Evaluation of the ultrastructural changes in the human sertoli cell in testicular disorders and the relationship of the changes to the levels of serum FSH

Sertoli cell ultrastructure was compared in men with testicular disorders (hypospermatogenesis; germ cell aplasia) and men with normal testes to determine if any specific cytological change could be correlated with diminished feedback from the testis resulting in elevated serum FSH levels. The normal Sertoli cell contained smooth endoplasmic reticulum, mitochondria and variable numbers of lipid inclusions, lipofuscin, crystals of Charcot-B?ttcher and specialised inter-Sertoli cell junctional complexes. The principal abnormalities in Sertoli cells of men with testicular disorders were: 1) dilated vesicles of smooth endoplasmic reticulum and occasional expansions of the intercellular space; 2) increased numbers of cytoplasmic filaments; and 3) with germ cell aplasia inter-Sertoli cell junctions were complexly arranged due to interdigitation of Sertoli cell processes. Occasionally, increased lipid and lipofuscin aggregations were seen and in germ cell aplasia, aggregations of cytoplasmic glycogen were often present. Although these changes were seen more consistently with germ cell aplasia they were observed frequently with hypospermatogenesis where some tubules contained Sertoli cells with normal features. No correlation was found between abnormal Sertoli cell cytology and serum FSH levels.     

Histological alterations in Leydig cells and macrophages in azoospermic men

The study aimed to compare the histological features of Leydig cells and macrophages in the testicular interstitium of obstructive versus nonobstructive azoospermia. Thirty‐nine azoospermic men undergoing testicular sperm extraction during intracytoplasmic sperm injection were allocated into obstructive azoospermia group (GI) and nonobstructive azoospermia group (GII) which was subdivided into Sertoli cell‐only syndrome (GIIA), germ cell arrest (GIIB) and hypospermatogenesis (GIIC) subgroups. Serum LH, FSH and testosterone levels were measured. Ultrastructural changes and the mean number of CD68‐positive cells were estimated in the different groups. In GIIA, Leydig cells' processes came in contact with macrophages and showed smooth endoplasmic reticulum dilatation. In GIIB, Leydig cells showed apoptotic changes. Macrophages were commonly encountered in their vicinity demonstrating large number of lysosomes. In GIIC, Leydig cells showed euchromatic nuclei. Macrophages showed expulsion of their lysosomal contents in the interstitium surrounded by apoptotic bodies. The mean count of total CD68‐positive macrophages was higher in cases of obstructive azoospermia with nonsignificant differences compared to nonobstructive azoospermia groups. Significant increase in FSH level was detected in GIIA compared to GI. It is concluded that structural interactions might take place between Leydig cells and macrophages in the interstitial tissue of azoospermic men.     

Regulatory influence of germ cells on sertoli cell function in the pre-pubertal rat after acute irradiation of the testis

While germ cell regulation of Sertoli cells has been extensively explored in adult rats in vivo, in contrast, very little is known about germ cell influence on Sertoli cell function at the time when spermatogenesis begins and develops. In the present study various Sertoli cell parameters (number, testicular androgen binding protein (ABP) and testin, serum inhibin-B and, indirectly, follicle-stimulating hormone (FSH)) were investigated after the exposure of 19-day-old rats to a low dose of 3 Grays of gamma-rays. Differentiated spermatogonia were the primary testicular targets of the gamma-rays, which resulted in progressive maturation depletion, sequentially and reversibly affecting all germ cell classes. Testicular weight declined to a nadir when pachytene spermatocytes and spermatids were depleted from the seminiferous epithelium and complete or near complete recovery of spermatogenesis and testicular weight was observed at the end of the experiment. Blood levels of FSH and ABP were normal during the first 11 days after irradiation, when spermatogonia and early spermatocytes were depleted. While the number of Sertoli cells was not significantly affected by the irradiation, from days 11-66 after gamma-irradiation, ABP production declined and FSH levels increased when pachytene spermatocytes and spermatids were depleted and the recovery of these parameters was only observed when spermatogenesis was fully restored. Comparison of the pattern of change in serum levels of inhibin-B and testicular levels of testin and of germ cell numbers strongly suggest a relationship between the disappearance of spermatocytes and spermatids from the seminiferous epithelium and the decrease in levels of inhibin-B and increase in levels of testin from 7 to 36 days post-irradiation. Levels of testin and inhibin-B were restored before spermatogenesis had totally returned to normal. In conclusion, this in vivo study shows that pre-pubertal Sertoli cell function is under the complex control of various germ cell classes. This control presents clear differences when compared with that previously observed in adult animals and depends on the Sertoli cell parameter of interest, as well as on the germ cell type.     

