bluuebunny/crossref_metadata_2025 huggingface dataset:
Growth in the basicranial synchondroses of adolescent Macaca mulatta
Authors: Giles William B. , Phillips Ceib L. , Joondeph Donald R.
Published: February 2005

Tritiated thymidine was administered to five Macaca mulatta monkeys ranging in skeletal age from 39 to 48 months. The animals were then serially sacrificed according to the following postinjection schedule: 6 hours, 12 hours, 2, 4, and 7 days. Each animal was given oxytetracycline 370, 103, and 7 days prior to sacrifice. The spheno‐occipital and midsphenoidal synchondroses were excised and sectioned midsagittally for histologic preparation and undecalcified “ground” sections. Results from this investigation indicate that from 39 to 48 months of age growth occurs primarily in the spheno‐occipital synchrondroses. The greatest mitotic activity occurs within the proliferative zones, while the central zone appears to be relatively inactive. The surface remodeling pattern, which tends to flex the basiocciput relative to the basisphenoid, appears to be compensated for by a supero‐inferior growth rate differential within the spheno‐occipital cartilage.
An ultrastructural morphometric study of developing rat substantia gelatinosa
Authors: Kirby M. L.
Published: February 2005

A morphometric analysis has been done on developing rat substantia gelatinosa of the lower cervical and upper thoracic levels of the spinal cord starting on the 15th day of gestation. The following parameters were measured: cell body diameter, cytoplasmic/nuclear areas, synaptic density, synaptic type and vesicle morphology of the presynaptic terminal in axodendritic synapses. Cell body size and cytoplasmic/nuclear areas of gelatinosal cells increase until the 15th day postnatally and then decrease somewhat to the adult values. The first synapses are seen on gestation day 17. Synaptic density increases linearly until the third day postnatally. Axodendritic synapses are most common throughout development and in the adult, while the proportion of axoaxonic synapses increases and axosomatic synapses decreases during development. Most of the terminals in axodendritic synapses contain clear‐spherical vesicles but the occurrence of clear‐flat vesicles and dense‐cored vesicles in the terminals increases during development. It appears that these morphological parameters provide a stable index of development in the substantia gelatinosa which can be correlated with functional development of the area. Hopefully, they will provide a means to assess subtle anomalies induced by nonteratogenic drugs or other environmental changes.
Aqueductal tanycytes in the rabbit brain: A Golgi study
Authors: Burnett Bruce T. , Felten David L.
Published: February 2005

Utilizing Golgi‐Cox impregnation, tanycytes were found in the ependyma of the cerebral aqueduct of the neonatal and adult rabbit. These tanycyte somas showed a variety of shapes, apical projections into the aqueduct, and basal processes (shafts) projecting into the mesencephalon, particularly into the periaqueductal gray (PAG). The shafts showed a variety of branching patterns, and sometimes abutted or terminated on capillaries or on specific neuronal elements. Other shafts coiled within the PAG or terminated within the neuropil of the mesencephalon. It is possible that these tanycytes provide a route for transport of cerebrospinal‐fluid‐borne substances from the aqueduct to the neuronal regions and vasculature of the mesencephalon. The presence of these tanycytes with complex branching patterns in proximity to neural and vascular structures suggests a permanent, active role for these specialized ependymal cells.
An interferometric analysis of nucleoli in cultured mesothelial cells
Authors: Blumenstein Robert , Amenta Peter S.
Published: February 2005

Previous studies have indicated that total nucleolar area and volume remain constant regardless of the number of nucleoli. The question remains whether this relationship is valid for mass. To answer this, total nucleolar mass values were obtained from nuclei of living mesothelial cells in culture possessing one to four nucleoli. The nucleolar mass was calculated using interferometry. The mean total nucleolar dry mass for cells with one, two, three, and four nucleoli was 40 × 10−12gm, 38.4 × 10−12gm, 39.1 × 10−12gm, and 41.4 × 10−12gm, respectively. These data suggest that on the average, each cell had approximately the same total nucleolar dry mass regardless of the number of nucleoli.

In an additional study, interferometry was employed to reveal changes in nucleolar mass and concentration during a seven‐hour period. It was concluded that the nucleolus is a dynamic organelle, with its total mass varying in time from an average 40 × 10−12gm with a mean concentration of 22.2gm/100cm3.
The mechanism of AV junctional reentry: Role of the atrio‐nodal junction
Authors: Mazgalev Todor , Dreifus Leonard S. , Bianchi John , Michelson Eric L.
Published: February 2005

Mapping of atrial‐AV nodal (AVN) activation patterns was performed in 10 superfused rabbit AVN preparations utilizing 3 bipolar electrodes placed simultaneously at the crista terminalis (CT), interatrial septum (IAS) and His bundle (H) regions in close proximity to the AVN, along with two or three microelectrodes in the AN, N and NH regions of the AVN. Basic and premature stimuli were introduced at either or both the CT and IAS regions of the AVN. The timing of the premature stimuli was varied to induce close interaction of inputs to the AVN. Summation and/or cancellation, as evidenced by changes in the morphology of the action potentials and alteration of H1–H2 intervals, were observed. Apparent reentry phenomena could be induced or terminated by appropriately timed stimulation at the CT and IAS inputs. Reentry was critically related to both the patterns and timing of the spread of excitation within AVN and surrounding atrial tissue. Slow conduction and unidirectional block were observed in various portions of the reentry circuit. It is concluded that (1) interaction between input waves engaging the AVN produced either summation or fragmentation; (2) slow conduction and reentry resulted from a critical collision of wavefronts: (3) in this preparation, AVN reentry circuits always appeared to involve conduction through atrial tissue immediately surrounding AVN; and (4) remarkably, reentry confined to the intranodal region was never observed.
Efferent projections of the septum in the tegu lizard, tupinambis nigropunctatus
Authors: Sligar C. M. , Voneida T. J.
Published: February 2005

