LncRNA Tug1 maintains blood-testis barrier integrity by modulating Ccl2 expression in high-fat diet mice

Sertoli cells are essential for spermatogenesis in the testicular seminiferous tubules by forming blood-testis barrier (BTB) and creating a unique microenvironment for spermatogenesis. Many lncRNAs have been reported to participate in spermatogenesis. However, the role of long noncoding RNAs (lncRNAs) in Sertoli cells has rarely been examined. Herein, we found that a high-fat diet (HFD) decreased sperm quality, impaired BTB integrity and resulted in accumulation of saturated fatty acids (SFAs), especially palmitic acid (PA), in mouse testes. PA decreased the expression of tight junction (TJ)-related proteins, increased permeability and decreased transepithelial electrical resistance (TER) in primary Sertoli cells and TM4 cells. Moreover, lncRNA Tug1 was found to be involved in PA-induced BTB disruption by RNA-seq. Tug1 depletion distinctly impaired the TJs of Sertoli cells and overexpression of Tug1 alleviated the disruption of BTB integrity induced by PA. Moreover, Ccl2 was found to be a downstream target of Tug1, and decreased TJ-related protein levels and TER and increased FITC-dextran permeability in vitro. Furthermore, the addition of Ccl2 damaged BTB integrity after overexpression of Tug1 in the presence of PA. Mechanistically, we found that Tug1 could directly bind to EZH2 and regulate H3K27me3 occupancy in the Ccl2 promoter region by RNA immunoprecipitation and chromatin immunoprecipitation assays. Our study revealed an important role of Tug1 in the BTB integrity of Sertoli cells and provided a new view of the role of lncRNAs in male infertility.

[ULTRASTRUCTURAL CHARACTERISTICS OF RATS TESTICLES UNDER SPERMATIC CORD STENOSIS AND AFTER BLOOD FLOW RESTORATION BY DIFFERENT METHODS]

Hemodynamic disorders in the testicles cause chronic organ hypoxia with damage of its stroma and seminiferous tubules, which plays a leading role in the pathogenesis of the testicular form of male infertility development. The aim of the work was to establish the features of ultrastructural reorganization of the testicles tissue and its vascular bed under circulatory hypoxia conditions and after restoration of blood flow in the organ. The study was conducted on 84 white adult male rats. The control group consisted of 12 intact animals. The experimental group was divided into 3 series: with stenosis of the spermatic cord (48 animals), with stenosis of the spermatic cord and its recanalization on the 3rd day without correction (12 animals) and with stenosis of the spermatic cord and its recanalization with correction on the 3rd day (12 animals). Under conditions of dosage spermatic cord stenosis (when the ligature is applied) in the remote monitoring period, with electron microscopic study, were detected destructive changes of spermatid and spermatozoa, which were combined with significant focal intracellular and extracellular edema. In part of the cells heads were deformed, the acrosomes were sophisticated and fragmented. At one-stage decompression of the spermatic cord (removal of the stenosing ligature on the third day), the above-described changes in accordance were deepened. At 14th day of the observation, collagen fibers and an electron-transparent amorphous component were found in the perivascular space. When the proposed method of dosed decompression of the spermatic cord (successive removal of three stenosing ligatures of different diameters) has been applied changes in the testicles parenchyma and its intraorganic vessels were less severe. Functional activity of the testicle after correction of reperfusion changes, was not significantly affected, what was proved by the presence in seminiferous tubules lumen of spermatozoa mature forms.

