THE INTER-SERTOLI CELL TIGHT JUNCTIONS IN GERM CELL-FREE SEMINIFEROUS TUBULES FROM PRENATALLY IRRADIATED RATS: A FREEZE-FRACTURE STUDY

1996 ◽  
Vol 20 (7) ◽  
pp. 513-522 ◽  
Author(s):  
A RIBEIRO
Keyword(s):  
Germ Cell ◽  
Tight Junctions ◽  
Sertoli Cell ◽  
Freeze Fracture ◽  
Seminiferous Tubules ◽  
Fracture Study

Correlation between blood-testis barrier development and onset of the first spermatogenic wave in normal and busulfan-treated rats

1990 ◽  
Vol 48 (3) ◽  
pp. 78-79
Author(s):  
Juan C. Cavicchia ◽  
Fabio L. Sacerdote
Keyword(s):  
Germ Cell ◽  
Tight Junctions ◽  
Basal Lamina ◽  
Sertoli Cells ◽  
Freeze Fracture ◽  
Seminiferous Epithelium ◽  
Seminiferous Tubules ◽  
Pregnant Rats ◽  
Synaptonemal Complexes ◽  
New Born

Pregnant rats (day 13) received 10mg/kg of Busulfan i.p. in order to deplete of germ cell the testes of the new born rats. The seminiferous tubules of their off spring from postnatal age 1 day up to day 35 were examined with TEM after fixation plus intercellular tracers, and with freeze-fracture techniques. During this period, the inter-Sertoli tight junctions of controls increase both in numbers and in length. Between days 10 and 13 the seminiferous cords have numerous preleptotene and leptotene spermatocytes (Fig.1) surrounded by tracer. The inter-Sertoli junctions are tortuous and predominantly perpendicular to the basal lamina. Between ages 13 and 20 days the seminiferous epithelium reaches zygotene-pachytene stages (fig.2) identified by the presence of synaptonemal complexes. The tracer is stopped at the inter-Sertoli junctions at this stage, whereas it still permeates tubules displaying preleptotene and leptotene spermatocytes.Freeze-fracture shows that the orientation of inter-Sertoli junctions has changed to parallel, both to each other and to the basal lamina (fig.3). In the Busulfan treated rats, the tubules continue having, up to postnatal day 30, only Sertoli cells and scanty spermatogonia.

Intercellular junctional complexes of the rat seminiferous tubules: A freeze-fracture study

1977 ◽  
Vol 189 (2) ◽  
pp. 211-231 ◽  
Author(s):  
Dennis McGinley ◽  
Zoltan Posalaky ◽  
Martin Porvaznik
Keyword(s):  
Freeze Fracture ◽  
Seminiferous Tubules ◽  
Fracture Study ◽  
Junctional Complexes

scholarly journals A freeze-fracture study on the developing satellite cells of spinal ganglia in the chick embryo

1988 ◽  
Vol 46 (1) ◽  
pp. 6-9
Author(s):  
Claudio A. Ferraz de Carvalho ◽  
Ciro F. da Silva
Keyword(s):  
Chick Embryo ◽  
Gap Junctions ◽  
Tight Junctions ◽  
Small Groups ◽  
Satellite Cells ◽  
Freeze Fracture ◽  
Fracture Analysis ◽  
Spinal Ganglia ◽  
Pinocytotic Vesicles ◽  
Fracture Study

A freeze-fracture analysis of the satellite cells of spinal ganglia of the chick embryo was performed in 8 successive stages of development, from the 5th incubation day to hatching. The characteristic laminar disposition of the cells were first observed on the 7th day. Tight junctions were found at the 20th incubation day. Small groups or irregular aggregates of particles, but not gap junctions, were described on the 7th and 8th days. Pinocytotic vesicles were pointed out in the different stages considered.

scholarly journals Tight-junctional strands first appear in regions where three cells meet in differentiating olfactory epithelium: a freeze-fracture study

1988 ◽  
Vol 89 (4) ◽  
pp. 495-505
Author(s):  
B.P. Menco
Keyword(s):  
Embryonic Development ◽  
Gap Junction ◽  
Tight Junctions ◽  
Olfactory Epithelium ◽  
Freeze Fracture ◽  
Subsequent Development ◽  
Epithelial Surface ◽  
Direction Parallel ◽  
Longitudinal Orientation ◽  
Fracture Study