Ultrastructural changes in Sertoli cells in ageing humans

Ultrastructural study of seminiferous tubules in ageing men revealed a varying degree of spermatogenetic arrest associated with changes in the Sertoli cells. Approximately half of the Sertoli cells showed a normal mature nuclear appearance although the cytoplasm was altered morphologically. These cells were classified as containing abundant lipid droplets (30%), containing large cytoplasmic vacuoles filled with an amorphous material similar to that in the tubule lumen and surrounded by junctional specializations (8%), multinucleated Sertoli cells (4%), or Sertoli cells with numerous mitochondria displaying tubular cristae (2%). The remaining 7% of Sertoli cells had an immature nuclear appearance and sparse development of the cytoplasmic organelles; these cells probably represent dedifferentiated Sertoli cells. Although individual differences were marked, a correlation between the increase in gonadotrophin levels and changes in both germ cell development and Sertoli cell structure was observed.     

Ultrastructure of Sertoli cells in cryptorchid goats

Sertoli cells of intra-abdominal testes from 25 naturally occurring, unilaterally cryptorchid, West African pygmy goats between the ages of 1-30 months were morphologically examined by light and transmission electron microscopy. Ultrastructurally, Sertoli cells in the intra-abdominal testes from 1-month-old goats were columnar and contained ovoid nuclei. The cytoplasm depicted clusters of rough endoplasmic reticulum cisternae (RER). In 3- to 4-month-old animals nucleolonemas of the Sertoli cells were associated with vesicles; the cytoplasm contained RER and areas of whorls of smooth endoplasmic reticulum. An abundance of lipid droplets was accompanied by lipofuscin granules in the cytoplasm. In 6- to 8-month-old goats RER cisternae presented circular or irregular profiles in the cells with an augmentation of cytoplasmic lipid droplets and lipofuscin granules. In 12- to 15-month-old animals intercellular spaces in the seminiferous epithelium exhibited focal expansions. Nuclear profiles of the Sertoli cells were irregular. In 24- to 30-month-old animals the Sertoli cells were in an advanced stage of degeneration.     

Specialized Cell Contacts and the Blood-testis Barrier in the Seminiferous Tubules of the Domestic Fowl (Gallus domesticus)

The ultrastructure of Sertoli-Sertoli and Sertoli-germ cell surface specializations in the domestic fowl was studied in material fixed by vascular perfusion through the thoracic aorta. Three main types of surface specializations were found between adjacent Sertoli cells. These are focal tight junctions, desmosome-like devices, and a specialization characterized by the presence of long and dilated subsurface cisternae of rough endoplasmic reticulum. Typical inter-Sertoli cell junctions similar to those of mammals were absent. Germ cells were attached to Sertoli cells mainly by desmosome-like devices of varying appearance. The junctions between Sertoli cells and elongating or elongated spermatids, "the mantle", consisted of only slight condensations of filamentous material in the Sertoli cell. The tight junctions between adjacent Sertoli cells were efficient in preventing lanthanum from passing towards the lumen beyond the level of the spermatogonia.     

Recognising the Sertoli-cell-only (SCO) syndrome: a case study

Total Sertoli-cell-only (SCO) syndrome is often confused with a focal SCO picture, in which testicular illness caused damage to seminiferous tubules and compromised the Sertoli cell range of maturation and functions, but from which still some spermatozoa can be retrieved for assisted reproductive techniques. Here, a possibly new SCO syndrome phenotype is reported exhibiting complete lack of germ cells despite normal architecture of the seminiferous tubules with presence of mature Sertoli cells and normal Leydig cells in the intertubular tissue. Sertoli cells are immunonegative for the prepubertal differentiation markers cytokeratin-18, anti-Muellerian hormone and M2A antigen, but reveal a positive signal for the gap junctional protein connexin 43 known to be expressed in Sertoli cells with an adult type of differentiation. The complete lack of germ cells in combination with fully differentiated adult-type Sertoli cells in this case is in contradiction with known SCO subtypes and with the current hypothesis of reciprocal regulation of Sertoli and germ cell differentiation.     

