bluuebunny/crossref_metadata_2025 huggingface dataset:
Control of the secretory cell cycle in cat oviduct by estradiol and progesterone
Authors: Bareither Mary L. , Verhage Harold G.
Published: February 2005

The control of the secretory cell cycle by estradiol and progesterone in the oviduct of the cat was studied using light and electron microscopy. The epithelium in ovariectomized animals was cuboidal with no evidence of secretory activity. Estradiol treatment induced hypertrophy, hyperplasia, and the differentiation of both secretory and ciliated cells. Differentiation of the secretory cell included the development of an extensive area of basal rough endoplasmic reticulum and a large supranuclear Golgi region. Apical secretory granules were already present after 3 days of estradiol treatment, and after 4 to 5 days maximum hypertrophy and differentiation had occurred. Most cells contained several apical electron‐dense granules; however, no large accumulation of granules in any one cell was ever observed. Occasional release of secretory product by exocytosis occurred during chronic treatment with estradiol. Rapid elevation of the serum levels of estradiol or progesterone by means of IV injection did not enhance exocytosis or result in any ultrastructural alterations. The chronic administration of progesterone to estradiol‐primed animals resulted in rapid cell atrophy, dedifferentiation, and death (apoptosis) within the epithelium of the oviduct. Secretory granules were no longer observed after 2 days of estradiol and progesterone treatment, and after 7 days the epithelium was approximately the same height as that measured in ovariectomized animals. These data illustrate that estradiol induces the differentiation and maintains the mature state of the secretory cell within the oviductal epithelium of the cat, and that progesterone has an immediate antiestrogenic effect on these cells. This study also suggests that the secretory product is released gradually, as the granules form and mature during chronic estradiol administration.
Circadian organization of thirteen liver and six brain enzymes of the mouse
Authors: North Chester , Feuers R. J. , Scheving L. E. , Pauly J. E. , Tsai T. H. , Casciano D. A.
Published: February 2005

The activities of 13 liver and 6 brain enzymes were studied in 7–12 week old CD2F1 male mice that had been fed ad libitum and standardized either to 12 hours of light (0600–1800) alternating with 12 hours of darkness (1800–0600) (LD 12:12), or to a reversed light‐dark cycle (darkness 0600–1800; light 1800–0600) (DL 12:12). Three separate studies were performed on two different days; in each experiment, subgroups of 14 animals were sacrificed at 3‐hour intervals. Livers were assayed for: isocitrate dehydrogenase, glutamate dehydrogenase, lactate dehydrogenase, alcohol dehydrogenase, glutathione reductase, glyoxylate reductase, L‐alanine aminotransferase, glutamate oxalacetate transaminase, pyruvate decarboxylase, fructose‐1‐phosphate aldolase, fructose diphosphate aldolase, fructose 1,6‐diphosphatase, and fatty acid synthetase. Brains were assayed for phosphoglucose isomerase, adenosine triphosphatase, creatine phosphokinase, pyruvate kinase, adenylate kinase, and malate dehydrogenase.

All 19 enzymes demonstrated a prominent circadian rhythm in at least one experiment. Moreover, each rhythmic variable showed a statistically significant fit to a 24‐hour cosine(sine) curve by the method of least squares. In general, peak activities of the liver enzymes analyzed were associated with the beginning of the dark cycle and initiation of the animal's activity, while the group of brain enzymes had peak activities which occurred at the beginning of the animals' rest span and were near the beginning of the light cycle. The phasing of each of the rhythms could be reversed within a two‐week span after reversing the environmental light‐dark cycle 180°.
Further observations on the Sertoli cell junctions of the mouse testis after metal contact freeze‐fracture, and comparisons with cellular junctions of other epithelial cells
Authors: Nagano Toshio , Toyama Yoshiro , Suzuki Fumie
Published: February 2005

Using a metal contact freezing method, the junctional complexes of Sertoli cells and other epithelial cells (intestine, liver, and epididymis) in the mouse were studied by freeze‐fracture in unfixed and in aldehyde‐fixed specimens. The tight junctions of the Sertoli cells without fixation consist of discrete rows of particles located preferentially on the E face. Continuous furrows with or without tight‐junctional particles are found on both fractured faces. The majority of the tight‐junctional particles of the Sertoli cells are situated at one side of the furrow rather than in the center. The “aisle” configuration of the gap junction is seen in developing Sertoli cells prepared without fixation. Tight junctions of epithelial cells other than Sertoli cells consist of discrete rows of particles on the E face and furrows on the P face when prepared without fixation. The tight and gap junctions of the Sertoli cells are not affected by fixation, but the tight junctions of other types of epithelial cells are affected as previously suggested. A distribution pattern of the gap‐junctional particles of the Sertoli cells and of other cells shows a pleomorphism. Changes in gap junctions produced by fixation could not be detected clearly. Characteristics of the Sertoli‐cell junctions are discussed. Desmosomes between the intestinal epithelial cells without fixation are presented.
Distribution of fiber types in locomotory muscles of dogs
Authors: Armstrong R. B. , Saubert C. W. , Seeherman H. J. , Taylor C. R.
Published: February 2005

The distribution of Type I and Type II fibers, as determined from histochemical estimation of myofibrillar ATPase activity, was studied within and among the locomotory muscles of the forelimb, trunk, and hindlimb of three mongrel dogs. All Type II fibers had high oxidative capacities as estimated from the histochemical assay for reduced nicotinamide adenine dinucleotide tetrazolium reductase, so they were not further divided into subpopulations. Furthermore, Type I and Type II fibers had similar oxidative potentials as indicated by both histochemistry and biochemistry.

