The normal fine structure of opossum testicular interstitial cells

Regeneration in the Auditory Organ in Cuban and African Dwarf Crocodiles (Crocodylus rhombifer and Osteolaemus tetraspis) Can We Learn From the Crocodile How to Restore Our Hearing?

Background: In several non-mammalian species, auditory receptors undergo cell renewal after damage. This has raised hope of finding new options to treat human sensorineural deafness. Uncertainty remains as to the triggering mechanisms and whether hair cells are regenerated even under normal conditions. In the present investigation, we explored the auditory organ in the crocodile to validate possible ongoing natural hair cell regeneration.

Materials and Methods: Two male Cuban crocodiles (Crocodylus rhombifer) and an adult male African Dwarf crocodile (Osteolaemus tetraspis) were analyzed using transmission electron microscopy and immunohistochemistry using confocal microscopy. The crocodile ears were fixed in formaldehyde and glutaraldehyde and underwent micro-computed tomography (micro-CT) and 3D reconstruction. The temporal bones were drilled out and decalcified.

Results: The crocodile papilla basilaris contained tall (inner) and short (outer) hair cells surrounded by a mosaic of tightly connected supporting cells coupled with gap junctions. Afferent neurons with and without ribbon synapses innervated both hair cell types. Supporting cells occasionally showed signs of trans-differentiation into hair cells. They expressed the MAFA and SOX2 transcription factors. Supporting cells contained organelles that may transfer genetic information between cells, including the efferent nerve fibers during the regeneration process. The tectorial membrane showed signs of being replenished and its architecture being sculpted by extracellular exosome-like proteolysis.

Discussion: Crocodilians seem to produce new hair cells during their life span from a range of supporting cells. Imposing efferent nerve fibers may play a role in regeneration and re-innervation of the auditory receptors, possibly triggered by apoptotic signals from wasted hair cells. Intercellular signaling may be accomplished by elaborate gap junction and organelle systems, including neural emperipolesis. Crocodilians seem to restore and sculpt their tectorial membranes throughout their lives.

Loose Morphology and High Dynamism of OSER Structures Induced by the Membrane Domain of HMG-CoA Reductase

The membrane domain of eukaryotic HMG-CoA reductase (HMGR) has the conserved capacity to induce endoplasmic reticulum (ER) proliferation and membrane association into Organized Smooth Endoplasmic Reticulum (OSER) structures. These formations develop in response to overexpression of particular proteins, but also occur naturally in cells of the three eukaryotic kingdoms. Here, we characterize OSER structures induced by the membrane domain of Arabidopsis HMGR (1S domain). Immunochemical confocal and electron microscopy studies demonstrate that the 1S:GFP chimera co-localizes with high levels of endogenous HMGR in several ER compartments, such as the ER network, the nuclear envelope, the outer and internal membranes of HMGR vesicles and the OSER structures, which we name ER-HMGR domains. After high-pressure freezing, ER-HMGR domains show typical crystalloid, whorled and lamellar ultrastructural patterns, but with wide heterogeneous luminal spaces, indicating that the native OSER is looser and more flexible than previously reported. The formation of ER-HMGR domains is reversible. OSER structures grow by incorporation of ER membranes on their periphery and progressive compaction to the inside. The ER-HMGR domains are highly dynamic in their formation versus their disassembly, their variable spherical-ovoid shape, their fluctuating borders and their rapid intracellular movement, indicating that they are not mere ER membrane aggregates, but active components of the eukaryotic cell.

Anatomical, histological and immunohistochemical study of testicular development in Columba livia (Aves: Columbiformes)

In this work, testicular ontogeny is analyzed at the anatomical, histological and immunohistochemical levels; the latter through the detection of GnRHR and PCNA in the testicles of embryos, neonates and juveniles of Columba livia. We analyzed 150 embryos, 25 neonates and 5 juveniles by means of observations under a stereoscopic magnifying glass and scanning electron microscope (SEM). The histological analysis was performed using hematoxylin-eosin staining techniques and the PAS reaction. For the immunohistochemical analysis, the expression of GnRHR and PCNA in embryos corresponding to stages 41, 43 and in neonates of 2, 5, 7 and 75 days post-hatch was revealed in testicular histological preparations. That gonadal outline is evident in stage 18. In stage 29, the testes are constituted of a medulla in which the PGCs are surrounded by the Sertoli cells, constituting the seminiferous tubules. From stage 37 a greater organization of the tubules is visualized and at the time of hatching the testicle is constituted of the closed seminiferous tubules, formed of the PGCs and Sertoli cells. The Leydig cells are evident outside the tubules. In the juvenile stages, the differentiation of germline cells and the organization of small vessels that irrigate the developing testicle begin to be visible. In the analyzed stages, the immunodetection of the GnRHR receptor and PCNA revealed specific marking in the plasma membrane and in the perinuclear zone for GnRHR and in the nucleus of the germline cells in juvenile testicles for PCNA. These results can be used as a basis for further study of endocrine regulation events during testicular ontogeny in avian species.

