bluuebunny/crossref_metadata_2025 huggingface dataset:
Simultaneous autoradiographic and immunohistochemical localization of estrogen and gonadotropin in the rat pituitary
Authors: Keefer Donald A. , Stumpf Walter E. , Petrusz Peter , Sar Madhabananda
Published: February 2005

A combined autoradiographic and immunohistochemical technique is introduced which is suitable to simultaneously localize hypophyseal sites of nuclear (3H)‐estradiol uptake and anti‐hCG‐characterized “gonadotropes”. Most, but not all, “gonadotropes” show significant nuclear concentration of radioactivity. A large percentage of non‐“gonadotropes” also show nuclear uptake of label.
Scanning electron microscopy of cardiac endothelium of the dog
Authors: Peine Craig J. , Low Frank N.
Published: February 2005

Tissue obtained from young dogs was fixed in buffered aldehydes by vascular perfusion or direct immersion. Selected hearts were maintained in modified mammalian Ringer's solution for three to five minutes prior to fixation. The chambers of the heart and related valves were exposed by dissection and prepared by routine techniques for observation by scanning electron microscopy (SEM). Subsequent to SEM studies, selected specimens were embedded in Epon 812 and sectioned for transmission electron microscopy (TEM).

The cardiac endothelium, when fixed immediately in buffered aldehydes, presents an essentially invariable surface throughout the interior of the heart. The predominant nuclear bulges and attenuated peripheral plasmalemma are consistently smooth, with occasional marginal ruffles, scattered microvilli and small blebs. Apart from the higher population of nuclear bulges on valvular surfaces, local variations in SEM of endocardium occur in response to the various stages of systole and diastole encountered. These physiological changes do not produce microappendages.

Immersion for three to five minutes in (Chenoweth's) Ringer's solution, prior to fixation, produces a substantial population of microappendages. The cellular surface acquires a swirled appearance erupting in microvilli, blebs and ruffles. These exhibit considerable pleomorphism.

There is great lability of the endocardial surface in response to a classic “holding solution” widely used in preparatory techniques. In preparing soft tissues for SEM caution must be used if physiological “holding solutions” are used prior to fixation.
Ultrastructural immunocytochemical localization of neurophysin in freeze‐substituted neurohypophysis
Authors: Silverman A. J. , Knigge K. M. , Zimmerman E. A.
Published: February 2005

Using an immunohistochemical technique at the electron microscopic level, we have observed that within the axon terminals of the guinea pig neurohypophysis neurophysin is present in the large neurosecretory granules, as well as in the axoplasm. A description of a freeze‐substitution technique for neural lobe is also present.
Developmental morphology of the subarachnoid space and contiguous structures in the mouse
Authors: McLone David G. , Bondareff William
Published: February 2005

Development of pia‐arachnoidal membranes in the mouse occurs in four stages: the first (prenatal days 10–13) follows closure of the neural tube and is a period of initial vascularization of the developing telencephalon; the second (prenatal days 14–16) is a period of delineation during which the limits of the subarachnoid space are defined; the third (prenatal day 17 to birth) is a period of ensheathment of pia‐arachnoidal blood vessels, and the fourth (birth to postnatal day 21) includes addition of smooth muscle to larger vessels, the appearance of macrophages in the subarachnoid space, and a general increase in extracellular collagenous and elastic fibers.

The mesenchyme over the telencephalic surface in the 10‐day fetus has a typically large extracellular space. By the 13th fetal day cerebrospinal fluid begins to seep into and replace it. The mesenchymal extracellular compartment is reduced peripherally, resulting in a compacted pia‐arachnoidal tissue which limits the peripheral extent of the subarachnoid space. By the 21st postnatal day a subarachnoid space typical of the adult animal has been established.
Localization of growth hormone‐release‐inhibiting hormone (somatostatin) in the rat brain
Authors: Pelletier Georges , Leclerc Rachel , Dube Donald , Labrie Fernand , Puviani Romano , Arimura Akira , Schally Andrew V.
Published: February 2005

Utilizing an immunoperoxidase technique at the light microscope level, growth hormone‐release‐inhibiting hormone (somatostatin) was localized in the external zone of the median eminence, the subcommissural organ, the organum vasculosum of the lamina terminal is and the pineal gland. No positive reaction was detected in any other brain area.
Radioimmunological evidence for early functional activity in chick embryonic alpha cells
Authors: Benzo Camillo A. , Stearns Susan B.
Published: February 2005

A radioimmunoassay for glucagon was utilized to investigate early developmental aspects of glucagon synthesis and release in the chick embryo. Immunoreactive glucagon was detected in both the pancreas and blood plasma from the fifth embryonic day onwards. The present data show that the chick embryonic alpha cell has the potential for secretory activity very early in development, and suggest a developmental role for glucagon in hepatic glycogen metabolism.
Localization of tropomyosin in mouse embryo fibroblasts
Authors: Jorgensen A. O. , Subrahmanyan L. , Kalnins V. I.
Published: February 2005