A H3 proline or H3 leucine mixture was injected into the septal region of the Tegu lizard in order to determine its efferent projections. The brains were processed according to standard autoradiographic technique and counterstained with cresyl violet. Septal projections were limited to either telencephalic or diencephalic areas. Intratelencephalic projections consisted of efferents to medial pallium, nucleus accumbens, bed nucleus of the anterior commissure, preoptic area and septum itself. Fibers entering the diencephalon projected to medial habenular nucleus, dorsomedial thalamic nucleus, dorsolateral thalamic area, periventricular nucleus of the hypothalamus, lateral hypothalamic area and mammillary nucleus. The results are discussed in relation to the efferent projections of the septum in other vertebrates.
Structure and function of the murine muscle–tendon junction
Authors: Trotter John A. , Corbett Karen , Avner Barry P.
Published: February 2005

The muscle‐tendon junctions of the extensor carpi radialis longus and brevis muscles from adult Balb C Bailey/J mice have been examined tensiometrically and ultrastructurally following removal of cellular membrane and soluble cytoplasm by exposure to nonionic detergent. As judged by the ability of the extracted muscle to generate tension upon exposure to ATP and to transmit the generated tension to the tendon, detergent extraction leaves the muscle‐tendon junction functionally intact. Electron microscopic analysis of the extracted muscle‐tendon junctions reveals that the relationship between the terminal myofilaments and the lamina densa of the basal lamina is retained, despite the extensive extraction of the plasma membrane. Fine filaments (2–7 nm) are seen to connect the lamina densa with an electron‐dense intracellular layer into which terminal actin filaments appear to insert. These fine filaments are considered to represent an important component of the structural linkage between myofilaments and connective tissue and hence to be a significant component of the tension transmitting mechanism. Their precise nature is not known, but some part of the filaments must pass through the hydrophobic compartment of the plasma membrane and thus must be a transmembrane component of considerable tensile strength. These studies suggest that detergent‐extractable membrane lipids play no significant role in the transmission of tension at the muscle–tendon junction, and that fine filaments, probably protein, are responsible for transmitting tension from myofilaments, through the plasma membrane, to the lamina densa of the basal lamina.
Age related increase in catecholamine‐containing paraganglia in male fischer‐344 rats
Authors: Partanen Matti , Chiueh Chuang C. , Rapoport Stanley I.
Published: February 2005

For identification of paraganglia (PG), samples of para‐aortic tissue, tissues containing the coeliac‐mesenteric ganglion complex, and the hypogastric ganglia were removed from 3‐ and 33‐month‐old male Fischer‐344 rats and were processed by the formaldehyde‐induced fluorescence method for visualization of catecholamines. Small PG containing 5–30 cells per section were found consistently in young animals. In each of six old rats, large PG containing 500–4000 brightly fluorescent cells per section were detected. Cell counting revealed a 13.5 × increase in number of PG cells between 3‐ and 33‐month old rats. Microspectrofluorimetric quantitation in old rats showed equal amounts of catecholemines in PG cells and in adrenal medullary cells. Most PG were located in samples from the para‐aortic area.
A case of the left innominate vein passing behind the ascending aorta
Authors: Kitamura Seiichiro , Sakai Akira , Nishiguchi Takahiko
Published: February 2005

The authors observed the postaortic left innominate vein, which passed behind the ascending aorta, in the body of a 69‐year‐old Japanese male during dissection in 1979. In this case, no rudiment of the ordinary left innominate vein could be found in front of the arteries arising from the arch of the aorta. There are few reports of this anomaly and an extensive search of the available literature revealed only ten cases, including three in Japan. Adachi classified the postaortic left innominate vein into two types, types I and II, on the basis of the positional relation between the left innominate vein and the ligamentum arteriosum. Our case was of type I, in which the left innominate vein passed ventral to the ligamentum arteriosum and ran across from left to right behind the ascending aorta to join the right innominate vein. The embryological explanation which generally is accepted for the postaortic left innominate vein lies in the transposition of a transverse connection, which becomes the left innominate vein in a later stage of development, between the left and right anterior cardinal veins from the ventral to dorsal sides of the rudiment of the ascending aorta.
Nuclear bodies as structural indicators of estrogenic stimulation in uterine luminal epithelial cells
Authors: Padykula Helen A , Fitzgerald Maryellen , Clark James H. , Hardin James W.
Published: February 2005

