bluuebunny/crossref_metadata_2025 huggingface dataset:
Arteriovenous anastomoses in the skin of seals. II. The california sea lion Zalophus californianus and the northern fur seal Callorhinus ursinus (Pinnipedia: Otariidae)
Authors: Bryden M. M. , Molyneux G. S.
Published: February 2005

The structure, distribution and density of arteriovenous anas‐tomoses (AVAs) were studied in body and flipper skin of a California sea lion and a northern fur seal. In both animals AVAs consisted of arterial, intermediate and venous segments, and were generally larger and more tortuous in the sea lion than in the fur seal. In the sea lion the majority of AVAs (72%) occurred in the deeper region of the dermis, and the density was significantly greater in the flippers than in the body. In the northern fur seal most AVAs (76%) occurred in the superficial region of the dermis; the density of AVAs in flipper skin was significantly higher than in body skin, and the density in the hind flipper was significantly greater than in the foreflipper.

Arteriovenous anastomoses are important in the regulation of body temperature in seals; when these animals are on land, AVAs function to dissipate body heat, and vascular thermoregulation occurs in the flippers but not over the general body surface. Due to differences in distribution and density, AVAs play a more significant role in thermoregulation in the northern fur seal than in the California sea lion.
Morphological and functional differentiation of the surface epithelium of the bursa Fabricii in chicken
Authors: Naukkarinen Anita , Arstila Antti U. , Sorvari Tapani E.
Published: February 2005

Morphological and functional differentiation of the mucosal surface epithelium of the bursa Fabricii was studied in White Leghorn chicken fetuses and newly hatched chickens. First signs of differentiation towards two types of epithelial cells appeared on the thirteenth day of incubation: The apical cells of the epithelial buds projected towards the lumen, and an increase in the number of Golgi regions was observed in the epithelial cells between the buds. On day 15 the follicle‐associated epithelium contained small apically situated vacuoles, and large mucin granules appeared in the interfollicular surface epithelium. Towards the day of hatching both epithelial cell types were arranged to a monolayered or pseudostratified cylindrical epithelium. The follicle‐associated epithelium had invaginations and small vacuoles in the apical cytoplasm, whereas the interfollicular surface epithelium had numerous microvilli on its apical surface and large mucin granules in the apical cytoplasm. In functional studies, endocytosis of colloidal carbon was demonstrated in four out of ten 19‐day‐old fetuses and in all chickens studied immediately after hatching.
The mammalian tubuli recti: Ultrastructural study
Authors: Osman D. I. , Plöen L.
Published: February 2005

The ultrastructure of the tubuli recti was studied in the testes of sexually mature bulls, boars, rams, goats, rabbits and rats fixed by vascular perfusion. The tubuli recti are lined with a simple epithelium that varies in height, from squamous to tall columnar according to the species and the region. The cells are characterized by extensive lateral and tortuous basal plasma membranes and a luminal border with microvilli. Tight junctions and desmosomes are found in the upper half of the lateral borders. The Golgi apparatus is sizable and associated with it are coated vesicles and may smooth vesicles concentrated towards the luminal border. A distal segment of the tubuli recti is found in bulls only and is characterized by a high epithelium which is thrown into folds giving the lumen a festooned appearance. It is suggested that the epithelial cells of the tubuli recti are involved in fluid exchange and in the removal of unwanted spermatozoa.
Vasectomy in rhesus monkeys. IV. Electron microscopic studies of the seminiferous epithelium
Authors: Chapman E. S. , Heidger P. M. , Harrison R. M. , Roberts J. A. , Domingue G. J. , Schlegel J. U.
Published: February 2005

Studies were undertaken to assess the fine structural effects of vasectomy upon the rhesus monkey testis, using 27 monkeys subjected to one of three surgical techniques: control sham operation (COS), unilateral silk vasoligation (USV), or unilateral clasp vaso‐occlusion (UCV). The monkeys were sacrificed from 1 to 66 weeks after surgery; tissues were fixed in glutaral‐dehyde in collidine buffer and processed for electron microscopy (EM) using routine techniques. No alterations were noted in the seminiferous epithelium of any COS animal; only focal lesions were found in vasectomized animals. These changes correlated with length of time post‐vasectomy, a finding consistent with earlier light microscopic studies (Heidger et al., '78). Even at the longest post‐operative periods studied, spermatogenesis appeared in most animals to be normal. One animal exhibited areas in which the seminiferous epithelium consisted of Sertoli cells and spermatogonia, only. The seminiferous epithelium of approximately one‐third of other animals, both on the vasectomized and contra‐lateral sides, exhibited such alterations as development of extensive infoldings and duplication within the basal lamina, and presence within the basal Sertoli cell cytoplasm of late spermatids and sperm tails. These alterations were observed in both UCV and USV animals. The presence of such late germ cells in the basal Sertoli cell cytoplasm was noted by light microscopy; however, lu‐minal spermiophages encountered in one animal at the light microscopic level were not detected in our EM study, which underscores the limitations of EM as a survey technique. All UCV animals developed spermatic granulomas of the vas, whereas only 3 of 13 USV animals developed such granulomas. It does not appear that the alterations exhibited by the animals in this study would necessarily dispose toward impaired spermatogenesis following vasovasostomy.
Formation of apical pseudopods by canine thyroid follicular cells: Induction by thyrotropin and 5‐hydroxytryptamine; antagonism by reserpine
Authors: Nunez Eladio A. , Gershon Michael D.
Published: February 2005