Antiserum to chick skeletal muscle tropomyosin was used to localize tropomyosin in mouse embryo fibroblasts by the indirect fluorescein labeled antibody technique. Specific staining was observed in cytoplasmic fibers, which extended out into the cell processes. The staining pattern in these cells is similar to that previously described by others for actin. This observation suggests that in fibroblasts tropomyosin, like actin, is localized in fibers in the cytoplasm.
Effects of fetal decapitation on the structure and function of leydig cells in rhesus monkeys (Macaca mulatta)
Authors: Tseng Michael T. , Alexander Nancy J. , Kittinger George W.
Published: February 2005

Fetal decapitation in utero has enabled us to study the role of fetal pituitary hormones in the development of the fetal testis. Testes from males decapitated near 80 days of gestational life and later delivered at 150 days were smaller than normal and about one‐tenth the normal weight. The size of the seminiferous tubules was similar in both groups; however, the number of Leydig cells seemed reduced. In addition, the Leydig cells of the experimental group contained smaller mitochondria with reduced tubular cristae, fewer lipid droplets, and reduced agranular endoplasmic reticulum. Androgen production was inhibited. Measured by radioimmunoassay, the testosterone level in the umbilical vein was 329 ± 82 pg/ml in six decapitated fetuses, 412 ± 62 pg/ml in ten normal fetuses. The level in the umbilical artery was 328 ± 56 pg/ml in five decapitated fetuses, 658 ± 140 pg/ml in normal fetuses. These studies suggest that chronic deprivation of fetal pituitary hormones inhibits the growth and development of the testis in general and of the Leydig cells in particular.
The dual origin of vaginal epithelium
Authors: Cunha Gerald R.
Published: February 2005

The absence of the cranial three‐fifths of the vaginae of male mice carrying the gene, Testicular Feminization, provides strong support for the view that vaginal epithelium is of dual origin, the cranial three‐fifths being of Mullerian in origin and the caudal two‐fifths being derived from the urogenital sinus.
Fine structure of hepatocytes from fasted and fed rats
Authors: Babcock Muriel B. , Cardell Robert R.
Published: February 2005

The fine structure of hepatocytes from rats maintained on a controlled feeding schedule are described. Liver samples were processed for electron microscopy, histochemistry and chemical determinations of glycogen at precise time‐intervals following a 30‐hour fast and a 2‐hour meal. Hepatocytes from 30‐hour‐fasted rats with extremely low hepatic glycogen levels were devoid of glycogen particles. Centrilobular cells showed areas of the cytoplasm rich in vesicles of smooth endoplasmic reticulum (SER) while periportal hepatocytes contained less extensive regions of SER. Soon after feeding the fasted rats, glycogen particles appeared in regions of the cell rich in SER. Centrilobular hepatocytes contained numerous glycogen areas which were infiltrated with tubules of SER, while periportal cells showed dense glycogen deposits with SER restricted to the periphery of the masses of glycogen. Throughout glycogen deposition each glycogen particle was closely associated with membranes of SER until maximum glycogen deposition was achieved 12 hours after initiation of feeding. At this point SER was reduced to the lowest amounts of the time‐periods studied. During stages of glycogen depletion SER proliferated and reached the highest concentration measured in this study. Tubules of SER were present throughout the glycogen masses of centrilobular hepatocytes, whereas in periportal cells the organelle was restricted to the periphery of the glycogen masses. It is concluded that SER is associated with glycogen particles in rat hepatocytes during both deposition and depletion of glycogen.
Renewal of the epithelium in the descending colon of the mouse. IV. Cell population kinetics of vacuolated‐columnar and mucous cells
Authors: Chang W. W. L. , Nadler N. J.
Published: February 2005

Proliferation and migration of cells in the vacuolated‐columnar and mucous cell lines were studied in the descending colon of adult female mice given a single injection or a continuous infusion of 3H‐thymidine and killed at various intervals from one hour to 12 days. This investigation was carried out using one μm‐thick Epon sections which were radioautographed after staining with the periodic acid‐Schiff technique and iron‐hematoxylin.

In the normalized crypts with ten equal segments, labeled vacuolated cells at one hour after injection of 3H‐thymidine were encountered in the lower four segments and in decreasing numbers in segments 5 through 7. From the percent labeled cells in segments of the crypt, the birth rate and fluxes of cells were computed. Moreover, it was found that a cell in the vacuolated‐columnar cell line would undergo three mitotic cycles on the average from its birth at the cryptal base to its extrusion from the surface; of these three cycles, the last one which took place from segment 3 to segment 7 appeared to be a changeover from dividing cells to non‐dividing cells, in accordance with the “slow cut‐off” model of Cairnie et al. ('65b).

Mucous cells located in segments 1 through 6 of the crypt were capable of incorporating 3H‐thymidine and thus capable of undergoing mitosis. However, the rate of turnover of mucous cells based on proliferative rate was found to be much lower than the rate of turnover of mucous cells based on the transit time in the non‐dividing segments of the crypt. Since there was a concomitant overproduction of cells in the vacuolated‐columnar cell line and some morphological similarity between vacuolated cells and newly formed mucous cells in the lower portion of the crypt, it was concluded that some vacuolated cells would give rise to mucous cells. This putative transformation occurred in the lower four segments of the crypt.