Epigallocatechin-3-gallate inhibits apoptosis and protects testicular seminiferous tubules from ischemia/reperfusion-induced inflammation

Testicular torsion (TT) is a urologic emergency that may result in future infertility problems. The pathologic process of TT is similar to an ischemia reperfusion injury (IRI). The purpose of this study was to evaluate the effect of epigallocatechin-3-gallate (EGCG) on reversing the damaging consequences of TT-induced IRI by examining its inhibitory effects on the expression of inflammatory and apoptosis mediators in a unilateral TT rat model. Eighteen male Sprague-Dawley rats were divided into 3 groups. Group 1 underwent a sham operation of the left testis under general anesthesia. Group 2 underwent ischemia for 1h followed by 4h reperfusion in the presence of saline. The third group was similar to group 2, however, EGCG (50 mg/kg) was injected i.p. 30 min after ischemia induction. The in vivo protective effect of EGCG was tested by measuring testicular levels of TNF-α, IL-6 and IL-1β by ELISA and mRNA expression of iNOS, MCP-1, p53, Bax, Bcl-2 and survivin by real-time PCR. Also, testicular morphological changes and damage to spermatogenesis were evaluated using H&E staining and Johnsen's scoring system, respectively. EGCG treatment improved testicular structures in the ipsilateral testis, markedly inhibited germ cell apoptosis (GCA) and significantly decreased testicular cytokine levels. In addition, EGCG was able to down regulate the mRNA expression of iNOS, MCP-1 and pro-apoptosis genes in favor of cell survival. For the first time we show that in vivo EGCG treatment rescued the torsed testes from IRI-induced inflammation, GCA and damage to spermatogenesis thus suggesting a new preventive approach to inhibiting the inflammatory and apoptotic consequences of TT-induced IRI.

Protective effect of L-carnitine on testicular ischaemia-reperfusion injury in rats

Testicular torsion is a urological emergency referred to as 'acute scrotum', because inappropriate treatment can lead to male subfertility and infertility. A possible cause of testicular damage is the ischaemia-reperfusion (I/R) injury attributed to oxygen free radicals. L-carnitine, a vitamin-like antioxidant, plays a pivotal role in the maturation of spermatozoa within the reproductive tract. The aim of the present paper was to determine the protective effect of L-carnitine on testicular I/R-induced injury. Thirty-two male rats were divided into 4 groups (n = 8). Testicular torsion was created by rotating the right testis 720 degrees in a clockwise direction. Group 1: sham-operated control; group 2: ischaemia; group 3: I/R; group 4: ischaemia-L-carnitine treatment-reperfusion group. L-carnitine (500 mg kg(-1), intraperitoneally) was administered before 30 min of detorsion in Group 4. After torsion (5 h) and detorsion (5 h), bilateral orchidectomy was performed. The malondialdehyde (MDA) level was evaluated in testes. Histopathologically, Johnsen's spermatogenesis criteria and mean seminiferous tubule diameter (MSTD) measurements were used. Testicular MDA levels were higher in the torsion group compared to the sham-control group (p < 0.05). Detorsion (reperfusion) caused a further increase in MDA levels (p < 0.05). Pretreatment with L-carnitine prevented a further increase in MDA levels (p < 0.05). Histologically, torsion caused some separation among germinal cells in the seminiferous tubules, which became much more prominent in the I/R group but was attenuated with L-carnitine pretreatment. In conclusion, L-carnitine pretreatment may have a protective effect in experimental testicular torsion-detorsion model in rats by its well-known antioxidant potential.

A vasculature-associated niche for undifferentiated spermatogonia in the mouse testis

Mammalian spermatogenesis produces numerous sperm for a long period based on a highly potent stem cell system, which relies on a special microenvironment, or niche, that has not yet been identified. In this study, using time-lapse imaging of green fluorescent protein-labeled undifferentiated spermatogonia (A(undiff)) and three-dimensional reconstitution, we revealed a biased localization of A(undiff) to the vascular network and accompanying Leydig and other interstitial cells, in intact testes. Differentiating spermatogonia left these niche regions and dispersed throughout the basal compartment of the seminiferous epithelium. Moreover, rearrangement of A(undiff) accompanied the vasculature alteration. We propose that the mammalian germline niche is established as a consequence of vasculature pattern formation. This is different from what is observed in Drosophila or Caenorhabditis elegans, which display developmentally specified niche structures within polarized gonads.