The role of biogenic amines in the activation of thyroid follicu‐lar cells by thyrotropin (TSH) was studied. 5‐hydroxytryptamine (5‐HT) was chosen as the amine to study and apical pseudopod formation, assessed by scanning electron microscopy, was used as the index of follicular cell activation. All experiments were done on dogs. TSH and 5‐HT were both potent inducers of pseudopod formation. The action of TSH but not that of 5‐HT was antagonized by the amine depleting drug reserpine. Reserpine depleted the thyroid of 5‐HT in newborn, adolescent, and adult dogs. It is concluded that one or more biogenic amines, such as 5‐HT, are probably involved in follicular cell activation by TSH.
Epithelial influences on membrane bone formation in the maxilla of the embryonic chick
Authors: Tyler Mary S.
Published: February 2005

In light of previous evidence that epithelial influences are required for membrane bone formation in certain instances (mandible, Tyler and Hall, '77 a,b; cranium, Benoit and Schowing, '70), the possibility that maxillary epithelium influences membrane bone formation within the maxillary mesenchyme was investigated. Intact maxillary processes, and enzymatically separated epithelial and mesenchymal components of the maxilla were obtained from embryonic chicks of three to five days of incubation (Hamburger and Hamilton ['51] stages (HH) 18‐25) were grown individually as grafts on the chorioallantoic membranes of host chick embryos. The histodifferentiation of grafted intact maxillary processes was similar to that in vivo. The histodifferentiation of grafted maxillary mesenchyme depended upon the embryonic age at which the mesenchyme was isolated from its epithelium. In grafts of maxillary mesenchyme isolated from its epithelium at HH 22 or earlier stages, cartilage differentiated, but membrane bone did not form. In grafts of maxillary mesenchyme isolated from its epithelium at HH 23 or later stages, membrane bone formed in addition to cartilage. The results indicate that maxillary mesenchyme requires the presence of epithelium through HH 22 in order for membrane bone to form within the mesenchyme. Cartilage formation within the mesenchyme does not require epithelial influences during the embryonic period tested (HH 18‐25). Maxillary epithelium isolated from its mesenchyme and grown as a graft became underlaid by host fibroblasts and achieved a limited degree of differentiation; the epithelium did not induce ectopic membrane bone formation within the host tissue, indicating that the presence of maxillary epithelium is not a sufficient condition for promoting membrane bone formation in normally non‐osteogenic tissue.
Filtration of circulating particles by splenic autotransplants
Authors: Dumont Allan E. , Martelli Amalia B.
Published: February 2005

To determine whether filtration in reconstituted perifollicular marginal zones underlies particle sequestration in regenerating spleen transplants, the distribution of IV injected particles of tantalum was examined in autografts freely transplanted into subcutaneous pouches in rats. In two to six weeks old autografts removed one to three hours after particle injection, the reconstituted marginal zones contained practically all of the sequestered tantalum. At 48 hours to‐20 weeks following injection, marginal zones were largely free of particles which were distributed extracellularly throughout the red pulp. This sequential pattern of distribution conformed closely to that observed in the intact spleen.

The findings indicate that a reconstituted marginal zone allows splenic autotransplants to function as simple mechanical filters. Increased demand for this activity rather than for phagocytosis may be the predominant factor regulating spleen growth.
Identity of a population of progenitor cells in gingival connective tissue of the mouse incisor
Authors: Everts Vincent , Beertsen Wouter
Published: February 2005

In the gingiva of the mouse incisor, connective tissue cells were observed which were undergoing mitosis and contained collagen fibrils enclosed in vacuoles in their cytoplasm. The presence of intracellular collagen was noted in the majority of the dividing cells. On the basis of this observation it is suggested that renewal of the fibroblast population in the gingiva occurs preferentially by division of differentiated fibroblasts rather than by division of cells with a lower degree of differentiation.
The effects of 5α‐reduced androgens on maintenance and regeneration of prostate glands and seminal vesicles in castrated and hypophysectomized rats
Authors: Ahmad Nazir , Warren Dwight W. , Haltmeyer Gary C.
Published: February 2005

The effects of 5α‐androstane‐3α,17β‐diol (3α‐diol) and 5α‐androstane‐3β, 17β‐diol (3β‐diol) were studied in rats hypophysectomized and treated daily for 30 days with the steroids, starting on the day of surgery (hypophysectomized, H) or 30 days following the removal of pituitary (hypophy‐sectomized regressed, HR). The ability of 3β‐diol to maintain and restimulate the prostate glands and seminal vesicles of castrated (C) and castrated regressed (CR) rats, respectively, was also studied. This androgen (3βdiol) was able to maintain as well as rejuvenate to some degree the sexual accessory glands of all treatment groups. The prostate glands and seminal vesicles in both castrated experimental groups showed increased stimulation with progressively higher dosages of 3β‐diol. At all dose levels, stimulation of seminal vesicles of CR rats was comparable to that of non‐regressed castrates. The prostate glands, on the other hand, showed better maintenance in the higher dosage group. In H rats, the stimulation of sexual accessory glands by both androgens was not significantly different than normal controls. The seminal vesicles and prostate glands of HR rats treated with 3α‐diol were well stimulated and comparable to those of H rats treated with 3α‐diol. The seminal vesicles of HR rats treated with 3β‐diol were also well stimulated, though not to the extent as those with 3α‐diol treatment. The prostate glands of the 3β‐diol treated HR rats were significantly smaller than those of the 3α‐diol treatment group. However, these miniature glands were morphologically stimulated as evidenced by mitosis of parenchymal cells and accumulation of secretory products in the alveoli. This study clearly indicates that 3β‐diol is biologically active and the degree of stimulation varies with the animal preparation in which the andro‐gens were tested.
Effects of testosterone enanthate on the structure of the male reproductive tract of the rat
Authors: Flickinger Charles J.
Published: February 2005

