scholarly journals Tight junctions in the testis: new perspectives

2010 ◽  
Vol 365 (1546) ◽  
pp. 1621-1635 ◽  
Author(s):  
Dolores D. Mruk ◽  
C. Y. Cheng
Keyword(s):  
Epithelial Cells ◽  
Cancer Cells ◽  
Tight Junctions ◽  
Germ Cells ◽  
Sertoli Cells ◽  
Systemic Circulation ◽  
Signalling Pathways ◽  
Future Studies ◽  
Cellular Event ◽  
Stage Viii

In the testis, tight junctions (TJs) are found between adjacent Sertoli cells at the level of the blood–testis barrier (BTB) where they coexist with basal ectoplasmic specializations and desmosome-gap junctions. The BTB physically divides the seminiferous epithelium into two distinct compartments: a basal compartment where spermatogonia and early spermatocytes are found, and an adluminal compartment where more developed germ cells are sequestered from the systemic circulation. In order for germ cells (i.e. preleptotene spermatocytes) to enter the adluminal compartment, they must cross the BTB, a cellular event requiring the participation of several molecules and signalling pathways. Still, it is not completely understood how preleptotene spermatocytes traverse the BTB at stage VIII of the seminiferous epithelial cycle. In this review, we discuss largely how TJ proteins are exploited by viruses and cancer cells to cross endothelial and epithelial cells. We also discuss how this information may apply to future studies investigating the movement of preleptotene spermatocytes across the BTB.

scholarly journals Sertoli–germ cell junctions in the testis: a review of recent data

2010 ◽  
Vol 365 (1546) ◽  
pp. 1593-1605 ◽  
Author(s):  
Ilona A. Kopera ◽  
Barbara Bilinska ◽  
C. Yan Cheng ◽  
Dolores D. Mruk
Keyword(s):  
Germ Cell ◽  
Germ Cells ◽  
Sertoli Cells ◽  
Seminiferous Epithelium ◽  
Cell Junctions ◽  
Molecular Architecture ◽  
Future Studies ◽  
Junction Type ◽  
Stage Viii ◽  
Immunological Barrier

Spermatogenesis is a process that involves an array of cellular and biochemical events, collectively culminating in the formation of haploid spermatids from diploid precursor cells known as spermatogonia. As germ cells differentiate from spermatogonia into elongated spermatids, they also progressively migrate across the entire length of the seminiferous epithelium until they reach the luminal edge in anticipation of spermiation at late stage VIII of spermatogenesis. At the same time, these germ cells must maintain stable attachment with Sertoli cells via testis-unique intermediate filament- (i.e. desmosome-like junctions) and actin- (i.e. ectoplasmic specializations, ESs) based cell junctions to prevent sloughing of immature germ cells from the seminiferous epithelium, which may result in infertility. In essence, both desmosome-like junctions and basal ESs are known to coexist between Sertoli cells at the level of the blood–testis barrier where they cofunction with the well-studied tight junction in maintaining the immunological barrier. However, the type of anchoring device that is present between Sertoli and germ cells depends on the developmental stage of the germ cell, i.e. desmosome-like junctions are present between Sertoli and germ cells up to, but not including, step 8 spermatids after which this junction type is replaced by the apical ES. While little is known about the biology of the desmosome-like junction in the testis, we have a relatively good understanding of the molecular architecture and the regulation of the ES. Here, we discuss recent findings relating to these two junction types in the testis, highlighting prospective areas that should be investigated in future studies.

Freeze-etch observations on the tight junctions of sertoli cells grown in organ culture with FSH

1978 ◽  
Vol 36 (2) ◽  
pp. 340-341
Author(s):  
Rita Meyer ◽  
Zoltan Posalaky ◽  
Dennis Mcginley
Keyword(s):  
Organ Culture ◽  
Tight Junctions ◽  
Sertoli Cell ◽  
Germ Cells ◽  
Sertoli Cells ◽  
Barrier Function ◽  
Cell Junction ◽  
Intramembranous Particles ◽  
Junctional Complexes ◽  
Oriented Parallel

The Sertoli cell tight junctional complexes have been shown to be the most important structural counterpart of the physiological blood-testis barrier. In freeze etch replicas they consist of extensive rows of intramembranous particles which are not only oriented parallel to one another, but to the myoid layer as well. Thus the occluding complex has both an internal and an overall orientation. However, this overall orientation to the myoid layer does not seem to be necessary to its barrier function. The 20 day old rat has extensive parallel tight junctions which are not oriented with respect to the myoid layer, and yet they are inpenetrable by lanthanum. The mechanism(s) for the control of Sertoli cell junction development and orientation has not been established, although such factors as the presence or absence of germ cells, and/or hormones, especially FSH have been implicated.