Light and electron microscopic studies on the Y organ of the freshwater crab Travancoriana schirnerae

The fine structure of the premoult Y organ in the freshwater crab Travancoriana schirnerae revealed elliptical epithelial gland cells with large, eccentric, multinucleolated nuclei and ample cytoplasm. The cytoplasm showed numerous polymorphic mitochondria with tubular cristae, highly anastomosed tubules and vesicles of smooth endoplasmic reticulum (SER), rich free ribosomes, small amounts of cisternae of rough endoplasmic reticulum (RER), microtubules and was devoid of Golgi complexes. Mitochondria were of two types the more abundant micromitochondria with electron dense matrix and the less abundant macromitochondria with moderately dense matrix. The tubular SER was particularly concentrated towards the basal region of the cell, intermingled with mitochondria and dense patches of free ribosomes while the vesicular SER lie close to the lateral plasma membrane. Large vesicles with flocculent substances, a few electron dense granules and multivesicular bodies could also be noticed in the gland cell cytoplasm. Aggregations of microvesicles which appeared close to the lateral plasma membrane, in association with dilated SER cisternae and microtubules, possibly suggest the intercellular exchange of substances. The plasma membrane beneath the basal lamina was composed of invaginations and the apical surface possessed numerous microvilli which serve to increase the surface area for metabolic exchange. Towards the apical region, the lateral plasma membrane of adjacent cells was linked by tight junctions. The presence of extraordinarily abundant tubular SER, high proportion of mitochondria with tubular cristae and rich free ribosomes could well be elucidated in favour of steroid production by the gland cells.

Morphological development of testes in ostrich (Struthio camelus) embryo

Although the histological structure of ostrich testis has been studied, very little information is currently available on the embryonic development of this organ. The aim of this study was to determine the sequence of the histological changes in diverse components of the testis in ostrich embryo from embryonic day (E) 20 to E42. The main findings were categorized into four histological features, i.e., development of sex cords, interstitial tissue and rete ducts, and the appearance of defective septa. While the lumen of sex cords, tunica albuginea, capsular rete ducts and Leydig cell precursors appeared at E26, the filum-shaped defective septa were visible at E36. The emersion of the lumen in the primary sex cords and formation of capsular rete ducts in the ostrich embryo is considerably different from that in other birds. However, tunica albuginea and Leydig cell precursors appeared in a similar pattern to those of other birds. An interesting observation was that the primordial germ cell (PGC)-like cells were completely distinct, while the capsular rete ducts were formed by trapping of some Sertoli cell aggregations in the tunica albuginea. This suggests that similar to the primary sex cords, the capsular rete ducts may originate from the Sertoli cell aggregations which had corralled some PGCs. Stereological estimations in the ostrich embryo testis showed the major proportion of testis is occupied by the seminiferous tubules, which is unlike the fowl embryo testis.

On the relationship of liver glucose-6-phosphatase to the proliferation of endoplasmic reticulum in phenobarbital induction

The differentiated effects of phenobarbital treatment on liver microsomal enzymes have been further studied. The relationship between the resulting decrease in the specific glucose-6-phosphatase activity and the enhancement of formation of endoplasmic reticulum membranes with high drug-hydroxylating activity has been investigated with biochemical and histochemical methods. Biochemically and histochemically demonstrable glucose-6-phosphatase activity was found to be present in all endoplasmic reticulum membranes, including the phenobarbital-induced smooth-surfaced proliferates, even though there was an over-all decrease in activity. Actinomycin D did not inhibit the decrease in glucose-6-phosphatase activity. The findings are discussed with reference to the enzyme-membrane relationship in phenobarbital induction.

THE FINE STRUCTURE OF TESTICULAR INTERSTITIAL CELLS IN GUINEA PIGS

In guinea pig testes perfused with either glutaraldehyde or osmium tetroxide fixative, the cytoplasm of the interstitial cells contains an exceptionally abundant agranular endoplasmic reticulum. The reticulum in central regions of the cell is a network of interconnected tubules, but in extensive peripheral areas the reticulum is commonly organized into closely packed, flattened cisternae which are fenestrated. Occasional small patches of the granular reticulum occur in the cytoplasm and connect freely with the agranular reticulum. The mitochondria have a dense matrix and contain cristae and some tubules. The Golgi complex is disperse and shows no evidence of secretory material. The cytoplasm also contains lipid droplets. Lipofuscin pigment granules are probably polymorphic residual bodies and contain three components: (1) a dense material which at high magnification shows a 75-A periodicity; (2) a medium-sized lipid droplet; and (3) a cap-like structure. In glutaraldehyde-perfused testis the interstitial cell cytoplasm appears to have the same density from cell to cell, and the agranular reticulum is tubular or cisternal but not in the form of empty vesicles. Thus the "dark" and "light" cells and the vesicular agranular reticulum sometimes encountered in other fixations may be artifacts. Biochemical results from other laboratories, correlated with the present findings, indicate that the membranes of the agranular endoplasmic reticulum in guinea pig interstitial cells are the site of at least two enzymes of androgen biosynthesis, the 17-hydroxylase and the 17-desmolase.

