The cycle of follicular and interstitial cells (Leydig cells) in the testis of the marbled newt, Triturus marmoratus (Caudata, Salamandridae)

Ultrastructural examination of the marbled newt (Triturus marmoratus) testis throughout the annual cycle revealed that during the period of testicular quiescence (November-February), primordial germ cells proliferate within cords of filament-rich epithelial cells that will become follicular cells (FCs). Fibroblast-like cells surround the FCs and form the lobule-boundary interstitial cells (ICs). During the period of germ cell development from primordial germ cells to round spermatids (March-June), the FCs surrounding the developing germ cells contain scanty cytoplasm with abundant rough endoplasmic reticulum and scarce filaments. With spermatid elongation (July-August), the FC size grows, its nucleus becomes irregularly outlined, and its cytoplasm displays abundant smooth endoplasmic reticulum, residual bodies, lipid droplets, and large vacuoles. After spermatozoon release by the FCs (August-September), the adjacent ICs increase their size and transform into Leydig cells with abundant smooth endoplasmic reticulum, mitochondria with tubular cristae, and lipid droplets. During the period of testicular quiescence (November-February), the Leydig cells undergo involution, eventually developing the morphological attributes of mesenchymal cells. Intermingled among these cells, cords of filament-rich cells are observed. During this period of the cycle, spermatozoon cysts supported by FCs are present. At the beginning of the germ cell proliferation period (March), these spermatozoa are released, and the adjacent ICs undergo a transformation into Leydig cells similar to those observed in August-September. Maturation and involution of ICs occur when testosterone levels are known to be rising and falling, respectively.     

Cytological differentiation of the interrenal tissue of the Japanese quail,Coturnix coturnix

Summary As reported for several other avian species there are clearly distinguishable subcapsular (SCZ) and inner (IZ) zones of interrenal tissue in the Japanese quail. The SCZ contains large columnar cells (type I) with rounded nuclei, polymorphic mitochondria with shelf-like cristae, and relatively small numbers of lipid droplets. The IZ contains two and possibly three types of cells. Type II consists of large columnar cells with moderately dense cytoplasm containing large numbers of lipid droplets and many rounded mitochondria with tubular cristae. Smooth endoplasmic reticulum (SER) and Golgi apparatus are well developed; coated vesicles occur in the Golgi area and at the cell surface. Type-III cells occur in IZ and especially in its more peripheral areas. They are columnar cells with strikingly clear cytoplasm (in comparison with type II) containing mitochondria with plate-like cristae and tubular SER. Type-IV cells are sparsely distributed in IZ and occur rarely in SCZ. Type IV may be a degenerating phase of type III.After adenohypophysectomy or section of portal vessels type-I cells atrophy somewhat with a decrease in lipid droplets; type-II cells, also atrophy with conspicuous increase in size and number of lipid droplets, enlargement of mitochondria, and gradual disappearance of SER; type-III cells decrease in number whereas type-IV cells increase.After injection of ACTH, type-I cells enlarge and their mitochondria, SER and Golgi apparatus become more conspicuous; there is a decrease in lipid droplets in type-II cells and a development of SER, polysomes and Golgi apparatus; there is also a decrease in lipid droplets and a development of SER in type-III cells after injection of 2IU ACTH and an almost complete disappearance of lipid droplets after 4IU ACTH; type-IV cells increase in number.The investigation reported herein was supported by Scientific Research Grants from the Ministry of Education of Japan to Professor Mikami; and by grants from the Japan Society for the Promotion of Science, the National Science Foundation (USA), and the Graduate School Fund of the University of Washington to Professor Farner     

Seasonal changes of the Leydig cells of viscacha (Lagostomus maximus maximus). A light and electron microscopy study

The Leydig cells of viscacha (seasonal rodent) show cytoplasmic hypertrophy and regional distribution during the breeding period (summer-autumn). The dominant organelles are smooth endoplasmic reticulum (SER) and mitochondria. A moderately well-developed Golgi, abundant lipid inclusions, dense bodies like lysosomes in different stages, and centrioles are observed. Extensive or focal desmosome and gap-like junctions between neighbouring Leydig cells are present. These cells exhibit an evident hypotrophy and an increase in the number of dense bodies during the gonadal regression in winter (July and August). Cells in different stages of involution are observed in this period. Their nuclei are irregular and heterochromatic. The cytoplasm contains few mitochondria. The vesicular SER is scarse. Irregular and large intercellular spaces with microvilli and amorphous material are present. The junctional complexes are absent. The nuclear and cytoplasmic volume and development of SER and mitochondria increase during the recovery period (spring). The lipid inclusions decrease. Dilatations of the intercellular space with microvilli and limited by focal desmosome-like junctions are observed. In conclusion, the Leydig cells of Lagostomus maximus maximus show deep changes alongside the reproductive cycle. The photoperiod variations, through pineal hypothalamus pituitary axis and the hormone melatonin, are probably responsible for them. Moreover, the fall of serum and tubular testosterone would be one of the factors responsible for gonadal regression.     

