Changes in seminiferous tubules after vasectomy

The histologic, immunohistochemical, and ultrastructural changes in the seminiferous tubules (ST) of 17 healthy adult males who had been vasectomized between 1 1/2 and 5 years are reported. There was minimal spermatogenesis in 4 cases. 8 of the cases underwent electron microscopy examination and 4 showed evidence of minimal histological spermatogenesis. The ST showed a thickening of the basement membrane and heavy deposits of lipofuchsin in the Sertoli cells (SC) seen as lipid infiltration. The spermatogenic cells presented variable changes characterized by the disorientation of cells, maturation arrest, and premature sloughing. No immune complex deposits were seen. Of the 9 cases followed, pregnancy occurred in 2 following vas reanastomosis; a regenerative capacity of the ST was seen in 6 cases. The follow-up studies also show that the morphological alterations initially produced by the vasectomy have little affect on the appearance of spermatogenesis after vas reanastomosis. Thus, we see that the vasectomy exerts its major effect on the SC and that the damage to these cells alters the testicular environment. However, these changes are apparently reversible following vasovasostomy.     

Leydig cells within the aspermatogenic seminiferous tubules

Cells identical to Leydig cells were found within a peritubular boundary layer and even inside a basal lamina of seminiferous tubules in three male patients (two with inguinal cryptorchism and one with infertility). The seminiferous tubules of all patients showed a moderate to marked thickening of the boundary layer and a complete loss of spermatogenic cells. The "ectopic Leydig cells" were characterized by the presence of Reinke crystals or an extensively developed smooth endoplasmic reticulum. These cells were believed to have differentiated in situ from myoid cells within the boundary layer and also to have invaded from the interstitial tissue in the form of mature Leydig cells. The occurrence of ectopic Leydig cells appeared to parallel the extent of loss of the Sertoli cells and also that of the thickening of the boundary layer. The functional significance of the ectopic occurrence might be implicated in the impaired spermatogenesis.     

Histopathological diagnosis of hypercurved seminiferous tubules

A simple method for the recognition of hypercurvature of the seminiferous tubules in otherwise normal biopsies from infertile males consists of the recognition of characteristic 'figure 8' profiles of sectioned seminiferous tubules. Nineteen cases of morphometrically verified hypercurvature and 24 controls were tested in order to determine the validity of the method, which showed virtually no overlap in the two groups when at least four x 100 fields were assessed for 'figure 8' and grazing profiles. A recommended diagnostic approach, with cautions concerning pitfalls, is presented, and incidence, pathogenesis, and potential treatment are briefly discussed.     

Three-dimensional structure of seminiferous tubules in the Syrian hamster

The hamster is useful for the study of male reproductive biology. However, unlike in the mouse and rat, the gross structure of seminiferous tubules in the hamster is largely unknown. The aim of the present study was to clarify the precise 3-dimensional (3D) structure of seminiferous tubules in hamsters. We reconstructed all seminiferous tubules in 3 and 1 testes from 0-day (P0) and 10-week (adult) Syrian hamsters, respectively, using serial paraffin sections and high-performance 3D reconstruction software. In P0 hamsters, the average numbers of seminiferous tubules, terminating points, branching points, and blind ends per testis were 9.0, 89.7, 93.0, and 0.7, respectively. There were two types of tubules: shorter and dominant ones. The dominant tubules, 2–4 in number per testis and accounting for 86% of the total tubule length, had many terminating and branching points and appeared to be derived from the anastomosis of many shorter tubules. In an adult hamster, there were 11 seminiferous tubules with a total length of 22 m, 98 terminating points, 88 branching points, and 2 blind ends per testis. Three of the 11 tubules were dominant ones, accounting for 83% of the total length, and occupied the testis from the surface over the circumference to the center, while the others were short and occupied only one side of the testis. The amplitude and direction of the curves of tubules were random, and there were no funnel-shaped networks of tubules present, in contrast to the mouse testis. The present study revealed the 3D structure of seminiferous tubules in developing and adult Syrian hamsters, which is different from that in mice and rats.     

Reticulin fibres in the tunica albuginea and peritubular tissue of seminiferous tubules of adult male Wistar rats

Reticulin fibres are fine fibres that contain primarily collagen type III and are found in soft blood-forming or blood-processing tissues, and are supportive elements in kidney, liver and thymus. This study demonstrates for the first time the presence of reticulin fibres in the tunica albuginea and peritubular tissue of seminiferous tubules of adult rat testes after staining with the metallic silver impregnation method. Reticulin fibres of peritubular tissues may provide a supportive framework for germinal epithelium of seminiferous tubules to allow the periphery-to-centre progression of spermatozoa during spermatogenesis. The presence of fibres in all stages of the spermatogenic cycle suggests that they have structural functions.     

