Functional morphology of the theca interna of the vesicular follicle in human ovary]

A study of histological serial sections of human ovaries and histochemical reactions established that several cell types differentiate in the theca interna during the formation and development of tertiary follicles (2nd growth period). This leads, in turn, to triple-layering of the theca interna in follicles of the 2nd resting period. The inner thecal layer consists of fusiform cells from the basement membrane, which are apposed to the membrana granulosa and show a strong positive reaction to alkaline phosphatases. A tropic function for the follicular epithelium must be assigned to this layer. The middle layer consists of epitheloid thecal cells, which show a strong positive reaction to 3beta-ol-steroid hydrogenase. These represent the estrogen glands of the follicle. The outer layer of the theca interna, whose transition to the theca externa is indistinct, also has fusiform cells, which are available as reserve material for the differentiation of further epitheloid thecal cells to pre-ovulatory follicles in later periods of development.     

Electron microscopy of two subcellular fractions isolated from cerebral cortex homogenate

The sporulation process in Bacillus subtilis has been studied principally with KMnO(4) fixation, but also, for the purpose of comparison, with OsO(4) and mixtures of both fixatives. At a very early stage, the pre-spore is seen to consist of what seems to be the nuclear material and granular substance, surrounded by a layer of dense material destined to become the innermost layer of the spore coat. At a subsequent stage, a light interspace is observed that is destined to become the spore cortex. The mature spore shows a very complex structure. The spore coat is composed of three layers, the middle layer of which consisted of 5 to 8 lamellae of thin membranes and interspaces, both about 20 to 25 A thick. Between the inner layer of the spore coat and the spore cortex, a thin membrane with an affinity to the cortex can be observed. The spore coat is enclosed within two envelopes, one loosely surrounding the core, and the other adhering to it. The process of spore maturation has been studied in detail. Certain peculiar cellular structures have been observed that seemed to represent features of abnormal sporulation processes.     

Electron microscopy of human interphase nuclei

Quantitative electron microscopy was used to analyze surface-spread, critical-point-dried human interphase nuclei and chromatin. The following information is presented: (1) Unstimulated interphase nuclei of lymphocytes from peripheral blood have a mean dry mass of 50.30×10^?12 g. The mean dry mass of stimulated nuclei of lymphocytes was determined to be 59.34×10^?12 g, a significant statistical difference from the unstimulated ones. (2) Mean diameter of chromatin fibers and mean fiber mass per micron were 199ű15% coefficient of variation (C.V.) and 5.95×10^?16g×29% C.V., respectively. (3) A line of regression of fiber mass on fiber diameter for 83 fibers indicated that a 200-Å fiber has a mass of 5.86×10^?16g/μ, or almost the same as the mean fiber mass of 5.95× 10^?16g/μ. (4) With the value 7×10^?12g for the DNA content of an unstimulated lymphocyte nucleus, a total length of 215 cm is calculated for the DNA double helix. When this length is compared to the mean length of chromatin fiber per nucleus (7.59 cm), a ratio of 28.3 to 1 results, which is called the DNA-packing ratio. (5) This DNA-packing ratio of 28.3 is reasonably close to the packing ratio of 26.9 suggested from model calculations for the second DNA supercoil in a 200-Å chromatin fiber.     

Electron microscopy of gold-labeled human and equine chromosomes

We present an immunochemical technique for the detection of 5-bromo-2'-deoxyuridine (BrdU) incorporated discontinuously into the chromosomal DNA. A monoclonal anti-BrdU antibody and a protein A-gold complex were used to produce chromosome banding of human and equine chromosomes, specific for electron microscopy (EM). Well-defined bands, symmetry of sister chromatids, concordance between homologues, and band patterns similar to those observed by light microscopy facilitate chromosome identification and karyotyping. From prophase to late metaphase, chromosomes condense and bands appear to fuse. The fusion appears to be owing to chromatin reorganization. Our results underline the value of using immunogold reagents, which are ideal probes for antigen localization on chromosomes.     

Granulosa theca cell tumor with luteoma in the ovary of a bonnet monkey (Macaca radiata)

A mass was identified on the left caudal region of the abdomen in a 13-year-old bonnet monkey (Macaca radiata). The mass was excised and diagnosed as granulosa theca cell tumor accompanied with luteoma based on the microscopic findings. Morphologically it appeared pink, round, firm multilobulated measured approximately 5 x 3 x 2.5 cm in dimension. Histologically the luteoma composed of polyhedral cells with pale strained vacuolated cytoplasm, centrally located nuclei with distinct cytoplasmic borders. Granulosa theca cell tumor appeared as densely packed spindle shaped fusiform cells arranged in interlacing bundles and whorled pattern with neoplastic cells appearing irregular shaped solid sheets. The concomitant development of granulosa theca cell tumor with luteoma in a single ovary is very rare and is the first reported case in a bonnet macaque to our knowledge.     