Tight junctions of the olfactory epithelium of rat embryos were studied at the 14th day of gestation and during their subsequent development. Two different epithelial morphologies could be distinguished at the 14th gestational day. In one group of embryos the epithelial surface appeared undifferentiated, with tight-junctional strands found exclusively in regions where three cells met. The main orientation of these strands is in a direction parallel to the longitudinal orientation of the epithelial cells. These junctions resemble tight junctions that interconnect three cells, i.e. tricellular tight junctions, in that respect. However, unlike these the junctions mainly have single strands of particles, whereas tricellular junctions usually consist of paired strands of particles. Tight-junctional strands were completely absent in areas where two cells met. These areas, i.e. those of incipient bicellular tight junctions, had gap-junction-like aggregates of intramembranous particles. Another group of 14-day-old embryos displayed a differentiating olfactory epithelial surface with bicellular as well as tricellular tight-junctional strands. The latter ones were paired. Here too the tight-junctional belts displayed some gap-junction-like aggregates of particles, but there were considerably fewer of these than earlier. As one or the other tight-junctional appearance was always seen in a single freeze-fracture replica, it is reasonable to assume that the two tight-junctional appearances reflect a sequential pattern of differentiation peculiar to the whole surface of the olfactory epithelium, i.e. to surfaces of receptor cells as well as to surfaces of supporting cells. It would appear that, at the onset of olfactory epithelial differentiation, tight junctions first interconnect cells in regions where three cells meet and that tricellular strand formation precedes the formation of bicellular strands. When strands were present at the 14th day of embryonic development, their numbers were lower than those found later. However, strand packing, expressed as the density per micrometre of strands parallel to the epithelial surface, increased beginning at the 16th day of embryonic development.

220 EFFECTS OF FOLLICLE-STIMULATING HORMONE AND 6-N-PROPYL-2-THIOURACIL ON BOAR SPERMATOGENESIS

2008 ◽  
Vol 20 (1) ◽  
pp. 189
Author(s):  
J. Baldrighi ◽  
W. Averhart ◽  
M. Mello ◽  
J. Ford ◽  
L. Franca ◽  
...  
Keyword(s):  
Thyroid Hormone ◽  
Germ Cell ◽  
Sertoli Cell ◽  
Sertoli Cells ◽  
Sperm Cell ◽  
Follicle Stimulating Hormone ◽  
Cell Development ◽  
Seminiferous Tubules ◽  
Post Surgery ◽  
Stimulating Hormone

Currently, swine biotechnologies related to reproduction increase considerably. Investments are made in order to improve the reproductive rates and performance of breeding stock. Understanding the physiology of spermatogenesis will help increase sperm production and improve boar efficiency. Sertoli cells are the only somatic cells present in the seminiferous tubules. Their function is to guarantee proper sperm formation and maturation. Each Sertoli cell is responsible for nursing a finite number of spermatogonia. At puberty, Sertoli cell maturation and lumen formation have occurred within the seminiferous tubules and germ cells have proliferated rapidly followed by the onset of spermatogenesis. At least two hormones are known to play a role in Sertoli cell proliferation and maturation: follicle-stimulating hormone (FSH) and thyroid hormone. FSH secretion has been assumed to be the stimulus for proliferation. The thyroid hormone is responsible for normal postnatal growth and development. Alterations in thyroid activity have frequently been associated with changes in male reproductive functions, since hypothyroidism, induced with 6-N-propyl-2-thiouracil (PTU) soon after birth, is associated with a marked delay in sexual maturation and development. The goal of this study was to report the effect of FSH and PTU on the stages of sperm cell development of young pigs. Six piglets of 1, 7, 14, 25, and 55 days of age were castrated and their testes were sectioned to grafts of 5 mm3. The grafts were then transplanted subcutaneously into the dorsum of 12 castrated nude mice per age group. Two days post-surgery mice were randomly assigned to one of four treatment groups: control, FSH (5 IU rFSH), PTU (0.015% solution), and FSH + PTU. Following 14 days of treatment, testicular tissue pieces were allowed to grow for 2 additional weeks. Tissues were then harvested, immersion-fixed in neutral buffered formalin, and embedded in paraffin. Five-micron-thick sections were stained using hematoxylin and eosin. Slides were evaluated under light microscopy and the oldest germ cell type present in each section was recorded. Germ cell types were recorded as spermatogonium, spermatocyte, early spermatid, and late spermatid. Statistical differences between all groups were detected using paired Student t-tests. There were no differences noted between control groups and those treated with PTU or FSH alone. No effect concerning age of castration on grafts development was observed. There was a slightly significant increase (P = 0.05) in the number of spermatocytes observed in the groups treated with FSH+PTU. These data suggest that there is a potential synergistic effect of FSH and PTU on sperm cell development. Based on these results, further studies need to be performed to completely understand the effect of these two hormones on Sertoli cells.