Autorevascularization of the testicle and spermatic vessels by bladder pedicle flap: an experimental study

PURPOSE

The aim of the study was to investigate revascularization of the testicle through its own tissue and spermatic vessels by a bladder pedicle flap in rabbits.

METHODS

Thirty male rabbits were used in the study. In 10 animals, the Fowler-Stephens (FS) procedure was applied to the right testicles (FS group). The FS procedure and revascularization of the testicle by a bladder pedicle flap were applied to the right testicles in 10 animals (FSO group). No surgical procedure was performed in the control group. Scintigraphic study was performed 3 weeks after the high ligation procedure in the FS and FSO groups. Both testicles were evaluated by radionuclide scintigraphy in all the animals. Macroscopic testicle weights were evaluated. Testicular biopsy scores and mean seminiferous tubule diameters were determined in the histopathologic study.

RESULTS

The testicular blood flow of the FSO group was better than the FS group (P < .05), but there was no statistically significant difference between the FSO and the control groups (P > .01). Testicle weights, testicular biopsy scores, and seminiferous tubule diameters in the FSO group were detected, and there was a statistically significant difference when compared with the FS group (P < .05) but not with the control group (P > .01).

CONCLUSION

We suppose that the surgical model of revascularization of the testicle through its own tissue and spermatic vessels by a bladder pedicle flap can be an alternative to the FS procedure in abdominal and high canalicular undescended testicles.

Inhibition of poly(adenosine diphosphate-ribose) polymerase decreases long-term histologic damage in testicular ischemia-reperfusion injury

OBJECTIVES

To evaluate the effect of 3-aminobenzamide, an inhibitor of poly(adenosine diphosphate-ribose) polymerase (PARP), on the long-term histologic damage in testicular ischemia-reperfusion injury. PARP inhibitors have been used successfully to decrease ischemia-reperfusion injury in several organ systems.

METHODS

Adult male Wistar rats were divided into four groups of 7 rats each. One group underwent 2 hours of testicular torsion; one received pretreatment with vehicle (dimethyl sulfoxide) before detorsion; one received pretreatment with 3-aminobenzamide, an inhibitor of PARP, before detorsion; and one group underwent a sham operation. All rats underwent bilateral orchiectomy 60 days after the experiment. The mean seminiferous tubular diameter, germinal epithelial cell thickness, and mean testicular biopsy score were determined by histologic examination of each testis.

RESULTS

Testicular torsion-detorsion caused a significant decrease in the mean seminiferous tubular diameter, germinal epithelial cell thickness, and mean testicular biopsy score in the ipsilateral testes (P <0.001), but not in the contralateral testes. The animals treated with 3-aminobenzamide had a statistically significant increase in these histologic parameters compared with the torsion-detorsion group (P <0.01).

CONCLUSIONS

The results of this study show that PARP may have a role in the testicular damage caused by ischemia-reperfusion. Administering PARP inhibitors before reperfusion may have the potential to decrease the long-term histologic damage that occurs after testicular torsion.

Rat testicular structure and ultrastructure after paracetamol treatment

The morphological modifications of Wistar rat testicles were investigated for animals treated with paracetamol. The rats (n = 6) received a single dose of 4.4 mmol/kg paracetamol, while controls (n = 6) received the same volume of physiological solution. After 5, 10 and 50 days, the rats were perfused with Karnovsky's fixative and processed by routine methods for light and electron microscopy. Some altered seminiferous tubules were found, as well as a few degenerating tubules. Within the tubules, Sertoli cells appeared fragmented while the spermatids showed unusually well-developed rough endoplasmic reticulum and Golgi complexes and had irregularly compacted chromatin. Morphologically altered late spermatids were found retaining a larger volume of residual cytoplasm than spermatids of controls. An indirect cause of alterations was also suggested based on the occurrence of dilated blood vessels and edema.