The histology and fine structure of the testis, epididymis and sex accessory glands were studied in young adult male rats administered testosterone enanthate, 120 μg/100 g body weight, three times weekly for 4, 8, or 12 weeks. The weights of the testis and epididymis decreased, and animals treated for 11 weeks were infertile. Alterations were found in the seminiferous tubules of all rats treated for 8 or 12 weeks, including the presence of many degenerating germ cells and a‐large decrease or absence of late spermatids. Study of different stages of the cycle of the seminiferous epithelium showed that the greatest number of degenerating germ cells, step 7 spermatids and pachytene primary spermatocytes, occurred at stages VII‐VIII of the cycle. Some normal appearing spermatogonia, primary spermatocytes and early spermatids remained in most seminiferous tubules. Sertoli cells contained many lipid droplets and lysosome‐like bodies, and degenerating cells were surrounded by Ser‐toli cell cytoplasm. The Leydig cells of treated animals were greatly reduced in size. Sperm progressively disappeared from the lumen of the middle segment and proximal part of the terminal segment of the epididymis after treatment for 8 or 12 weeks. Changes in the middle segment also included the appearance of intraepithelial cavities containing debris, and the presence within the epithelium of phagocytic cells that resembled leukocytes. The lumen of the proximal part of the terminal segment was often collapsed, while in the distal part of the terminal segment, the lumen was filled with cellular debris and degenerating sperm. Organelles of the principal cells of the epididymal epithelium appeared to be qualitatively unaltered. The weight of the sex accessory glands remained close to normal, and the presence of normal ultrastructural features suggested that production of secretions continued.
Linear arrays of intramembrane particles on microvilli in primate large intestine
Authors: Neutra Marian R.
Published: February 2005

Distinctive linear arrays of intramembrane particles were present in microvillar membranes of approximately 5% of surface columnar cells observed in freeze‐fracture replicas of monkey colon and human rectum. On these cells, longitudinally‐oriented rows of P face particles and corresponding E face grooves appeared on all exposed microvilli. The constituent particles varied from round (8‐9 nm in diameter) to rod‐shaped (18 nm long). Microvilli of the great majority of columnar cells displayed randomly distributed P face particles similar to those previously observed in small and large intestine of birds and small mammals. The significance of the linear arrays is not known. It is postulated that they may represent protein assemblies which are specific to a functionally‐distinct subpopulation of primate intestinal columnar cells.
Histochemical characteristics of the masseter and temporalis muscles of the rhesus monkey (Macaca mulatta)
Authors: Maxwell Leo C. , Carlson David S. , McNamara James A. , Faulkner John A.
Published: February 2005

The histochemical characteristics, cross‐sectional area and capillary of the skeletal muscle fibers of the anterior and posterior regions of the superficial masseter and the temporalis muscles are described for juvnile and adult rhesus monkeys of both sexes. Slow twitch fatigue resistant (S), fast twitch fatigue resistant (FR) and fast twitch fatigable (FF) fibers were found in varying proportions throughout the muscles; however some fibers with an intermediate myofibrillar ATPase activity were observed in the anterior masseter. No significant differences for any of the variables were found between male and female juveniles for a specific muscle sample site. However, consideable variation was found between juvenile and adult and between adult male and female monkeys in the percentages of different fiber types and the cross‐sectional area of fibers in specific regions of the superficial masseter and temporalis muscles. We conclude from these observations that significant differences in funtion exist both within and between the different masticatory muscles of rhesus monkeys. Functional differences may result from the pronounced sexual dimorphism evident in the dentofacial complex of rhesusmonkey.
The distribution of alkaline phosphatase activity in normal and cross‐species regenerated rat and mouse taste buds
Authors: Zalewski Andrew A.
Published: February 2005

Alkaline phosphatase (ALK Pase) activity can be detected histochemically in the taste buds of rats but not mice. Since taste buds develop, regenerate and are maintained under the influence(s) of the sensory nerve it was decided to study cross‐species regenerated buds of these two animals to determine whether the nerve also regulated ALK Pase development in taste cells. Grafts of rat sensory ganglion and mouse tongue or mouse ganglion and rat tongue were combined in the anterior chamber of the eyes of immunologically‐deficient nude mice and the cross‐species buds that developed at 35 days were examined histochemically for ALK Pase. The results revealed that the rat nerve did not cause ALK Pase to appear in any buds found in mouse tongue grafts and that mouse nerve could support buds containing ALK Pase in rat tongue tissue. Because the cross‐species regenerated buds were histochemically characteristic of those normally found in rat or mouse tongue, there is no evidence that the foreign nerve altered gene expression for ALK Pase in the target organ, and the action of the nerve on gustatory epithelium appears to be that of activation and maintenance.
Chromatin substructure: An electron microscopic study of thin‐sectioned chromatin subjected to sequential protein extraction and water swelling procedures
Authors: Cameron Ivan L. , Pavlat William A. , Jeter James R.
Published: February 2005