On the Postnatal Development of the Terminal Segment of the Seminiferous Tubules in Normal and Germ Cell Depleted Rat Testes

The development of the terminal segment of the seminiferous tubules was studied in 5 to 50 days old normal rats. At the age of 5, 10, and 15 days the terminal segment contained fewer gonocytes or spermatogonia than did the corresponding seminiferous tubule. The differentiation of the terminal segment was obvious at 20 days of age due to the high number of germ cells in the seminiferous tubules, where the epithelium became stratified at this stage. The blood-testis barrier in the terminal segment was chiefly established between 15 and 20 days of age as revealed by the lanthanum tracer technique.
To study the effect of the germ cells on the differentiation, the germ cell depleted testes of prenatally irradiated rats were also studied. The modified Sertoli cells of the terminal segment were more vacoulated and had fewer lipid droplets and inter-Sertoli cell junctions than did the Sertoli cells of the seminiferous tubules. The ultrastructure of the modified Sertoli cells of the terminal segment was similar in adult normal and adult SCO (Sertoli cell only) rats. The amount of lipid droplets in the Sertoli cells of SCO rats showed considerable variation among different tubular cross-sections within one testis.     

Immunohistochemical localization of inhibin-α in the testes of normal men and in men with testicular disorders

Testicular biopsies from normal men and from men with testicular disorders were examined by immunohistochemistry for the presence of the inhibin-alpha subunit using two different antisera. Immunoreactive inhibin-alpha (irI-alpha) was found in Leydig cells in normal, oligospermic, and azoospermic men and in men with Klinefelter's syndrome, and it was also found in a Leydig cell tumour. hCG-treatment apparently increased the amount of immunoreactive inhibin-alpha, particularly in Leydig cells. Sertoli cells also contained irI-alpha but the staining intensity was considerably stronger in testes with impaired spermatogenesis or Sertoli-cell-only syndrome than in normal testes. It is suggested that the serum concentration of irI-alpha and inhibin in humans may, in a complex way, be related to both Leydig and Sertoli cell function, and that the relative contribution from these cells may change in cases of testicular malfunction.     

Predictive factors of successful testicular sperm recovery in non-obstructive azoospermia patients

Recovery of testicular spermatozoa from non-obstructive azoospermic patients for intracytoplasmic sperm injection (ICSI) is a recent advance in the treatment of male infertility. The purpose of this study is to identify predictive factors for sperm recovery in non-obstructive azoospermic patients. A total of 178 men with non-obstructive azoospermia had multiple testicular sperm extraction (TESE) procedures to recover spermatozoa for intracytoplasmic sperm injection (ICSI) from June 1996 to February 1999. Testicular volume, serum follicle stimulating hormone (FSH) level and testicular histology were examined as positive predictive factors for sperm recovery. Testis biopsies were categorized as severe hypospermatogenesis, maturation arrest and Sertoli cell-only syndrome based on the most advanced pattern of spermatogenesis seen on histology. Sperm retrieval success rates for the patients in three histopathological categories were compared. Spermatozoa were successfully recovered in 94 of 178 (52.8%) men. Sperm were retrieved in 13 of 80 (16.3%) with Sertoli cell-only syndrome, 15 of 24 (62.5%) with maturation arrest, and 66 out of 74 (89.2%) with severe hypospermatogenesis. Spermatozoa recovery has no correlation with testicular volume or serum FSH level. When compared against Sertoli cell-only syndrome, the odds of sperm retrieval success rate was 44.3 times higher in severe hypospermatogenesis and 8.4 times in maturation arrest. These results demonstrate meaningful correlation between successful testicular sperm recovery and testis histopathology. Only testicular histopathology can be used as a predictor of successful sperm recovery.     

Melatonin prevents testicular damage in hyperlipidaemic mice

The damaging effect of hyperlipidaemia on testicular structure was determined, and the influence of melatonin was evaluated in testicular damage related to hyperlipidaemia. Hyperlipidaemia was induced in ApoE-knockout C57BL/6J male mice fed with high-fat diet alone (group A), or with high-fat diet and melatonin (group B). Six ApoE wild-type C57BL/6J male mice were fed with normal diet, served as controls. At the end of the experimental period, ultrastructural observations showed dramatically histopathological alterations in testicular tissues of group A. The basement membranes of seminiferous tubules were partially thickened and wavy-like in testes of mice with hyperlipidaemia, and vacuolar degeneration of mitochondria and dilation of endoplasmic reticulum were identified as well as the number of mitochondria and lipid droplets decreased significantly in Leydig cells and Sertoli cells. Electrondense deposits were observed in cytoplasms of germ cells. The testicular histostructure in group B treated with melatonin was similar to that of control. Apoptosis was determined by terminal-deoxynucleotidyl-transferase-mediated dUTP nick end labelling. Apoptotic germ cells were significantly more numerous in group A than in group B and controls. The results suggest that melatonin may be potential to attenuate testicular damage by improving histopathological changes and reducing germ cell apoptosis in hyperlipidaemic mice.     