Mucous cells which were formed by transformation would migrate upward along the cryptal wall and accumulate more mucus in the theca; in doing so, they would undergo two divisions, on the average, before they became non‐dividing mucous cells.

In ascending the cryptal walls, both vacuolated‐columnar cells and mucous cells appeared to migrate at a similar speed; they moved much slower at the base of the crypt and accelerated toward the upper portion of the crypt, but they migrated at a constant speed in the non‐dividing segments of the crypt.
The two to four‐cell embryos as source tissue of the tetrapeptide preventing ovulations in the hamster
Authors: Kent Harry A.
Published: February 2005

A tetrapeptide compound, derived from oviductal contents at 40 hours post‐coitus, prevents ovulation when injected subcutaneously into cyclic hamsters (Kent, '73). The present experiments were designed to determine whether the source of the tetrapeptide is from the ova, embryos, oviducts or semen. Oviducts were either untouched or ligated at the ovarian or uterine end to limit contents to embryos, semen or ova and the contents then recovered at 40 hours pc and injected into cyclic hamsters. The results indicate that the source of the tetrapeptide is the embryos.
Anti‐horseradish peroxidase associated with tubular structures in the endoplasmic reticulum of plasma cells in stimulated lymph nodes of mice
Authors: Tomonaga Susumu , Schoefl Gutta I.
Published: February 2005

Tubular structures are described in dilated cisternae of the endoplasmic reticulum in plasma cells of lymph nodes stimulated with horseradish peroxidase (HRP). A positive reaction for anti‐HRP antibody suggests that they are formed of immunoglobulins or are at least closely associated with them.
Ultrastructural observation of anterior pituitary gonadotrophs following hypophysial portal vessel infusion of luteinizing hormone‐releasing hormone
Authors: Luborsky‐Moore J. L. , Poliakoff Steven J. , Worthington W. Curtis
Published: February 2005

Luteinizing hormone‐releasing hormone (LHRH) (50 ng) was infused with a microcannula into hypothalamo‐hypophysial stalk portal vessels of adult male rats. Anterior pituitaries were prepared for electron microscopy at 1, 5, 10, 15, 30 and 60 minutes after infusion. Granule release (exocytosis) from gonadotrophs was stimulated within one minute. Evidence of increased protein synthesis began at 5–10 minutes but was not maximal until 15 minutes. The majority of new granules appeared in the Golgi apparatus at 15 and 30 minutes. This study provides morphological evidence for LHRH‐induced hormone and synthesis release under physiological conditions.
Microvascular structure of the human epididymis
Authors: Kormano Martti , Reijonen Kalevi
Published: February 2005

The microvascular anatomy of the human epididymal duct system from rete testis to vas deferens was studied using microangiography and histology. Various segments of the duct system show significant differences in the density and arrangement of the small blood vessels. The rete testis is poorly vascularized while the first lobulated segment of the epididymis, which is formed by the efferent ducts is provided with a dense subepithelial capillary bed. The more distal segments of the epididymis have less dense capillarization surrounding the epididymal duct. In the vas deferens the blood vessels form a double capillary network. The outer capillary network surrounds the smooth muscle layers and the inner is located immediately beneath the duct epithelium. The organization of blood capillaries in the human epididymis and the differences seen in different portions of the excurrent duct system follow basically the general pattern seen in some experimental animals.
The andrenocortical homolog in the lake sturgeon, Acipenser fulvescens rafinesque
Authors: Youson J. H. , Butler D. G.
Published: February 2005

The adrenocortical homolog in the chondrostean fish, Acipenser fulvescens, is confined within yellow corpuscles located at the dorsal junction of the two kidneys near the cardinal veins. The concentration and distribution of this tissue in chondrosteans appear to be a condition intermediate between that of cyclostomes and teleosts. The homology of this tissue to adrenocortical tissue of higher vertebrates is demonstrated in its Δ5‐3β‐hydroxysteroid dehydrogenase activity and the ultrastructure of the cells.

The cells contain large lipid droplets and an abundance of smooth endoplasmic reticulum and mitochondria. The abundance of smooth endoplasmic reticulum, a large Golgi apparatus and an extensive elaboration of the plasma membrane suggest the high degree of steroidogenic activity of these cells. Apposed plasma membranes make contacts through the unique cell contacts described in the adrenocortical cells of mammals (Friend and Gilula, '72). The Golgi apparatus is described as a most conspicuous component of the cytoplasm and is presented as further evidence for the important involvement of this organelle in corticosteroidogenesis in vertebrates.