Type I fiber populations ranged between 14% and 100% in the muscles sampled. The highest percentages of Type I fibers were found in deep muscles of physiological extensor groups in the arm and thigh that serve to resist gravity (antigravity muscles) when the dog is in the quadrupedal standing position. More superficial muscles in these same groups had fewer Type I fibers. The patterns of Type I fiber distribution among muscles in the antigravity groups of the forearm and leg were the opposite of those in the arm and thigh, with the more superficial muscles of the distal limb segments having more Type I fibers than the deeper muscles. In all limb segments, muscle groups that do not serve to resist gravity did not show as much intermuscular variation. Type I fiber populations in these muscles did not exceed 50%. A stratification of fiber types also existed within muscles, both in extensor and flexor groups, with the deeper portions of the muscles having more Type I fibers than the more superficial portions.
Advanced pulmonary development in newborn guinea pigs (Cavia porcellus)
Authors: Lechner Andrew J. , Banchero Natalio
Published: February 2005

Morphological and morphometric evidence is presented to support the hypothesis that lung growth is advanced in mammals born at a relatively mature stage. The lungs from fetal and postnatal guinea pigs ranging in age from gestational age 56 days (normal gestation is 68 days in this species) through 16 days postpartum were fixed in situ by intratracheal glutaraldehyde. Morphometry included measurements of lung volume (VL), tissue and air‐space volumes, fraction of respiratory parenchyma, alveolar (SA) and capillary (SC) surface areas, and the arithmetic mean thickness of the tissue barrier (\documentclass{article}\pagestyle{empty}\begin{document}$ \bar \tau _t $\end{document}). VL, SA, and SC all increased monoexponentially versus body weight (W) from birth to adulthood; the lungs appeared to be in the equilibrated growth phase, with no postnatal period of pronounced tissue proliferation as reported in the newborn rat and mouse. The prepartum value for \documentclass{article}\pagestyle{empty}\begin{document}$ \bar \tau _t $\end{document} was 1.96 μm; this value decreased by parturition to 1.27 μm and did not change significantly with additional age.

At the light‐microscopic level, respiratory bronchioles could be visualized giving rise to alveolar ducts by a gestational age of 58 days (10 days preterm) with welldeveloped alveolar septal partitioning evident. Structures resembling the primitive pre‐alveolar saccules of newborn rats were never seen in even the youngest fetal animals. Elastin fibers were also evident at this age, both in bronchiolar and duct walls, as well as in alveolar septa. Using electron microscopy, the airblood barrier appeared mature by a gestational age of 61 days and thereafter, double capillary layers were only rarely seen in septal walls.
Effects of guanethidine‐induced sympathectomy on morphology of the pre‐ and postclosure lleum of the neonatal rat
Authors: McKenzie James C. , Klein Robert M.
Published: February 2005

The disappearance of the characteristic supranuclear vacuole and extensive apical canalicular system from enterocytes of the ileal villi occurs during the third postnatal week in rats. This phenomenon is associated with loss of permeability of these cells to macromolecules and is therefore termed closure. The present study was designed to analyze the influence of neonatal guanethidine (GTN)‐induced sympathectomy on the morphology of the pre‐ and postclosure ileum of the rat. Light and electron microscopy of control and GTN‐sympathectomized rats demonstrated the retention of immature, vacuolated cells on ileal villi as late as 23 days postnatally in GTN‐treated rats. Villi from control rats contained only adultlike nonpermeable cells. Electron microscopy further demonstrated no structural differences in the apical canalicular system or storage vacuoles of the delayed cells in GTN rats when compared to the ileal epithelium from preclosure time periods (7 and 15 days) in both GTN‐sympathectomized and control rats. Goblet cells were counted on Periodic‐Acid‐Schiff‐stained sections of ileum from 7, 15, and 23‐day GTN and control rats. The percentage of goblet cells in the total epithelial cell population of the villus was significantly higher in control versus GTN rats at all time periods. The percentage of goblet cells increased in both groups from day 7 to 15. However, closure in the control group (approximately day 18) was coincident with a steep increase in the percentage of ileal goblet cells which was not evident in the goblet‐cell population of the GTN villus. This pattern of change in control versus GTN goblet‐cell production was correlated with a similar pattern of variation in the number of crypt cell mitoses between the two groups over the same time period.
Primary epithelial cell cultures derived from canine prostate: Isolation, culture, and characterization
Authors: Terracio Louis , Douglas William H. J. , Pennachio Dominic , Vena Richard L. , Ofner Peter
Published: February 2005