THE ENDOPLASMIC RETICULUM OF GASTRIC PARIETAL CELLS

An electron microscopic survey has been made of the gastric parietal or oxyntic cell of the human, cat, beaver, dog, hamster, rat, mouse, and bat, and of the corresponding cell type in two species of frog, two species of toad, and the horned lizard. A feature consistently found in the parietal cells of the mammals or their equivalent in the lower vertebrates is the agranular endoplasmic reticulum, which takes the form of branching and anastomosing small tubules approximately 200 to 500 A in diameter, sometimes expanded into flattened cisternae. In mammalian parietal cells this form of the endoplasmic reticulum is found only in limited amounts, but in the corresponding secretory cells of the amphibia and reptilia the tubular agranular reticulum is abundant. It is believed to comprise a more or less continuous system of channels, but owing to their tortuous course only short profiles are seen in thin sections. Immediately subjacent to the plasmalemma at the free surface, the cytoplasm is relatively free of organelles but is occasionally traversed by the agranular reticulum, which appears to be continuous at some points with the cell surface. The possible participation of the agranular endoplasmic reticulum in hydrochloric acid secretion is discussed.

Testis differentiation in the glowworm, Lampyris noctiluca, with special reference to the apical tissue

The gonads of Lampyris noctiluca are sexually undifferentiated during the first larval instars. They consist of many gonadal follicles that include the germ stem cells enclosed by the somatic cells of the follicle wall. Follicle wall cells are more numerous at the follicle apices than at the distal parts, but different cell types cannot be distinguished. In male larvae, the appearance of apical follicle tissue, derived from follicle wall cells, marks the onset of testis differentiation. When maximally expressed, the apical tissue occupies about the upper half of the testis follicles and can be observed in larvae of the fifth and sixth instar. The apical tissue is characterized by its "light" appearance (due to poor stainability) caused by the small number cellular organelles, especially a paucity of free ribosomes. Maximal expression of the apical tissue must be very brief, since in most examined fifth and sixth instar larvae the apical tissue is partly or mostly translocated into the center of the upper half of the follicles and spermatogonia then occupy the apical follicle tips. During and after translocation apical cells form projections that grow around clusters of spermatogonia (spermatocysts). Thus, the apical cells transform into spermatocyst envelope cells. They retain their "light" appearance but undergo dramatic subcellular differentiation: smooth ER becomes extremely prominent, forming stacks and whorls of parallel cisternae. Golgi complexes are also conspicuous. The cellular organization suggests secretory activity. The possibility of ecdysteroid production and its function is discussed. The spermatocyst envelope cells persist into the pupal stage. When spermiohistogenesis takes place in cysts, cyst envelope cells show signs of regression. At all stages of testis development apical cells and their derivatives, the spermatocyst envelope cells, phagocytize degenerating spermatogonia. Although this is an important task of these cells, the impressive formation of sER in the cyst envelope cells is indicative of an additional, as yet unknown, function.

Pregnenolone synthesis in immature rat Sertoli cells

It has been reported that testicular Sertoli cells can be induced to synthesize the steroidogenic acute regulatory (StAR) protein. StAR mediates the rate-limiting step of steroidogenesis, which is the transfer of cholesterol to the inner mitochondrial membrane. Since Sertoli cells are thought to be unable to utilize cholesterol for the synthesis of steroids the role of StAR in these cells was questioned. In the present studies we have corroborated the induction of StAR protein in immature cultured Sertoli cells in response to either trophic hormone or cAMP analog stimulation. Further, we have shown that long term stimulation of Sertoli cells with cAMP analog results in the induction of P450scc enzyme and increased pregnenolone production. In this manner, the Sertoli cell may resemble its ovarian homolog, the granulosa cell, more closely than previously thought with regards to its steroidogenic capacity. Thus, StAR may play the same role in Sertoli cells as it does in other steroidogenic tissues.

Contrast between osmium-fixed and permanganate-fixed toad spinal ganglia

Chains of vesicles are prominent near the plasma membranes of both the neurons and satellite cells of osmium-fixed toad spinal ganglia. In permanganate-fixed specimens, however, such vesicles are absent, and in their place are continuous invaginations of the plasma membranes of these cells. The discrepancy suggests that the serried vesicles seen in osmium-fixed preparations arise through disintegration of plasma membrane invaginations, and do not represent active pinocytosis, as has been suggested previously. A second difference between ganglia fixed by these two methods is that rows of small, disconnected cytoplasmic globules occur in the sheaths of permanganate-fixed ganglia, but not in osmium-fixed samples. It is suggested that these globules arise from the breakdown of thin sheets of satellite cell cytoplasm which occur as continuous lamellae in osmium-fixed specimens. Possible mechanisms of these membrane reorganizations, and the relevance of these findings to other tissues, are discussed.

The absorption of fat by intestine of golden hamster in vitro

Everted sacs of intestine from golden hamsters were incubated at 37°C for at least 1 hour in vitro with emulsified lipid after removal of both pancreatic lipase and bile salts. The fine structure of intestinal epithelium is well preserved under these conditions. Absorption of fat by the intestinal mucosa in vitro closely resembles lipid absorption in vivo, as observed by both light and electron microscopy. The physiological significance of these observations is discussed. Tubular elements of the agranular endoplasmic reticulum are often strikingly abundant in the apical cytoplasm of intestinal absorptive cells. These have a role in the intracellular transport of fat since they frequently contain droplets of lipid derived from the incubation medium. The rate of fat accumulation in the epithelium appears to be proportional to the concentration in the medium.