Differential expression of acidic cytokeratins 18 and 19 during sexual differentiation of the rat gonad

Development ◽  
1992 ◽  
Vol 115 (2) ◽  
pp. 503-517
Author(s):  
V. Fridmacher ◽  
O. Locquet ◽  
S. Magre
Keyword(s):  
Monoclonal Antibodies ◽  
Germ Cells ◽  
Sertoli Cells ◽  
Sexual Differentiation ◽  
Somatic Cells ◽  
Positive Staining ◽  
Female Rat ◽  
Male And Female ◽  
Future Studies ◽  
Testicular Differentiation

The expression of cytokeratins (CKs) 8, 18 and 19 was analyzed in male and female rat gonads from the undifferentiated stage (12.5 days of gestation) until two weeks after birth by indirect immunofluorescence, using specific monoclonal antibodies anti-CK 8 (LE41), anti-CK 19 (LP2K) and anti-CK 18 (LE65 and RGE53). In the undifferentiated blastema, the somatic cells were stained for CK 8 and CK 19, whereas no detectable immunoreactivity for CK 18 was obtained. The same staining CK pattern was observed in ovaries, in the somatic cells of ovigerous cords and in primary follicles. The staining was progressively decreasing in growing follicles after one week after birth. At the onset of testicular differentiation, when the first Sertoli cells differentiate in the gonad of 13.5-day old male fetuses, positive staining for CK 18 became evident, in addition to CK 8 and CK 19 expression. In the following days, CK 8, CK 18 and CK 19 were detected in Sertoli cells in the differentiating seminiferous cords, but progressively the reactivity for CK 19 decreased and was no longer observed after 18.5-19.5 days of gestation. In all cases, CKs were found to be coexpressed with vimentin, and germ cells were negative for both vimentin and CKs. The results reported here show first, that CKs are expressed before sexual differentiation in gonadal blastema in which no epithelial organization is observed, and second, that there is a CK 18/CK 19 shift in expression during morphogenesis of the testis which is not observed in the differentiating ovary. Future studies will have to determine whether these differences in CK expression are due to epitope-masking phenomena or to the regulation of CK synthesis.

scholarly journals MAP/microtubule affinity-regulating kinases, microtubule dynamics, and spermatogenesis

2013 ◽  
Vol 217 (2) ◽  
pp. R13-R23 ◽  
Author(s):  
Elizabeth I Tang ◽  
Dolores D Mruk ◽  
C Yan Cheng
Keyword(s):  
Sertoli Cells ◽  
Microtubule Dynamics ◽  
Seminiferous Epithelium ◽  
Morphological Transformation ◽  
Future Studies ◽  
Quiescent Cells ◽  
Morphological Studies ◽  
Stage Viii

During spermatogenesis, spermatids derived from meiosis simultaneously undergo extensive morphological transformation, to become highly specialized and metabolically quiescent cells, and transport across the seminiferous epithelium. Spermatids are also transported back-and-forth across the seminiferous epithelium during the epithelial cycle until they line up at the luminal edge of the tubule to prepare for spermiation at stage VIII of the cycle. Spermatid transport thus requires the intricate coordination of the cytoskeletons in Sertoli cells (SCs) as spermatids are nonmotile cells lacking the ultrastructures of lamellipodia and filopodia, as well as the organized components of the cytoskeletons. In the course of preparing this brief review, we were surprised to see that, except for some earlier eminent morphological studies, little is known about the regulation of the microtubule (MT) cytoskeleton and the coordination of MT with the actin-based cytoskeleton to regulate spermatid transport during the epithelia cycle, illustrating that this is a largely neglected area of research in the field. Herein, we summarize recent findings in the field regarding the significance of actin- and tubulin-based cytoskeletons in SCs that support spermatid transport; we also highlight specific areas of research that deserve attention in future studies.

scholarly journals Coxsackievirus and Adenovirus Receptor Is Up-Regulated in Migratory Germ Cells during Passage of the Blood-Testis Barrier

Endocrinology ◽  
2007 ◽  
Vol 148 (11) ◽  
pp. 5459-5469 ◽  
Author(s):  
Momina Mirza ◽  
Cecilia Petersen ◽  
Katarina Nordqvist ◽  
Kerstin Sollerbrant
Keyword(s):  
Tight Junctions ◽  
Adhesion Molecule ◽  
Germ Cells ◽  
Sertoli Cells ◽  
Rt Pcr ◽  
Adult Testis ◽  
Functional Complex ◽  
Coxsackievirus And Adenovirus Receptor ◽  
Adenovirus Receptor ◽  
Blood Testis Barrier

The coxsackievirus and adenovirus receptor (CAR) is a cell adhesion molecule expressed in epithelial tight junctions and other cell-cell contacts. Using indirect immunofluorescence, quantitative RT-PCR, and Western blots, the expression and distribution of CAR in developing and adult testis are examined. CAR is highly expressed in both Sertoli and germ cells during perinatal and postnatal development, followed by a rapid down-regulation of both mRNA and protein levels. Interestingly, we find that CAR is a previously unknown downstream target for FSH because CAR mRNA levels were induced in primary cultures of FSH-stimulated Sertoli cells. In contrast to other epithelia, CAR is not a general component of tight junctions in the seminiferous epithelium, and Sertoli cells in the adult testis do not express CAR. Instead, CAR expression is stage dependent and specifically found in migratory germ cells. RT-PCR also demonstrated the presence of junctional adhesion molecule-like (JAML) in the testis. JAML was previously reported by others to form a functional complex with CAR regulating transepithelial migration of leukocytes. The expression of JAML in the testis suggests that a similar functional complex might be present during germ cell migration across the blood-testis barrier. Finally, an intermediate compartment occupied by CAR-positive, migrating germ cells and flanked by two occludin-containing junctions is identified. Together, these results implicate a function for CAR in testis morphogenesis and in migration of germ cells across the blood-testis barrier during spermatogenesis.