Blockade of the hypothalamic-pituitary-testicular axis with a GnRH antagonist in the neonatal marmoset monkey: changes in Leydig cell ultrastructure

Little is known of the cell biology of Leydig cells during the neonatal activation of the hypothalamic-pituitary-testicular (HPT) axis. The current study examined the effect of blockade of the HPT axis with a GnRH antagonist (antide) on the neonatal population of Leydig cells in the new world primate, the common marmoset. Three sets of twins, age 7 weeks, were studied: in each pair one twin was used as a control, while the other received treatment with GnRH antagonist from the day of birth to suppress pituitary gonadotrophin secretion. Leydig cells of treated animals were dramatically different from those of controls. The cells were atrophic and exhibited very irregular nuclei. The organelles involved in steroid synthesis were reduced to the extent to being barely evident. The smooth endoplasmic reticulum (SER) was greatly diminished in quantity and distribution. The usual form of the SER (anastomosing tubules) was not evident, but, instead, the SER was relatively unbranched. Peroxisomes, organelles involved in transfer of cholesterol to the mitochondria, were greatly reduced in number. Mitochondria were relatively sparse and exhibited a non-typical morphology, as tubular elements of the cristae were rarely evident. Thus, the central apparatus in steroid production, the SER, mitochondria and peroxisomes, was essentially shut down in the GnRH-antagonist-treated animals. Storage of cholesterol, the precursor of steroid biosynthesis, was also not in evidence, as lipid droplets were extremely rare. Two prominent features of control in neonatal marmoset Leydig cells, the membranofibrillar inclusion (MFI) and basal laminae, remain prominent in the Leydig cells of treated animals. Evidence of apoptosis was not observed. These results provide strong support that the gonadotrophic hormones are the primary regulator of neonatal Leydig cell development in primates, and also suggest cell regression, rather than apoptosis, being the mechanism of this inhibition.     

Morphometry of fetal Leydig cells in the monkey (Macaca fascicularis), correlation with plasma testosterone

The evolution of Leydig cells in Macaca fascicularis fetuses was followed throughout gestation (50-150 d) by morphometric procedures (volume densities of: cells, SER, mitochondria and lipid droplets). Testosterone from umbilical artery plasma was radioimmunoassayed starting on day 57. After predifferentiation and differentiation phases, Leydig cells entered the maturity phase (57-66 d), they occupied 19% of testicular volume, SER and lipid droplets represented 19% and 5% respectively of cytoplasmic volume. Then Leydig cells regressed dramatically (involution phase I: 66-83 d), their volume density decreased to 8%, that of SER to 12% whereas lipids doubled. Leydig cell volume density diminished to 5% during the second half of gestation (involution phase II), but their ultrastructure was not significantly altered. High plasma testosterone level (2.4 ng/ml) was observed during the maturity phase of Leydig cells, decline of testosterone occurred during involution phases I and II (1.13 and 0.58 ng/ml respectively). Its was shown that from day 57 to the end of fetal development the evolution of the plasma testosterone level correlated with the Leydig cell volume density and the SER volume density.     

Observations on the Leydig cells in the male East African spring hare (Pedetes surdaster larvalis).

The morphology of Leydig cells of the testis of sexually mature and sexually immature spring hares was studied. The cytoplasm of the Leydig of cells the sexually immature spring hares was packed with large lipid droplets leaving little space for the other organelles. Smooth endoplasmic reticulum was poorly developed and occasionally formed concentric layers of fenestrated cisterns around the large lipid droplets. The Leydig of cells the sexually mature spring hares were almost devoid of lipid droplets and their cytoplasm was occupied by abundant tubular smooth endoplasmic reticulum. Cells which shared characteristics with both immature Leydig cells and undifferentiated mesenchymal cells were observed in the limiting membrane of the seminiferous tubulus. These Leydig-like cells may play a role in the differentiation of Leydig cells in the spring hare.     