Observations on the fine structure of lutein cells

Corpora lutea from the period of delayed implantation and from early postimplantation stages of the armadillo, mink, and rat were fixed in buffered osmium tetroxide-sucrose or potassium permanganate. After rapid dehydration, the portions of the corpora lutea were embedded in either methacrylate or epoxy resin. Examination of the lutein cells by electron microscopy revealed the presence, in the better preserved material, of an extensive development of tubular agranular endoplasmic reticulum. Although the membranes of the endoplasmic reticulum are the most striking feature of the lutein cells of both stages of the three animals examined, very numerous large mitochondria with cristae that exhibit a variety of forms tending toward villiform, and protrusions and foldings of the lutein cell margins on the pericapillary space are also characteristic of these cells. Certain minor differences in the lutein cells of the species examined are also noted. No indications of conversion of mitochondria into lipid, of accumulation of lipid in the Golgi area, or of the protrusion of lutein cells into spaces between the endothelial cells, as suggested by other authors, were noted in these preparations. Some of the difficulties inherent in the visualization of the secretory activity of cells producing steroid hormones are briefly discussed.

Constitutive expression of cyclooxygenase-2 in rat vas deferens

Prostaglandins, lipoid substances discovered in human semen as modulators of uterine muscle contractility, are known to play significant roles in virtually all mammalian organ systems, but their male reproductive functions are unclear. Cyclooxygenase, the rate-limiting enzyme in prostaglandin synthesis, occurs in two isoforms distinguished on the basis of constitutive (COX-1) or inducible (COX-2) expression patterns in mammalian tissues. However, in the adult rat male reproductive system, immunohistochemistry and Western and Northern analysis showed that COX-2 is the predominant isoform and is heavily localized to the epithelium of the distal vas deferens, where constitutive expression is manyfold greater than in any other organs of the body. COX-2 is not detected in the proximal one-half of the vas nor in the testis, epididymis, seminal vesicles, or prostate. Elimination of luminal sperm by vasectomy does not affect COX-2 levels, whereas castration severely depletes COX-2 and androgen replacement after castration restores COX-2, indicating that COX-2 expression in the vas is androgen dependent. Because the distal vas also comprises an extensive submucosal venous plexus connected to the penile corpora cavernosa, prostaglandins from the vas may play a role in erection.

FINE STRUCTURE OF CHLORIDE CELLS FROM THREE SPECIES OF FUNDULUS

A morphological basis for osmoregulation in the teleosts was studied by comparing the fine structure of chloride cells found in epithelia of the gills of three species of fish: Fundulus heteroclitus which can survive in a wide range of salinities, and F. similis and F. chrysotus which are usually restricted to salt water and fresh water environments, respectively. Gills were removed from F. heteroclitus which had been laboratory adapted to either sea water or pond water. For a comparison, gills were also removed from the marine F. similis and the fresh water F. chrysotus which had been adapted to their natural environments. Gill-filaments were fixed in Millonig's phosphate buffered (pH 7.4), 1 per cent osmium tetroxide and were embedded in Epon. Thin sections of filaments were stained with lead hydroxide. The cytoplasm of chloride cells of all three species of Fundulus is heavily populated with mitochondria and is filled with tubules of the agranular endoplasmic reticulum (ER). An orderly secretory cycle was indicated for chloride cells of salt water adapted F. heteroclitus and the marine F. similis. An amorphous material is observed in the agranular ER. Its density increases towards the apical end of the cell. In the apical cytoplasm, tubules of the agranular ER appear to converge and to discharge the amorphous material into an apical cavity. Except for the actual opening of the apical cavity, the distal end of salt water adapted chloride cells is characteristically shielded from the hypertonic environment by thin cytoplasmic flanges projecting from the neighboring epithelial cells. Chloride cells of the fresh water F. chrysotus resemble chloride cells of pond water adapted F. heteroclitus, in that these cells do not have apical cavities with the functional appearance of those in the sea water adapted forms. The distal end of fresh water adapted chloride cells is typically exposed to the free surface of the gill-filament. The possible function of the cell type is discussed.