[Varicocele at a prepubertal age. Adolescent varicocele]

Varicocele is a dilatation of the spermatic veins, particularly on the left side, and represents one of the most frequent causes of male infertility. Its frequency in pre-adolescence varies from 10% to 15%. Even today varicocele pathogenesis is not clear. In the period from August 1990 to August 1999, 35 males between 10 and 16 years of age were treated surgically in our Institution via interruption of the internal spermatic vein using Palomo's technique. Patients that reached the age of 18 after surgery have had a spermiogramm. The problem of varicocele therapy in pre-adolescence has not yet been resolved with regard to surgical therapy and follow-up.

Immunohistochemical demonstration of cytoskeletal proteins in the testis of the Japanese black bear, Ursus thibetanus japonicus

The seasonal changes of the cytoskeletal protein expressions were immunohistochemically investigated in the testes of Japanese black bear, Ursus thibetanus japonicus. A strong immunoreaction for alpha-smooth muscle actin is restricted to the vascular smooth muscle cells and the peritubular cells which surround the seminiferous tubules by several layers throughout the year. Weak immunoreactions for B4 antigen and desmin were observed in the vascular smooth muscle cells and in a part of peritubular cells throughout the year. A strong immunoreaction for vimentin was also detected in the fibroblasts and Leydig cells, in addition to the vascular smooth muscle and epithelial cells and the peritubular cells throughout the year. A strong alpha-tubulin immunoreaction was detected in the elongating spermatids during the acrosome phase of spermiogenesis in May and June. The cytoplasm of several Sertoli cells was faintly immunoreacted for vimentin in the basal and lateral region, while an intense alpha-tubulin reaction was seen in the entire cytoplasm in May, April and June. In November, January and March, the immunoreactions for vimentin and alpha-tubulin strongly accumulate in a perinuclear region of Sertoli cells when developmental spermatids are not seen in the seminiferous tubules. These accumulations in the immunoreactions for vimentin and alpha-tubulin seem to be caused by the reduction in size of Sertoli cells cytoplasm with season. However, the seasonal changes of distributions in the cytoskeletal proteins are obscure in the bear testes. These results suggest that the contents of cytoskeletal proteins may not change in relation to the morphological differences with season in the testes of the seasonal breeders.

Capillaries in the lamina propria of human seminiferous tubules are partly fenestrated

The three capillary parts of the microvasculature of the human testis, namely the arterial side inter-Leydig cell capillaries, the intramural capillaries, and the venous side inter-Leydig cell capillaries, were studied in detail by dual detection of alkaline phosphatase enzyme activity and endothelial marker immunoreactivity, and by means of light- and transmission-electron microscopy. Alkaline phosphatase enzyme activity was seen in intertubular arterioles, capillaries, and venules, and in intramural capillaries of the human testis, whereas the lamina propria of human seminiferous tubules showed no staining. Alkaline phosphatase enzyme activity and the endothelial marker detected by the Qbend 30 antibody co-existed within the endothelial cells of the microvasculature. Electron-microscopically, the endothelial cells of the arterial and venous side inter-Leydig cell capillaries, and of the intertubular capillaries free of Leydig cells were of the continuous type without fenestrations (A-1-alpha type). The intramural capillaries consisted of non-fenestrated (A-1-alpha type) and fenestrated sections (A-2-alpha type). The fenestrations faced the germinal epithelium. Capillaries with a continuous non-fenestrated endothelium contained a large number of transcytotic vesicles and channels. These were numerous in the endothelial cells of the inter-Leydig cell capillaries and the non-fenestrated part of the intramural capillaries. Capillaries partly ran in between the layers of the lamina propria and therefore represented the capillarization of the seminiferous tubules. Thus the multilayered lamina propria probably requires its own capillary supply to allow rapid exchange between the microvasculature and the epithelium of the human seminiferous tubules.