Peroxisomes and intracellular cholesterol trafficking in adult rat Leydig cells following Luteinizing hormone stimulation

The present study was designed to explore the intracellular cholesterol trafficking in Leydig cells of adult rats following Luteinizing hormone (LH) injection. Histochemical techniques were used to demonstrate distribution of free cholesterol in Leydig cells of control and LH-injected rats. Two groups of sexually mature male Sprague Dawley rats (n=4/group) were used. Fifteen min following an injection of 200 microl of either saline (control) or luteinizing hormone (LH, 500 microg in saline) testes of rats were fixed by whole body perfusion using 0.5% glutaraldehyde and 4% paraformaldehyde in 0.1 M cacodylate buffer for 20 min. Fixed testes were cut into 3 mm3 and kept immersed in the fixative for further 15 min. Tissue cubes were then incubated at 37 degrees C in a medium containing cholesterol oxidase, 3,3'-diaminobenzidine tetrahydrochloride, horseradish peroxidase and dimethyl sulfoxide to histochemically localize free cholesterol in Leydig cells and processed for electron microscopy. Thin sections of these tissues were stained with aqueous uranyl acetate and lead citrate and examined with a Philips 201C electron microscope. In Leydig cells of control rats, free cholesterol was detected primarily in lipid droplets and plasma membrane. In the majority of Leydig cells, peroxisomes were unstained for free cholesterol, but occasionally few stained ones were present. Staining was not detected in mitochondria and smooth endoplasmic reticulum (SER) in Leydig cells of control rats. In LH-injected rats, lipid droplets, many peroxisomes, inner and outer mitochondrial membranes and some cisternae of SER in Leydig cells showed staining for free cholesterol. Fusion of Leydig cell peroxisomes with lipid droplets and mitochondria was also observed in the LH treated rats. These findings suggested that peroxisomes in adult rat Leydig cells participate in the intracellular cholesterol trafficking and delivery into mitochondria during LH stimulated steroidogenesis. Lipid droplets are used as one source for cholesterol for this process.     

A light- and electron-microscopic investigation of gametogenesis in Typosyllis pulchra (Berkeley and Berkeley) (Polychaeta: Syllidae)

Summary The ultrastructure of the interrenal (adrenocortical) cells of trout (Salmo fario L.) was studied after dexamethasone treatment. A procedure for identifying and isolating interrenal tissue fragments from the surrounding head kidney tissue prior to their preparation for electron microscopy is described. The peripheral plasma cortisol concentrations were measured in order to evaluate the steroidogenic activity of this tissue.The interrenal cells of control animals contain numerous mitochondria with tubular cristae, and a well developed and highly organized smooth endoplasmic reticulum (SER). The scarcity, or absence, of lipid droplets contrasts markedly with the abundance of SER.Treatment with dexamethasone results in a decrease steroidogenic activity of the interrenal cells, as indicated by the fall in plasma cortisol concentrations. The interrenal cells are small, but still contain numerous mitochondria. The SER is poorly developed, but masses of densely intermeshed smooth cisternae subsist. Lipid droplets do not accumulate in these cells; this peculiarity is discussed in connection with the virtual absence of liposomes in teleost interrenal cells.     

Fine structural changes in Sertoli and Leydig cells during the reproductive cycle of the ground squirrel, Citellus lateralis

During spermatogenesis in sexually mature ground squirrels Leydig and Sertoli cells were morphologically well differentiated. For Leydig cells the most prominent organelles were lipid droplets, mitochondria with tubulo-vesicular cristae and abundant agranular reticulum organized as a mass of anastomosing tubules. These morphological criteria suggest that the Leydig cells were steroidogenically active. Sertoli cells exhibited a topographical distribution of certain organelles with basal regions containing stacks of granular reticulum, and large areas of agranular reticulum. The cytoplasm surrounding maturing germ cells contained numerous microtubules, and an adluminal layer of spermatids at a certain stage of spermiogenesis became enveloped by Sertoli cytoplasm containing an enormous proliferation of agranular reticulum. The presence of these organelles in Sertoli cells suggests that during spermatogenesis they are active in the synthesis of proteins and steroids. In particular the mass of agranular reticulum surrounding late stage spermatids indicates that steroids may be required for spermatid maturation and/or spermiation. By contrast Leydig and Sertoli cells observed during testicular regression, when only spermatogonia remain in the seminiferous tubules, had undergone structural changes. Leydig cells were still numerous and large with abundant agranular reticulum that was now organized as a loose assemblage of single unbranched tubules. Sertoli cells were drastically reduced in both cytoplasmic volume and content of organelles.     

