain. Our analysis demonstrates that although LGR7.10 and LGR8.1 are expressed at the cell surface, LGR7.2 is predominantly retained within cells and LGR7.1 is partially secreted. mRNA expression analysis revealed that several variants are co-expressed in various tissues. None of these variants were able to stimulate cAMP production following relaxin or INSL3 treatment. Unexpectedly, we did not detect any direct specific relaxin or INSL3 binding on any of the splice variants. The large number of receptor splice variants identified suggests an unforeseen complexity in the physiology of this novel hormone-receptor system.     

Oncofetal protein glypican-3 in testicular germ-cell tumor

The expression of an oncofetal protein, the glypican-3 (GPC3), was immunohistochemically evaluated in a wide variety of primary testicular germ-cell tumors (GCTs) in comparison with other markers, alpha-fetoprotein (AFP), human chorionic gonadotropin (hCG)-beta, and OCT3/4. Eighty-nine cases of GCT including 22 cases of mixed GCT were evaluated with reference to each tumor component. GPC3 expression was observed in neoplastic cells of yolk-sac tumor (YST) (25/25), teratoma (2/10), components of syncytiotrophoblastic giant cells (STGCs) (10/14), and choriocarcinoma (1/3), but none in intratubular germ-cell neoplasias, unclassified type (0/33), seminomas (0/61), or embryonal carcinoma (0/19). All cases of YST showed diffuse labeling of neoplastic cells in cytoplasmic and membranous patterns, and the positive area of GPC3 was much larger than that of AFP. Glandular structures in teratomas showed GPC3 immunostaining as well as AFP. Although the number of GPC3-positive cells was smaller in STGC components and choriocarcinoma, there was no diffusion artifact in GPC3 immunostaining, as was frequently encountered in hCG-beta staining. Thus, GPC3 is a unique oncofetal protein, which is useful as an immunohistochemical marker for GCT differentiated to extraembryonic tissue, especially YST.     

Isozymes of glyceraldehyde-3-phosphate dehydrogenase in man and other mammals

Multiple electrophoretically distinct forms of glyceraldehyde-3-phosphate dehydrogenase have been observed in human and other mammalian tissues. The human isozymes appear to have essentially the same structural and kinetic properties. An apparent correlation between red-cell age and the relative intensities of the isozymes supports the idea that the isozymes arise as a result of post-translational modification of the polypeptide chain. The possibility that a second locus is involved in the determination of these isozymes is discussed.     

Valproic acid induces caspase 3-mediated apoptosis in microglial cells

Valproic acid is widely used for the treatment of epilepsy and mood disorders, but its mode of action is unclear. Treatment of neuronal cells with valproic acid promotes neurite sprouting, is neuroprotective and drives neurogenesis; however its effects on non-neuronal brain cells are less clear. We report that valproic acid induces apoptosis in the mouse microglial cell line, BV-2, at concentrations within the therapeutic range. When BV-2 cells were incubated for 24 h with 500–1000 μM valproic acid we observed a reduction in cell number, the appearance of apoptotic morphology and increased caspase 3 cleavage. Exposure of a macrophage cell line (RAW 264.7) to similar concentrations of valproic acid also led to reduced cell number but no caspase 3 cleavage, suggesting these cells responded to valproic acid with reduced proliferation rather than apoptosis. This was confirmed using bromodeoxyuridine incorporation studies. Similar concentrations of valproic acid added to Neuro-2a, SK-N-SH and C6 cell lines as well as human NTera-2 astrocytes did not evoke cell death. The caspase 3 inhibitor DEVD-CHO inhibited valproic acid-induced apoptosis in BV-2 cells whereas the MEK inhibitor U0126 potentiated valproic acid-mediated apoptosis. These results demonstrate that valproic acid selectively induces apoptosis in BV-2 cells by way of a caspase 3-mediated action. As activated microglia secrete neurotoxins in neurodegenerative diseases such as Alzheimer’s, Parkinson’s, and HIV dementia, valproic acid may alleviate these diseases by selectively killing microglia.     