Electron microscopic observations and measurements were made on thin‐sectioned chromatin fibers and fibrils obtained from nuclei of mature chicken erythrocytes. The nuclei were isolated in low ionic strength gum arabic and octanol then extracted sequentially with (1) 0.14M NaCl, (2) 0.25 N HCl, (3) buffer saturated phenol, (4) hot 5% SDS and 0.14 M 2‐mercapto‐ethanol and, (5) 0.4 N NaOH. The amount of nuclear protein removed at each of the first four extraction steps was 1, 86, 3 and 11% of the total, respectively. Each extract was characterized by electrophoretic profiles. At each extraction the chromatin was fixed by adding large quantities of a mixture of equal volumes of sodium cacodylate buffered 8% (w/v) glutaraldehyde (pH 6.8) and 2% OsO4 (w/v), directly into (1) an aliquot of the chromatin in extraction fluid, and (2) an aliquot of the chromatin after water washing and swelling. Three size classes of chromatin structure were seen in thin sections prepared for high resolution transmission electron microscopy and stained with uranyl acetate and lead citrate. A thick fiber of about 25 + nm diameter was the predominant large fiber seen in freshly isolated nuclei or in nuclei after salt extraction. This 25 + nm fiber has a substructure consisting of 3.2‐5.2 nm diameter fibrils. After water swelling of such freshly isolated or salt extracted nuclei a fiber of about 10 nm diameter was the predominant large fiber instead of the 25 nm diameter fiber. The HCl extraction step which is known to remove histones, caused the disappearance of both the 25 nm and the 10 nm fibers. High magnification (600,000 × ) micrographs of the chromatin at all procedural steps, except the last NaOH step, reveal the fibril to be omnipresent. This fibril tends to decrease somewhat in diameter during the protein extraction steps to a 2.5 nm diameter fibril after the hot SDS extraction. A fibril of 2.5 nm diameter is expected of naked double helical DNA stained with a positive stain. The NaOH, which is known to denature DNA, completely destroyed the remaining fibril. We interpret our results to indicate that the larger chromatin fiber seen in micrographs of thin‐sectioned chromatin has a fibrillar substructure which probably represents a double coil of native DNA which may have a thin protein coating of its own. The latter fibril may in turn be wrapped around a hydrophobic histone domain, perhaps reflected in the 10 nm diameter fiber which is seen upon swelling of the chromatin. This 10 nm diameter fiber is thought to be further packaged by folding into the 25 + nm diameter chromatin fiber most frequently reported in thin sections of eukaryotic cell nuclei in situ.
Resorption of connective tissue in the gingiva of the mouse incisor
Authors: Schellens J. P. M. , Everts V. , Beertsen W.
Published: February 2005

During eruption of the mouse incisor part of the periodontal ligament moves along with the tooth in occlusal direction and is degraded in the gingiva, just apically of the junctional epithelium. When studied with the electron microscope some connective tissue cells (fibroblasts) showed disorganization of both nucleus and cytoplasm. In other cells vacuoles were observed containing partly degraded cellular constituents. Sometimes within these vacuoles electron dense material with the appearance of clumped chromatin was observed. On the basis of this observation it is concluded that heterophagocytosis contributes to the process of fibroblast breakdown. The ultrastructure of these heterophagic cells resembled that of fibroblasts.

Collagenous fibrils were observed within cytoplasmic vacuoles of fibroblasts indicating that collagen is phagocytosed and probably digested in the lysosomal apparatus. Part of the intercellularspace was filled with a homogeneous material of moderate electron density, intermingled with some collagenous fibrils.

Within some cells of the junctional epithelium partly degraded material was observed which may indicate that the epithelium contributes to the removal of residual products of connective tissue degradation.
The effect of colcemid on the structure and secretory activity of ameloblasts in the rat incisor as shown by radioautography after injection of 3H‐proline
Authors: Karim A. , Warshawsky H.
Published: February 2005