Changes in Leydig cell ultrastructure and function during pubertal development in the boar

Changes in the ultrastructure of Leydig cells during pubertal development in the boar (40 to 250 days of age) were assessed using quantitative morphometric procedures, and the results were compared to the in vitro steroid-producing capacity and gonadotropin sensitivity of testicular tissue obtained from the same boars. Volume of individual Leydig cells declined through 100 days of age, increased rapidly to a peak at 130-160 days (i.e., puberty), and then declined to intermediate levels by 220-250 days of age. The pattern of change in the number of intracellular organelles per Leydig cell was very similar to the change that occurred in Leydig cell volume. Changes in the total intracellular volume occupied by each type of organelle were highly correlated with changes in Leydig cell volume (r = 0.40-0.99, p less than 0.01), and this was particularly true for the nucleus (r = 0.63), mitochondria (r = 0.88), smooth endoplasmic reticulum (SER; r = 0.97), and total cytoplasm (r = 0.99) of the boar Leydig cell. In vitro production of testosterone and estradiol, expressed per Leydig cell, also peaked at 130-160 days, and was highly correlated to average Leydig cell volume, volume of SER, and number and total volume of mitochondria (r = 0.63-0.84; p less than 0.01). Observations in the present study indicated that onset of puberty in boars coincides with a dramatic increase in average Leydig cell size and SER volume per Leydig cell, accompanied by an increase in number of other intracellular organelles, including mitochondria, lysosomes, and lipid droplets, and a peak in the steroid-producing capacity per Leydig cell. A decline in Leydig cell size, intracellular organelles, and sensitivity to gonadotropin stimulation occurred postpubertally.     

Structural changes occurring in interrenal tissue of the duck (Anas platyrhynchos) following adenohypophysectomy and treatment in vivo and in vitro with corticotropin

Adrenal glands from ACTH-treated intact ducks and chronically adenohypophysectomized ducks showed clear zonation into a subcapsular zone (SCZ) and an inner zone (IZ). Adenohypophysectomy caused ultrastructural changes in the IZ but not in the SCZ cells. These included increases in lipid droplets, changes in mitochondrial cristae from tubular to shelf-like, and changes in the shape of the nuclei from spherical to crenated. These changes were reversed by treatment with ACTH. Also, cells of the IZ, but not the SCZ, of adrenals from intact birds given ACTH showed more SER, more dense bodies, fewer lipid droplets and more prominent Golgi complexes. IZ cells incubated in buffer containing no ACTH developed mitochondria with shelf-like cristae and numerous opaque granules in the matrix. Exposure to buffer containing ACTH caused the mitochondrial cristae to become tubular and the matrix granules either decreased in number or disappeared. The granules could be extracted by incubating sections with chelating agents. The mitochondria in SCZ cells did not respond structurally to the presence of ACTH in the incubation medium but the matrix granules, like those in IZ cells, responded to the presence of chelating agents.     

A quantitative morphological study of human Leydig cells from birth to adulthood

Summary Human testicular specimens were obtained from biopsies and autopsies covering the period from birth to adulthood. The number of testosterone-containing Leydig cells was determined using the peroxidase-anti-peroxidase method. This number decreased markedly from 3–6 months of age to the end of the first year of life and, up to 6 years of age, only a small number of testosterone-containing cells was found. From 6 years onwards the number of Leydig cells progressively increased. Ultrastructural examination revealed four types of Leydig cells: (1) fetal-type Leydig cells (from birth to 1 year of age) with round nuclei, abundant smooth endoplasmic reticulum and mitochondria with tubular cristae; (2) infantile-type Leydig cells (from birth to 8–10 years of age), showing a multilobated nucleus, moderately abundant smooth endoplasmic reticulum, some lipid droplets and mitochondria with parallel cristae; (3) prepubertal, partially differentiated Leydig cells (from 6 years of age onwards) with regularly-outlined round nuclei, abundant smooth endoplasmic reticulum, mitochondria with tubular cristae, and some lipid droplets and lipofuscin granules; and (4) mature adult Leydig cells (from 8–10 years of age onwards). The ultrastructure of the infantile-type Leydig cells and the lack of delay between the disappearance of the fetal-type Leydig cells and the appearance of infantile-type Leydig cells suggest that fetal-type Leydig cells give rise to the infantile-type Leydig cells. Before puberty, myofibroblast-like precursor cells differentiate into the prepubertal, partially differentiated Leydig cells, which complete their differentiation into the adult Leydig cells.This work was supported by grants from the Comisión Asesora de Investigation Científica y Técnica, and the Fondo de Investigaciones Sanitarias de la Seguridad Social, Madrid, Spain     