Preliminary evidence has indicated that the number of nuclear bodies in uterine luminal epithelial cells of the immature rat may be related to the duration of nuclear retention of the estrogen receptor complex (Clark et al., 1978). To test this hypothesis, an ultrastructural analysis of nuclear and cytoplasmic differentiation was performed at 4, 12, 24, 48, and 72 hr after a single injection of estradiol or nafoxidine (synthetic estrogen agonist/antagonist) into 21 day female rats. Variations in nuclear and cytoplasmic differentiation and in the frequency of occurrence of nuclear bodies (simple and complex) were determined and compared with established biochemical changes in the concentration of nuclear estrogen receptor and RNA polymerase activity (Clark et al., 1978). Following nafoxidine there is sustained elevation of the nuclear concentration of the estrogen receptor as well as RNA polymerase I and II activities over the entire 72‐hr period. From 4 to 72 hr the height of the luminal epithelial cells as well as the frequency of nuclear bodies increase at linear rates. Through steady expansion of the cytoplasmic membrane systems (RER and Golgi) the relatively undifferentiated epithelial cells of the control uterus are converted progressively into ones equipped for protein secretion. At 72 hr the effects of an estradiol implant resemble closely those observed after a single injection of nafoxidine; these include sustained nuclear receptor occupancy, elevated RNA polymerase activity, epithelial hypertrophy, and high frequency of nuclear bodies. However, after a single injection of estradiol, the luminal epithelial cells become slightly but significantly taller than the control cells and remain close to this size from 24 to 72 hr; the frequency of nuclear bodies decreases linearly from 4 to 72 hr to fall below the control level. In addition, limited cytoplasmic autolysis is evident from 24 to 72 hr. A single injection of estradiol results in short‐term nuclear receptor occupancy and elevated RNA polymerase activities which return to control levels by 24 hr. This collective evidence offers further support to the hypothesis that the duration of nuclear occupancy by the estrogen receptor is reflected in the size of the nuclear body populations in these epithelial target cells. Also during hyperestrogenization, epithelial hypertrophy is accompanied by steady formation of nuclear bodies.
Carbohydrate histochemistry of rat respiratory glands
Authors: Mochizuki I. , Setser M. E. , Martinez J. R. , Spicer S. S.
Published: February 2005

Cytochemical methods applied to examination of rat respiratory tract glands have revealed diversity of secretory complex carbohydrates. With the Alcian blue‐periodic acid Schiff (AB‐PAS) and the high iron diamine (HID) techniques at the light microscopic level, certain patterns of glycoprotein content were noted at various levels of the respiratory tract. Serous tubules and demilunes found in abundance in laryngeal and tracheal glands contained neutral glycoprotein. Mucous tubules found in abundance in epiglottal and laryngeal glands and in lesser number in tracheal glands most often produced sulfated glycoprotein. However, mucous tubules in epiglottal and tracheal glands contained a few cells with sialylated glycoprotein, and mucous tubules in some areas in laryngeal glands contained mainly cells producing sialylated glycoprotein. Mucous ducts found in abundance in lower laryngeal and tracheal glands formed mainly sialylated glycoprotein and contained infrequent cells with sulfated glycoprotein. The type of glycoprotein found in each cell type by light microscopy was confirmed at the ultrastructural level by the periodic acid‐thiocarbohydrazide‐silver proteinate (PA‐TCH‐SP), dialyzed iron (DI) and high iron diamine (HID) methods. Serous cell granules displayed light reactivity with the PA‐TCH‐SP method and no DI or HID affinity and were judged to contain sparse neutral glycoprotein. Serous granules disclosed negative central foci with the PA‐TCH‐SP method. Granules of most mucous tubule cells stained strongly with the PA‐TCH‐SP and HID procedures and contained abundant sulfated glycoprotein. Occasional mucous tubules stained with the PA‐TCH‐SP but not with the HID method and apparently corresponded with cells judged to form sialylated glycoprotein from their blue staining with the HID‐AB sequence. Two zones within individual granules in some cells revealed different HID staining intensity and appeared to differ in the amount or kind of sulfated glycoprotein they contained. Some cells exhibited granule heterogeneity containing both HID‐positive and unstained granules. Spherical cores present in granules of mucous tubules below the upper laryngeal level occasionally appeared bizonal and invariably lacked reactivity demonstrative of complex carbohydrate. Mucous duct cell granules stained heavily with the PA‐TCH‐SP and DI methods and reacted infrequently with the HID procedure and were considered generally to contain sialylated glycoprotein, and occasionally to form sulfated glycoprotein. The three carbohydrate stains distinguished a heavily and a moderately reactive zone in the cortex outside the monophasic or biphasic, carbohydrate‐free cores in granules of some mucous duct cells.
Electron microscopic studies on the potential loss of crystallites from routinely processed sections of young enamel in the rat incisor
Authors: Bishop M. A. , Warshawsky H.
Published: February 2005