Myoid cell proliferation in rat seminiferous tubules after ischaemic testicular atrophy induced by epinephrine. Morphometric and immunohistochemical (bromo-deoxyuridine and PCNA) studies

The proliferation of peritubular myoid cells in the testes of rats treated for 1-11 weeks with intra-scrotal injections of epinephrine was investigated using immunohistochemistry and quantitative histology. The percentage of peritubular cells that were immunopositive for proliferating cell nuclear antigen (PCNA) or that were labelled with 5'-bromodeoxyuridine (BrdU) in the S-phase of the cell cycle, were calculated in control and treated rats after 1,3,5,8 and 11 weeks of treatment. In addition, the change in the number of peritubular cells per testis was calculated using two different stereological methods. The possible correlation between the changes observed using the two proliferation indices (PCNA immunoreaction and labelling of BrdU) in peritubular myoid cells was evaluated by regression analysis. The results of the study indicate that both proliferation indices increased in peritubular cells between the third and the eighth weeks of treatment, and that this increase was correlated with an increase in the number of these cells. From weeks 8-11 of treatment, both proliferation indices decreased and the same occurred with the number of peritubular cells. We hypothesize that proliferation of the peritubular cells occurs in order to increase their secretion of extracellular matrix components leading to enlargement of the lamina propria of the seminiferous tubule.

Microvasculature of the human testis in correlation to Leydig cells and seminiferous tubules

The microvasculature of the human testis is closely related to the Leydig cells and the seminiferous tubules. Semi-thin sections of testicular tissue serve as a basis for the computer-aided 3-D reconstruction of the microvasculature, the seminiferous tubules and the Leydig cells. After vascular perfusion with glutaraldehyde (5.5%) and paraformaldehyde (4%), it is possible by means of light and electron microscopy, to analyse the organization of the capillaries between the Leydig cells (inter-Leydig cell capillaries) as well as of those within the lamina propria (intramural capillaries). These arise from arterioles, deriving from branches of the segmental arteries. The capillaries ramify between the Leydig cells and run either semi-circumferentially around the seminiferous tubules (peritubular capillaries) or penetrate the lamina propria of the neighbouring tubules. This is the beginning of the intramural capillary which after leaving the tubular wall continues to a further capillary path. Consequently, the microvasculature of the human testis with regard to the seminiferous tubules is subdivided into afferent, intramural and efferent capillaries. Leydig cell clusters are present on both the arterial and the venous sides of the microvasculature.

Segmental angioarchitecture of the testicular lobule in man

There is a close correlation between the angioarchitecture of the human testis and its inner subdivision into testicular lobules. Serial sections from paraffin and epon-embedded testicular tissue were used to examine the angioarchitecture of the human testis, and computer-aided 3-D-reconstruction was used to demonstrate the correlation between blood vessels and tissue organization. The recurrent arteries arise from the centripetal arteries, and run in the central axis of the testicular lobule. At regular intervals of on average, 300 microns the segmental arteries arise from the recurrent artery, which supplies segments of the testicular parenchyma perpendicular to the long axis of the testicular lobules. Within such a segment, the segmental artery supplies the microvasculature, which is partly surrounded by Leydig cells and partly stands in close contact with the wall of the seminiferous tubules. The venous drainage occurs through the intralobular veins, which run to the periphery of the lobule (towards the septum). These veins lead into the septum and there they join the collecting veins. A lobule can have several segments depending on its size. The base of such a tissue segment is directed towards the septum whereas the top is directed towards the centre of the lobule. Sections of several seminiferous tubules can be found in such a segment. The flow of blood from the arterial to the venous side of the testicular circulation occurs radially from the centre of the lobule to the septum.

[Doppler color echography in the diagnosis of impotence]

This study reports the experience achieved with duplex and color Doppler ultrasonography in 120 impotent patients. The following morphodynamic parameters of the cavernosal arteries were studies before and after intracorporal injection of a mixture of vasoactive drugs: arterial diameter, wall pulsatility, morphology of the spectral waveform, peak systolic velocity, end diastolic velocity and flow volume. The veno-occlusive mechanism of the corpora cavernosa was studied directly by determination of flow along the deep dorsal vein of the penis and indirectly by serial evaluation of the diastolic flow of the cavernous arteries.