These morphological observations are discussed in relation to the known secretory products of this tissue in the sturgeon, and it is suggested that there is a need for further examination of the corticosteroids produced by lower vertebrates.
Morphological changes in the trophoblast, uterus and corpus luteum during delayed implantation and implantation in the western spotted skunk
Authors: Sinha Akhouri A. , Mead Rodney A.
Published: February 2005

Morphological interactions of trophoblast and uterus from stages of preimplantation and implantation were studied in 14 western spotted skunks. In addition, the granulosa lutein cells and plasma progesterone levels were studied. In animals several days from implantation the height of epithelial cells decreased, but began to increase in animals approaching implantation. During the preimplantation period a few leucocytes infiltrated the epithelium, but in animals just prior to implantation many leucocytes infiltrated the epithelium. However, in the implanted animals leucocyte infiltration was not observed. The increased infiltration of epithelium was possibly in response to the proximity of trophoblast or due to some antigenic material from the trophoblast. The unimplanted blastocyst had a layer of trophoblast and the embryonic disc. As implantation approached, the trophoblast formed trophoblastic knobs which apposed the luminal epithelium. Subsequently microvilli of trophoblastic and epithelial cells interdigitated. Junctional complexes were observed between many adhering microvilli and/or cell processes. The first attachment of trophoblast and epithelium occurred in the abembryonic region. Later the trophoblastic cell processes and/or individual cells penetrated the epithelium and reached the basal lamina. In addition to the penetration of the trophoblast, sometimes individual trophoblastic and epithelial cells fused. In the fused cells, remnants of junctional complexes and plasma membranes were observed. The fused cells did not penetrate the basal lamina and were not observed in the stroma.

During the delay period the corpus luteum contained predominantly small granulosa cells and some large granulosa lutein cells, but only large lutein cells were observed in the implanted animals. The plasma progesterone levels fluctuated during the time of implantation and should not be regarded as a basis to predict nidation in the skunk.
A quantitative analysis of muscle cell changes in compensatory hypertrophy and work‐induced hypertrophy
Authors: Seiden David
Published: February 2005

The cytological characteristics of two modes of muscle hypertrophy were studied in the extensor digitorum longus muscle of the rat. Compensatory hypertrophy (CH) was produced by tenotomy of the tibialis anterior muscle and work‐induced hypertrophy (WIH) was produced by forced swimming of the animal. While both methods produced an increase in muscle weight and cell size, these two parameters did not correlate. Morphometric analyses of the hypertrophied muscle cells demonstrated that in CH‐muscle there was an increase in mitochondrial volume density, a decrease in myofibrillar volume density and no change in sarcotubular or nuclear volume density. WIH‐muscle demonstrated an increase in sarcotubular volume density but no change in mitochondrial, myofibrillar or nuclear volume density. It is concluded that in CH‐muscle, the cell volume increase is attributable to mitochondrial volume increase and that there is no increase in the contractile myofibrillar component of the cell. WIH‐muscle, on the other hand, has a cell volume increase which is attributable to a proportional increase in these organelles.
Light cells within the limiting membrane of rat seminiferous tubules
Authors: Hermo L. , Clermont Y.
Published: February 2005

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.
The paraganglia, a persisting endocrine systen in man
Authors: Hervonen Antti , Vaalasti Annikki , Partanen Matti , Kanerva Lasse , Vaalasti Tapio
Published: February 2005

The paraganglia have been traced in surgical samples of para‐aortic and pelvic retroperitoneal tissues using the formaldehyde‐induced fluorescence method for catecholamines. Clusters of catecholamine‐storing cells were found in all (12) patients studied. Microspectrofluorometric recordings showed high amounts of catecholamine in the well‐vascularized cell groups. A large proportion of the paraganglia, which are most prominent during the fetal period, also persist during postnatal life.
Fine structure of the testis and epididymis of rats treated with cyproterone acetate
Authors: Flickinger C. J. , Loving C. K.
Published: February 2005

Adult male rats were administered the antiandrogen, cyproterone acetate, for 4, 8 or 12 weeks, and the histology and fine structure of the testis and several parts of the epididymis were studied. After treatment for 8 or 12 weeks, the testes of treated animals displayed a great reduction in the abundance of late spermatids. Necrotic cells, many of which were identified as cap‐phase spermatids, were present in the seminiferous epithelium. Sertoli cells contained many large lipid droplets and lysosome‐like structures with a content of cellular debris, including parts of spermatids. Leydig cells of treated rats were smaller than those of control animals at all the intervals studied. Sperm were absent from the lumen of the middle segment, or caput epididymidis, of severely affected specimens. In the terminal segment, or cauda epididymidis, the microscopic appearance varied in different regions. In the proximal part of the cauda epididymidis, the lumen was usually clear of sperm. The epithelium was tall and the light cells were very large and distended with many dense bodies resembling lysosomes. In contrast, in the distal part of the cauda epididymidis, the lumen was filled with sperm and debris, which appeared to be derived from germ cells. It is suggested that the light cells of the epididymal epithelium may have a role in clearing the lumen in the proximal part of the cauda epididymidis, in which they are particularly large and numerous. The results suggest that in the presence of cyproterone acetate, germ cells develop up to cap‐phase spermatids and then begin to undergo degeneration and death. This alteration may have an important role in the antifertility effect of the drug, but changes in the epididymis may contribute also.
Observations on the microcirculatory bed in rat mesocecum using differential interference contrast microscopy in vivo and electron microscopy
Authors: Beacham W. S. , Konishi A. , Hunt C. C.
Published: February 2005

The microvascular bed of the rat mesocecum has been examined in vivo using differential interference (Nomarski) optics and subsequently by electron microscopy. The preferential channel, from terminal arteriole to collecting venule, has been examined.