Newly formed rat incisor enamel was fixed aqueously by perfusion with glutaraldehyde and anhydrously by immersion in ethylene glycol. Ultrathin sections were studied using transmission electron microscopy and electron diffraction. Aqueously processed enamel was shown to lose its mineral content when sectioned on distilled water. This mineral loss was minimized by limiting the exposure of sections to the water. In such preparations, enamel crystallites were seen by virtue of their intrinsic electron density only. Selected area electron diffraction provided corroborative evidence for the presence or absence of crystallites in the sections. Observations on mineralized sections and on stained mineralized and distilled‐water‐demineralized sections revealed organic material apparently in the same location as the crystallites. Anhydrously processed enamel which was sectioned on ethylene glycol showed a similar appearance of the crystallites. This appearance was not obviously altered after staining despite evidence that organelles in the ameloblasts were stained. In view of the observations that both methods yielded similar crystallite morphology, it was concluded that aqueous techniques can be used to study the relationship between organic and inorganic components. However, valid description of crystallites in such preparations requires minimal exposure of ultrathin sections to water.
Ultrastructural demonstration of chemical modification of melanogenesis in hairless mouse skin
Authors: Nishimura Masayuki , Gellin Gerald A. , Hoshino Shimpei , Epstein John H. , Epstein William L. , Fukuyama Kimie
Published: February 2005

We investigated chemical and physical modifications of the genetically determined ultrastructure of melanosomes. The flank skin of hairless mice was treated with ultraviolet energy (UV) shorter than 320 nm or with a combination of a photosensitizer and UV (PUVA treatment). All melanosomes in the induced melanocytes and those in resident melanocytes in the ear skin showed eumelanogenesis, although the degree of melanin deposition differed considerably according to the induction process. Eumelanogenesis was most advanced in the resident melanocytes while PUVA‐induced melanocytes showed more immature premelanosomes. We then topically applied 4‐tertiary butyl catechol on the skin. The depigmenting agent caused an appearance of pheomelanosomes. The alteration in melanogenesis was seen most distinctly in premelanosomes of the PUVA‐induced cells. Altered ultrastructure was also observed in matured melanosomes; this change was most apparent in the resident melanocytes. These findings indicate that cells with eumelanogenesis may undergo pheomelanogenesis. The present study demonstrated effects of chemicals on genetically determined function of melansome ultrastructure.
Ethanol‐induced alterations in the morphology and function of the rat ovary
Authors: Bo Walter J. , Krueger Wayne A. , Ruenen P. Kevin , Symmes Sandra K.
Published: February 2005

The purpose of this study was to compare the effects of different dosages of ethanol on ovarian morphology and function. Holtzman rats, 20 days old, were divided into groups as follows: The rats in Group I were autopsied at 20 days of age, and those in Group II were placed on ad libitum chow and water diet; the rats in Groups III and V were fed on a liquid diet containing 2.5% or 5% ethanol respectively; Groups IV and VI were pair‐fed controls to Groups III and V, respectively. Rats in Groups II, III, IV, and VI were maintained on the diets for 50–55 days and killed at late proestrus‐estrus, while the animals in Group V did not exhibit estrous cycles and were killed on day 55 of treatment. The average increase in body weights of rats in Groups II, III, and IV was significantly greater than the increase in body weights of rats given 5% ethanol or their pair‐fed controls. In the rats treated with 5% ethanol, vaginal opening was significantly delayed from the controls, estrous cycles were absent, ovarian weights were similar to those of the 20‐day‐old rats, ovaries contained corpora lutea of only one estrus, uteri weighed less than controls, and histologically, the uteri and vaginae were similar to those of 20‐day‐old rats. However, in the rats treated with 2.5% ethanol, all of the parameters were similar to those of the controls. The average serum alcohol level for the rats on the 5% ethanol diet was 249 mg%; the serum alcohol levels were at the lower limit of detection for the rats on the 2.5% ethanol diet. The data show that ovarian function was suppressed in the rats that received the 5% ethanol but not in rats on the 2.5% ethanol diet.
Comparative fine structure of the osteichthyan dermotrichia
Authors: Geraudie Jacqueline , Meunier Francois‐Jean
Published: February 2005

This study shows that camptotrichia constitute the only skeleton of the Dipnoan fins. Their fine structure is indeed quite different from the two other Osteichthyan dermotrichia, namely the actinotrichia and the lepidotrichia found simultaneously in the fin margin of both Actinopterygians and Crossopterygians fins. Although different from lepidotrichial bone, the fine structure of camptotrichia is more reminiscent of it than of the elastoidin‐formed actinotrichia.
Defective thyroid ontogenesis in fetal hypothyroid (hyt/hyt) mice
Authors: Beamer Wesley G. , Cresswell Lisa A.
Published: February 2005

Thyroid glands of fetal hypothyroid (hyt/hyt) mice were studied to determine the effects of the mutant gene during embyrogenesis. Comparisons of mutant and normal thyroids were made with respect to morphology, iodine‐concentrating ability, and glandular thyroxine (T4) content at day 18 of gestation. Fetal hyt/hyt thyroid tissue was properly located, but incompletely differentiated. The mutant thyroid was characterized microscopically by small, poorly developed follicles with colloid diminished in PAS‐staining properties. The mutant glands' ability to concentrate iodine was found to be only 5–16% of that exhibited by normal glands. When litters contained both mutant and normal offspring, the differential iodine‐concentrating ability allowed fetuses to be separated into two distinct, nonoverlapping populations. The distribution of fetal mice into high or low iodine‐concentrating groups agreed closely with predicted frequencies for normal and mutant phenotypes. Thyroid content of T4 in mutant mice was found to be approximately equal to that found in age‐matched normal controls.