Tight and gap junctions in the intestinal tract of tunicates (Urochordata): a freeze-fracture study

1986 ◽  
Vol 84 (1) ◽  
pp. 1-17
Author(s):  
N.J. Lane ◽  
R. Dallai ◽  
P. Burighel ◽  
G.B. Martinucci
Keyword(s):  
Gap Junctions ◽  
Tight Junctions ◽  
Thin Section ◽  
Intestinal Tract ◽  
Freeze Fracture ◽  
Intestinal Cells ◽  
Fracture Profile ◽  
Tracer Studies ◽  
Septate Junctions ◽  
Fracture Study

The intestinal tracts from seven different species of tunicates, some solitary, some colonial, were studied fine-structurally by freeze-fracture. These urochordates occupy an intermediate position phylogenetically between the vertebrates and the invertebrates. The various regions of their gut were isolated for examination and the junctional characteristics of each part investigated. All the species examined exhibited unequivocal vertebrate-like belts of tight-junctional networks at the luminal border of their intestinal cells. No septate junctions were observed. The tight junctions varied in the number of their component strands and the depth to which they extended basally, some becoming loose and fragmented towards that border. The junctions consisted of ridges or rows of intramembranous particles (IMPs) on the P face, with complementary, but offset, E face grooves into which IMPs sometimes fractured. Tracer studies show that punctate appositions, the thin-section correlate of these ridge/groove systems, are sites beyond which exogenous molecules do not penetrate. These junctions are therefore likely to represent permeability barriers as in the gut tract of higher chordates. Associated with these occluding zonular junctions are intermediate junctions, which exhibit no identifiable freeze-fracture profile, and macular gap junctions, characterized by a reduced intercellular cleft in thin section and by clustered arrays of P face particles in freeze-fractured replicas; these display complementary aggregates of E face pits. The diameters of these maculae are rarely very large, but in certain species (for example, Ciona), they are unusually small. In some tissues, notably those of Diplosoma and Botryllus, they are all of rather similar size, but very numerous. In yet others, such as Molgula, they are polygonal with angular outlines, as might be indicative of the uncoupled state. In many attributes, these various junctions are more similar to those found in the tissues of vertebrates, than to those in the invertebrates, which the adult zooid forms of these lowly chordates resemble anatomically.

Focal Orchitis in Undescended Testes

2002 ◽  
Vol 126 (1) ◽  
pp. 64-69
Author(s):  
Manuel Nistal ◽  
María Luisa Riestra ◽  
Ricardo Paniagua
Keyword(s):  
Germ Cell ◽  
Sertoli Cell ◽  
Sertoli Cells ◽  
Seminiferous Tubule ◽  
Immune Cell ◽  
Laboratory Data ◽  
Rete Testis ◽  
Seminiferous Tubules ◽  
Inflammatory Infiltrates ◽  
Lymphoid Infiltrates