Identification of gamma-aminobutyric acid and its binding sites in the rat ovary

Gamma-aminobutyric acid (GABA), GABA synthesizing enzyme and GABA binding sites were measured in rat ovaries. The concentration of GABA in the ovary (0.56 μg/mg protein) was less than that in the brain (1.2–3.4 μg/mg protein), but was six-fold higher than any other non-neuronal tissue examined. Glutamate decarboxylase, the GABA synthesizing enzyme was also found in high concentrations in whole ovarian homogenate but not in enriched ovarian granulosa cells, testis, anterior pituitary or muscles. Furthermore, high affinity (Kd = 15–21 nM), specific GABA binding sites were identified in the ovaries by specific [³H]muscimol binding and the majority of GABA binding sites were associated with the granulosa cells. These data suggest a possible role of GABA in the regulation of ovarian functions.     

Electron microscopy morphology of the mitochondrial network in human cancer

Mitochondria have been implicated in the process of carcinogenesis, which includes alterations of cellular metabolism and cell death pathways. The aim of this review is to describe and analyze the electron microscopy morphology of the mitochondrial network in human cancer. The structural mitochondrial alterations in human tumors are heterogeneous and not specific for any neoplasm. These findings could be representing an altered structural and functional mitochondrial network. The mitochondria in cancer cells, independently of histogenesis, predominantly are seen with lucent-swelling matrix associated with disarrangement and distortion of cristae and partial or total cristolysis and with condensed configuration in minor scale. Mitochondrial changes are associated with mitochondrial-DNA mutations, tumoral microenvironment conditions and mitochondrial fusion–fission disequilibrium. Functionally, the structural alterations suppose the presence of hypoxia-tolerant and hypoxia-sensitive cancer cells. Possibly, hypoxia-tolerant cells are related with mitochondrial condensed appearance and are competent to produce adequate amount of ATP by mitochondrial respiration. Hypoxia-sensitive cells are linked with lucent-swelling and cristolysis mitochondria profile and have an inefficient or null oxidative phosphorylation, which consequently use the glycolytic pathway to generate energy. Additionally, mitochondrial fragmentation is associated with apoptosis; however, alterations in the mitochondrial network are linked with the reduction in sensitivity to apoptosis induces and/or pro-apoptotic conditions. Pharmacological approaches designed to act on both glycolysis and oxidative phosphorylation can be considered as a new approach to selectively kill cancer cells.     

Electron microscopy of G-banded human mitotic chromosomes

Trypsin-treated human metaphase chromosomes stained with Giemsa and uranyl acetate showed clear, reproducible band structures under the transmission electron microscope (TEM). The banding pattern observed with TEM corresponded very closely to the G-band pattern visualized by light microscopy. The TEM images were used for karyotype analyses. Trypsin-treated chromosomes stained with uranyl acetate alone also showed clear G-bands under TEM. Shadow casting in addition to uranyl acetate staining revealed more structural detail of the chromosomes. Chromosome fibers, 200 Å–300 Å in diameter, were observed in the interband regions. Most chromosomes showed the major G-bands under the higher TEM magnification wit0out any trypsin treatment.     

Electron microscopy of human articular cartilage]

Scanning and transmission microscopy of the articular cartilage was performed in femoral condyles of persons at the age of 30-50 years. It was demonstrated that hyaline cartilage is covered with a protective fibrillar layer consisting of tightly pressed collagenous fibrillae with an underlying layer of fibroblastic cells. In the intracellular substance of the hyaline cartilage fibrillar structures form a complex reticular web with vertical arrangement of the main collagenous fasiculi. In the superficial layer of the hyaline cartilage the collagenous fibrillae and their fasciculi form arcade-like structures. Lacunar chondrocytes have a rough villose surface, cellular secrete is discharged as round granules through cytoplasmic membrane. Ultrastructural changes in chondrocytes are observed simultaneously with their degenerative-dystrophic changes.     

Electron microscopy of the cell wall complex ofMethylomonas albus

In surface view, the cell wall complex ofMethylomonas albus possesses a hexagonal pattern of ridges. Thin sections reveal a continuous layer of goblet-shaped elements attached to the outermost surface of the lipopolysaccharide membrane. A possible interpretation of the cell wall complex ofM. albus, based on the fine-structural data is presented.     

Localization of some steroidogenic enzymes in the ovary of the rabbit

The distribution of delta 5-3 beta-HSD, peroxidase and cytochrome oxidase in immature, sexually mature and pregnant rabbit ovary has been studied histochemically. Corpora lutea are found only in pregnant rabbits. delta 5-3 beta-HSD is present in the theca interna of mature follicles, corpora lutea and interstitial gland cells but is absent in the granulosa cells of both developing and mature follicles. The granulosa cells of mature and developing follicles, hypertrophied theca interna and the luteal cells all show intense cytochrome oxidase activity. Peroxidase is present in the corpora lutea only. It is suggested that delta 5-3 beta-HSD in the theca interna and interstitial gland cells is the enzyme responsible for steroid synthesis in the ovaries of immature as well as sexually mature rabbits, while peroxidase and delta 5-3 beta-HSD present in the corpora lutea together regulate luteal steroidogenesis during pregnancy. The intense cytochrome oxidase activity together with peroxidase and delta 5-3 beta-HSD confirms the observations that this tissue is a site of intense oxidative activity.     

Electron microscopy in cell biology: integrating structure and function

Electron microscopy (EM) is at the highest-resolution limit of a spectrum of complementary morphological techniques. When combined with molecular detection methods, EM is the only technique with sufficient resolution to localize proteins to small membrane subdomains in the context of the cell. Recent procedural and technical developments have increasingly improved the power of EM as a cell-biological tool.