The formation of glandular secretion in larval Austramphilina elongata (Amphilinidea)

The ultrastructure of three types of gland cells of embryos and free-swimming larvae of Austramphilina elongata is described. Type I gland cells contain large, more or less round electron-dense granules which are formed by numerous Golgi complexes. Type II gland cells contain thread-like, membrane-bound secretory granules with longitudinally arranged microtubules inside the granules; secretory droplets are produced by Golgi complexes and the microtubules apparently condense in the cytoplasm or in the droplets. Type III gland cells contain irregular-ovoid membrane-bound granules with coiled up microtubules which have an electron-dense core; the granules are formed by secretionderived from Golgi complexes and the microtubules aggregate around and migrate into the secretion; microtubules are at first hollow and the early secretory granules have a central electron-dense region.     

Postnatal differentiation of Leydig cells in the African green monkey

At two years of age the interstitial tissue of Cercopithecus aethiops is composed principally of undifferentiated, fibroblast-like cells. Also present during this time are scattered differentiating Leydig cells, which are characterized by a large nucleus, numerous mitochondria, elements of smooth reticulum, and small cisternae of rough reticulum. A mean level of 1.69 ± 0.66 ng/ml of testosterone was found. At three years Leydig cells are much more numerous and developed; since all the elements of steroid secreting cells are present, even their morphology differs from that observed in mature cells. Lipid accumulation is characteristic during this period. A mean testosterone level of 2.28 ± 0.47 ng/ml was found. Mature Leydig cells are basically similar to that of other mammals, while they differ significantly from that of human Leydig cells.     

Organization of interstitial tissue in the testis of the salamander Necturus maculosus (Caudata: Proteidae)

In Necturus maculosus the organization of the interstitial tissue varies according to the stage of spermatogenesis. Leydig cells at various stages of differentiation and myoid cells are always present in this tissue. The Leydig cells are undifferentiated at all phases of germ cell activity and only hypertrophy following spermiation and degeneration of Sertoli cells. These Leydig cells are structurally analogous to mammalian Leydig cells. They do not form part of the lamina propria of the seminiferous lobules and hence cannot be referred to as lobule-boundary cells previously described in the urodele testis (Lofts, '74). When the Leydig cells hypertrophy, numerous unmyelinated axons appear in the interstitial tissue. These axons, often devoid of Schwann-cell cytoplasm, occur in close proximity to Leydig cells. Because the levels of both Substance P and neurotensin increased in the testis of Necturus maculosus as Leydig cells differentiated, we concluded that these neural elements may regulate Leydig-cell function locally, through the release of neuropeptides.     

An ultrastructural study of the clitellar epithelium of the earthworm Metaphire posthuma (vail.)

The ultrastructure of clitellar epithelium of Metuphire posthuma revealed mainly three types of secretory cells. Most prominent among these are the large slender granular cells which contain a large number of secretory granules filling in the entire columncr region of the cell. The secretory granules are 2-4mu in diameter with a limiting membrane and containing numerous tiny vesicles in a matrix of varying electron density. Basolateral rough endoplasmic reticulum and extensive Golgi cisternae were seen interspersed with the secretory granules. The Golgi cisternae in these cells were quite prominent extending all around the secretory granules. The secretory granules of type 2 cells are spheroid bodies with motley appearance due to varying electron density of the matrix. The immature granules contain fibrillar material. Type 3 cells contained electron lucent membrane-bound mucous like secretory granules which are reticulated with filamentous materials. All the three cell types open to the exterior at the cuticular region which is characterised by the presence of numerous microvilli.     