Enamel secretion by ameloblasts was investigated in the incisors of 100 gm normal and colcemid‐injected male rats. Morphological studies were done on rats given a single intraperitoneal injection of 0.1 mg (1.25 mM) of colcemid and sacrificed 1 to 4 hours after injection. Protein synthesis and secretion were investigated with radioautography in normal and colcemid‐treated rats injected with 3H‐proline and sacrificed at intervals between 0.5 and 3.5 hours after injection. Colcemid was injected 0.5 hours prior to 3H‐proline in each experimental rat. Electron microscopic examination revealed several morphological alterations between 1 and 4 hours after injection of colcemid. These changes included fragmentation of the normally elongated rough endoplasmic reticulum into shorter profiles; a disorganization of thenormally tubular configuration of the Golgi apparatus into a number of separate but intact stacks of Golgi saccules; the disappearance of secretion granules and profiles of smooth endoplasmic reticulum from Tomes' processes; and the accumulation of secretion granules at the mature face ofthe Golgi stacks, as well as in the infranuclear cytoplasm where they are normally not found. Radioautography revealed that protein synthesis by the rough endoplasmic reticulum had continued in colcemid‐altered ameloblasts. Labeled secretion granules were found at the mature surface of the Golgi stacks and in the infranuclear cytoplasm, however they did not migrate into Tomes' processes. Consequently, labeled enamel matrix did not appear extracellularly at the same time as in normal controls. Quantitative radioautography in the light microscope revealed that the effect of colcemid, although reversed within 4 hours, had temporarily inhibited normal migration and exocytosis of secretion granules.
Hormones and the lung II. Immunohistochemical localization of thyroid hormone binding in type II pulmonary epithelial cells clonally‐derived from adult rat lung
Authors: Wilson Marjorie , Hitchcock Karen R. , Douglas William H. J. , Delellis Ronald A.
Published: February 2005

The type II pulmonary epithelial cell is the recognized site of surfactant synthesis and storage. Results of recent studies indicate that the thyroid hormones, triiodothyronine (T3) and thyroxine (T4), may be important regulators of surfactant production and/or release. Direct and indirect immunofluorescence techniques were used in an attempt to demonstrate binding of T3 and T4 in monolayer cultures of isolated type II cells. These cultured epithelial cells are clonally‐derived from adult rat lung, retain a diploid karyotype through 35 population doublings in vitro, contain granular inclusions (lamellar bodies) in the perinuclear cytoplasm, and synthesize phosphatidylcholine via the CDP‐choline pathway.

In isolated type II cells, either of two fluorescent patterns was observed: (a) nuclear fluorescence accompanied by a reticular perinuclear network; or (b) diffuse cytoplasmic accumulations with concentrations around perinuclear cytoplasmic inclusions. Ultrastructurally these inclusions had the typical appearance of lamellar bodies. Histochemical studies demonstratedthat these inclusions contained surfactant‐associated nonspecific esterases and stained with Nile blue hydrochloride. The positive reactions with these two recognized markers for pulmonary surfactant indicate that these inclusions are indeed lamellar bodies, the putative sites of surfactant synthesis and/or storage. These findings suggest that the type II pulmonary epithelial cell contains specific binding sites for thyroid hormones, and support the hypothesis that thyroid hormones are regulators of surfactant metabolism.
Distribution of wheat germ agglutinin binding sites on normal human and guinea pig bone marrow cells: An ultrastructural histochemical study
Authors: Ackerman G. Adolph
Published: February 2005

The wheat germ agglutinin‐gold labeled ovomucoid (WGA‐Ovo‐G) method has been employed in the ultrastructural localization of WGA surface receptor sites on gluteraldehyde‐fixed normal human and guinea pig bone marrow cells. The number of gold particles per micron of cell surface were counted and data subjected to statistical analysis. WGA labeling ofthe bone marrow cells was found to be quite heavy and evenly distributed along the cell surface. Only macrophages, in both species, and a number of lymphocytes in the guinea pig exhibited limited WGA labeling. Comparison of morphologically similar cell types in human and guinea pig marrow indicated that WGA receptor sites were more abundant on the guinea pig hemic cells. WGA surface labeling was found to be not only related to cell type and to animal species but, in some instances, varied with the stage of maturation of a given cell line; viz., neutrophilic cell series in both man and guinea pig and erythrocytic cell series in the guinea pig.
Surface morphology of macrophages in the regressing corpus luteum, as revealed by scanning electron microscopy
Authors: Paavola Laurie G. , Boyd Charles O.
Published: February 2005

Activated macrophages phagocytize moribund luteal cells and thus play a central role in the postpartum regression of corpora lutea in guinea pigs (Paavola, '79). When viewed by transmission electron microscopy (TEM), these luteal macrophages exhibit many surface protrusions. To characterize more fully the nature and extent of these evaginations, as well as to gain further understanding of phagocytes in their natural surroundings, luteal macrophages were studied in situ by scanning electron microscopy of regressing corpora lutea. Correlated TEM was carried out to confirm the identity of the various cell types. Even in low power scanning electron micrographs, macrophages are conspicuous, and can be readily distinguished from luteal cells by their surface topography. Luteal cell surfaces bear low ridge‐like folds and sparse microvilli. In contrast, macrophages characteristically exhibit highly developed surface projections, the most common of which are knob‐like or clubbed processes of varying size and shape. Other distinctive surface modifications displayed by luteal macrophages include long, slender filopodia, and well developed pseudopodia. These processes generally have an uneven distribution over the cell; thus, luteal macrophages may appear polarized with regard to surface activity. Both filopodia and pseudopodia occur in close contact with luteal cell surfaces. In addition, occasional luteal macrophages have surfaces that are covered with large, crater‐like depressions. The phagocytosis ofcells and cellular debris by macrophages was also observed. In summary, the highly pleomorphic surface activity of luteal macrophages appears to be correlated with their role in the removal of senescent luteal cells.
Roentgen cephalometric studies on skull development in rats. III. Gigantism versus acromegaly: Age differences in response to prolonged growth hormone administration
Authors: Savostin‐Asling Irene , Nakaiye Roy , Asling C. Willet
Published: February 2005