Epithelial‐cell‐enriched primary cultures were established from canine prostate. Minced tissue was dissociated with 750 units/ml of collagenase in F12K tissue culture medium containing 1% fetal bovine serum. This treatment resulted in the gradual removal of stromal elements from the base of the epithelial cells. After 30 minutes of digestion, aggregates of epithelial cells free of stroma were dislodged from the minced pieces of prostate. These aggregates were washed and plated at high density in F12K plus 10% fetal bovine serum. After 12–16 hours in vitro the unattached cellular aggregates were removed from the culture dishes, washed, and reinoculated into new culture vessels containing fresh medium. After 48 hours in vitro, the aggregates had attached to the culture vessels and spread out to yield discrete patches of epithelial cells. By 120 hours in vitro the patches of cells had grown and coalesced to form a confluent monolayer of epithelial cells. Ultrastructural examination of these cultures indicated that adjacent cells were joined by desmosomes and tight junctions and had tonofilaments and microvilli, giving the cells an epithelial appearance. The cells contained rough endoplasmic reticulum, Golgi apparatus, and secretory granules similar to those of the epithelial cells in the intact organ. In addition, intracellular “blebs” containing acid phosphatase were observed in the monolayers and were found to increase in size and number with time in vitro. Differentiated function of the cultures was demonstrated by the presence of ornithine decarboxylase and acid phosphatase and the ability of the cultures to metabolize testosterone to primarily 5α‐reduced metabolites.
Permeability of the neonatal rat choriocapillaris to hemeproteins and ferritin
Authors: Pino Richard M. , Essner Edward , Pino Linda C.
Published: February 2005

The permeability of the endothelium of the capillaries of the rat choriocapillaris to circulating macromolecules was examined during the first postnatal week of development using hemeproteins of different molecular dimensions and ferritin. At this stage of development capillaries and photoreceptor cells in the neural retina are not fully formed, but the choriocapillaris has an adult‐like morphology. Thus, through these differences in neural and vascular architectures the possible functional relationships between the retina and choriocapillaris can be explored. High levels of horseradish peroxidase [Einstein‐Stokes radius (ESR) 3 nm] activity were localized in Bruch's membrane within 2 minutes after intravenous tracer injection. In contrast, scant levels of hemoglobin (ESR, 3.2 nm) and no catalase (ESR, 5.2 nm) activity were observed here at 75 and 90 minutes, respectively. Only a few ferritin particles (ESR, 6.1 nm) crossed the choriocapillary endothelium after a 90‐minute circulation. The results demonstrate that in the neonatal rat the choriocapillaris has the same restrictive properties as have been described for the adult eye (Pino and Essner, 1980, 1981), even in the absence of retinal capillaries and functional photoreceptor cells.
Testosterone action on the ventral prostate lobe of the castrated rat as assessed with a stereologic morphometric method
Authors: Huttunen Eero , Romppanen Timo , Helminen Heikki J.
Published: February 2005

The effects of testosterone (1 mg testosterone propionate/100 g body weight for 30 days) on the ventral prostates of rats castrated 30 days prior to the onset of hormone treatment was investigated with a stereologic morphometric method. Testosterone induced rapid growth of the prostate, which was reflected by a 29‐fold increase in acinar parenchyma but only a 2.6‐fold increase in interacinar tissue. There was a 23‐fold increase in the total amount of glandular epithelium and a 36‐fold increase in total luminal amount. Various volumetric fractions, total surface area, total tubule length, height of the epithelium, mean diameter of the tubules, and mean distance between the tubules and between the glandular centers were calculated. Growth of the acinar parenchyma, especially of the glandular lumen, was the dominant pattern. We could not demonstrate any remarkable responses in the interacinar tissue during any phase of testosterone treatment.
Monoamines in the early chick embryo: Demonstration of serotonin synthesis and the regional distribution of serotonin‐concentrating cells during morphogenesis
Authors: Wallace James A.
Published: February 2005

Monoamine compounds, such as serotonin (5‐HT), have been previously suggested to regulate the early development of the chick embryo. Possible roles for 5‐HT in chick morphogenesis were investigated further by examining the distribution of sites that concentrate 5‐HT as well as the ability of embryos to synthesize 5‐HT during this period. Following the in vitro incubation of chick embryos with 5‐HT, cells accumulating 5‐HT were localized by the formaldehyde‐induced fluorescence (FIF) technique; these sites of 5‐HT concentration were mapped and studied with respect to changes in their developmental patterns during morphogenesis. Locations of 5‐HT FIF included two regions of the brain within the floor plate of the mesencephalon and caudal myelencephalon, and within scleratome cells of somites advanced in differentiation. Additionally, two separate zones of 5‐HT FIF appeared in the neural tube caudal to the somites in conjunction with a small band of intense FIF in the caudal end of the notochord. Once established, the capabilities for 5‐HT concentration in the brain and somites persisted at the same locations during development, whereas these capabilities in caudal portions of the embryo were transient and appeared to move down the embryo as the embryo lengthened. These changes in the patterns of 5‐HT FIF in caudal segments of the neural tube and notochord correlated spatio‐temporally with the progression of caudal neuropore closure. Additional experiments, involving the use of anti‐5‐HT immunocytochemistry, were undertaken to examine the characteristics of 5‐HT concentration. The mechanism(s) of 5‐HT concentration at all locations appeared to have a high affinity and specificity for 5‐HT; however, in contrast to the transient mechanism situated more caudally in the embryos, the uptake mechanism at rostral locations required energy and was blocked by a 5‐HT uptake inhibitor (fluoxetine). The ability of embryos to synthesize 5‐HT was demonstrated by the generation of 5‐HT (localized by FIF and immunocytochemistry) in embryos treated with the 5‐HT precursors, 5‐hydroxytryptophan or L‐tryptophan. Confirming evidence of 5‐HT synthesis was provided by a marked reduction in immunostaining obtained with either precursor in the presence of 5‐HT synthesis inhibitors (R04–4602 or para‐chlorophenylalanine). Although the sites of synthesis remain uncertain, endogenous 5‐HT was detected (after monoamine oxidase inhibition) at all sites of 5‐HT concentration. These results provide further support for the suggestion that 5‐HT may be involved in various aspects of morphogenesis at specific sites within the chick embryo.
The effect of zinc deficiency on the ultrastructure of rat adrenal cortex
Authors: Dupree Alphonse E. Leure , Rothman Richard J. , Fosmire Gary J.
Published: February 2005