Distribution of macromolecular components in calf dermal connective tissue

Distribution of type I and type III collagens, glycosaminoglycans and non-collagenous glycoprotein(s) in calf skin has been investigated in five horizontally sliced layers of 250 microns thickness from the surface to the bottom. The upper dermis (the top three layers) consisting of fine collagen fibers had a higher ratio of hyaluronic acid/dermatan sulfate than the lower layers where coarse collagen fibers are mainly located. The ratios of total glycosaminoglycans/collagen and glycoprotein(s) collagen were higher in the upper dermis, while dermatan sulfate/collagen remained constant throughout the dermis. Relative content of type III collagen/total collagen (type I + III collagens) was also higher in the upper dermis. Possible involvement of these macromolecular constituents in collagen fibrillogenesis in vivo is also discussed.     

Alterations of the connective tissue components induced by β-aminopropionitrile

The ultrastructural and biochemical alterations induced by β-aminopropionitrile on aorta, lung, and skin of 7-day-old chicks have been studied. The inhibition of elastin formation by β-aminopropionitrile was associated with: (i) apposition of elastin on the old fiber in the form of button-like appendices; (ii) absence of microfibrils around this abnormally deposited elastin; (iii) presence of ruthenium red and toluidine blue O-positive material within the lathyritic elastin; (iv) increase of proteoglycan content; (v) increase of the mean diameter of collagen fibers; (vi) increased vesiculation of the endoplasmic reticulum of both fibroblasts and smooth muscle cells in aorta. The role of lysyl oxidase in the assembly of elastin and collagen fibers is discussed. Particular attention has been paid to the relationship between elastin, microfibrils, and proteoglycans in the formation of the elastic fiber.     

Intracellular potentials in cells of the seminiferous tubules of rats.

1. Membrane potentials have been recorded from cells of seminiferous tubules of rats in vitro using micro-electrodes. The value in 808 impalements was -28-2 +/- 0-3 mV (mean +/- S.E.) at 33 degrees C. 2. Increasing the potassium concentration depolarized the cells, a tenfold increase in concentration causing a depolarization of 16 mV. Removal of sodium from the bathing solution caused a hyperpolarization of 3 mV at a potassium concentration of 5-9 m-equiv/l. Removal of chloride and replacement with impermeant anions had no effect on potential. Removal of calcium from the bathing solution caused a minor but significant depolarization. 3. Ouabain (10-3 M), dinitrophenol (2-5 times 10-4 M) or removal of glucose from the bathing fluid all caused depolarization. The membrane potentials of the cells were sensitive to temperature over the range 10-33 degrees C, the apparent activation energy for the reactions maintaining the potential being approximately 6 kcal/mole. 4. Membrane potentials in seminiferous tubules were independent of age of the animal, were insensitive to previous hypophysectomy and were insensitive to a number of hormones (FSH, LH, HCG, oxytocin). In high concentration prostaglandin E1 caused depolarization. 5. Acetazoleamide (4 times 10-5 M) caused a rapid, but reversible, depolarization of the tubular cells. This was also true in conditions when the HCO'3/CO2 buffer system was replaced with Tris-buffer. Another carbonic anhydrase inhibitor (p-sulphonamido-benzoic acid) had similar effects on cell potentials as acetazoleamide. These results are discussed in relation to the nature of the ionic secretion produced in the tubules. 6. Occasional cells showed phasic variations in membrane potential. A possible connexion between these variations and the contractile activity of the tubules is discussed.     

Effect of formalin fixation on the ultrastructure of connective tissue components

Electron microscopic examinations of fibrillar components and the ground substance of human skin derma fixed in formaldehyde showed good preservation of the fibrillar structures. The typical changes in fixed collagen fibrils in negative staining include the lack of transversal lines in the zone A and poor manifestation of microfibrillarity in the zone B. Alterations in the ground substance are more significant. Staining with rutenium red reveals no reticular structure here, but floccular formations appear in the amorphous interfibrillar substance. Other species of rutenium-positive structures (sheaths of elastic fibers and collagen fibrils as well as lines of thin cross-striation of the latter) are well preserved. All these alterations should be taken into consideration in ultramicroscopical examinations of formalin-fixed connective tissue.     