SOME OBSERVATIONS ON THE FINE STRUCTURE AND METABOLIC ACTIVITY OF NORMAL AND GLYCERINATED VENTRICULAR MUSCLE OF TOAD

Fine structure, enzyme activity, and transmembrane potentials of normal and glycerinated ventricular muscle of the toad were studied. For electron microscopy, osmium tetroxide and Araldite were used. Plasma membranes are firmly attached to Z bands. Both the T system and sarcoplasmic reticulum are poorly developed. Small bodies of medium density may be lysosomes derived from the Golgi zone. Denser bodies may be catecholamine granules. Fine tubules of unknown significance, about 200 A in diameter and of considerable length, lie in conspicuous, although infrequent bundles. Glycogen and mitochondria are abundant. After weeks of extraction in 50 per cent buffered glycerol, most organelles were still present, and much of the gross damage was probably due to osmotic destruction of membranes weakened by extraction. Many mitochondria were well preserved. Plasma and nuclear membranes had diffuse outlines and tended to be broken. Considerable activity remained of the enzymes succinic dehydrogenase, cytochrome oxidase, and phosphorylase after the extraction, but decreased with prolonged soaking. The normal transmembrane potential was about 95 mv; in extracted muscle after 6 weeks it was about 35 mv. The view that glycerinated muscle is a simple system of actin and myosin is clearly wrong. The activity of other organelles still present must affect the actions of many drugs and ions experimentally added.

AN ELECTRON MICROSCOPE STUDY OF THE DEVELOPMENT OF A MOUSE HEPATITIS VIRUS IN TISSUE CULTURE CELLS

Samples taken at different intervals of time from suspension cultures of the NCTC 1469 line of mouse liver—derived (ML) cells infected with a mouse hepatitis virus have been studied with the electron microscope. The experiments revealed that the viruses are incorporated into the cells by viropexis within 1 hour after being added to the culture. An increasing number of particles are found later inside dense cytoplasmic corpuscles similar to lysosomes. In the cytoplasm of the cells from the samples taken 7 hours after inoculation, two organized structures generally associated and never seen in the controls are observed: one consists of dense material arranged in a reticular disposition (reticular inclusion); the other is formed by small tubules organized in a complex pattern (tubular body). No evidence has been found concerning their origin. Their significance is discussed. With the progression of the infection a system of membrane-bounded tubules and cisternae is differentiated in the cytoplasm of the ML cells. In the lumen of these tubules or cisternae, which are occupied by a dense material, numerous virus particles are observed. The virus particles which originate in association with the limiting membranes of tubules and cisternae are released into their lumen by a "budding" process. The virus particles are 75 mµ in diameter and possess a nucleoid constituted of dense particles or rods limiting an electron transparent core. The virus limiting membrane is sometimes covered by an outer layer of a dense material. In the cells from the samples taken 14 to 20 hours after inoculation, larger zones of the cell cytoplasm are occupied by inclusion bodies formed by channels or cisternae with their lumens containing numerous virus particles. In the samples taken 20 hours or more after the inoculation numerous cells show evident signs of degeneration.

OBSERVATIONS ON THE FINE STRUCTURE OF LUTEIN CELLS. II. THE EFFECTS OF HYPOPHYSECTOMY AND MAMMOTROPHIC HORMONE IN THE RAT

Corpus luteum formation was induced in 26-day-old rats which were subsequently hypophysectomized and injected with mammotrophic hormone (MH, LTH). Sections of corpora lutea from these animals were examined with the electron microscope and compared with similarly prepared (Caulfield's fixed, Araldite embedded) corpora from normal pregnancy and from controls, the latter consisting of corpora prior to hypophysectomy and corpora from uninjected rats 7 to 14 days after hypophysectomy. Lutein cells from corpora lutea of injected animals and of normal pregnancy are characterized by abundant, tortuous, tubular agranular endoplasmic reticulum and by mitochondria, many of which are disc-shaped with dense matrices and both villiform and lamelliform cristae. The endoplasmic reticulum is most abundant in lutein cells from pregnant animals, in which cells it is in the form of thin, highly tortuous tubules. The form of the lipid droplets seen in cells of stimulated animals varies greatly. Marginal foldings of the lutein cells on the perivascular space were found in all instances. Lutein cells from hypophysectomized animals have a less highly developed agranular endoplasmic reticulum. The mitochondria have irregular outlines and a relatively lucid matrix. The lipid droplets in these cells show less tendency to be extracted, but are not so large or abundant as in the cells of onset controls. Granules believed to contain lipid pigments are common in the lutein cells of these control animals. It is suggested that lutein cells from corpora lutea which are actively secreting progesterone may be readily distinguished from lutein cells from non-active corpora by means of the multiple characteristics enumerated. It is further suggested that mammotrophic hormone has a general effect on the metabolism of lutein cells rather than solely affecting a specific organelle, the abundance or composition of which may be the limiting factor in the production of progesterone.