Sulfated glycoprotein-2 induced endogenous resistance to ischemia and reperfusion injury in the seminiferous tubules

Evidence of increased resistance of Sertoli cells to ischemia and reperfusion injury was presented by numerous histological, morphological, and quantitative studies. In situ hybridization techniques and immunocytochemical studies demonstrated intense expression of sulfated glycoprotein-2 (SGP-2) in Sertoli cells. We propose that protective effects of SGP-2 are the core of the differential tolerance of ischemia by the various testicular cells and the morphology of the postischemic testis. We believe that suppression of ischemic damage selectively in Sertoli cells is the consequence of the ability to produce SGP-2, an endogenous inhibitor of ischemic injury. This hypothetical function of SGP-2 is supported by its immunosuppressive properties and its structural and functional identity to several types of human complement cytolysis inhibitors.

Morphological evidence for a blood-epididymis barrier and the effects of gossypol on its integrity

Ultrastructural and micropuncture techniques were used to obtain morphological evidence for a blood-epididymis barrier ( BEB ) in the rat and to determine whether gossypol, an oral male contraceptive, alters the permeability of the BEB or blood-testis barrier ( BTB ) in rats made infertile with gossypol. Rats were treated by gavage with 20 mg/kg per day of gossypol for 6 weeks; control animals received the vehicle alone. For electron microscopy the components of the BEB were analyzed in each region of the epididymis with intravascularly perfused lanthanum nitrate. Throughout the epididymis in both control and gossypol-treated animals it was found that the zonula occludens at the apicolateral surface of the epididymal epithelial cells was the sole and ultimate structural component of the rat BEB ; the flow of intravascularly perfused lanthanum was not significantly impeded by the vascular endothelium, the peritubular myoid layer or other lateral cell surface specializations. For micropuncture, control and treated rats were administered 0.3 mCi [3H]inulin via the jugular vein. Radioactivity was determined in samples collected from the seminiferous tubules, caput and cauda epididymidis, and carotid artery. Results showed that [3H]inulin entry in seminiferous tubules, caput and caudal luminal fluid from blood was similar for control and treated groups. It was concluded that gossypol treatment does not alter the permeability properties of the BTB and BEB to macromolecules such as inulin or to small electron-dense tracers such as lanthanum.

The fine structure of the terminal segment of the bovine seminiferous tubule

The intratesticular excurrent duct system of the bull is composed of rete testis, tubuli recti, and the terminal segment of the seminiferous tubules. Each terminal segment is surrounded by a vascular plexus and may be subdivided into a transitional region, middle portion, and terminal plug. The modified supporting cells of the middle portion and the terminal plug no longer display the typical Sertoli-Sertoli junctions seen in the transitional region and the seminiferous tubule proper. In the region of the terminal plug a distinct central lumen is generally not observed: spermatozoa and tubular fluid must pass through an intricate system of communicating clefts between the apices of the closely attached modified supporting cells. Vacuoles in the supranuclear region of the cells in the middle portion indicate strong transepithelial fluid transport. In analogy to the epithelium of rete testis and tubuli recti, the supporting cells of the terminal segment are capable of phagocytosing spermatozoa. The vascular plexus investing the terminal segment serves a dual purpose: it is a regulatory device for fluid and sperm transport, as well as an area of increased diapedesis for white blood cells.

Microvascular architecture of rat and human testes

We made corrosion casts of the testicular vessels in rats and humans and investigated their architecture by scanning electron microscopy. Two types of capillaries, intertubular and peritubular, were clearly demonstrated in the rat testis; the former formed a dense network with a polyhedral shape and the latter had a rope-ladder-like appearance. The architecture of the human testis was very complicated; the intertubular capillaries formed either no clear capillary network or a very loose one. The peritubular capillaries did not show a rope-ladder-like appearance.

The fine structure of the boundary tissue of the seminiferous tubule of the camel (Camelus dromedarius)

An ultrastructural study of the boundary tissue of the seminiferous tubule of the camel reveals that it consists of three lamellae; inner fibrous, inner cellular and outer cellular. The inner lamella is subdivided into two homogeneous layers enclosing a third one that contains collagenous fibres and fine filaments. The inner cellular lamella consists of several layers of myoid cells; each layer is separated from the adjacent layer by homogeneous material and varying amounts of collagen. The outer cellular lamella consists predominantly of fibrocytes together with some fibroblasts and scattered collagen.