Experimental conditions simulating the induction of clinical pituitary gigantism and acromegaly were established by prolonged administration of growth hormone in high dosage to adult male rats starting at two different ages: 6 months (growth still active) and 14½ months (growth virtually arrested). Treatment continued for 14½ months, controls receiving saline injections. Each group numbered eight at onset. Standardized x‐rays of skull were made in ventro‐dorsal and lateral planes, at onset, mid‐period, and end of the study. Representative dimensions of cranial and facial segments were measured, including lengths, widths, palate dimensions, gnathic and interzygomatic angles, and incisor curvature. Some related indices were calculated. Means and standard errors were computed, usually on five to eight rats (oldest controls: three only). The response pattern of overall skull length was most illustrative. Younger adult controls grew actively until 14 months of age (5%) while injected rats grew still faster (8%); thereafter, controls grew negligibly (1%) and injected rats only slightly (2%). Older controls showed negligible skull elongation from 14½ to 29 months of age, and growth hormone stimulated no gain. In the younger group, skull length gains were almost entirely in the facial region; cranium gained no length and widened only slightly. Cranial index increased slightly with the hormone. Facial (bizygomatic) width increased in both injected groups—proportionately in younger rats (to gigantism) and disproportionately in older rats. Palatal and dental growth followed facial patterns in both groups. Cranial vault bones thickened and, in older rats, developed surface irregularities, giving them a more massive, acromegaloid structure.
Morphology of the guinea pig respiratory tract
Authors: Schreider Jay P. , Hutchens John O.
Published: February 2005

A morphologic description of the airways of the guinea pig was developed from measurements of casts of the lungs and nasal cavity and from measurements of frozen sections of the lungs. The lengths, diameters, branching pattern, and numbers of elements of the respiratory tract formed the basis for a representative model of the system. The brainching pattern is irregular to the pulmonary region but regularly dichotomous thereafter. The nasopharyngeal‐tracheobronchial region contributes 2.64 cm3 of the total respiratory volume of 21.62 cm3. The alveoli contribute 16.31 cm3 of the 18.98 cm3 pulmonary region. The nasal region consist of convoluted and irregular airways with a functional volume of 0.48 cm3.
The occurrence of an unusual tubular organelle in surface epithelial cells of the mouse ascending colon after injection of diazo‐oxo‐norleucine
Authors: Michaels John E.
Published: February 2005

Tubular structures were observed in surface epithelial cells of mice that had been injected with high dosages of diazo‐oxo‐norleucine (DON), a glutamine antagonist. The tubules often occurred in bundles which contained a variable number of tubules, often as many as one hundred being present. Within the bundles, the tubules were oriented either randomly or parallel to one another. They measured 25 to 35 nm in diameter with angular or circular profiles and were as long as 1 to 2 μm. In the center of each tubule, a smaller tubule‐like component was evident that measured 5 to 7 nm in diameter. With the exception of endoplasmic reticulum, often with attached ribosomes, organelles were excluded from the bundles. Since the tubules and the endoplasmic reticulum occasionally were observed to be continuous, it is suggested that the tubules may originate from this organelle.
A new organic solvent for use in the clearing of tissues. I. Soft tissue histology
Authors: Wishe Harvey I. , Roy Martin , Piliero Sam J.
Published: February 2005

Histosol is a non‐flammable solvent mixture of synthetic aromatic hydrocarbons with a flash point of 124°F (T.C.C.). It has a lower vapor pressure and evaporation rate than other organic solvents, such as xylene, routinely used as clearing and deparaffinizing agents. Although both xylene and Histosol clear and deparaffinize soft organ tissues effectively in the preparation of permanently mounted stained slides, Histosol appears, in many instances, to be the choice solvent: tissues are easier to section; cell bordrs and cell surface modifications are most distinct; cytoplasmic eosinophilia is more vivid; and nuclear detail is improved. Of prime importance, Histosol is a safer and more efficient solvent for use in histological and pathological laboratories.
Proliferation of epithelial cells in the adult primate choroid plexus
Authors: Kaplan Michael S.
Published: February 2005

An adult rhesus monkey was injected intraperitoneally with [H3] thymidine (2.3 μCi/gram body weight) and perfused 90 minutes later with a mixture of aldehydes. One and a half micrometer plastic sections were then cut and dipped into liquid emulsion for radioautography. Labeled cells were observed in the choroid plexus of the anterior lateral ventricle; cell identification was evaluated using electron micrographs taken from serial thin sections of reembedded. radioautographic 1.5‐μm sections. The ultrastructure and location of both mitotic figures and labeled cells confirmed the presence of undifferentiated basal choroid plexus epithelial cells in the adult primate central nervous system.
Ultrasonographic determination of lumbar spine angulation
Authors: Jones Norbert A. , Gonzalez Antonio C.
Published: February 2005