Zinc has no effect on IL-3-mediated apoptosis of BAF-3 cells but enhances CD95-mediated apoptosis of jurkat cells

The feasibility of using a zinc-inducible gene expression system for the study of apoptosis-controlling genes in BAF-3 murine B cells and Jurkat human T cells was evaluated. Initially, cell sensitivity to a range of zinc concentrations was examined. It was found that zinc concentrations above 60 microM were toxic to BAF-3 cells and those above 50 microM were toxic to Jurkat cells. Secondly, the zinc concentration required to achieve maximal gene expression was examined. BAF-3 cells transiently transfected with the pMTCB6+/luciferase vector were exposed to zinc concentrations ranging from 0-120 microM, whilst stably transfected Jurkat cells were exposed to 0-70 microM zinc. At zinc concentrations nontoxic to each cell type, the maximum induction achieved was 20-fold (at 60 microM) in BAF-3 cells, and 7.5-fold (at 50 microM) in Jurkat cells. Thirdly, the effect of zinc on apoptosis was examined. It was shown that exposure to nontoxic zinc concentrations had no effect on IL-3 withdrawal-mediated apoptosis of BAF-3 cells. However, in the case of Jurkat cells, pre-exposure to zinc augmented CD95-mediated apoptosis. These results illustrate the importance of characterizing individual cell lines when using zinc-inducible gene expression systems.     

Visual control of action in step descent

Visual guidance of forwards, sideways, and upwards stepping has been investigated, but there is little knowledge about the visuomotor processes underlying stepping down actions. In this study we investigated the visual control of a single vertical step. We measured which aspects of the stepping down movement scaled with visual information about step height, and how this visual control varied with binocular versus monocular vision. Subjects stepped down a single step of variable and unpredictable height. Several kinematic measures were extracted including a new measure, “kneedrop”. This describes a transition in the movement of the lower leg, which occurs at a point proportional to step height. In a within-subjects design, measurements were made with either full vision, monocular vision, or no vision. Subjects scaled kneedrop relative to step height with vision, but this scaling was significantly impaired in monocular and no vision conditions. The study establishes a kinematic marker of visually controlled scaling in single-step locomotion which will allow further study of the visuomotor control processes involved in stepping down.     

R171H missense mutation of INSL6 in a patient with spermatogenic failure

Insulin-like peptide 6 (INSL6) is a newly identified insulin/relaxin family peptide hormone that is predominantly expressed by the male germ cells in testes. A recent murine study demonstrated that INSL6-knockout results in spermatogenic failure. In the present study, human INSL6 gene was screened for mutations that may contribute to human spermatogenic failure. Of 249 patients and 249 healthy control subjects, a heterozygous R171H missense mutation was found in one patient. The R171H mutation probably disturbed the in vivo processing of the INSL6 prohormone because it was located at the absolutely conserved tetrabasic cleavage site between the C-peptide and the A-chain, therefore the R171H missense mutation might be responsible for human spermatogenic failure.     

Toll样受体3介导抑制Bewo细胞中乙型肝炎病毒复制

目的探讨Toll样受体3（TLR3）介导的天然免疫对Bewo细胞中乙型肝炎病毒（HBV）复制的影响。方法首先用TLR3配体polyI：C处理Bewo细胞,观察细胞TLR3 mRNA表达的动力学。然后将2μg 1.3倍HBV全基因重组质粒pcDNA3.1（＋）-HBV1.3转染Bewo细胞,12h后,以polyI：C处理3d。最后,用抗TLR3处理Bewo细胞1h后,加入25μg/ml polyI：C刺激。采用荧光定量RT-PCR、微粒子酶免疫分析法（MEIA）和荧光定量PCR法分别检测细胞TLR3mRNA表达、HBsAg、HBeAg及HBV DNA水平。结果 polyI：C可显著诱导Bewo细胞TLR3 mRNA表达（P〈0.05）,呈时间和剂量依赖性;与对照组比较,polyI：C可显著抑制HBV复制（P〈0.001）,抗TLR3可显著逆转polyI：C对HBV复制的抑制作用（P〈0.01）。结论 TLR3介导的天然免疫能一定程度抑制Bewo细胞中HBV复制,为防治HBV宫内感染提供了新的途径。