Ultrastructural study of seminiferous tubules in the rat after prenatal irradiation

Summary Is the presence of germinal cells necessary for the Sertoli cells to acquire normal features? To respond to this question we have studied the development of the Sertoli cells in rats irradiated at the end of the foetal life.In the prenatal irradiated rats, the lumen of the seminiferous tubules appears later than in the control rats. The Sertoli cells show numerous flexuous apical processes, with central microtubule bundles. These processes regress progressively after the 40th day of life when the tubular lumen appears; numerous junctional complexes differentiate with the same structure as those of control animals. There are important dilatations of the intercellular spaces. The cytoplasmic organelles show a normal development up to the 40th day of life. After this period, the rough endoplasmic reticulum and the Golgi apparatus clearly regress while important dilatations appear in the smooth endoplasmic reticulum and persist in the adult animal. From the 35th day on, the basal lamina of the seminiferous tubules is irregular and multilayered.The differentiation of the Sertoli cells seems to be independent of the presence of germinal cells until the 40th day of life and presents several particularities; thereafter the Sertoli cells show signs of regression.     

Ultrastructure of the seminiferous tubules in human testes before and after varicocelectomy

Ultrastructure of the membrana propria and the seminiferous epithelium was studied in infertile human testis both before and 3–6 months after varicocelectomy. The frequent alterations, observed before and after the operation, were extremely thickened membrana propria, deep invaginations, multilamination and knob-like formation of basal laminae and formation of multinucleated spermatids, which were all considered as the common response of the testis to different noxious agents. Although the cells of the seminiferous epithelium were clearly affected by varicocele before varicocelectomy, many areas exhibited normal features after the operation. Furthermore, multinucleated cells, sharing common features of Sertoli cell and spermatogonium, were observed, as well as presence of well-developed annulate lamellae in the Sertoli cells, exhibiting centrioles in the vicinity of their nuclei after varicocelectomy. These multiple ultrastructural observations indicate that Sertoli cell division takes place. This study suggests that if the observation period of the tissue samples after varicocelectomy is long enough, the reversible changes of the tubular cells would be seen much more frequently.Part of this study was submitted as a PhD thesis by Asst. Prof. Hülya Özgür and presented at the 12th National Congress on Electron Microscopy held in Antalya, Turkey, 1995     

Interactions between mast cells, fibroblasts and connective tissue components

It has long been recognized that mast cells occur throughout connective tissues. Histologic studies have revealed that such cells release their granules into the surrounding environment upon exposure to both immunologic and nonimmunologic stimuli. By microscopy these extracellular granules appeared to be phagocytosed by fibroblasts and by blood-borne phagocytic cells as they entered the site of mast cell degranulation. Such in vivo observations led to the suggestion that mast cells both altered connective tissue components and influenced fibroblast function through these discharged granules. Recent in vitro studies using cultured fibroblasts and isolated mast cells and mast cell granules have confirmed both these hypotheses. In addition, such studies have also documented that fibroblasts degrade ingested mast cell granules. Such studies document that a number of critical interactions may occur between mast cells and connective tissue components.     

Light cells within the limiting membrane of rat seminiferous tubules

Light-staining cells, distinct from myoid cells, were identified in electron micrographs of the limiting membrane of rat seminiferous tubules. While these cells were also found free in the interstitial space, they were observed mostly in the myoid cell layer of the limiting membrane but were never seen within the seminiferous epithelium itself. The light cells were characterized by a pale-stained cytoplasm containing a spheroidal Golgi apparatus next to a polymorphous often kidney-shaped nucleus, a few cisternae of rough endoplasmic reticulum and some granules of various types including multivesicular bodies. In hematoxylin-stained whole mounts of dissected tubules, these light cells were readily identified under the light microscope by nuclear morphology and light-staining juxtanuclear Golgi apparatus. The incidence of these cells, per unit surface area of tubular wall, was calculated, taking into consideration the stages of the cycle of the seminiferous epithelium with which they were associated. Distributed along the entire length of seminiferous tubules, their number varied significantly during the cycle. Low numbers were found in stages II–IV and XIII of the cycle, while high numbers were found in stages IX to XII and XIV–I of the cycle. These observations indicate that the seminiferous epithelium may exert an influence on the population of light cells present in the tubular limiting membrane.