Ultrastructure of the testis in Klinefelter's syndrome

The ultrastructure of the testis in 5 cases of Klinefelter's syndrome was studied. In 3 cases there was complete hyalinization of the seminiferous tubules. In one case Sertoli cells were present, and in another case focal areas of spermatogenesis were seen in the tubules. Hyperplasia of the Leydig cells was found in every case. The Leydig cells had usually abundant smooth endoplasmic reticulum and lipofuscin pigment in the cytoplasm. This suggested that the function of the Leydig cells was normal. The Sertoli cells contained lipid droplets and glycogen-filled vacuoles in the cytoplasm.     

Inhibin and steroid response to testicular stimulation with pure FSH (Metrodin) in infertile men with unilateral cryptorchidism

Summary. Static measurements of immuno-reactive inhibin have proven of little relevance in the diagnosis of testicular disorders. Dynamic evaluation of the inhibin secretory reserve might detect a specific Sertoli cell defect in a subgroup of infertile men. We compared the response of inhibin and steroids to an intravenous injection of pure FSH (Metrodin, Serono, 300 IU) in 13 infertile men with unilateral cryptorchidism to that in eight normal fertile men. Blood was aspirated before, 24, 48, and 72 h after the FSH injection. Two subgroups of patients with unilateral cryptorchidism were detected: those who responded by secreting inhibin in a pattern similar to normal men (seven patients), and those who responded poorly or not at all (six patients). The presumed cause of this difference is a defect of Sertoli cell reserve function due to a combination of insults to the testes, and not to cryptorchidism itself. The difference in response to FSH cannot be predicted from semen analysis nor from static hormone measurements. Overall, inhibin levels correlated significantly with the serum concentrations of FSH (r = -0.36, P <0.05), testosterone (r = 0.37, P <0.05), and 17-hydroxyprogesterone (r = 0.66, P <0.001).
It is concluded that, in infertile men with unilateral cryptorchidism, stimulation of Sertoli cells by FSH can identify a subgroup of patients with Sertoli cell malfunction involving inhibin synthesis.     

The Terminal Segment of the Seminiferous Tubules and the Blood-Testis Barrier Before and After Efferent Ductule Ligation in the Rat

The ultrastructure of modified Sertoli cells in the terminal segment of the seminiferous tubules in the rat was studied in material fixed by perfusion through the thoracic or the abdominal aorta. The central lumen of the terminal segment was not distinct under normal conditions, but became quite evident with an increased intratesticular pressure caused by efferent ductule ligation. The modified Sertoli cells were characterized by a marked increase in number of microtubules and microfilaments, extensive inter-Sertoli cell junctions, vacuolated cytoplasm, and considerably dilated intercellular spaces. Three types of specialized cell contacts were found between modified Sertoli cells: typical inter-Sertoli cell junctions, desmosome-like devices, and septate-like tight junctions. These specialized cell contacts were efficient in preventing lanthanum to penetrate into the lumen of the terminal segment both before and after efferent ductule ligation. Moreover, it was found that typical inter-Sertoli cell junctions prevented lanthanum penetration into the adluminal compartment of the seminiferous tubules even after efferent ductule ligation.     

Significance of Serum FSH Levels and Testicular Morphology in Infertile Males

Objectives: To determine the relationship between plasma levels of FSH and testicular spermatogenic patterns. Methods: Testicular biopsies were obtained from 99 infertile men. Biopsies were performed either in order to distinguish the type of azoospermia (obstructive/non-obstructive) or because of severely subnormal semen variables. Serum FSH was measured by immunoassay (normal range is less than 7 mIU/ml). Results: Statistically significant difference was detected between patients with Sertoli cell only syndrome and normal spermatogenesis, hypospermatogenesis and maturation arrest (p<0.01, p<0.01, p<0.05, respectively). No statistically significant differences were found between normal spermatogenesis, hypospermatogenesis and maturation arrest. Conclusion: Our study revealed that elevation of serum FSH correlates only with the appearance of Sertoli cell only syndrome. We think that azoospermic or severely oligoasthenoteratozoospermic patients with highly elevated plasma FSH levels (three times the normal) could be excluded from separate testicular biopsy, because these patients are not suitable for conventional treatments. If he is willing to undergo an IVF program the sperm will often be present, no matter what the testicular histology is to be used for assisted reproductive techniques, particularly ICSI.     