The adrenal cortex of male Sprague‐Dawley weanling rats maintained on a zinc‐deficient diet was studied by electron microscopy. There was a gradual increase in lipid droplets in the zona fasciculata which was quite marked at 7 weeks, but increased lipid was not observed in the zona glomerulosa or reticularis of zinc‐deficient rats. The adrenal cortex of the control animals did not show altered lipid content. A possible explanation for the effect of zinc deficiency on the adrenal cortex is offered.
Ultrastructural changes associated with the mineralization of deer antler cartilage
Authors: Newbrey J. W. , Banks W. J.
Published: February 2005

The maturation and mineralization of deer antler cartilage were investigated ultrastructurally by using enzymatic digestions and subsequent staining with ruthenium red (RR) or phosphotungstic acid (PTA).

RR staining of matrix granules was observed in the immature prechondroblastic matrix and became more intense as the cartilage matured into a mineralized tissue. The granules got larger and more numerically dense in the mature matrix. There were matrix granules that coalesced around matrix vesicles or remnants of such in the mineralized zone. These granules were observed after demineralization, and they were RR and acidic PTA‐positive (they were not susceptible to hyaluronidase nor trypsin digestion, however). It appears that the granules were modified such that the matrix vesicle formed a centralized nidus for mineralization. The growth of hydroxyapatite crystals along matrix granules (which in this zone may or may not represent proteoglycan monomers) may have caused the coalescence.

Microfibrils associated with matrix granules probably represented the hyaluronic acid core of the large proteoglycan complexes because of their susceptibility to hyaluronidase digestion.
Structure and growth activities of the mandibular condyle in monkeys (Macaca fascicularis): I. Intracondylar variations
Authors: Luder H. U.
Published: February 2005

Eight condyles of four growing monkeys (Macaca fascicularis) of estimated ages between 1.6 and 3.6 years (minimum and maximum) were analyzed using radioautographic, histometric, and stereologic techniques. The aim of the study was to examine the relationship between intracondylar variations in structure and growth activities. The animals received 3H‐proline (1 mCi/kg body weight) and 3H‐thymidine (0.5 mCi/kg body weight) 24 and 3 hours, respectively, prior to sacrifice. The perichondral and chondral layers of the condylar articular covering as well as the subchondral zone of erosion were examined at different sampling sites distributed systematically in the anteroposterior and lateromedial dimension of the articulating surface. Intracondylar variations observed with respect to morphometric and radioautographic parameters suggest the following biologic mechanisms contributing to mandibular growth in a superior‐posterior direction. Greater mitotic activity at the central and posterior sites of the condylar perichondrium generates a population of progenitor cells that is larger in these than in other regions. On the other hand, the rate of differentiation of these progenitor cells into chondroblasts and chondrocytes, i.e., the “migration” into and through the chondral layers of the articulating covering, seems to be enhanced in the same superior and posterior areas. Additionally, while “migrating” faster, these cartilage cells become larger and produce greater amounts of extracellular matrix than those in the anterior parts of the condyle. Finally, enhanced resorptive activities in the superior and posterior regions of the subchondral zone of erosion provide an increased “loss” of degenerated chondrocytes, thereby establishing the basis for a cartilaginous drift in the superior‐posterior direction.
Follicular growth and intraovarian and extraovarian oocyte release after daily injections of melatonin and 6‐chloromelatonin in the Syrian hamster
Authors: Spanel‐Borowski Katharina , Richardson Bruce A. , King Thomas S. , Petterborg Larry J. , Reiter Russel J.
Published: February 2005