Annual cycle of the chromaffin cells of Triturus cristatus

Morphology of the chromaffin cells of Triturus cristatus during a complete annual cycle has been investigated. General ultrastructural characteristics are similar for all chromaffin cells, including numerous small mitochondria, well-developed Golgi apparatus and rough endoplasmic reticulum with short cisternae. The primary difference among cells is the type of the chromaffin granules they posses. These are of two kinds: adrenalin (A) and noradrenalin granules (NA). Both types are simultaneously present in the chromaffin cells but with different ratios during the year. During December–January and May–August, NA granules largely prevail, while in September–November and February–April, A and NA granules are present in about equal quantities. The total quantity of catecholamine granules, however, is relatively constant throughout the year. These findings suggest that T. cristatus has a single type of chromaffin cell, the granule content of which varies according to different functional states. The catecholamines are apparently discharged by exocytosis.     

Subcellular localization and dynamics of components of the respiratory burst oxidase

Membrane and cytosolic factors cooperate to generate NADPH-oxidase. The study of the syndrome of NADPH-oxidase deficiencies, chronic granulomatous disease, has enabled the identification of two membrane factors: a flavin adenine dinucleotide flavoprotein and ab cytochrome. The nature of the cytosolic components is still unknown, but a 47-kD protein, whose phosphorylation occurs in parallel with the generation of a respiratory burst in intact cells, seems to be one of the cytosolic factors. The subcellular localization of the membrane-bound NADPH-oxidase components has been studied in neutrophils: In unstimulated cells, only a minute fraction of the NADPH-oxidase components is localized in the plasma membrane, whereas 80% is localized in the membrane of the specific granules and the majority of the rest is in a newly described membrane-bound compartment, the secretory granules, identified by latent alkaline phosphatase. During stimulation, these NADPH-oxidase components are translocated to the plasma membrane as a result of fusion of granule membrane with plasma membrane. Only the NADPH-oxidase components present in the plasma membrane are incorporated in the respiratory burst oxidase generated in intact cells.     

Cytological identification of cell types in the testis of Esox lucius and E. niger

Summary Testes of Esox lucius and Esox niger were investigated histologically, cytochemically, and ultrastructurally in reproductive fish. Intralobular Sertoli cells possessed numerous lipid droplets in Esox lucius, but not in Esox niger. In both species, interlobular cell types included myoid cells and lipid-negative Leydig cells within the extravascular space. Evidence is presented for a contractile network of myoid cells within the testes of these teleosts. The presence of Leydig cells and myoid boundary cells in the testis of Esox lucius refutes the reported homology between lobule boundary cells and Leydig cells in this species.     

Physiological and anatomical properties of Leydig cells in the segmental nervous system of the leech

Summary Each of the 21 segmental ganglia in the American leechMacrobdella decora contains a pair of Leydig cells (ca. 45 m) each of which is located in a posteriolateral glial packet. Leydig cells exhibit spontaneous action potentials (1–10/s) whose duration and undershoot depend upon membrane polarization. The two Leydig cells within each ganglion are bidirectionally-coupled (V ₂/V ₁0.3). Pairs of ipsilateral Leydig cells within adjacent ganglia are mutually excitatory such that an impulse in one generates an impulse in the other. The interganglionic latency for any cell pair is constant regardless of the direction of impulse conduction and is unchanged by 20 mM Mg²⁺ saline. These data indicate that the interactions are not mediated by chemical synapses. Additionally, the results of collision experiments lead us to infer that ipsilateral Leydig cell pairs utilize common axonal pathways for interganglionic interactions. If Leydig cells are driven by current injection to fire impulses at frequencies of six to ten per s, cells in adjacent ganglia exhibit impulse failures. The combination of spontaneous activity, intraganglionic coupling and interganglionic interactions results in the generation of constant, low frequency impulse activity and can cause impulse reverberations.The branching pattern of Leydig cells filled with HRP is consistent with their functional properties and connectivity. Each cell sends axons to both adjacent ganglia through the ipsilateral connectives and projects to the periphery only by the lateral roots of these adjacent ganglia. This unusual morphology was verified Lucifer Yellow CH.In addition to intraganglionic dye-coupling, dye coupling was occasionally evident between ipsilateral cells in adjacent ganglia. Electron microscopy of Leydig cells depicts abundant 100 nm granules in both their somata and neuropilar processes. Although this fine structure suggests a neurosecretory role, we were unable to discern a peripheral function for these neurons.Abbreviation H R P horseradish peroxidase     

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...     