Testis development in the opossum Monodelphis domestica

Testis development in the grey short-tailed opossum, Monodelphis domestica, was investigated by light and electron microscopy in 180 animals. On the day of birth, half the karyotyped males were found to have histologically differentiated testes. By day (d) 1 testicular cords were clearly distinguished in all XY gonads and the tunica albuginea was fully developed. At this stage the large and pale primordial germ cells could be differentiated from dark pre-Sertoli cells. From d 3 the testis became progressively rounded and testicular cords were surrounded by peritubular cells. Leydig cells were then distinguishable by the expected ultrastructural features of steroidogenically active cells, showing abundant vesicles of SER, extensive mitochondria with tubular cristae and numerous lipid inclusions. Subsequently these cells formed clusters and were surrounded by envelope cells until wk 12. Testes were located in the abdomen, attached to the large mesonephroi, until d 24 after birth when they began their descent to the scrotal sac. From 7 wk the interstitial tissue became less cellular. At the prepubertal stage (12 wk), the seminiferous tubules lacked lumina. Leydig cell cytoplasm was electron-dense with increased amounts of SER forming parallel profiles. By 4 mo (pubertal stage), seminiferous tubules were patent and various spermatogenic stages, including spermatozoa, were seen for the first time. Leydig cells then greatly outnumbered other interstitial tissue cells and were closely-packed around blood vessels but no longer clustered by envelope cells; their SER was very highly organised into masses of parallel arrays and lipid inclusions were reduced. In the adult (1 y) Leydig cells reached their greatest size; their morphological features resembled those seen at 4 mo except that lipid inclusions were sparse. In ageing Leydig cells (2-3 y), large amounts of SER were present but disorganised.

The fine structure of the epithelial lining of the epididymis of the camel (Camelus dromedarius) with special reference to regional differences

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Ultrastructural characteristics of the interdigitating dendritic cell in dermatopathic lymphadenopathy of mycosis fungoides patients

The ultrastructure of interdigitating dendritic cells in dermatopathic lymphadenopathy from patients with mycosis fungoides was investigated. The most remarkable findings were: a marked hypertrophy of the smooth endoplasmic reticulum with a peculiar concentric arrangements of the cisternae around lipid droplets, an abundance of cytoplasmic lipid droplets and the presence of paranuclear chromatoid-like bodies. It is suggested that these ultrastructural features may correspond to some unknown functional capability of the interdigitating dendritic cell.

Purification and properties of testicular 3 beta-hydroxy-5-ene-steroid dehydrogenase and 5-ene-4-ene isomerase

Through the treatment of rat testicular microsomes with sodium cholate, 3 beta-hydroxy-5-ene-steroid dehydrogenase and 5-ene-4-ene isomerase (abbreviated as the 3 beta-hydroxysteroid dehydrogenase and isomerase, respectively) were solubilized, and then purified by DEAE and hydroxylapatite column chromatographies. The findings were as follows: With this purification procedure, the 3 beta-hydroxysteroid dehydrogenase activity could not be separated from the isomerase. For 3-oxo-4-ene-steroid formation from 3 beta-hydroxy-5-ene-steroids, NAD+ was required as a cofactor. While the 3 beta-hydroxysteroid dehydrogenase required NAD+, the isomerase also required NAD+ or its reduced form, in contrast to the microbial enzyme. On treatment of the purified enzyme with 5'-p-fluorosulfonyl-benzoyladenosine (FSBA), both enzyme activities were markedly reduced. The enzyme, affinity labeled with [adenine-8-14C]FSBA, showed a mol. wt of 46.8 K. During 4-androstenedione production from DHA, 5-androstenedione was detected as an intermediate.

Macrophages in the interstitial tissue of the rat testis

Macrophages were identified in the intertubular tissue of the rat testis by loading animals with a particulate vital dye (trypan blue or India ink) and by localizing immunocytochemically a macrophage membrane antigen (MRC W3/25). Leydig cells were identified by the histochemical staining reaction for 3 beta-hydroxysteroid dehydrogenase activity and by a monoclonal antibody. Macrophages were scattered in the interstitial tissue closely attached to and mixed with the Leydig cells. They were never found in the seminiferous tubules. The macrophages comprised about 25% of all the cells in the interstitium. Double staining with a vital dye and a marker antibody showed that all the phagocytosing cells were macrophages and that the Leydig cells did not take up vital dyes. Double staining for the demonstration of the 3 beta-hydroxysteroid dehydrogenase activity and the macrophage antigen likewise revealed two distinctly different cell populations. Crude Leydig cell preparations obtained by collagenase treatment of the testis contained macrophages (12-14%). Macrophages were present throughout the postnatal prepuberal development of the testis. Their density was increased in the cryptorchid and irradiated testis.

Immunocytochemical localization of 17 beta-hydroxysteroid dehydrogenase in porcine testis

The immunocytochemical localization of 17 beta-hydroxysteroid dehydrogenase (17 beta-HSD) in porcine testes was examined by applying an indirect-immunofluorescence method using an antiporcine testicular 17 beta-HSD antibody. Only the Leydig cells located in the interstitial tissue exhibited a positive immunoreaction for 17 beta-HSD: the germ cells and Sertoli cells located in the seminiferous tubules were entirely negative. These results suggest that, in porcine testis, the biosynthesis of testicular testosterone, the final step of which is the conversion of androstenedione to testosterone, takes place in the Leydig cells.