Groups of adult female Syrian hamsters (Mesocricetus auratus) were injected daily at 17:00 hr with 2.5, 15, or 25 μg of melatonin (Mel) or 6‐chloro‐melatonin (Cl‐Mel) for 12 weeks. An ovary from each animal was completely serially sectioned for light microscopic investigation. Judging from the presence of corpora lutea, there were some animals in each group that continued to cycle, although the postestrous, white mucous discharge had disappeared. Noncycling animals were most often found in the 25‐μg group of Cl‐Mel. Only uterine weights of noncycling animals treated with either 25 or 15 μg of Mel or Cl‐Mel were statistically significantly depressed versus controls. Cl‐Mel (25 μg) significantly suppressed the total number and size of antral follicles (P> 0.05). Follicular ruptures with incomplete or complete release of the oocyte out of the follicular compartment were observed. The oocyte release occurred either into the ovary (“intraovarian oocyte release: IOR”) or outside of the ovary (“extraovarian oocyte release: EOR”). Compared with controls, the total number of IOR was increased in all experimental groups with the exception of the 2.5‐μg group of Cl‐Mel. IOR appeared in both preantral and antral follicles, and often IOR was complete. In controls, only preantral follicles were involved in IOR; these were primarily incomplete ones. IOR was seen in cycling and noncycling animals. By contrast, EOR was exclusively observed in noncycling hamsters. It is concluded that the cessation of postestrous, white mucous discharge is not necessarily an index for a halt in cyclic ovarian function. Injections of 25 μg of Cl‐Mel are more effective than 25 μg of Mel in suppressing ovarian function. Both Mel and Cl‐Mel increase the frequency of IOR. Finally, noncycling hamsters show EOR that is regarded as an abnormal ovulation.
[3H]thymidine uptake in cells of rat condylar cartilage
Authors: Heeley J. D. , Dobeck J. M. , Derice R. A.
Published: February 2005

Weanling rats were injected intraperitoneally with [3H]thymidine and sacrificed from 5 min to 20 days later. Their mandibular condylar cartilages were examined histologically, by thin‐layer autoradiography, and by using liquid scintillation and microscopic counting methods.

Labeled DNA appeared in some of the chondrocytes of the resting zone as early as 10 min postinjection, and reached the proliferative zone by 24 hr and the hypertrophic zone by 4 days. The labeling pattern in the last zone was more disperse, being oriented toward the periphery of the cells as they became hypertrophic.

The maximum number of labeled chondrocytes was reached by 2 hr postinjection. These amounted to approximately 11% of the total chondrocyte population, the majority of which were located in the resting zone (73%). It is concluded that, over this period, the mitotic index for these cells is 50–60 per thousand resulting in approximately 100 labeled chondrocytes.

In addition, some of the chondroclasts at the erosion front contained labeled DNA as early as 5 min after [3H]thymidine administration. By 10 min, 65% of these cells exhibited one or more labeled nuclei, and the ratio of labeled cells remained high through 20 days. Chondroclasts were seen to contain a diffuse label within their cytoplasm after 5 days. This label was similar to that seen in hypertrophic chondrocytes that had reached the erosion front by that time.

Clearly, chondroclasts exhibit nuclear division and do not form from fusion of hypertrophic chondrocytes, although which specific mononuclear cells may act as chondroclast progenitors is not clear. In addition, these multinucleate resorbing cells are capable of ingesting or phagocytizing nuclear remnants from hypertrophic chondrocytes at the eroding face of cartilage.
Three‐dimensional characteristics of the endoplasmic reticulum in the columnar cells of the rat small interstine: An electron microscopy study in thick sections
Authors: Thiéry G. , Gaffiero P. , Bergeron M.
Published: February 2005

The endoplasmic reticulum (ER) of the columnar cells of the rat jejunum was studied with a specific block‐staining technique and standard transmission electron microscopy. A new three‐dimensional model, based on the analysis of stereo pair photographs, is proposed; this model suggests that the endoplasmic reticulum may constitute a transcellular route.

Thick sections (0.5–1 μm) of columnar cells were made after a 5‐day impregnation with osmium tetroxide and were examined by standard transmission electron microscopy at 80–100 kV. The evolution of the ER during the cellular ascent of cells from the crypt to the top of the villus is toward a greater complexity. At the base of the crypt of Lieberkühn, no definite organization is noted, and most often only the nuclear envelope and canalicular elements are stained. The endoplasmic reticulum of the mature columnar cells forms a continuous network of canaliculi and fenestrated saccules; it extends from the apex, below the microvilli, to the lateral and basal plasma membranes, and sends many projections to the nuclear envelope. In the basal part of the cell, below the nucleus, the ER consists mainly of tubular canaliculi, whereas mostly saccules, are observed in the supranuclear part. The canaliculi have a diameter, of 40–60 nm. Fenestrated saccules appear to form a continuous tubular structure surrounding mitochondria; the saccules have a thickness of 25–40 nm and possess irregular perforations of 35–60 nm. Finally, in some cells, the endoplasmic reticulum seems to show functional differences as reflected by the absence of reaction in cells adjacent to well‐stained cells in the same part of the villus; thus the osmium impregnation technique appears to be a valid tool for studying the ER organization.
Quantitative ultrastructural characteristics relating to transport between luteal cell cytoplasm and blood in the corpus luteum of the pregnant rat
Authors: Dharmarajan A. M. , Bruce N. W. , Meyer G. T.
Published: February 2005