The poorly developed morphology and deficient iodine‐concentrating ability of fetal thyroids from day 18 hyt/hyt mice indicated that the mutant gene acts during the ontogeny of this gland. Although such data are not available on human fetuses affected by thyroid dysgenesis, postnatal hyt/hyt mice display characteristics similar to those of infants born with this form of congenital primary hypothyroidism. Thus, elucidation of the site of mutant gene action in the mouse should contribute to our knowledge of disturbed fetal thyroid development and its implications in the adult mammal.
A study on the localization of the sternocleidomastoid and trapezius motoneurons in the rat by means of the HRP method
Authors: Kitamura Seiichiro , Sakai Akira
Published: February 2005

The sternocleidomastoid and trapezius muscles of the rat, which are innervated by the spinal accessory nerve (SAN) and cervical spinal nerve (CSN), consist of five smaller muscles: the sternomastoid, cleidomastoid, clavotrapezius, acromiotrapezius, and spinotrapezius. In this study, the location of cell somata of the motoneurons supplying each of these smaller muscles and the peripheral course of their axons have been studied by means of the horseradish peroxidase retrograde axonal transport technique (the HRP method) in combination with cutting of the SAN. The sternocleidomastoid and trapezius motoneurons formed three cell columns, column‐M, ‐L, and ‐5, in the ipsilateral ventral horn of the cervical spinal cord. Column‐M and ‐L, extend longitudinally in the medial nucleus of C1 and C2 and in the ventrolateral nucleus from the middle of C2 to the middle of C6, respectively. These columns consist of the motoneurons whose axons pass through the SAN and they merge in the caudal C2 to constitute the spinal accessory nucleus. Column‐5, which consists of the motoneurons passing through the CSN, extends longitudinally from C3 to C5 close to column‐L in the ventrolateral nucleus. Motoneurons supplying the sternomastoid, cleidomastoid, clavotrapezius, acromiotrapezius, and spinotrapezius muscles showed a rostrocaudal somatotopic distribution in the spinal accessory nucleus and in column‐5 in this order, though the sternomastoid motoneurons were not found in column‐5.
Further evaluation of the superficial and deep tendons of the human temporalis muscle
Authors: Harn Stanton D. , Shackelford Lee S.
Published: February 2005

The superficial and deep tendons of the human temporalis muscle and their fasciae were examined for specific attachments. It was found that as they pass inferiorly along the ramus of the mandible, a structure consisting of tendon and fascia (herein referred to as the fascial‐tendinous complex or FTC) is projected anteromedially and inferiorly. The FTC is a unifying structure in the oralbuccal area, serving as a common point of attachment for three muscles of mastication (temporalis, masseter, and medial pterygoid) as well as the buccinator, superior pharyngeal constrictor (SPC), and the mylohyoid muscles, and their corresponding fasciae. The FTC creates a defined fascial space containing loose connective tissue, the buccal nerve, and corresponding blood vessels between the posterior buccal region and the anterior ramus and posterior body of the mandible. The FTC has two components: (1) a medial part which merges into the posterior buccal region in the area of the pterygomandibular depression and (2) a lateral part which continues inferiorly to the posterior area of the body of the mandible.

A distinct slip of the medial pterygoid muscle was found to attach to the FTC which caused the lingual nerve to be sandwiched between this slip and the main bulk of the medial pterygoid as it inserts into the mandible.

The pterygomandibular raphe, as previously described, was not found. Because of the FTC, the buccinator and SPC do not have simple hamulus‐raphe‐mylohyoid line attachments. The exact relationship of the buccinator and SPC is dependent upon the extent of the FTC. The larger the FTC, the greater are the muscle attachments and vice versa. In large FTCs a separate muscle (Hamular‐FTC muscle) was found attaching from the hamulus to the FTC.

The pterygomandibular fold was found not to coincide with the “raphe.” The concavity of the pterygomandibular depression upon depression of the mandible was found to be the result of the FTC.
Whole population cell kinetics of mouse duodenal, jejunal, iieal, and colonic epithelia as determined by radioautography and flow cytometry
Authors: Cheng Hazel , Bjerknes Matthew
Published: February 2005