Histochemical aspects concerning the synthesis and the fate of cholesterol into the epidermis

By means of a suitable histochemical method free cholesterol and its esters could be detected into the epidermis layers. The results show that in the stratum spinosum keratinocytes free cholesterol appears as an amorphous or granular structure apparently protein unbound; into the stratum granulosum keratinocytes the cholesterol becomes protein-bound and its most part undergoes esterified. The extracellular compartment nearly the stratum granulosum contains a little amount of cholesterol esters loosely bound to proteins. The results suggest that free cholesterol after being synthesized into the cytoplasm of the stratum spinosum and granulosum keratinocytes, it is partially esterified and becomes protein-bound, appearing as fine granules within the cytoplasm of the granulous cells. From this site it takes to fates:1. Its most part remains into the granulous cell cytoplasm and at the same time the granulous cell develop to the horny cell it is placed on the thick cell membrane inner surface contributing to its thickness; 2. Another part after reaching the extracellular compartment it is spread over the thick membrane out surface. Inside the thick cell membrane, into the horny layer, free cholesterol is continuously esterified since the keratinizing cell migrate to the periphery; however even at the most peripheral layers the free cholesterol predominates. Either free cholesterol or its esters, contained into the keratinizing cell thick membrane, were excreted throughout the horny layer exfoliation. The keratinizing cell cytoplasm does not contain neither free cholesterol nor its esters.

The testis and its excurrent ducts in American caenolestid and didelphid marsupials

The present study examines and compares the structure of the testis and its excurrent ducts in a caenolestid and four didelphid marsupials. Of particular interest was the site of sperm pairing in the epididymis and whether this feature, shared by both American marsupial families but not by any Australian marsupial, was associated with changes in the morphology of the duct. In contrast to the testes of most Australian marsupials, except the peramelids (bandicoots), the intertubular space in the American marsupials was filled by Leydig cells (around 20% of testis volume). The opossum testes were unusual compared with those of eutherian mammals in that histological sections of individual seminiferous tubules contained only a single cellular association irrespective of the length of the tubule sectioned. The rete testis, as in the Australian dasyurids (devil, quoll, etc.), was a simple branching duct system that arose deep within the testis and emerged as a single duct at the testicular hilus. This arrangement is completely different from that in Kangaroos and Australian possums, indicating a diversity of rete form in the marsupials similar to that seen in eutherian mammals. The rete emptied into a single, essentially straight, efferent duct that became convoluted towards the epididymis, where it formed a distinct structure adjacent to the caput epididymidis. The efferent ducts were highly variable in diameter and epithelial height, suggesting that the duct was not of uniform character along its length, or that the initial single duct had divided to form ducts of different characters. Sperm pairs were first seen in the proximal cauda epididymis, and their appearance was correlated with changes in the character of the duct and its epithelium. The distal ductus deferens of Caenolestes, in contrast to those of the didelphids and indeed all other marsupials, was a convoluted ampulla-like structure adjacent to the prostate gland. In the other marsupials the only accessory sex glands are a segmented prostate and bulbourethral glands.

Studies on zonation in the epididymis of the guinea pig. I. Ultrastructural and biochemical analysis of the zone rich in large lipid droplets (zone II)

In the epididymis of the guinea pig, zone II exhibits striking histological features that distinguish it readily from the other six regions of the epididymis. At the light microscope level, the pseudostratified epithelium of zone II is characterized by tall principal cells that are densely packed with large, intensely staining granules or droplets ranging up to 8 mu in diameter. At the electron microscope level, the principal cells exhibit numerous large lipid droplets and abundant agranular endoplasmic reticulum, which is frequently arranged in concentric whorls around one or more of the droplets. Quantitative biochemical studies comparing zone II with zones I and III show that zone II contains 2.5 - 3-fold more cholesterol and a significantly greater amount of cholesterol ester than the other two zones. These data indicate that the epididymal duct of the guinea pig includes a clearly defined region of epithelial cells possessing ultrastructural and biochemical characteristics consistent with steroidogenic activity. The potential significance of these observations to the epididymal physiology of the guinea pig and epididymal physiology in general is discussed.

Early ultrastructural changes of developing oocytes in the dog

Many aspects of the developmental stages of the oocytes of the dog resemble those of other mammalian species. The oocytes of the dog, however, contains large amounts of lipid yolk material. A study of the ultrastructural morphology of early growth and maturation of dog oocytes was undertaken to clarify the nature and appearance of this yolk material. The lipid yolk first appears in early primary oocytes as aggregated dense bodies that gradually fill the ooplasm as the oocyte matures. The site of the yolk's initial appearance is consistently related to a single centriole and often to the lamellae of smooth endoplasmic reticulum that surrounds groups of forming lipid yolk bodies. Dense cortical granule-like vesicles are found to lie deep within the maturing oocyte and often are enclosed within the lamellar yolk space. Granules within this space undergo changes in size, matrix configuration, and vacuolization. These changes suggest a mechanism whereby material is added to the lipid yolk bodies. Light microscope histochemistry for lipid and polysaccharide material is described.

Single cilia formation in cells of the testicular interstitium in fertile men

Testicular biopsies from 4 infertile men showing germinal cell aplasia with interstitial cell hyperplasia on light microscopy were studied by electron microscopy. Single cilia formation was observed in myoid cells, fibroblast-like cells and Leydig cells in the interstitium. Only 1 cilium was seen per cell. Transverse sections of most of cilia showed a 9 + 0 pattern of microtubule configuration. Cross striated rootlet fibers were attached to the basal bodies. The significance of the presence of cilia in the testicular interstitium is discussed.