The synthesis and secretion of progesterone by the corpus luteum (CL) may be limited or controlled by transport mechanisms operating between circulating blood and luteal cell cytoplasm. To examine this possibility, the structural features involved in transport, including membrane surface areas and diffusion distances, were quantitated in the CL of 16‐day pregnant rats. One ovary from each of eight rats was fixed by perfusion via a cannula inserted into the parametrial artery, and two CL from each ovary were processed for electron microscopy and examined with standard morphometric techniques. For comparison, one CL from each of a further eight ovaries was diced into small cubes, fixed by immersion, and analyzed similarly. In perfusion‐fixed CL, there was a substantial volume of vascular space (20% of the total) and interstitial space (5%) and an extensive surface area of capillaries (441 mm2 per CL). The luteal‐cell membrane had numerous projections which increased its surface area by a factor of 3.08. Almost 60% of the luteal‐cell surface directly faced a capillary, and a further 37% faced interstitial space which probably extended to a capillary surface. Only 3% was in direct contact with a neighboring luteal cell. Despite the extensive interstitial space the harmonic mean thickness, an estimate of likely effective diffusion distance between luteal cell cytoplasm and blood, was only 0.42 μm. This was less than half of the calculated arithmetic mean thickness owing to the presence of surface projections and an uneven capillary endothelium. Results from immersion‐fixed CL were qualitatively similar; but the proportion of interstitial space was only 59% of that in perfusion‐fixed CL, and the contribution of surface projections to the total area of luteal‐cell membranes was significantly reduced. Collectively, these results suggest that membranes and spaces between blood and luteal‐cell cytoplasm are structured so as to minimize transport distances.
Characterstics of motor innervation of muscle spindles in the monkey
Authors: Kucera Jan
Published: February 2005

The motor nerve supplies of four whole muscle spindles and 16 half spindles (equator and one pole) from lumbrical muscles of the monkey were reconstructed by light microscopy of serial, 1‐μm‐thick transverse sections. The 24 poles of spindle were innervated by 37 fusimotor (γ) axons and 18 skeletofusimotor (β) axons. Sixty‐seven percent of spindle poles received γ axons only, 25% were supplied by both γ and β axons or β axons only, and 8% were not innervated by motor axons. All β axons except one and 35% of the γ axons innervated one type of intrafusal fiber only. The other 65% of γ axons coinnervated two or three different types of intrafusal fiber. Gamma axons innervated the (dynamic) bag1 intrafusal fiber together with the (static) bag2 and/or chain fibers in 65% of the poles of spindle in which the bag1 fiber received motor supply. The bag2 fiber shared γ‐innervation with either the bag1 or chain fibers in nearly every spindle pole. The chain fibers were usually coinnervated with the bag2 fiber by γ axons. Compared to spindles in the cat tenuissimus muscle, the monkey spindle received fewer γ axons and had a higher incidence of shared γ‐innervation between the dynamic and static intrafusal fibers. Unlike cat tenuissimus spindles, the monkey spindles lacked γ axons selective to the bag2 fiber. However, the β motor system within the monkey lumbrical muscle was organized in a manner similar to the cat tenuissimus muscle. The significance of these observations is discussed relative to the general motor organization and function of spindles in different muscles and species of mammals.
Perivascular cells in cartilage canals of the developing mouse epiphysis
Authors: Cole Ada A. , Wezeman Frederick H.
Published: February 2005

Morphological variability among perivascular cells adjacent to cartilage matrix during the elongation of canals through both uncalcified and calcified matrix has not been reported. Cartilage canals were located in distal femoral epiphyses of 5‐ to 7‐day‐old mice and identified as vascular channels arising from perichondrial surfaces along the condyles and intercondylar fossae. Three stages of canal development were identified based on the length of canals and on characteristics of chondrocytes and matrix surrounding the canals. Superficial canals terminated in uncalcified matrix of resting cartilage; intermediate canals terminated in matrix containing hypertrophic chondrocytes; deep canals terminated in calcified matrix. The ultrastructural morphology of perivascular cells in contact with the matrix varied in the three stages. Cells resembling fibroblasts and vacuolated macrophages were present adjacent to the uncalcified matrix in superficial canals. At the tips of intermediate canals, cells resembling fibroblasts were larger, contained numerous lysosomes and phagolysosomes, and were in intimate contact with the matrix. At the tips of deep canals, chondroclasts with ruffled borders and clear zones contacted the calcified matrix. The results indicate that (1) mouse epiphyses provide a suitable model for studying cartilage‐canal perivascular cells, (2) calcification of cartilage matrix occurs along the course of the canal, and (3) the morphology of perivascular cells in contact with the matrix may be determined, in part, by matrix calcification.
Fluctuations in follicular structures of rat thyroid glands during 24 hours: Fine structural and morphometric studies
Authors: Uchiyama Yasuo , Oomiya Akemi , Murakami Gen
Published: February 2005

The thyroid follicles of adult male Wistar rats were examined at six evenly spaced times over 24 hr with a morphometric technique. Follicular structures were subjected to distinct variations during 24 hr, with respect to volume and numerical densities of follicles in the thyroid gland, and diameters, volumes, cell numbers, and luminal surface areas of individual follicles. Variations in follicular structures were divided into two phases: a large follicular phase at 1200, 1600, and 2000 hr and a small follicular phase at the other times. Although volume densities of follicles in the gland varied with a small amplitude, diameters, volumes, and cell numbers of individual follicles exhibited distinct fluctuations during 24 hr. Numerical densities of follicles in the gland changed distinctly during the small follicular phase as well. Degenerating follicular cells appeared in the follicular lumen especially at 1600 hr. No mitotic follicular cells were found throughout the experiment. Furthermore, one to three follicular cells of two adjacent follicles were often in contact with each other at 0400, 0800, and 1200 hr, and these follicles were lined by the common basement membranes. These results suggest that the variations in follicular structures during the small follicular phase occur in the form of follicle separation and fusion. Moreover, the morphological and morphometric variations in follicles reflect those in subcellular structures of follicular cells previously reported by us.
Capillary permeability in the pancreas and colon: Restriction of exogenous and endogenous molecules by fenestrated endothelia
Authors: Hart Timothy K. , Pino Richard M.
Published: February 2005