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.     

Morphology and ultrastructure of the venom glands of the northern pacific rattlesnake Crotalus viridis oreganus

The venom gland of Crotalus viridis oreganus is composed of two discrete secretory regions: a small anterior portion, the accessory gland, and a much larger main gland. These two glands are joined by a short primary duct consisting of simple columnar secretory cells and basal horizontal cells. The main gland has at least four morphologically distinct cell types: secretory cells, the dominant cell of the gland, mitochondria-rich cells, horizontal cells, and “dark” cells. Scanning electron microscopy shows that the mitochondria-rich cells are recessed into pits of varying depth; these cells do not secrete. Horizontal cells may serve as secretory stem cells, and “dark” cells may be myoepithelial cells. The accessory gland contains at least six distinct cell types: mucosecretory cells with large mucous granules, mitochondria-rich cells with apical vesicles, mitochondria-rich cells with electron-dense secretory granules, mitochondria-rich cells with numerous cilia, horizontal cells, and “dark” cells. Mitochondria-rich cells with apical vesicles or cilia cover much of the apical surface of mucosecretory cells and these three cell types are found in the anterior distal tubules of the accessory gland. The posterior regions of the accessory gland lack mucosecretory cells and do not appear to secrete. Ciliated cells have not been noted previously in snake venom glands. Release of secretory products (venom) into the lumen of the main gland is by exocytosis of granules and by release of intact membrane-bound vesicles. Following venom extraction, main gland secretory and mitochondria-rich cells increase in height, and protein synthesis (as suggested by rough endoplasmic reticulum proliferation) increases dramatically. No new cell types or alterations in morphology were noted among glands taken from either adult or juvenile snakes, even though the venom of each is quite distinct. In general, the glands of C. v. oreganus share structural similarities with those of crotalids and viperids previously described.     

Ultrastructure of germ cells, the Leydig cells, and Sertoli cells during spermatogenesis in Boleophthalmus pectinirostris (Teleostei, Perciformes, Gobiidae)

The ultrastructures of germ cells, Leydig cells, and Sertoli cells during spermatogenesis in male Boleophthalmus pectinirostris were investigated by electron microscopic observations. During the period of maturation divisions, well-developed Leydig cells have three major morphological characteristics: a vesicular nucleus, mitochondria with tubular cristae, and a number of smooth endoplasmic reticulum. Based on cytoplasmic features, it appears that Leydig cells are responsible for the synthesis of male sex steroids. Although no clear evidence of steroidogenesis was found in the Sertoli cells, they were found to perform a phagocytic function in the seminiferous lobules. Most Sertoli cells contain granules thought to represent deposited glycogen or lipid but there is no indication of a transfer of nutrients to the spermatids. During the period of germ cell degeneration, several characteristics of phagocytosis appear in the cytoplasm of the Sertoli cells. In particular, it is assumed that the Sertoli cells are involved in the degeneration and resorption of undischarged spermatids after spermiation. No acrosome of the sperm is formed. The structure of the spermatozoon in B. pectinirostris is very similar and closely resembles to those of suborder Gobioidei (perciform type teleosts). The flagellum or sperm tail shows the typical 9+2 array of microtubules.     