We report methods for the determination of whole population cell kinetics in the mouse intestinal epithelium by means of radioautography and flow cytometry. Epithelium was isolated from the four regions of the mouse intestine by the perfusion method described in Bjerknes and Cheng (1981a). Two experimental series were performed. In the first series, the tissue from one set of animals was fixed in 3.5% paraformaldehyde, dissociated by serial filtration, and then processed for flow cytometry. In the second series, fixed epithelium from a second set of animals was dissociated by gentle pipetting and then used to prepare dried cell suspensions on slides which were radioautographed. The whole population kinetic parameters determined by the two techniques, flow cytometry and radioautography, were not significantly different, indicating the reliability of both techniques for whole population kinetics determinations. In all regions of the intestinal tract, 12–14% of epithelial cells were in the S‐phase. From this value, the whole epithelial turnover time was calculated to be about 60 hours in all regions of the intestine. The whole epithelial growth fraction was calculated to be 0.23 for the small intestinal epithelium and 0.31 for the colonic epithelium. Detailed analysis of the flow cytometric data showed that there were significantly more cells in early S‐phase than in mid and late S‐phase. From the isolated epithelial sheets a mean number of crypts per villus was determined for the duodenum, jejunum, and ileum. Single villi and crypts were microdissected for the preparation of squashes. From the squashes a mean number of cells per villus as well as per crypt was determined. From the results, the ratio of the number of epithelial cells in the villus population to the number of cells in the crypt population was determined to be 1.41, 1.31, 1.36 in duodenum, jejunum, and ileum, respectively. The proportion of the three main epithelial cell types, columnar, mucous, and Paneth, was determined with the dried cell suspension preparations. There was a decreasing gradient in the proportion of columnar cells from the proximal to the distal intestine while an increasing gradient was observed in the proportion of mucous cells. We found that mucous cell divisions account for only one half of mucous cell production in the small intestine. In the colonic epithelium, mucous cell divisions account for two‐thirds of mucous cell production. This was in agreement with previous findings.
A radiographic study of the longitudinal growth of primary ossification centers in limb long bones of the human fetus
Authors: Bagnall K. M. , Harris P. F. , Jones P. R. M.
Published: February 2005

This paper describes an extensive study of the growth of ossification centers in limb long bones of the human fetus from 8 to 26 weeks of conceptual age. Longitudinal measurements were made of the femur, tibia, fibula, humerus, radius, and ulna. Comparisons were made between bones on the left and right sides of the body and between the sexes. Standards are presented for the growth of these centers. They compare well with previous studies, any differences being accounted for by different methods of aging and measurement.

A complicated picture of growth of the two sides of the fetal body is presented. Growth of the humerus, tibia, and fibula appears to be dominant on the left side of the body while growth in the femur is dominant on the right. At present, no explanation is available, but it is possible that factors such as manual dominance may be related. Evidence also is presented which suggests that the female fetus is in advance of the male in terms of ossification but only after 21 weeks gestation.
Intercellular contacts between migrating blood cells and cells of the sinusoidal wall of bone marrow. An ultrastructural study using tannic acid
Authors: Campbell Ferrell R.
Published: February 2005

The migration of blood cells across the sinusoidal wall of murine bone marrow was studied following fixation with tannic acid‐glutaraldehyde. Electron microscopic examination showed regions of close membrane apposition (referred to in this study as “intercellular contacts”) between migrating blood cells and cells of the sinusoidal wall (adventitial and endothelial cells). Ultrastructurally the intercellular contacts are pentalaminar structures resembling gap junctions of other organs after tannic‐acid fixation. The possibility that these contacts are regions of intercellular communication and/or sites of membrane attachment utilized for locomotion of the migrating blood cells is discussed.
Dorsal cerebral arterial collaterals of the rat
Authors: Coyle Peter , Jokelainen Pentti T.
Published: February 2005

This study demonstrated that distal branches of the anterior cerebral artery (ACA) are joined by interarterial anastomoses to rami of the middle cerebral artery (MCA) in the normal Wistar rat. Arteries of 36‐ and 56‐day‐old animals were dilated with papaverine and injected with Vultex. Vultex arrived at corresponding ACA and MCA collaterals simultaneously as determined by microscopy through a skull window and photography. There were about 29 ACAMCA junctions per hemisphere. Junction density was nearly constant along the frontal‐occipital axis. The anastomoses were most numerous between 2 and 3 mm lateral to the midline and were less than 120 μm in internal diameter. No significant difference was found between total numbers of junctions for right versus left hemispheres or between age groups. The most evident collateral pattern was characterized by two ACA end rami joining two MCA end branches to form a closed, diamond‐shaped collateral unit. Considerations were given to alternate routes of blood flow into the MCA tissue field. We conclude abundant dorsal anastomoses exist in 36‐ and 56‐day‐old rats and are the prime potential source for ACA collateral supply to the MCA tissue field.
Intramuscular variation of fiber types in the brachial biceps and the lateral vastus muscles of elderly men: How representative is a small biopsy sample?
Authors: Nygaard E. , Sanchez J.
Published: February 2005

The aim of the study was to investigate the reliability of the distribution of muscle fiber types determined in small fragments of human skeletal muscle. Fiber‐type distribution was analyzed in small areas, equivalent to a needle biopsy in size, and in large areas, at nine sites of the brachial biceps (BB) and the lateral vastus (LV) muscles obtained at autopsy from five elderly subjects. It was concluded that in the BB the site of a biopsy should be well defined, since, the incidence of fiber types varied systematically. In the LV the biopsy should be large to permit a reliable estimate of the incidence of fiber types; with the needle technique, repeated sampling may be necessary. Small samples are not suited for the analysis of fiber type grouping.
A new morphological procedure for viewing microvessels: A scanning electron microscopic study of the vasculature of small intestine
Authors: Miller Bryan G. , Woods Richard I. , Glenn Bohlen H. , Evan Andrew P.
Published: February 2005