Structural changes in bovine oocytes during final maturation in vivo

On the basis of structural observations bovine oocytes were grouped into four successive classed: 0, those before the luteinizing hormone (LH) surge; 1, those up to 8 h following the LH peak level; 2, those between 8 and 19 h after the LH peak level; and 3, those between 19 h after the LH peak level and ovulation. Oocytes in class 0 had mitochondria located in a generally peripheral position. Interior to the mitochondria were elements of rough endoplasmic reticulum (RER) and numerous membrane-bound vesicles which bore ribosome-like particles on their outer surface. The first visible changesater the LH peak level as seen in class 1 were the formation of the periviteline space with loss of contact between the cumulus cells and the oocyte, and ruffing of the nuclear envelope. These changes were followed b the resumption of meiosis as defined by germinal-vesicle breakdown (GVBD), the disappearance of RER, and the formation fo clusters of mitochondria in association with lipid droplets and elementrs of smooth endolasmic reticulum (SER). The period between 8 and 19 h following LH peak level (class 2) was characterized by intensive clustering of mitochoncria in association with lipid droplets and elements of SER, conversion of lipid, fusion of vesicles, and the appearance of ribosomes in the cytoplasm. During the final stage (class 3), the polar body was extruded, the mitochondria dispersed, and the majority of the organelles became located toward the center of the cell. The relatively organelle-free cortical region contained cortical granules immediately adjacent to the plasma membrane together with aggregates of tubular SER. The structural changes are discussed in the context of follicular steroidogenesis and oocyte developmental competence.     

乌梢蛇精巢间质细胞微细结构与血清 睾酮浓度的相关性

用光镜及透射电镜观察了乌梢蛇(Zaocys dhumnades)精巢间质细胞的显微与超微结构,并利用放射免疫测定法测定了血清中睾酮浓度.结果表明,在一个年生殖周期中,乌梢蛇间质组织所占区域相对大小、间质细胞数量和显微结构均存在较明显的变化;5月份的间质细胞具有发达的管状嵴线粒体、丰富的滑面内质网、大量的脂滴等合成和分泌...     

Histological, histochemical, enzyme histochemical and ultrastructural investigations of the testis of Padogobius martensi between annual breeding seasons

From July to March, the testis of the spring‐spawning freshwater goby Padogobius martensi is characterized by spermatogonial proliferation. A close correlation exists among type of proliferating spermatogonia, gonado‐somatic (I_G) profiles and morphological and functional variations of the Leydig cells. The I_G reach their minimal levels by the end of summer and increase progressively but modestly during autumn and winter. Declining I_G levels are associated with proliferation of primary spermatogonia only, whereas increasing I_G levels are associated with predominant proliferation of secondary spermatogonia. Minimal I_G levels are reached when the germinal epithelium is formed by a continuum of primary spermatogonia and associated Sertoli cells. The proliferation of secondary spermatogonia begins only at this time. Spermatogenesis in autumn occurs when spermatogonial cysts contain at the most 16 cells and it rarely results in the maturation of several cysts so that the amount of sperm cells produced is either negligible or scarce. A number of degenerating cells are usually present within the spermatogonial and meiotic cysts. Leydig cells are the unique cells that display features of steroidogenic cells: mitochondria with tubular cristae, extensive smooth endoplasmic reticulum (SER), 3β‐hydroxysteroid dehydrogenase (3β‐HSD) and glucose‐6‐phosphate dehydrogenase (G6PD) activity and sudanophilia. Light and dark Leydig cell varieties are always present. During regression, Leydig cells undergo a marked decrease in SER amount, mitochondrial sizes and number of mitochondrial cristae. In parallel, the 3β‐HSD and G6PD activities and sudanophilia decrease progressively until they become undetectable by the end of regression. In autumn, mitochondria increase in size, reaching sizes similar to those observed at the end of the spawning season in the light cells, but not in the dark cells. The SER, on the contrary, undergoes a modest and irregular increase only in a part of the Leydig cells, mostly of the light type. In parallel, the 3β‐HSD and G6PD activities increase until they become moderately intense by the end of autumn. At the end of winter, the SER is extensive and regularly dilated in both Leydig cell types, whereas mitochondria still have sizes similar to those observed in December. The 3β‐HSD and G6PD activities are strong and sudanophilia is again detectable. Sertoli cells undergo changes in shape and position in relation to the proliferation of primary spermatogonia and the development of cysts. A junction modulation occurs in association with these changes. Sertoli cells also undergo changes indicative of a decrease in activity immediately after spawning (loss of mitochondrial cristae and clarification of the mitochondrial matrix) and of an increase in activity by the end of the regressing phase (darkening of the mitochondrial matrix and increase in mitochondrial cristae, rough endoplasmic reticulum (RER) and free ribosomes). In addition, they are involved in the phagocytosis of degenerating germ cells at all stages of their development. Macrophages are found in the testis interstitium only, where they are usually adjacent to Leydig cells, myoid cells and blood capillaries and do not participate in the phagocytosis of degenerating germ cells. Myoid cells do not undergo ultrastructural changes except for an increase in the amount of heterochromatin by the end of spawning. The meaning of the autumnal spermatogenic wave and the relationships between the development of the germinal epithelium and the changes of the Leydig and Sertoli cells are discussed.     