Ultrastructure of the Acidophilic Aerobic Photosynthetic Bacterium Acidiphilium rubrum

The ultrastructure of cells of Acidiphilium rubrum, which is an acidophilic aerobic photosynthetic bacterium containing zinc-complexed bacteriochlorophyll a, was studied by electron microscopy with the rapid substitution technique. Thin-section electron microscopy indicated that any type of internal photosynthetic membranes was not present in this organism despite a relatively high content of the photopigment. The majority of cells had poly-β-hydroxybutyrate granules and electron-dense spherical bodies identified as being polyphosphate granules. When the organism was grown chemotrophically with 0.1% FeSO₄, it produced another group of electron-dense granules that were associated with the inner part of the cytoplasmic membrane. An energy-dispersive X-ray analysis showed that these membrane-bound, electron-dense granules contained iron. Received: 24 November 1999 / Accepted: 5 January 2000     

Ultrastructural studies of vagal paraganglia in Syrian hamsters

Summary Typical vagal paraganglia of Syrian hamsters are encapsulated in connective tissue and consist of groups of epithelial cells. Ganglion cells, a few fenestrated capillaries, and bundles of unmyelinated nerve fibers are intermingled among the parenchymal cells. The parenchymal cells are of two types: chief or paraganglion and sustentacular or supporting cells. The processes of the supporting cells partly or completely surround the paraganglion cells. In addition to the nucleus, Golgi complex, mitochondria, parallel-arrayed granular endoplasmic reticulum, and lipofuscin pigment, the chief cells are characterized by the presence of numerous membrane-bound, electron opaque granules. After an injection of ³H-dopa, labelings were concentrated over the chief cells and were associated predominantly with the granules. Following glutaraldehyde-dichromate treatment the granules gave a positive reaction for unsubstituted amines. These results suggest that the chief cells contain catecholamines in the electron opaque granules.Research supported by USPHS Grants NS 05665, 00690 and HE 12751. A preliminary report of this research was presented before the American Society for Cell Biology, 1969.Sponsored by National Council on Science Development, Republic of China.Recipient of Career Research Development Award 1 K3 GM 28064.     

Organization of testicular interstitial tissue of an Australian rodent,the spinifex hopping mouse,Notomys alexis

Summary The organization of testicular interstitial tissue of the spinifex hopping mouse, Notomys alexis differs from that of other rodents. It comprises between 10.3% and 17.3% (average 15.0%) of the total testicular volume, and is variable in its organization both at different locations within the testis of the one animal and among different individuals. Abundant, closely packed Leydig cells are usually present; however, in some regions large, thick-walled blood vessels and extensive peritubular lymphatic spaces, often lacking an endothelium adjacent to the Leydig cells, are also prominent. The Leydig cells in contact with the large blood vessels and lymphatics, unlike those in regions where lymph is sparse, are not densely packed and sometimes contain numerous lipid droplets. Ultrastructure of Leydig cells is typical of steroid-producing cells; however, mitochondria are often extremely large, unusual in shape or bizarely arranged in relation to one another. Also electrondense bodies displaying a paracrystalline-like internal structure of parallel, electron-dense filaments arranged in a lattice pattern occur in the cytoplasm of many cells. The significance of these unusual ultrastructural features and the organization of the interstitial tissue remain to be determined conclusively, but may relate to steroid synthesis, secretion and uptake.     

An Ultrastructural Study of the Hemocytes of the Pericardial Body in the Ascidian Ciona intestinalis (L.)

Abstract The hemocytes of the pericardial body of Ciona intestinalis were studied by electron microscopy. Our findings showed that stem cells, clear vesicular granulocytes, microgranulocytes, unilocular granulocytes and globular granulocytes are present at the periphery of the smaller-sized pericardial bodies. The stem cells are small round cells with a large nucleus, with or without nucleolus, and homogeneous cytoplasm containing numerous ribosomes. The clear vesicular granulocytes are characterized by an ameboid shape and cytoplasm containing several large electron-lucent vacuoles and small electron-dense granules. The microgranulocytes are variable in shape and contain numerous large electron-dense granules. The unilocular granulocytes show a single large vacuole with an electron-dense or electron-lucent content and a thin layer of peripheral cytoplasm that contains the flattened nucleus. The globular granulocytes are characterized by the presence of large vacuoles containing either fibrogranular material or electron-dense aggregates.     

Cytochemical study of developing anthers of Amomum villosum Lour.