The permeability properties of fenestrated capillaries in the colon and exocrine and endocrine pancreas to exogenous and endogenous molecules were examined. The exogenous tracers horseradish peroxidase (Einstein‐Stokes radius [ESR], 3.0 nm), hemoglobin (ESR, 3.2 nm), and ferritin (ESR, 6.1 nm) were injected intravenously and allowed to circulate for 5–90 min. Tissues were removed and processed for cytochemical or standard electron microscopic examination. The endogenous plasma proteins albumin (ESR, 3.5 nm) and IgG (ESR, 5.5 nm) were localized by immunocytochemistry using the protein A‐gold technique. All vessels examined were permeable to HRP in less than 5 min. In contrast, these vessels were restrictive to the slightly larger hemoglobin molecule (60‐min circulation) and to ferritin (90‐min circulation). Capillaries in the exocrine and endrocrine pancreas were restrictive to albumin and IgG. These results demonstrate the presence of fenestrated capillary beds, in addition to the choriocapillaris, that are restrictive to molecules with ESR ≥ 3.2 nm. Capillaries in the mucosa of the colon were restrictive to hemoglobin and ferritin but did not restrict albumin or IgG. This indicates that these vessels are of the permeable type. However, the rate of transendothelial movement of molecules is slower than that of other permeable vessels, such as in the ileo‐jejunum. This study has provided further evidence for the existence of fenestrated endothelia that are restrictive to exogenous and/or endogenous molecules.
Differentiation of tracheal epithelium during fetal lung maturation in the rhesus monkey Macaca mulatta
Authors: Plopper Charles G. , Alley Janice L. , Weir Alison J.
Published: February 2005

Of the eight categories of epithelial cells identified in pulmonary conducting airways, four are found in the trachea of adult primates: basal, mucous goblet, intermediate, and ciliated cells. While their ultrastructure is well characterized, little is understood about their origin or differentiation. This study describes the pattern of differentiation of the tracheal luminal epithelium in a species of nonhuman primate, the rhesus monkey, Macaca mulatta. Tracheas of 57 fetal and postnatal rhesus were fixed with glutaraldehyde/paraformaldehyde: ten at 29–54 days gestational age (GA), ten at 59–80 days GA (pseudoglandular stage), sixteen at 82–130 days GA (canalicular stage), ten at 141–168 days GA (saccular stage), eight at 1–134 days postnatal, and three adults (2 yr 11 months to 11 yr 11 months). Slices taken proximal to the carina were processed for electron microscopy by a selective embedding procedure. In the youngest fetuses, essentially one population of cells lined the tracheal epithelial surface. These cells were columnar in shape with a central nucleus, few organelles, and large amounts of cytoplasmic glycogen. At 46 days GA, ciliated cells were observed on the membranous side of the trachea. Some nonciliated cells had concentrations of organelles in the most apical portion of their cytoplasm. At 59 days GA, membrane‐bound cored granules were intermixed with organelles in the apices of some glycogen‐filled cells. They were observed first on the cartilaginous side. Between 59 and 100 days GA, a large number of cell forms which appeared to be transitional between ciliated, secretory, basal, and undifferentiated cells were present. These included ciliated cells with electron‐lucent inclusions resembling mucous granules. Mucous secretory cells were more numerous and had more granules and less glycogen in older fetuses. By 105 days GA, few of the secretory cells had significant amounts of glycogen and the cytoplasm was condensed. Secretory granules were very abundant in some cells and minimal in others. The Golgi apparatus was prominent. In animals 120 days GA and older, small mucous granule cells and basal cells resembling these cells in adults were present. By 134 days postnatal age, the epithelium resembled that in adults. We conclude that (1) most of the differentiation of tracheal epithelium in the rhesus monkey occurs prior to birth; (2) the cells differentiate in the following sequences: ciliated, mucous goblet, small mucous granule, basal; and (3) basal and small mucous granule cells do not play a role in ciliated and mucous cell formation in the fetus.
Architecture of the masticatory apparatus in eastern raccoons (Procyon lotor lotor)
Authors: Gorniak Gerard C.
Published: February 2005

The structure and function of the masticatory apparatus of raccoons resemble those found in carnivores. In this study, the architecture of the skull, dentition, and masticatory apparatus is described, and a model is proposed that suggests a mechanism used by raccoons to reduce different foods. The model suggests that (1) jaw movements are similar to those of cats, (2) the posterior regions of the superficial and deep parts of the temporalis and the anterior region of the medial pterygoid generate horizontal jaw movements, and (3) the anterior portions of the superficial and deep temporalis as well as portions of the masseteric complex generate vertical closing movement. The distributions of slow, fast fatigable, and fast fatigue‐resistant fibers for the temporalis and masseteric complex are related to the possible actions of these muscles during mastication, as are the regional cross‐sectional areas of the masticatory muscles.
Immunochemical and cytochemical studies of relaxin‐containing cells in the guinea pig uterus
Authors: Larkin Lynn H. , Renegar Randall H.
Published: February 2005