An ultrastructural stereologic study of aldosterone secreting adrenal adenomas and of adjacent zona glomerulosa

The ultrastructure of four aldosterone secreting adenomas and of the adjacent zona glomerulosa has been described by the use of stereological techniques. Adenomatous cells (about 2800 microns 3 in volume) invariably displayed a striking abundance of lipid droplets, which occupied about 30% of the cytoplasm. Mitochondria prevalently contained tubulo-lamellar or lamellar cristae, but some cells exhibited organelles with vesicular cristae. Smooth endoplasmic reticulum (SER) was not very abundant. Small lipofuscin-pigment granules were frequently seen and in a few cells they were exceedingly numerous. Zona glomerulosa cells were smaller (about 950 microns 3 in volume) and possessed mitochondria with typical tubulo-lamellar cristae, a plentiful SER and few lipid droplets. They showed the ultrastructural features of elements actively engaged in steroid synthesis. The possible origin of aldosteronoma cells from the zona glomerulosa is discussed.     

Spontaneous testicular neoplasm in mice with testicular feminization

Summary Testicular neoplasms occur spontaneously in androgen insensitive mice with testicular feminization (tfm/y); they are composed of Leydig cells, lipid-laden cells, fibroblastlike cells, and macrophages. The small Leydig cells in the periphery of the tumor are structurally similar to nontumorous tfm/y Leydig cells, whereas centrally located large Leydig cells contain numerous lipid droplets, mitochondria with tubular cristae, and abundant smooth endoplasmic reticulum. The lipid-laden cells exhibit a crescentic nucleus which is displaced toward the periphery of the cytoplasm by a large lipid vacuole. The fibroblastlike cells have a large amount of rough endoplasmic reticulum, lysosomes, free ribosomes, and lipid vacuoles. Macrophages are characterized by numerous layered and dense osmiophilic structures closely associated with crystalshaped bodies. An in vitro study shows that, in comparison with the normal testes, the tfm/y tumors produce significantly less testosterone but a larger quantity of androstenedione. Also, the tumors are capable of converting progesterone to estrone and estradiol-17. The plasma level of testosterone is significantly lower in tumor-bearing animals than in normal littermates, but slightly higher than in the nontumorous tfm/y animals. Since the abnormal steroid enzyme activity is found in both tumor-bearing and nontumorous tfm/y mice, the basic cause of aberrations in sex steroid production appears to be genetic rather than the direct result of alterations in their Leydig cells.     