We analyzed anther development in Amomum villosum Lour. (Zingiberaceae) using the periodic acid-Schiff's technique and Sudan black staining to test for the presence of starch and lipids, respectively. Our analyses showed that microspore mother cells of A. villosum lack typical callose walls, and numerous lipid granules appear in the cells early in development. Some starch granules are present in anther wall cells, but not in tapetal cells. After meiosis, numerous lipid granules remain unchanged in the microspores. During microspore development, some small starch granules first appear in the central cell region, and then the starch granules increase in size. After microspore division, the bicellular pollen grains become filled with starch and lipids, and remain in this state until the pollen grains reach maturity. At anthesis, the anther wall of A. villosum consists of several layers of endothecium cells with an evidently thickened radial wall, and some layers of parenchyma cells containing numerous starch granules.     

Electron microscopic study of the optic tentacle collar cells of the snail Helix aspersa and immunolocalization of methionine enkephalin-like material in their granular content

Summary— An ultrastructural and immunocytological study was carried out on the collar cells of the optic tentacle of Helix aspersa. These cells are supposed to be the source of a reproduction controlling hormone. The immunocytological study was performed using an anti-methionine enkephalin antibody obtained from rabbits in our laboratory. The collar cells are characterized by an enlarged rough endoplasmic reticulum, numerous mitochondria and Golgi bodies surrounded by secretory vesicles, suggesting an intense synthesizing activity. Their principal feature consists of numerous various-sized granules where methionine enkephalin immunoreactivity is localized. No classical neurosecretory granules are observed while synapse-like structures are often encountered. The cells should not be regarded as neurosecretory cells but rather as glandular cells which could ensure different functions, one in relation to reproduction, and another in relation to perception processes, particularly as they contain methionine enkephalin-like material.     

The ultrastructure of guinea pig heterophil granulocytes and the heterogeneity of the granules

Summary The development of the heterophil granulocytes in the bone marrow of the guinea pig is described. During the maturation of these cells, three types of granule are formed, not only the azurophil and specific granules already described in other mammals but also a third type of granule referred to here as the nucleated granule. During the process of maturation of the cells, these three types of granule are formed successively. On this basis, two steps can be distinguished in the promyelocyte phase in which primary (nucleated and azurophil) granules are formed, i.e. an early and a late stage, nucleated granules being formed in early and azurophil granules in late promyelocytes. Secondary (specific) granules occur first in myelocytes. In mature heterophils of the guinea pig the granule population is composed of about 85% secondary granules, about 10% azurophil granules, and about 5% nucleated granules. The changes in the granule population during the maturation process were quantified. The observations and calculations point to the occurrence of three mitoses: one in the early and one in the late promyelocyte and the third in the myelocyte.     

The testicular interstitial tissue of the amphibian Physalaemus fuscumaculatus

Summary The fine structure of the interstitial tissue of the testis of Physalaemus fuscumaculatus is described. Epithelioid cells identified as Leydig cells occur scattered in the interstitial tissue. Their cytoplasm contains a well developed smooth and rough surfaced endoplasmic reticulum arranged in whorls. The mitochondria present typical tubular cristae and unusual inclusions of a granular material. In spite of the distinctive characteristics reported here, it is assumed that the function of the Leydig cells is basically similar to that of the steroid synthetizing cells of the testicular interstitial tissue of higher vertebrates.An unusual feature is the presence of numerous melanophores randomly distributed in the capsule of the testis and in the interstitium. They are polyhedric cells with poorly developed organelles, numerous melanosomes, and long cytoplasmic processes.A large amount of collagen is present in the intercellular spaces closely related with undifferentiated cells, most of which are assumed to be fibroblasts.This work was supported by a Grant of the Consejo Nacional de Investigationes Científicas y Técnicas, and by Grant M-63-121 from the Population Council.Career investigators of the Consejo Nacional de Investigationes Científicas y Técnicas.Research Fellow of the same Institution.