scholarly journals Spermatogenesis in sheep supplemented with detoxified castor bean (Ricinus communis L.) as a replacement for soybean meal

2020 ◽  
Vol 21 ◽  
Author(s):  
Laiara Fernandes ROCHA ◽  
Márcio de Oliveira RIBEIRO ◽  
Ana Lúcia Almeida SANTANA ◽  
Ronival Dias Lima de JESUS ◽  
Rosiléia Silva SOUZA ◽  
...  
Keyword(s):  
Germ Cells ◽  
Soybean Meal ◽  
Sertoli Cells ◽  
Castor Bean ◽  
Ricinus Communis ◽  
Panicum Maximum ◽  
Future Studies ◽  
Ricinus Communis L ◽  
The Mean ◽  
Level Of Significance

ABSTRACT The objective was to evaluate the effect of replacing soybean meal with the detoxified castor bean cake on testicular morphometry and spermatogenesis of sheep. Were used 24 uncastrated, 9-month old sheep weighing 29±0.8 kg they were randomly distributed among three treatments: T1 = 0%, T2 = 50%, and T3 = 100% substitution of soybean meal with detoxified castor bean cake. The animals were fed with Aruana grass pastage (Panicum maximum ‘Aruana’) and a ration for 90 days. After slaughtering, the testicles were collected and histological slides were prepared with tissue fragments. The data were evaluated for normality using the Shapiro-Wilk test, and analysis of variance was carried out at 5% level of significance. Substitution of soybean meal with detoxified castor bean cake had no effect on any of the assessed variables at the tested levels (P >0.05). The mean yield of spermatogenesis was 72.91 rounded spermatids per spermatogonium; the mean of total number of germ cells held by a Sertoli cell was 12.09; the mean of the testicular spermatic reserve was 31.82×109 and that per testicular gram was 238.28×106; the mean of daily spermatic production was 3.03×109 and that per testicular gram was 22.69×106; and the total number of Sertoli cells was 4.15×109 and that per testicular gram was 34.51×106. The results show that it is possible to replace 100% of the soybean meal with detoxified castor bean cake in sheep diet without any effects on spermatogenesis; however, it is important to perform seminal evaluations in future studies.

Male Reproductive Function

2011 ◽  
Author(s):  
William J. Kovacs
Keyword(s):  
Tight Junctions ◽  
Sertoli Cell ◽  
Germ Cells ◽  
Sertoli Cells ◽  
Leydig Cells ◽  
Reproductive Function ◽  
Rete Testis ◽  
Seminiferous Tubules ◽  
Male Reproductive Function ◽  
Peritubular Tissue

The testes are the source of both germ cells and hormones essential for male reproductive function. The production of both sperm and steroid hormones is under complex feedback control by the hypothalamic-pituitary system. The testis consists of a network of tubules for the production and transport of sperm to the excretory ducts and a system of interstitial cells (called Leydig cells) that express the enzymes required for the synthesis of androgens. The spermatogenic or seminiferous tubules are lined by a columnar epithelium composed of the germ cells themselves as well as supporting Sertoli cells surrounded by peritubular tissue made up of collagen, elastic fibers, and myofibrillar cells. Tight junctions between Sertoli cells at a site between the spermatogonia and the primary spermatocyte form a diffusion barrier that divides the testis into two functional compartments, basal and adluminal. The basal compartment consists of the Leydig cells surrounding the tubule, the peritubular tissue, and the outer layer of the tubule containing the spermatogonia. The adluminal compartment consists of the inner two-thirds of the tubules containing primary spermatocytes and germ cells in more advanced stages of development. The base of the Sertoli cell is adjacent to the basement membrane of the spermatogenic tubule, with the inner portion of the cell engulfing the developing germ cells so that spermatogenesis actually takes place within a network of Sertoli cell cytoplasm. The mechanism by which spermatogonia pass through the tight junctions between Sertoli cells to begin spermatogenesis is unknown. The close proximity of the Leydig cell to the Sertoli cell with its embedded germ cells is thought to be critical for normal male reproductive function. The seminiferous tubules empty into a network of ducts termed the rete testis. Sperm are then transported into a single duct, the epididymis. Anatomically, the epididymis can be divided into the caput, the corpus, and the cauda regions. The caput epididymidis consists of 8 to 12 ductuli efferentes, which have a larger lumen tapering to a narrower diameter at the junction of the ductus epididymidis.

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