大鼠睾丸间质细胞的自体吞噬活动

本文结合超微结构和细胞化学观察,研究大鼠睾丸间质细胞(Leydig细胞)中溶酶体的结??构与功能。观察结果表明,大鼠睾丸间质细胞中高尔基体非常发达,在高尔基体的成熟面存在着CMP酶阳性反应的GERL系统,说明这种细胞有不断产生溶酶体的能力。细胞化学结果也证实在睾丸间质细胞有较多的初级和次级溶酶体。睾丸间质细胞不仅有较多的溶酶体,而且还有相当数量的自噬小体,存在着活跃的自体吞噬活动。自噬小体的界膜来源于特化的光面内质网或高尔基体膜囊,包围的内容物主要是光面内质网和少量线粒体。当自噬小体与溶酶体融合后即成为自体吞噬泡,由于酶的消化作用,自体吞噬泡内的细胞器有一系列形态变化。根据CMP酶细胞化学反应,可以区分自噬小体和自体吞噬泡,后者是一种次级溶酶体,呈CMP酶阳性反应。睾丸间质细胞是分泌雄性激素的内分泌细胞,其光面内质网和线粒体在类固醇激素分泌中起重要作用,自体吞噬活动的结果是去除部分内质网和线粒体,可能在细胞水平上起着对雄性激素分泌的调节作用。     

Relationships between Leydig cell morphometry and plasma testosterone during postnatal development of the monkey, Macaca fascicularis

In neonates (0 to 3-4 months), the testis contained a mean number of 4.6 X 10(6) Leydig cells representing 4.2 % of its volume; Leydig cell cytoplasm contained 10.2 % of SER. In infants (up to 45 months), Leydig cells regressed but their number increased; their volume density did not change. Leydig cell cytoplasmic volume (454 microns3 ), which was about 2.5-fold less than in neonates (1 119 microns3 ) or adults (1 170 microns3 ), contained only 8.7% of SER. During meiosis stage (38-52 months). Leydig cell numbers and volume density did not vary but the cells reached a maximal size and an amount of SER comparable with that at birth was measured. When spermatogenesis was complete, the Leydig cells represented no more than 0.8% of testis volume, but their number and SER content were significantly increased. Except for a significant decrease when spermatogenesis was completed, Leydig cell lipid content did not change during development, and the volume density of mitochondria did not vary. The mean level of plasma testosterone was 2 ng/ml in neonates and 0.4 ng/ml in infants; it increased to 3 ng/ml during onset of meiosis and reached 10 ng/ml in adults. The profile of testosterone was positively and significantly correlated with the total volume and total number of Leydig cells (P less than 0.01 and P less than 0.02, respectively) and with changes in their cytoplasmic volume (P less than 0.001). Moreover, plasma testosterone levels were positively and significantly correlated with changes in Leydig cell SER content i.e. SER volume density and mean absolute volume per cell (P less than 0.001), total SER in the whole testis (P less than 0.01).     

Changes in Leydig cell activity during the annual testicular cycle of the bat Myotis lucifugus lucifugus: histology and lipid histochemistry

Changes in Leydig cell histology and testicular sudanophilic lipids were examined in relation to spermatogenic activity in the bat Myotis lucifugus lucifugus (Chiroptera: Vespertilionidae) throughout the annual cycle in the northeastern United States. These changes were correlated with annual variations in plasma testosterone concentrations which have recently been described for this species. Gametogenic activity occurred during the months of May-August when bats were metabolically most active. During hibernation (October-April), when sperm are stored in the epididymides, and accessory glands are hypertrophic, the seminiferous tubules were at rest, and the germinal epithelium was reduced to reserve spermatogonia and Sertoli cells. Based on their structure and cyclic pattern of sudanophilic lipids, Leydig cells exhibited a pattern of activity that closely paralleled that of the seminiferous epithelium. On renewal of spermatogenesis in spring, Leydig cells became hypertrophied and accumulated lipid inclusions. These inclusions, seen as vacuoles in plastic sections and sudanophilic droplets in frozen sections, reached maximal accumulations in late June. In late July and during August, when peak testosterone levels occur in blood, lipid droplets were dramatically depleted, and Leydig cells were weakly sudanophilic. In September, when testosterone titers return to low baseline levels, Leydig cells had regressed but exhibited a marked increase in sudanophilic inclusions which appeared to be mostly lipofuscins. During the ensuing mating and hibernation periods, Leydig cells were involuted and filled with lipofuscins. During the periarousal period, however, Leydig cells became weakly Sudan-positive while many large, intensely sudanophilic cells were scattered throughout the interstitium. In electron micrographs these cells were identified as macrophages. They appear to play an important role in the annual testicular cycle by phagocytizing the residues of Leydig cell involution in preparation for a new steroidogenic cycle. Seasonal changes in lipid inclusions were also observed in the seminiferous tubules. In addition, the relationship of the Leydig cell cycle to androgen action and the accessory organs in this bat is discussed.