In the terminal arteriolar segment the endothelial layer is covered by a continuous layer of smooth muscle cells which, in turn, are surrounded by adventitia. In the metarteriolar segment the periendothelial cells still resemble smooth muscle cells but the tunica media is discontinuous. In the distal segment periendothelial cells are more scattered and have the appearance of pericytes. There appears to be a continuous transition of the periendothelial cell layer from terminal arteriole to distal segment.

Nerve endings were seen in both the terminal arteriolar and metarteriolar segments.

During contraction smooth muscle cells, oriented circumferentially, shorten and thicken. Endothelial cells appear anchored by myoendothelial junctions.

Endothelial cells have filaments which show increased banding during vasoconstriction, suggesting that such cells may contract.

Capillary offshoots leave the preferential channel, usually at right angles. Smooth muscle cells are oriented to form a sphincter and there are many myoendothelial junctions at the branch point. Within a short distance the capillary branch loses its periendothelial coat.
Selection of operating wavelength‐pair for two‐wavelength microspectrophotometry
Authors: Black‐Schaffer W. Stephen , Floyd Alton D.
Published: February 2005

The two‐wavelength method is the microspectrophotometric method of choice for thick specimens. Its accuracy is dependent on the accuracy of selection of the operating wavelength‐pair. The “slope zero test,” offered as a check upon the accuracy of this selection (Garcia and Iorio, ′66) is shown to be invalid by analysis of experimental data, by computer model and by mathematical derivation. A means of checking the accuracy of selection of the operating wavelength‐pair via scanning measurements is suggested. A new formulation of the two‐wavelength method, permitting use of different operating wavelength‐pairs, is also given.
The autonomic innervation of the interstitial gland of the rat ovary during pregnancy
Authors: Lawrence Irvin E. , Burden Hubert W.
Published: February 2005

The autonomic innvervation of the interstitial gland of the rat ovary was studied on days 4, 6, 10, 14 and 18 of pregnancy with the acetylcholinesterase procedure, the Falck‐Hillarp technique and electron microscopy after 5‐hydroxydopamine treatment. Acetylcholinesterase‐positive nerves were present as perivascular plexuses at all stages studied. Adrenergic nerves were present in the interstitial gland in all stages studied. The number and intensity of interstitial fluorescent adrenergic nerves increased as pregnancy progressed. Measurement of norepinephrine with the fluorometric procedure showed a highly significant (p < 0.05) increase in the neurotransmitter in the ovary on days 14 and 18 as compared to day 4. Fine‐structural studies after administration of the false transmitter, 5‐hydroxydopamine, showed that the innervation of the steroidogenic cells of the interstitial gland is adrenergic.
Functional differentiation of the chick endocrine pancreas. II. The alpha cells and glucagon
Authors: Benzo Camillo A. , Stearns Susan B.
Published: February 2005

A radioimmunoassay for glucagon, together with electron microscopic observations of early embryonic alpha cells were utilized to examine developmental aspects of glucagon accumulation and release in the chick embryo. Immunoreactive glucagon was detected in both the pancreas and blood plasma from the fifth embryonic day onwards. In addition, emiocytotic events were observed in alpha cells as early as the fifth embryonic day. The early appearance of glucagon and its subsequent developmental profile correlate well with major events in carbohydrate metabolism occurring in the embryonic chick, and are discussed in relation to a functionally responding system, the developing liver. The present data show that glucagon is secreted at earlier embryonic stages than hitherto demonstrated, and suggest a developmental role for glucagon in hepatic glycogen metabolism.
Stereo high‐voltage electron microscopy of whole cells of the human diploid line, WI‐38
Authors: Wolosewick John J. , Porter Keith R.
Published: February 2005

The human diploid cell line, WI‐38, has proven to be an especially good object for high‐voltage electron microscopy using whole cells. Cells of intermediate passages were grown on plastic‐coated, carbon‐shadowed gold grids, fixed with glutaraldehyde, post‐fixed with osmium tetroxide, stained with uranyl salts and critical‐point dried. The absence of an embedding matrix produces images of increased contrast and resolution.

The approach combined with stereo‐microscopy has extended our knowledge of cellular ultrastructure. Stereo‐images of whole cells reveal nuclei, mitochondria, microtubules, microfilaments, the endoplasmic reticulum and ribosomes in their expected forms. At high magnifications a continuity of microtubules, microfilaments and membranous elements with thin (3–6 nm) strands of the ground substance has been observed. These strands form a three‐dimensional lattice or mesh that pervades all parts of the cytoplasm. The entire structure is referred to as a microtrabecular lattice or mesh, the strands being the trabeculae. The inclusion of microtubules, microfilaments, ribosomes and vesicles of the endoplasmic reticulum within the material of the lattice makes them all part of a totally organized cytoplast.
Dissociation of epithelial cells from rabbit trachea and small intestine with demonstration of APUD endocrine cells
Authors: Sonstegard K. S. , Cutz E. , Wong V.
Published: February 2005

In this study the entire epithelial lining of tracheas and a 15‐cm segments of small intestine were dissociated into individual cell components after 45‐minute incubation with 1% pronase. Light and electron microscopy of isolated cells confirmed good morphologic preservation of various epithelial cell types dissociated from the trachea and small intestinal mucosa.