Ultrastructural changes in the seminiferous tubule wall and intertubular blood vessels in human cryptorchidism

Biopsy material was obtained from adult men whose both testes had descended into the scrotal sac either spontaneously by use of pharmacologic agents or through surgery at age 7--16 yr, and from undescended testes obtained during orchipexy in men 8--40 yr of age. Testes appeared normal until the 10th yr, when progressive alterations were observed with the onset of puberty and through the adult age both in retained testes and cases of testes that descended through chemical or surgical methods before or after puberty. A thickening of the inner and outer acellular layers of the seminiferous tubule wall was due to an accumulation of collagen fibers and microfibrillar material. The basement membrane was also thickened and appeared as a homogeneous or a multilaminar structure. The intertubular blood vessels presented a thickening of the tunica media and a laminar accumulation of basement-membrane-like material.

Scanning electrons and light microscopy of the equine seminiferous tubule

Changes within the equine seminiferous tubules during the cycle of the seminiferous epithelium were studied light and scanning electron microscopy (SEM). Once observed with SEM, tubules were sectioned and staged using light microscopy. As viewed by SEM, the weblike, spongy cytoplasm of germ cells or Sertoli cells in stages I and II extended over the entire height of the germinal epithelium. The cytoplasm of the basal portion of the germinal epithelium in stages III to VIII was similar to that in stages I and II. However, the cytoplasm which occupied the luminal third of the epithelium in stages III to VII was smooth appearance. The smooth-surfaced, periluminal cytoplasm diminished in stages VIII. Principal pieces of flagella from spermatids extended into the tubular lumina in all stages whereas the middle pieces extended into the lumen only in stage VIII. Later in stage VIII, the middle pieces, which were thickened with cytoplasm, were connected to the germinal epithelium by stalks. After spermiation, the diameter of the middle pieces was similar to that of ejaculated spermatozoa. Thus, the cytoplasm within the thickened middle pieces contributed to the formation of the cytoplasmic droplets.

Movement of spermatocytes from the basal to the adluminal compartment of the rat testis

The progressive movement of primary spermatocytes from the basal to the adluminal compartment of the seminiferous tubule was studied after testes were fixed with standard and hypertonic solutions. In stages VI, VII and VIII of the cycle (classification of Leblond and Clermont, '52), preleptotene spermatocytes were observed within the basal compartment of the seminiferous tubule. Resting on the basal lamina, these cells were bound tightly to neighboring Sertoli cells by desmosome-like junctions. In late stage VIII and early stage IX, basal processes of Sertoli cells were observed between the newly formed leptotene cells and the basal lamina, and in stage IX, the Sertoli processes met to form a junction of the zonula adherens type. This junction formed a permeability barrier which restricted the free access of fixative into the spaces around leptotene cells. Evidence for this was found in the absence of the shrinkage artifact produced with hypertonic solutions in earlier stages. In longitudinal sections, the permeability barrier was first observed in an area of the tubule in which sperm release was also taking place. In mid-stage IX and in stage X, sertoli-Sertoli junctional specializations formed de novo below the leptotene spermatocyte, while those from the preceding stages, present above the leptotene spermatocytes, remained intact. Thus, tight junctions were in evidence for a considerable period of the time, both above and below the leptotene spermatocytes. At no time in the process of germ cell movement toward the lumen did these cells exhibit evidence of amoeboid movement or lose desmosome-like contacts with the surrounding Sertoli cells. From this study it is concluded that the Sertoli cells play an active role in the transfer of spermatocytes to the adluminal compartment. A transient intermediate compartment of the seminiferous tubule is described, one which allows for the continual maintenance of the blood-testis barrier during transit of spermatocytes from the basal to the adluminal compartment.