Abstract Objective.—To evaluate seminiferous epithelium lesions in adult cryptorchid testes showing lymphoid infiltrates in seminiferous tubules and interstitium (ie, focal orchitis). Also, to consider the possible role of this lesion in the etiology of tubular atrophy. Methods.—We performed a histopathologic study of the cryptorchid testes and adjacent epididymides removed from 50 adult men who had not been previously treated for cryptorchidism. The study included morphologic and semiquantitative evaluation of seminiferous tubule pathology (according to germ cell numbers), Sertoli cell morphology, tubular lumen dilation, rete testis pattern (normal, hypoplastic, or cystic), and epididymal pattern (normal or epididymal duct hypoplasia). The study also included immunohistochemical evaluation of immune cell markers. The results were compared with clinical and laboratory findings. Results.—Focal lymphoid infiltrates (mainly lymphocytes) in seminiferous tubules and interstitium were found in 22 patients (44%), all of whom had unilateral cryptorchidism. The course of orchitis was asymptomatic, and laboratory data were normal. According to the seminiferous tubule pathology, a variety of histopathologic diagnoses, were made: (1) mixed atrophy consisting of Sertoli cell–only tubules intermingled with tubules showing maturation arrest of spermatogonia (11 testes, 4 of which also showed hyalinized tubules); (2) Sertoli cell–only tubules plus hyalinized tubules (4 testes); (3) Sertoli cell–only tubules (3 testes); (4) intratubular germ cell neoplasia (2 testes, 1 of which also showed hyalinized tubules); (5) complete tubular hyalinization (1 testis); and (6) tubular hyalinization plus some groups of tubules with hypospermatogenesis (all germ cell types were present although in lower numbers, 1 testis). Dysgenetic Sertoli cells, that is, Sertoli cells that had undergone anomalous, incomplete maturation, were observed in all nonhyalinized seminiferous tubules with inflammatory infiltrates. Tubular ectasia was observed in 13 cases. The rete testis was hypoplastic and showed cystic transformation in 18 testes, and the epididymis was hypoplastic in 15 testes. Conclusions.—The causes of these focal inflammatory infiltrates are unknown. It is possible that tubular ectasia and Sertoli cell dysgenesis are involved and that these alterations cause a disruption of the blood-testis barrier and allow antigens to enter the testicular interstitium, giving rise to an autoimmune process.

scholarly journals Complementary expression and phosphorylation of Cx46 and Cx50 during development and following gene deletion in mouse and in normal and orchitic mink testes

2015 ◽  
Vol 309 (3) ◽  
pp. R255-R276 ◽  
Author(s):  
R.-Marc Pelletier ◽  
Casimir D. Akpovi ◽  
Li Chen ◽  
Nalin M. Kumar ◽  
María L. Vitale
Keyword(s):  
Protein Expression ◽  
Germ Cell ◽  
Gap Junction ◽  
Sertoli Cell ◽  
Cell Communication ◽  
Seminiferous Tubules ◽  
Junction Protein ◽  
Mrna And Protein Expression ◽  
Autoimmune Orchitis ◽  
The Impact

Gap junction-mediated communication helps synchronize interconnected Sertoli cell activities. Besides, coordination of germ cell and Sertoli cell activities depends on gap junction-mediated Sertoli cell–germ cell communication. This report assesses mechanisms underlying the regulation of connexin 46 (Cx46) and Cx50 in mouse testis and those accompanying a “natural” seasonal and a pathological arrest of spermatogenesis, resulting from autoimmune orchitis (AIO) in mink. Furthermore, the impact of deleting Cx46 or Cx50 on the expression, phosphorylation of junction proteins, and spermatogenesis is evaluated. Cx46 mRNA and protein expression increased, whereas Cx50 decreased with adulthood in normal mice and mink. Cx46 mRNA and protein expression increased, whereas Cx50 decreased with adulthood in normal mice and mink. During the mink active spermatogenic phase, Cx50 became phosphorylated and localized to the site of the blood-testis barrier. By contrast, Cx46 was dephosphorylated and associated with annular junctions, suggesting phosphorylation/dephosphorylation of Cx46 and Cx50 involvement in the barrier dynamics. Cx46-positive annular junctions in contact with lipid droplets were found. Cx46 and Cx50 expression and localization were altered in mink with AIO. The deletion of Cx46 or Cx50 impacted on other connexin expression and phosphorylation and differently affected tight and adhering junction protein expression. The level of apoptosis, determined by ELISA, and a number of Apostain-labeled spermatocytes and spermatids/tubules were higher in mice lacking Cx46 ( Cx46−/−) than wild-type and Cx50−/− mice, arguing for life-sustaining Cx46 gap junction-mediated exchanges in late-stage germ cells secluded from the blood by the barrier. The data show that expression and phosphorylation of Cx46 and Cx50 are complementary in seminiferous tubules.

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