Of particular interest was the recovery and preservation of APUD endocrine cells, which are known to be widely dispersed amongst various non‐endocrine epithelial cells in both the trachea and small intestine. The APUD cells were demonstrated in dissociated cell preparations by a formaldehyde‐induced fluorescence method, Grimelius' silver nitrate stain, and electron microscopy. The isolated APUD cells retained their characteristic features, e.g., amine‐handling properties, argyrophilia and cytoplasmic dense‐core vesicles.

The cell dissociation method described in this report provides high yields of viable epithelial cells in single cell suspensions which are suitable for further cell separation into homogeneous populations of single kinds of cells, including the APUD endocrine cells. Availability of methods for isolation of tracheal and intestinal APUD cells will facilitate further studies, in vitro, on secretory, metabolic and functional aspects of these cells.
Age‐related change in the neuronal microenvironment: Penetration of ruthenium red into extracellular space of brain in young adult and senescent rats
Authors: Bondareff W. , Lin‐Liu S.
Published: February 2005

The volume of the extracellular space, which contributes to the microenvironment of neurons, is diminished in the brains of senescent (as compared to adult) rats and an age‐related change in its composition has been hypothesized. To test this hypothesis we have compared the penetration of ruthenium red, a polyanion selectively distributed in the extracellular space, into the dentate gyri of young adult and senescent Fischer 344 rats.

Slices of hippocampal formation were fixed by immersion, first in a glutaraldehyde solution containing ruthenium red, then in a solution ofosmium tetroxide containing ruthenium red. A specific area of the dentate gyrus was identified, sectioned and examined by electron microscopy. Dense particles of ruthenium red reaction product were readily localized in intercellular channels and synaptic clefts and the depth of penetration was measured in a standardized manner so as to derive a mean depth of penetration for each of the 11 animals studied. A 28% decrease in the mean depth of penetration of ruthenium red in 25‐month‐old rats, as compared with 3‐month‐old animals, was found.

These data indicate an age‐related change in the charge density of the intercellular channels in the dentate gyrus of 25‐month‐old rats. They suggest a primary age‐related change in the charge density of extracellular macromolecules, presumed to be primarily glycosaminoglycans, with a consequent change in water binding capacity and volume of the extracellular space.
Electron microscopic studies of the parathyroid gland of senile dogs
Authors: Setoguti Takao
Published: February 2005

The parathyroid gland of healthy senile dogs aged 8.5 to 15 years was compared with that of mature control dogs by examination with the electron microscope. Preparations fixed by perfusion with glutaraldehyde showed the cytoplasmic matrix of most parenchymal cells to be uniformly dense. None of the cells were of the extremely light type and dark cells were much less frequently noted than in preparations fixed by immersion in glutaraldehyde or osmium tetroxide. Syncytial cells and so‐called colloid follicles were more frequent in senile dogs than in control dogs. It was suggested that the content of the latter structures is not colloid but necrotic substance having origin from the parenchymal cells and that perhaps the occasional cells containing large, membrane‐bound inclusions may be degenerating cells which ultimately produce this necrotic substance. Oxyphil cells and mitochondria‐rich cells of another type were found in all senile dogs, but not in the controls. These cells, especially the mitochondria‐rich cells, frequently contained bizarre mitochondria that were modified in shape, size and arrangement. The most striking feature of these mitochondria was the concentric arrangement of elongated mitochondria which seemed to consist of densely layered cup‐shaped mitochondria. Such mitochondria were noted in all senile dogs aged ten years and over. The significance of mitochondrial pleomorphism in the parathyroid gland of senile dogs was discussed.
Freeze‐fracture study of the carotid body
Authors: Hansen John T.
Published: February 2005

Replicas of freeze‐fractured rat carotid body chief (Type I) cells reveal the normal complement of cytoplasmic organelles. En face fractures of the chief cell plasmalemma exhibit occasional sites of fusion of the amine‐containing vesicles which characterize the carotid body. The endothelial cells lining the capillary network of the carotid body display numerous pinocytotic vesicles often oriented in linear arrays, and occasional fenestrae. The endothelial cells are joined together by tight junctions which appear as grooves (B face) forming a continuous network over the membrane.
The ultrastructure of endocrine cells in the corpus of the stomach of human fetuses
Authors: De Lemos Carmen
Published: February 2005

The ultrastructural development of endocrine cells from the corpus of fetal human stomachs is described. Samples were taken from fetuses ranging in fertilization age from 6–8 to 22 weeks.

The identifying features used for the classification of the various types of endocrine cells were their basal location in the epithelium, the presence and morphology of their characteristic granules and the sizes of the mitochondria. Five types of endocrine cells with specific granules were found: D, EC, ECL, AL and D1. The type and number of endocrine cells increased as development proceeded. The endocrine cells were confined to the epithelium, they did not reach the lumen and they appeared to develop in situ. The D, EC and ECL cells were the most numerous. The fetal endocrine cells resembled morphologically those found in the stomachs of various adult animals. The EC, ECL and D1 cells contained small slender mitochondria with few cristae. Intramitochondrial granules were absent in all the cell types. Agranular electron‐lucent cells with small mitochondria were considered to be immature endocrine cells.