Abdominal ultrasonograms of recumbent, supine adult subjects were used to measure the angle formed between the horizontal plane and a plane along the anterior border of upper lumbar vertebral bodies. The angle, referred to as Φ, for male and female subjects averaged 8.8°. When this angle was compared in subjects with the hips flexed and extended, there was no significant difference. There was a significant difference between subjects in a recumbent position and a standing position. The amount of angulation was compared to the age of the individual and found to have a low correlation coefficient. The angle Φ appears to be a good indicator of the amount of lordosis, it relates well to previous methods of measuring lordosis, and it is a benign procedure in a genetically sensitive region.
The ultrastructure of cultures from the swarm rat chondrosarcoma
Authors: Hascall Gretchen K. , Kimura James H.
Published: February 2005

When chondrocytes from the Swarm rat chondrosarcoma are isolated by trypsin and collagenase digestion and cultured in Petri dishes, they form a new extracellular matrix within 24 hours, with proteoglycan matrix granules and collagen fibrils. This rapid synthesis of new matrix, together with the biochemical and morphological characterization of the proteoglycans as typical of cartilage, demonstrates the value of these cultures as a model system for studies of synthesis, secretion, and organization of extracellular matrix.
Mitosis in pituitary MSH/endorphin cells of adult male rat pars intermedia: Light and electron microscopic observations
Authors: Saland L. C.
Published: February 2005

Small numbers of dividing cells were observed in the pituitary intermediate lobe of normal and p‐chloroamphetamine‐treated adult male rats. Ultrastructural examination reveals that the mitotic elements are granulated MSH/endorphin cells. Nerve fibers providing direct innervation could be found on dividing cells. The observations illustrate a limited potential for proliferation in the adult MSH/endorphin cell population.
The development of enamel structure in rat incisors as compared to the teeth of monkey and man
Authors: Warshawsky H. , Josephsen K. , Thylstrup A. , Fejerskov O.
Published: February 2005

The rat incisor is an excellent model system in which to study amelogenesis. However, the information obtained has not been extrapolated to the human because of alleged structural differences between the teeth. The obvious differences include continuous eruption in rat incisors and an enamel rod pattern in rats which seemingly differs from the keyhole pattern of human enamel. A comprehensive analysis was made of those features of enamel structure considered fundamental to the understanding of its formation. This was done by applying the knowledge of amelogenesis obtained in rat incisors to the teeth of monkey and man. The following points of basic similarity were established between these species: (1) Interrod enamel is secreted first. It forms the side walls of cavities which are initially occupied by Tomes' processes. (2) The formation of interrod cavities is followed by deposition of enamel rods within these spaces. (3) The rods conform to the shape of the cavities and are secreted from one surface of Tomes' process. (4) At the initial site of rod deposition its enamel is continuous with the interrod enamel wall. (5) Growth of the rod compresses the process to one side of the cavity resulting in an arcade‐shaped “space” between the rod and the remaining interrod walls. This study demonstrates that it is no longer necessary to postulate a keyhole structure for primate enamel, and it has established that a fundamental similarity exists in the basic structure and in the mode of formation of enamel in all three species.
Further electrophysiologic and anatomic correlates in a canine model of chronic myocardial infarction susceptible to the initiation of sustained ventricular tachyarrhythmias
Authors: Michelson Eric L. , Spear Joseph F. , Moore E. Neil
Published: February 2005

A canine model of chronic myocardial infarction has been studied in which animals are susceptible to the initiation of sustained ventricular tachyarrhythmias using routine methods of programmed stimulation. The pacinginduced arrhythmias in this model are similar to those observed in man in their mode of initiation and termination, as well as in their response to both pacing and pharmacologic interventions. Indirect evidence has suggested a localized protected reentrant mechanism for these arrhythmias. The susceptibility to arrhythmia initiation in this model has been related to both electrophysiologic and histopathologic findings. Consistently, animals have demonstrated a marked heterogeneity of local properties of excitability and refractoriness at sites within areas of infarction. Correspondingly, animals have shown a marked inhomogeneity of histopathologic findings within areas of infarction, with close interspersing of normal and abnormal myocardium. Remarkably, even animals with small mottled infarctions, often less than 1 cm × 2 cm and electrocardiographically silent, were highly susceptible to the initiation of ventricular tachyarrhythmias, and especially fibrillation. Thus, initial provocative studies in this model have suggested its potential importance both in studying arrhythmia mechanisms and in evaluating the efficiency of potential antiarryhthmic interventions. In addition, this should be an ideal model in which to correlate pathophysiologic and morphologic alterations in the setting of chronic myocardial infarction.
A congenital abnormality in the arrangement of muscle bundles in a segment of the distal ileum, producing obstruction: A variant of the so‐called “giant meckels's diverticulum”
Authors: Valdes‐Dapena Marie A. , Marchildon Michael B. , Poole Catherine A.
Published: February 2005

This 4‐year‐old male child was diagnosed at birth as having several minor congenital anamolies. X‐rays taken during the first year of his life showed a single, massively dilated loop of bowel in the upper abdomen, not appreciated at the time.

In 1980 he was admitted to Jackson Memorial Hospital with the diagnosis of small bowel obstruction. An upper gastrointestinal series showed one tremendously dilated loop of distal ileum. At laparotomy, the patient was found to have extreme segmental dilatation of one loop of distal ileum which ended abruptly; there was no evident external cause for obstruction.