The present study details a new method for the exposure and viewing of individual microvessels located within the small intestine of rats. This procedure will selectively and consistently remove the outer muscle layers and underlying submucosa of the intestinal wall and thereby expose a variety of arterioles in their normal location within the tissue, with their normal relationship to each other undisturbed. The small intestine of the rat was initially fixed by vascular perfusion with 2.5% glutaraldehyde in 0.1 M cacodylate/HCL buffer, reinfused with heparinized whole blood, removed from the animal, and secured to a dissecting petri dish for further fixation. Subsequently, the external muscularis was dissected from the sample which exposed the submucosa. In order to remove the connective tissue elements from this layer and uncover the submucosal vasculature, the samples were first transferred to a solution of 30% potassium hydroxide for 2–5 minutes and then to a final digesting solution containing collagenase. Thereafter, the samples were routinely processed for light microscopy and for scanning (SEM) or transmission (TEM) electron microscopy. Examination of the samples revealed excellent preservation of the three‐dimensional organization of the arteriolar wall with minimal membrane damage. This new technique now makes it possible to visualize the shape and position of individual smooth muscle cells along arterioles of differing size and branching order.
A histochemical analysis of identified compartments of cat lateral gastrocnemius muscle
Authors: English Arthur Wm. , Letbetter William D.
Published: February 2005

The lateral gastrocnemius muscle of cats can be divided into four discrete subvolumes or compartments which are supplied by the primary branches of its muscle nerve. The histochemical profile of each compartment was determined from the reaction for myosin ATPase after acid preincubation. Fibers were classified as fast‐twitch glycolytic (FG), fast‐twitch oxidative‐glycolytic (FOG), or slow‐twitch oxidative (SO). Each compartment in each cat examined was found to contain a relatively uniform distribution of different types of fibers. The most proximal LG compartment contains mainly type FG fibers, with relatively few type SO fibers; the most distal compartment, while still predominated by type FG fibers, contains a significantly larger proportion of type SO fibers. The histochemical profile of the intermediate compartments indicates that they contain fibers which lie intermediate in composition between these two. These results are consistent with the notion that LG compartments consist of aggregations of motor units, arranged such that muscle fibers comprising a single motor unit are contained within a single compartment.
Myocardial fiber architecture of the human heart ventricles
Authors: Fernandez‐Teran M. A. , Hurle J. M.
Published: February 2005

The ventricular fiber architecture has been studied anatomically and histologically in 25 human hearts. Special attention has been paid to the form of insertion of the myocardial fibers and to the existence or nonexistence of an independent system of fibers for each ventricle. Three different myocardial layers—superficial (subepicardial), middle, and deep (subendocardial)—have been distinguished according to the fiber direction through the ventricular mass. All the fibers are common for both ventricles with the exception of a thick middle layer peculiar to the left ventricle. The tendinous cords, the central fibrous body, and the arterial fibrous rings are the major zones of insertion of myocardial fibers. On the basis of our results we have attempted to correlate the ventricular architecture with the valvular dynamics.
Distribution of fibronectin in normal and regenerating skeletal muscle
Authors: Gulati Adarsh K. , Reddi A. H. , Zalewski Andrew A.
Published: February 2005

The distribution of fibronectin in normal and regenerating skeletal muscle (the latter caused by autotransplantation) was investigated by means of indirect immunofluorescent technique. Normal myofibers exhibited a thin, continuous pericellular (endomysium) fibronectin distribution; however, their sarcoplasm was devoid of fibronectin. After autotransplantation, the skeletal muscle fibers underwent a process of degeneration that was followed by regeneration from the premyogenic satellite cells. These cells multiplied, fused to form myotubes, and matured into new myofibers. A decrease and an eventual loss of endomysial fibronectin was seen in the degenerating myofibers. At the same time, fibronectin appeared in the sarcoplasm. No significant fibronectin was expressed in the myogenic zone until the formation of myotubes which possessed a complete, circular fibronectin ring. The sarcoplasm of the myotubes lacked fibronectin. Since fibronectin is a component of basement membrane of several tissues, its disappearance and reappearance can be used to follow the fate of basement membrane. We conclude that fibronectin may not be essential for early myogenesis and that regenerated myotubes form an entirely new or at least certain new molecular components of their basement membrane. The present muscle autotransplantation model can be used to further study the role of fibronectin during myogenesis and cell transformation in vivo.
Fine structural criteria for pituitary thyrotrophs in immature and mature rats
Authors: Yoshimura Fujio , Nogami Haruo , Yashiro Takashi
Published: February 2005

Fine structural criteria for identifying thyroid‐stimulating hormone (TSH) cells in immature and mature rats have been studied by a modified superimposition technique. On days 10 and 20, some small oval immature TSH cells are scattered individually throughout the glandular tissue with a peripheral immunoreactive rim resulting from the sparse distribution of minute secretory granules less than 50 nm in diameter. The immunostained stellate TSH cells are clustered and have secretory granules 50–100 nm in diameter at the cell margins. On day 60, a few small immature TSH cells still remain. Although a few polygonal TSH cells that may not fully mature accumulate secretory granules 100–150 nm in diameter at the cell margins, the majority of TSH cells take the form of large stellate cells filled with secretory granules with the corresponding diameter, and surround an acidophil. These stellate TSH cells are characterized by dense arrangement of parallel arrays of rough endoplasmic reticulum (rER) or rER cisternae. The clustered or isolated elongate TSH cells are also observed to be vesiculated and to have numerous secretory granules 150–250 nm in diameter. In addition, large oval vesiculated TSH cells storing numerous secretory granules 150–250 nm in diameter appear sporadically in the gland, ultrastructurally resembling the gonadotrophs. It is concluded that the rat TSH cell is not a single type with a particular ultrastructure, but modifies its morphology according to its maturation or functional phase.
The maturation of the end bulb of Held in the rat anteroventral cochlear nucleus
Authors: Neises G. R. , Mattox D. E. , Gulley R. L.
Published: February 2005