Fine structural study of postcastrational adrenocortical carcinomas in female CE-mice

Postcastrational adrenocortical carcinomas in the CE/Ki inbred strains of mice and the adrenals of noncastrated CE/Ki mice were studied using light and electron microscopic techniques. Most of the tumors appeared as large nodules of cells separated by septae comprised of collagen and blood sinusoids. The majority of tumor cells (Type 1) showed few or no lipid droplets (sudanophobic), polymorphic hyperchromatic nuclei, lack of SER, abundant RER and free ribosomes, prominent Golgi complexes, and few mitochondria with scant internal membranes. Clusters of Type 1 cells were surrounded by a basal lamina. In contrast, Type 2 cells revealed abundant and dilated tubules of SER, large number of lipid droplets and mitochondria with tubulovesicular cristae. These results suggest that Type 2 cells were probably active in steroid hormone synthesis and secretion while Type 1 cells were highly anaplastic and apparently non-steroid-secreting cells.

Changes in the fine structure of the testicular Leydig cells of the seasonally-breeding bat, Myotis adversus

Leydig cells of the bat, Myotis adversus, have been examined by electron microscopy throughout fourteen months. During the breeding season the Leydig cells become hypertrophied and are characterised by prominent areas of agranular endoplasmic reticulum and numerous small, membrane-bound granules. Microperoxisomes are also observed. During the period of testicular regression. Leydig cell size and the number of membrane-bound granules are greatly reduced. Lipid droplets and dense bodies are more numerous.

A correlated thin-section and freeze-fracture analysis of guinea pig adrenocortical cells

Comparison of the fine structural features of guinea pig adrenocortical cells as seen in thin sections with those revealed by freeze-fracture confirms the structural appearance of steroid-secreting cells as interpreted from thin sections and reveals significant new features of the membranous organelles. Smooth-surfaced endoplasmic reticulum appears as a network of tubules, interwoven or in parallel, and as cisternae, fenestrated and non-fenestrated. These elements are tightly packed in the deeper cortical cells, excluding other organelles from their domain. Tubules and fenestrated cisternae possess randomly distributed intramembranous particles on their PF faces, while closely packed non-fenestrated cisternae possess aggregates of particles interspersed with aparticulate regions on their PF faces. These differences in particle distribution suggest functional specialization among the various forms of reticulum. Mitochondria appear as elongated structures of varying shape. Freeze-fracture reveals that all their cristae have circular origins from the inner membrane. Sinuous tubules, which appear as tubules in section, and straight tubules, which appear as lamellae in section, arise from single sites. Flattened sac-like cristae may have multiple circular origins. Definite contact points seen between inner and outer membranes may facilitate passage of molecules, including steroids, into the mitochondrial compartments. Lysosomes and peroxisomes, which are easily identified in thin sections with the aid of cytochemistry, are difficult to identify with certainty by freeze-fracture. Single membrane-bound granules of slightly smaller diameter than mitochondria may represent lysosomes. Smaller granules interconnected with the tubular reticulum, as well as dilated regions of this organelle, may represent peroxisomes. Plasma membranes show no indication of tight junctions but do have abundant gap junctions which show a zonal differentiation: small gap junctions throughout the cortex, medium-sized regularly shaped gap junctions in zona fasciculata externa, and large irregular gap junctions in zona fasciculata interna and zona reticularis. The large junctions cover planar areas as well as surfaces of projections of one cell into another. Such junctions may allow passage of ions as well as of low-molecular-weight substances between the cells, facilitating or even amplifying the response to trophic hormone stimulation.

Structure of the chicken's inner ear: SEM and TEM study

The inner ears of 35 adult chickens were studied by TEM, SEM and light microscopy. Two well differentiated hair cell/nerve ending units were present: tall hair cells with small vesiculated nerve endings were located on the attached part of the basilar membrane; short hair cells with large vesiculated nerve endings were located on the free basilar membrane except for the distal tip. In this respect the chicken ear is similar to that of the pigeon. The chickens examined did have some unique features. Sensory cells of lenticular and hemispheric shape were also present at the proximal end. Bundles of long dense tubules were seen frequently within the sensory cell cytoplasm. Kinocilia were absent from the hair bundles of many of the sensory cells. The internal structure of the kinocilia which were present was atypical and consisted of a variable number of doublets. Eight peripheral plus one central doublet were found most frequently.

Differential effects of primary fixation with glutaraldehyde and osmium upon the membranous systems of the strial and external sulcus cells

Ultrastructural preservation of the lateral cochlear wall differs between primary osmium fixation and primary glutaraldehyde fixation. Of significance in this study was the fact that whereas glutaraldehyde fixation preserves the parallel plasma membranes of interdigitations of the strial and external sulcus cells, fixation with osmium occasionally produces a breakdown of selected areas of membranes into apparent vesicles. The occurrence of these membrane artifacts was more common within the external sulcus cells. Reasons for the differential effects of the fixatives may include their differing modes of action. Care should be taken when evaluating unusual ultrastructure, since the type of fixative employed may be causal.

Ultrastructural changes in the guinea-pig placenta, with special reference to organelles associated with steroidogenesis

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