The advanced stage of differentiation observed in these cells suggests that they may be capable of producing and storing biogenic amines and polypeptide hormones. Their possible involvement in the synthesis of serotonin, enteroglucagon and intrinsic factor is discussed.
The surface characteristics of the plasma membrane of the exocrine pancreas
Authors: Katsuyama T. , Spicer S. S.
Published: February 2005

Regional differentiation of the plasma membrane and related structures of the exocrine pancreas has been studied ultrastructurally and cytochemically. Fixation with an osmium tetroxide‐silver acetate solution produced abundant fine precipitates on the luminal and basal surface of the centroacinar but not the acinar cells. Staining with dialyzed iron (DI) revealed the heaviest concentration of anionic sites on the luminal plasma membrane of the acinar cells, including the surface of both the intercellular canaliculi and the main lumen. The reactive sites on the apical acinar plasmalemma appeared to consist of discrete globules. DI‐reactivity of the lateral basal membranes was most prominent in the centroacinar cells and essentially absent in the acinar cells but was weak relative to that of the acinar‐cell apical plasmalemma. The lamina lucida of the basement membrane of the duct stained with DI, but that of basement membrane under acinar cells did not. Sialidase digestion prior to DI staining abolished the staining of plasma membranes. These results indicate that duct epithelial cells, including most prominently the centroacinar cells, are chiefly responsible for electrolyte and fluid transport.
The caudal luminous organs of lanternfishes: General innervation and ultrastructure
Authors: Anctil Michel , Case James F.
Published: February 2005

Neuroanatomical, light and electron microscopic investigations of the caudal luminous organs of two lanternfish species, Stenobrachius leucopsarus and Parvilux ingens, were coducted in a search for morphological correlates underlying their luminescent behavior and control mechanisms. Complex neural pathways involving the spinal nerves and the sympathetic nerve chain of the caudal peduncle are associated with profuse segmental innervation to both the supracaudal and infracaudal organs. Neural composition of these segmental subunits indicates that pre‐ganglionic (spinal) as well as post‐ganglionic (sympathetic) fibers are involved in the neural control of luminescence of these organs. Neuro‐photocyte units, in which multiple nerve branches are sandwiched between two lamellar photocytes and establish large surface areas of close apposition, as well as gap junctions apparently interconnecting all photocytes throughout the luminous organs, may account for the very rapid and simultaneous displays of spontaneous or electrically driven luminescence. The organization of the caudal luminous organs is compared with that of lanternfish photophores. Relatively few granular and agranular synaptic vesicles are present in some nerve processes of the photocyte units, suggesting that adrenergic neurotransmission as well as electrotonic spread of excitation may be involved at the neuro‐photocyte junctions.
Innervation of myocardial microcirculation; terminal autonomic axons associated with capillaries and postcapillary venules in mouse heart
Authors: Forbes M. S. , Rennels M. L. , Nelson E.
Published: February 2005

Efferent terminal axons are associated with numerous capillaries and postcapillary venules in both the atria and ventricles of mouse heart. These axons possess ultrastructurai characteristics which are typical of peripheral autonomic fibers in other tissues. Many are found near pericytes, in a relationship closely resembling that between terminal axons and smooth muscle cells of larger vessels. To demonstrate adrenergic terminals, mice were pretreated with 5‐ or 6‐hydroxydopamine; examination of these animals' hearts revealed that both adrenergic and cholinergic axons terminate near pericytes and endothelial cells. The results of this study are consistent with the view that there may be a functional innervation of capillaries and postcapillary venules of the mouse heart.
The fenestrated collar of mammalian cardiac sarcoplasmic reticulum: A freeze‐fracture study
Authors: Van Winkle W. B.
Published: February 2005

Freeze‐fracture studies of papillary muscles from cat, rabbit and dog reveal the presence of a fenestrated collar of the sarcoplasmic reticulum (SR) in the region of the M band. This membrane specialization is structurally similar to that observed previously in skeletal muscle. This report includes mammalian cardiac muscle on the list of those muscles containing this SR membrane structure.
Immunocytochemical localization of a gastric inhibitory polypeptide‐like material within A‐cells of the endocrine pancreas
Authors: Smith Phillip H. , Merchant Frederick W. , Johnson David G. , Fujimoto Wilfred Y. , Williams Robert H.
Published: February 2005

In rat pancreatic islets, the glucagon‐producing A‐cells also contain a GIP‐like material as revealed by the peroxidaseantiperoxidase immunocytochemical technique. Control studies showed that this dual staining was not due to the cross‐reactivity of anti‐GIP with glucagon. It is concluded either that the A‐cells synthesize a GIP‐like peptide or that it is taken up from the circulation.
Glial cells in the earthworm ventral nerve cord make an A‐type nexus
Authors: Kensler Robert W. , Brink Peter , Dewey Maynard M.
Published: February 2005