Effect of orchiopexy on human testicular ultrastructure.

The effect of orchiopexy performed before puberty on the testicular ultrastructure in sexually mature infertile men have been levels, as well as an analysis of spermogram and karyotype was carried out. It was found an elevation of FSH and LH, while T levels were decreased. Disturbances in the ultrastructure of all testicular cell types-germ, Sertoli and Leydig cells are related with the smooth and rough endoplasmic reticulum and mitochondria as well. It is concluded that the application of orchiopexy in 8-10 years old cryptorchid boys have no curative effect on the descended testes.     

Selective uptake by the Sertoli cells of cytoplasm from normal spermatogonia in the rat testis

Electron microscopical examination of germ cells during their development from early type A spermatogonia to late pachytene spermatocytes showed that small, spherical pseudopodia emerged from type B spermatogonia and, to a lesser degree, from intermediate spermatogonia and early spermatocytes. Serial sections showed that the pseudopodia pinched off from the type B spermatogonia and were engulfed by the adjacent Sertoli cells. Groups of dense bodies were found in the Sertoli cells adjacent to the engulfed islands of germ cell cytoplasm. At a few instances islands of germ cell cytoplasm were seen to fuse with dense bodies in the Sertoli cells. The fate of the cytoplasmic islands is unknown, but phagocytosis by the Sertoli cells may be suggested. The findings indicate a new type of interaction between Sertoli cells and certain classes of spermatogonia.     

The influence of LH and/or FSH on Leydig and Sertoli cell morphology after testicular involution in the Djungarian hamster, Phodopus sungorus, induced by hypophysectomy or short photoperiods

In the Djungarian hamster, Phodopus sungorus, the morphological alterations of Sertoli and Leydig cells were investigated under the influence of gonadotropins (LH and/or FSH) after testicular regression induced either by hypophysectomy or photoinhibition. Stimulation with LH or LH/FSH lead to a redifferentiation of morphological features of Leydig cells such as nuclear structure, smooth endoplasmic reticulum and size of cell and nucleus area within 7 days of hormone treatment. Similarly, stimulation with FSH or LH/FSH caused redifferentiation of Sertoli cell nuclear structure, rough endoplasmic reticulum and nuclear size within 7 days. Incomplete restoration of Leydig and Sertoli cell morphology was observed under FSH and LH treatment respectively. In both Leydig and Sertoli cells combined LH and FSH application resulted in an increased response in respect to morphological redifferentiation, possibly indicating paracrine regulatory mechanisms. In all groups treated an intact blood-testis barrier (BTB) was reestablished after a minimum of 7 days, indicating that the existence of the blood-testis barrier is not dependent on specific gonadotropin supply but on the developmental stage of the seminiferous epithelium. Sham-operated animals showed increased cell and nucleus area of Leydig cells in comparison to photostimulated animals. After testicular involution as well as after LH or FSH treatment there were no significant morphological differences between hypophysectomized and photoinhibited animals in respect to the documented ultrastructural and morphometrical characteristics.(ABSTRACT TRUNCATED AT 250 WORDS)     

Local regulation of Leydig cells by the seminiferous tubules. Effect of short-term cryptorchidism

Unilateral cryptorchism was induced in adult rats for 24 h, and its effect on testicular morphology and intratesticular testosterone concentration after hCG-stimulation were studied. In seminiferous, tubules from abdominal testes an increased number of degenerating germ cells was noted in stages XIV-III of the spermatogenic cycle and Sertoli cells contained an increased amount of lipid droplets in stages XIV-VIII. However, germ cells and Sertoli cells from tubules at other stages of the cycle appeared unaffected. In scrotal testes the size of peritubular Leydig cells varied in phase with the spermatogenic cycle. The largest cells were found adjacent to stage VII-VIII and the smallest adjacent to stage XI-XII. In abdominal testes no stage-dependent variation in the size of peritubular Leydig cells was seen. Perivascular Leydig cells were of equal size in abdominal and scrotal testes. The testicular testosterone concentration following stimulation with a low dose of hCG was significantly lower in abdominal testes. It is suggested that the seminiferous tubules locally modulate Leydig cell function and that the stage specific stimulatory influence from stage VII-VIII is rapidly lost during experimental cryptorchidism.