The maturation of the end bulb of Held was studied in serial thin sections through the rostral pole of the rat anteroventral cochlear nucleus (AVCN) at 2‐day intervals from birth through 16 days of age. In the neuropil of newborn rats primary auditory terminals occasionally synapse with large dendritic processes of spherical cells. Between 6 and 10 days of age, the spherical cell has numerous, long, fingerlike appendages at the base and proximal part of its primary dendrite which extend into the neuropil and envelope a single primary terminal. Small processes from the terminal extend along the appendages toward the cell body. At 10 days, these processes reach the dendritic pole of the soma and fill the interstices between the appendages. Synaptic contacts are present between the end bulb processes and the cell body. At 12 days, the end bulb covers most of the dendritic pole of the spherical cell. The remaining somatic appendages are small and are clustered beneath the end bulb. Synapses between the end bulb and soma are frequent. At 16 days, the end bulb resembles that seen in the mature rat. Nonprimary terminals appear on the soma at 10 days. These terminals are randomly distributed, with fine processes which extend from the end bulb over the remaining regions of the cell body.
Genetic comparisons of eumelanosome ultrastructure
Authors: Zimmerman Joel , Winfrey Frank , Brumbaugh John
Published: February 2005

We recently reported the existence of several new ultrastructural components of the eumelanosome matrix from developing chick pigment epithelium. The material used in the original study was obtained from a random sample of heterogeneous chicken. We have now extended this analysis to four genetically well‐characterized chicken types: jungle fowl, blue, dominant white, and recessive wheaten. In these four genotypes there are specific ultrastructural alterations in the eumelanosome matrix. These alterations are different for each of the genotypes studied and are probably reflective of differences in the functional nature of the genes involved. The data thus provide evidence as to which genes are structural and which regulatory in action. Furthermore, since the material analyzed was all derived from pigmented pigment epithelium, it is clear that these melanosomes are affected by genes previously thought to leave them untouched. Finally, data are presented that these new ultrastructural elements are also found in a different class of animals, the C57BL/10 mouse.
Autoradiographic evidence of a loss of iodination within hormone‐dependent GR mouse mammary tumors as they progress to independence
Authors: Strum Judy M.
Published: February 2005

The purpose of this study was to determine by use of light‐ and electron‐microscope autoradiography whether or not iodination occurred in mammary tumors of female GR mice. Of the sixty tumors studied it was found that pregnancy‐dependent and hormone‐induced tumors possessed iodinating ability. Although mammary glands from nonpregnant GR mice lacked the ability to iodinate, by the 16th day of pregnancy in response to hormonal stimulation the glands readily iodinated casein, and some epithelial cells contained ultrastructural cytochemical evidence of mammary peroxidase. Preneoplastic mammary gland lesions known as hyperplastic alveolar nodules were also able to iodinate, as were plaques, the disc‐shaped lesions which give rise to the hormone‐responsive mammary tumors in this strain. Plaques also contained epithelial cells with mammary peroxidase activity. When hormone‐induced mammary tumors were transplanted into syngeneic mice they retained the ability to iodinate for several generations. However, as the tumors progressed to hormone independence, the ability to iodinate was gradually lost. Hormone‐independent mammary tumors from GR mice lacked both iodinating ability and cytochemical evidence of mammary peroxidase. These findings suggest that iodination depends upon hormone‐responsive cells within the mammary tumors and that as these cells become hormone unresponsive, the ability to iodinate is lost.
Evidence for a blood‐ganglion barrier in the superior cervical ganglion of the rat
Authors: Depace Dennis M.
Published: February 2005

The permeability of the blood vessels in the superior cervical ganglion of the rat was tested by intravenous injection of horseradish peroxidase (HRP).

By light microscopy, peroxidase activity was found in three locations: in the capsule of the ganglion, in the lumina of the blood vessels, and within macrophages. Electron microscopy revealed that virtually all ganglionic blood vessels contained HRP 5 minutes following its administration. The intensity of peroxidase activity declined over the period of 15 minutes. The enzyme was localized on the luminal surface of the endothelial cells, attaching to the glycocalyx. Endothelial microvilli, projecting into the vessel lumen, were also covered with peroxidase. Micropinocytotic vesicles on the luminal surface of the endothelium contained reaction product. Some of these vesicles were free within the cytoplasm of the endothelium but none was observed on the abluminal surface. Peroxidase activity was not detected in the extracellular space even after 15 minutes.

The majority of blood vessels in the superior cervical ganglion possess a continuous endothelium with tight junctions; features associated with the blood‐brain barrier of the central nervous system and peripheral nerves. It is proposed that these vessels perform a barrier function between the capillary circulation and the superior cervical ganglion.