Nexuses have been demonstrated between glial cell processes in the earthworm ventral nerve cord. The nexuses have been demonstrated by freeze‐cleavage to be A‐type nexuses, thus demonstrating for the first time the type of nexus present in the Annelida. If the nexal cleavage pattern has physiological significance then the results suggest that physiologically the nexuses of the earthworm may be similar to those of vertebrates.
The perineural sheath in the urodele amphibian
Authors: Krishnan N. , Singer Jon F. , Singer Marcus
Published: February 2005

The perineural epithelial cells of the peripheral nerve sheath in Triturus are elongated flat cells with long and thin cytoplasmic processes. Structural characteristics of the processes include a relative absence of common cytoplasmic organelles of the periniuclear cytoplasm but an abundance of vesicular profiles similar to fully formed pinocytotic vesicles. Unlike pinocytotic vesicles, vesicles of the processes often contain an 8‐nm thick filament attached to their cytoplasmic face. Vesicles are also interconnected by similar filaments or by tubules. In addition, almost all vesicles appear to have openings at the cell surface, a feature not seen for pinocytotic vesicles. The concentration of exogenous peroxidase in the vesicles, and the subsequent appearance of peroxidase in the endoneural fluid, myelin sheath and axon, support the notion that the vesicles function in the exchange of substances between extraneural and endoneural fluids.
The effect of vinblastine‐induced microtubule loss on kidney podocyte morphology
Authors: Andrews Peter M.
Published: February 2005

The effect of intravenous injections of vinblastine sulfate on the renal glomerular epithelium was studied by scanning and transmission electron microscopy. Two hours after treatment with vinblastine, microtubules were almost completely lost from the podocyte cell bodies and major processes, and crystalline inclusions of a tubular nature had appeared within the cytoplasm. Coincident with this loss of microtubules, podocyte major processes at first collapsed and then became significantly thinner as they appeared to lose much of their cytoplasm to the nucleated cell body. These observations suggest that microtubules serve to maintain the shape and integrity of podocyte major processes. At no time after vinblastine treatment did we note any alteration in podocyte pedicel morphology.
Ultrastructure of the aging myocardium: A morphometric approach
Authors: Sachs Howard G. , Colgan James A. , Lazarus Marlene L.
Published: February 2005

Left ventricular tissue from adult and aging Syrian hamster heart was compared at the ultrastructural level, using both qualitative and morphometric electron microscopy. The aging myocardium often showed indented nuclei, lipid droplets and aggregations of dense bodies. The volume fractions of muscle cells occupied by mitochondria, lipid and lysosomes (including both primary lysosomes and residual bodies) was significantly greater in the old animals, while there was no significant difference in nuclear volume fraction or myofibrillar mass. Sarcoplasmic reticular volume and membrane surface area fell during aging. The area of mitochondrial inner membrane plus cristae per mitochondrial volume also fell. When sarcoplasmic reticular and mitochondrial area were expressed per myofibrillar volume fraction, the sarcoplasmic reticular ratio fell, while the mitochondrial parameter remained constant. Discoordinate aging of cellular components in the mammalian myocardium is proposed.
A study by scanning electron microscopy of the bladder epithelium of the guinea pig
Authors: Wong Y. C. , Martin B. F.
Published: February 2005

Under scanning electron microscopy (SEM) the surface cells of the guinea pig bladder have pentagonal or hexagonal outlines. Their borders are clearly defined since they are elevated. They possess a large reserve of surface membrane which is markedly folded and wrinkled when the bladder is empty. The folds disappear and the cells become flat during distension. The luminal surface is characterized by numerous reticular ridges which are a remarkably constant feature and persist even under acute artificial distension. A small proportion of the surface cells are small and have less than five sides. Since they show only sparse microvilli as a surface feature, they have a smooth appearance. These are believed to be young surface cells which have just emerged from the intermediate layer, and have not yet acquired the ridged pattern of mature cells.
Allometry and sexual dimorphism in the primate innominate bone
Authors: Mobb G. E. , Wood B. A.
Published: February 2005

Allometric growth in the innominate bone has been studied in eight primate taxa. A total of 266 skeletons were examined and the lengths of the ischial and pubic rami of the right innominate bone and the bicondylar length of the right femur were measured. These data were converted to natural logarithms and the allometric relationships were studied. The taxa could be divided into two groups on the basis of the allometric coefficients.

Slopes were similar in Homo, Colobus, Presbtis, and Ceropithecus; in these taxa mean ischial length was greater in male skeletons but pubic length showed either no significant increase in the larger males or mean pubic length was greater in the smaller female skeletons.

A second group of taxa, Gorilla, Pan, Papio and Cerecocebus all showed a similar pattern of allometric coefficints, a pattern which contrasted with those in Homo etc. Ischial and pubic length in the second group increased in the larger males but the rate of increase in ischial length always exceeded the rate of increase in pubic length. The net effect of these two different mechanisms is to produce sexual differences in the “ischium‐pubic” index, but in the first group of taxa, which show selective pubic growth in the female, sexual dimorphism in the index is greater. Concentration in earlier studies on the “ischium‐pubic” index to study sexual differences in innominate growth have masked these relative growth differences.