Uteri and ovaries from cycling, pregnant, and lactating guinea pigs were studied for immunolocalization of relaxin with the light microscope. Endometrial gland cells (EGC) from the same group of animals were examined in the electron microscope for the presence of secretory granules. Those EGC that exhibited high numbers of granules were stained either for relaxin with the protein A colloidal gold method or for carbohydrate with the thiocarbohydrazide technique. Relaxin was found in EGC from middle and late pregnant animals but was not detected in ovaries or uteri from cycling animals. While cytoplasmic granules were noted in most EGC from cycling animals examined, the number of granules was greatest in uteri from estrus and proestrus animals. Granules in EGC from estrus animals contained a carbohydrate‐rich material but did not contain relaxin. Endometrial gland cells from animals in early to middle stages of pregnancy (days 15 and 30) contained limited numbers of granules, almost all of which contained carbohydrate. At day 45 of pregnancy, EGC containing many granules were noted. The majority of granules contained relaxin; however, a significant number of EGC contained carbohydrate‐rich granules. Infrequently, EGC were noted that contained two populations of granules, and these two populations were assumed to be made up of relaxin‐containing and carbohydrate‐rich granules. EGC from animals on day 60 of pregnancy typically contained granules, and the majority of these contained relaxin. Carbohydrate‐rich granules were observed in EGC of the day 60 animals but were smaller in diameter and were noted in much lower numbers than the relaxin‐containing granules. Endometrial gland cells from lactating animals infrequently contained granules. These studies are consistent with the hypothesis that the uterus is the primary source of relaxin in the guinea pig and that relaxin plays an important role in pregnancy and parturition of this species. The observations implicate endometrial glands and their products in the physiology of the cycling animal as well as the pregnant and parturient animal.
Early development of the hypoglossal nerve in the chick embryo as observed by the whole‐mount nerve staining method
Authors: Kuratani Shigeru , Tanaka Shigenori , Ishikawa Yuji , Zukeran Chosei
Published: February 2005

The developmental morphology of the hypoglossal nerve and associated structures were studied in the chick embryo (Hamburger and Hamilton stages 16‐27) stained by the immunohistochemical technique. Ventral rootlets of the occipital nerves, including 01, were seen at stage 16. The distal ends of these nerves anastomosed to form the hypoglossal nerve at stage 20. At stage 23, four occipital and the first three cervical nerves were observed to be involved. The transient contribution of C3 at this stage seemed to be correlated with the formation of the longitudinal anastomosis of the distal end of the spinal nerves which begins around stage 23. The anterior hypoglossal roots appeared between 01 and the abducens nerve at stage 20. These rootlets were observed to arise as the rostral continuation of the occipital sequence and were found to be arranged in a straight line from 01 to the abducens nerve. The recurrent branch of the abducens was also observed. The posterior end of the ganglion crest produced dorsal root ganglion (DRG)‐like structures transiently at the level of C2, and sometimes at the level of C1 also. The ganglion crest developed descending processes in the occipital region seemingly related to the spinal dorsal root formation. These phenomena seemed to represent the potential of the ganglion crest to produce the spinal nerve components which are depressed in the occipital region.
Epicardial formation in embryonic chick heart: Computer‐aided reconstruction, scanning, and transmission electron microscopic studies
Authors: Hiruma Tamiko , Hirakow Reiji
Published: February 2005

Epicardial formation in the embryonic chick heart from initial to final stages was revealed by means of computer‐aided reconstructions based on serial resin sections for light microscopy, with further detailed observations using scanning and transmission electron microscopy. The origin of the epicardium was recognized as protrusions of mesothelial cell clusters on the right side of the external surface of the sinus venosus at 23 somites (stage 14+). These protrusions elongated to give rise to several villous processes, the tips of which eventually touched the dorsal wall of the embryonic heart at 30 somites (stage 17). Originating from these adhesion sites, mesothelial cells spread gradually onto myocardial cells in all directions to form a monolayered sheetlike cover. Thus, by stage 23, the ventricle was completely overlaid with epicardium, and blood‐island‐like structures appeared within the subepicardial layer. The atrium was not enveloped by epicardium until stage 25, and the extreme distal end of the bulbus cordis was reached by the advancing epicardium at stage 27. A chronological table of epicardial formation in the chick heart is presented.
Palmar‐digital arterial networks in fifty pairs of human fetal hands: Arteriographic models for clinical consideration
Authors: Maher William P.
Published: February 2005

Arterial networks in 50 pairs of human fetal hands, made visible by perfusion with radiopaque media, were compared between right and left hands. The imaged primary arterial networks in the fetal hands were also compared with those in adult human and rhesus monkey hands. It was found that superficial arch configurations and their primary ramifications are bilaterally similar in human fetal hands. The configurations of the primary arterial networks are established very early in prenatal growth and may be maintained into adulthood. The similarities in the arterial network arrangements between fetal human and rhesus monkey hands suggest that the rhesus monkey hand could provide and appropriate model for studies of surgical neurovascular anastomosis.