The resected loop contained in excess of 200 cc of watery brown liquid. The mucosal folds and underlying smooth muscle bundles, in the dilated portion only, were not arranged circumferentially but rather in a distinctive finger‐print‐like pattern with trifurcations, whorls, and intricate interdigitations which had probably produced contractions of a circus type rather than normal peristalic waves.

We have been able to find only three reports in the literature in which, as was the case here, the so‐called “giant Meckel's diverticulum” presented as a single tremendously dilated segment of ileum, sharply demarcated at its distal end. In none of them is there any description of the orientation of muscle bundles. We believe that the abnormal arrangement of smooth muscle in the muscular coat in this specimen, and perhaps in the others, probably represents the underlying cause for the extreme localized dilatation.
The origin of the hippocampal commissure in the rat
Authors: Voneida Theodore J. , Vardaris Richard M. , Fish Stephen E. , Reiheld Craig T.
Published: February 2005

The present study was designed to determine the origin of commissural axons in the hippocampus. One hippocampus of 94 rats was pressure injected with 40% horseradish peroxidase (Sigma VI), or with 2–4% wheat germ agglutinin HRP (E‐Y Labs). Injections (0.001 to 0.1 μ1) were made through glass micropipettes with fitted plungers. Pipettes were positioned stereotaxically, and by electrophysiological monitoring through the injection syringe. An ipsilateral stimulating electrode activated CA3 and CA1 cells via Schaffer collaterals. Population potentials were monitored as the recording pipette was advanced from the cortical surface into the hippocampus. Wave forms of monosynaptically elicited field potentials provided an accurate indicator of its position. Following survival periods of 24 hours, the brains were processed according to the Mesulam method. Forty‐micron sections were serially mounted and counterstained. Injection sites and filled cells were plotted manually on a standard set of coronal sections. Our results indicate that field CA1 receives input from contralateral subfields CA1a and c, as well as from all CA3 subfields. In addition, rostral CA1 injections resulted in labeling of cells in the contralateral subiculum and entorhinal cortex. Homotopic connections exist between subfields CA3a and b; it appears that a major input to CA3c is from the contralateral polymorph cells of the dentate hilus. Commissural input to the dentate granule cells appears to be the giant polymorph and CA3c cells of the contralateral dentate hilus. With respect to the question of homotopicity our results suggest that commissural connections are predominantly homotopic in the mediolateral plane, although CA1 and CA3 injections also resulted in contralateral labeling of hippocampal cells caudal to the levels of injection.
The somatotopic organization of the cat trigeminal ganglion as determined by the horseradish peroxidase technique
Authors: Marfurt Carl F.
Published: February 2005

The somatotopic organization of the cat trigeminal ganglion has been investigated in the present study by using the horseradish peroxidase (HRP) technique. In separate animals, the corneal, supraorbital, infraorbital, inferior alveolar, or mental branches of the trigeminal nerve have been transected and then soaked in concentrated solutions of HRP. Retrogradely labeled corneal and supraorbital neurons have been found, with extensive overlap between the two cell populations, in the anteromedial region of the trigeminal ganglion. Inferior alveolar and mental neurons have been found to possess similar distributions within the posterolateral part of the trigeminal ganglion. Infraorbital cells have been localized in a central position. The cell bodies of any given nerve are found in at least minimal numbers in all dorsoventral levels of the trigeminal ganglion. However, cell bodies of origin of the supraorbital nerve and the lateral branch of the infraorbital nerve, innervating more posterior or lateral areas of the head and face, are found in greater numbers dorsally. Conversely, cell bodies of origin of the medial branch of the infraorbital nerve, the inferior alveolar nerve, and the mental nerve, supplying more rostral or intraoral areas of the orofacial region, are present in greater numbers ventrally. In contrast, corneal neurons are distributed uniformly in the dorsoventral axis. The ophthalmic and maxillary regions of the trigeminal ganglion appear to be well segregated, whereas the maxillary and mandibular regions exhibit a somewhat greater degree of overlap. Cell bodies of corneal afferent neurons range from 20 to 50 μm in diameter, whereas those of supraorbital, infraorbital, inferior alveolar and mental neurons measure from 20 to 85 μm. It is concluded from the findings of the present work that much of the cat trigeminal ganglion is organized somatotopically in not only the mediolateral axis but also in the dorsoventral axis.
An improved method for processing single cells for electron microscopy utilizing agarose
Authors: Yuan Lydia C. , Gulyas Bela J.
Published: February 2005

An improved method is presented for processing single cells for electron microscopy. Agarose, which has a low (30°C) gelling temperature, was used as an initial embedding medium for single cells (spermatozoa and oocytes) and dissociated cell preparations (luteal cells and spleen cells). Dispersed cells of corpus luteum, spleen, and epididymal spermatozoa were placed in 1.5% agarose after aldehyde fixation. These fixed cells, embedded in agarose, were packed into a dense pellet by centrifugation, postfixed, then embedded in Epon. Mammalian eggs were not centrifuged; instead, they were embedded in agarose discs. Cells embedded in agarose were cooled below 30°C to allow for gelling, then processed for electron microscopy. Because agarose has a low gelling temperature, some heat‐labile substances were preserved, as demonstrated by retention of peroxidase activity using the DAB histochemical method. The agarose embedding procedure is both rapid and facile, and has proven to be of value in the handling of fragile single cells for electron microscopic studies.