bluuebunny/crossref_metadata_2025 huggingface dataset:
Quantitative cell changes and vascularisation in the early corpus luteum of the pregnant rat
Authors: Meyer Geoffrey T. , Bruce Neville W.
Published: February 2005

Early corpora lutea (CL) of the rat were histologically examined on Day 1, 2, 4, and 6 of gestation. Measurements were taken of total volume and of the number of luteal and endothelial cells in one CL of both ovaries of five rats at each stage examined. CL volume increased over the 6 days from ‐‐0.76 to 1.39μl and peripheral plasma progesterone levels from 8.1 to 33.2 ng/ml. The number of luteal cells per CL (range 303,000 to 37,000) did not significantly change, and there was no evidence of mitosis or death amongst these cells. Luteal cell volume increased from 1.74 to 3.49 pl and nuclear volume from 0.25 to 0.38 pl, the former being the major cause of CL growth. The CL appeared to be richly vascularized, even on Day 1, and the number of endothelial cells per CL (range 289,000 to 354,000) remained relatively constant over the period examined.

It was concluded that the number of luteal cells per CL is determined prior to or around ovulation in the rat and that subsequent growth of the CL is due to hypertrophy and not hyperplasia.
Tridimensional study of the deep cortex of the rat lymph node. III. Morphology of the deep cortex units
Authors: Bélisle C. , Sainte‐Marie G.
Published: February 2005

Recently we reported that the deep cortex of the rat lymph node is made up of semi‐rounded “units,” some of which are partially fused into “complexes”. We further found that each unit is centered on the opening(s) of an afferent lymphatic vessel, the topographical organization of the deep cortex of a node correlating with the distribution pattern of the opening(s) of its afferent lymphatic(s). The present study aims to clarify the morphology of the deep cortex unit, particularly with regard to its reticular framework, its lymphatic sinuses, as well as its network of postcapillay venules. For that purpose, we analyzed rat nodes from various locations by way of tridimensional reconstruction. The observations revealed that each unit is formed of a “center” and a “periphery,” distinguishable from one another on the basis of their morphological features. The center is nearly devoid of reticular fibers, whereas the periphery exhibits a dense framework of fibers. Moreover, the periphery is the site of concentration of most postcapillary venules of a unit and contains lymphatic sinuses which, peculiarly, are often loaded with small lymphocytes. While both regions are populated mainly by small lymphocytes, the periphery usually contains a lower concentration of these cells than the center. The overall findings support the view that the center is a site of cellular retention and proliferation, whereas the periphery is a site of rapid lymphocyte migration in and out of the unit.
Tridimensional study of the deep cortex of the rat lymph node. IV. Differential labelling of the deep cortex units with 3H‐uridine
Authors: Sainte‐Marie G. , Peng F.‐S. , Bélisle C.
Published: February 2005

Using tridimensional reconstruction, it was recently found that the deep cortex of rat lymph nodes comprises one to several basic “units”. Each unit is a semi‐rounded structure contiguous to the peripheral cortex and bulging into the medulla of a node. Other investigators reported that transfused lymphocytes, heavily labelled in vitro by 3H‐uridine, became concentrated in an illdefined region of nodes, referred to as the mid and deep cortex. This suggested to us that the in vivo labelling of nodes with 3H‐uridine, might allow to further characterize the units on a physiological basis. Therefore, rats were injected intraveously with a dose of 1–20 μCi of 3H‐uridine/gm body weight and sacrificed 1 hour to 3 days later. The radioautographs of their nodes were exposed up to 535 days. The observations revealed that a large dose of 3H‐uridine combined with a long exposure of the radioautographs yielded a differntial labelling of the cell population of the units, characterized by a much more intense reaction than that of the surrounding structures. This demonstrated that the physiology of the lymphocyte population of the deep cortex units differs from the morphologically similar lymphocyte population of the extrafollicular zone of the peripheral cortex. The possible reason(s) for the differential labelling of the units is discussed.
Unusually complex basement membranes in the midgut of two decapod crustaceans, the stone crab (Menippe mercenaria) and the lobster (Homarus americanus)
Authors: Factor Jan Robert
Published: February 2005

Ultrastructural studies of the stone crab (Menippe mercenaria) and the lobster (Homarus americanus) demonstrate that the basement membrane of the midgut (intestine) is unusually complex. In both species, the basement membrane is three‐layered and has processes that form extensive networks protruding into the connective tissue. The possible functional significance of this complex structure is discussed.
The origin of the epicardium and the embryonic myocardial circulation in the mouse
Authors: Viragh Szabolcs , Challice Cyril E.
Published: February 2005

The origin of the epicardium and the formation of the early blood vessels of the heart prior to the opening of the coronary arteries from the aorta have been studied in the 9–13.5 day post coitum (dpc) mouse embryo heart. The epicardium begins to appear by 9 dpc. The majority of the epicardial cells derive from the somatopleural investment of the septum transversum, from where they migrate, associated to form vesicles, to the dorsal aspect of the ventricles and atria. The epicardial cells then migrate over the lateral surfaces and the AV sulcus to the ventral aspect of the heart. In the subepicardial space around the sulcuses, the proliferating epithelial tissue is found, also in vesicular form, for a time. The ventrally migrating primordial epicardial tissue ensheaths lastly the truncus arteriosus, while the sinus venosus is coated with epicardium ab initio, where (and also in the SA sulcus) the epicardial cells derive in part from the cuboidal cells of the pleuroperitoneal canal and in part from the somatopleural cells. The early blood vessel formation follows in space and time the development of the epicardium. The first blood vessels appear by 10 dpc by the invagination of the endocardium into the early sinus muscle, and at the same time in the ventricular chamber by the encasing of the endocardium, as the trabeculae become consolidated into the myocardial walls. By this process sinusoids are formed, some of which penetrate through the myocardium and which, by rapid proliferation, form an interconnected subepicardial plexus. These capillaries proliferate ventrally in the wide subepicardial space, reaching the septating truncus, in which the aorta and pulmonary artery are developing. The definitive coronary artery openings appear by 13 dpc, allowing the high pressure blood from the aorta to flow into a preexisting vascular bed.
The wolff‐parkinson‐white syndrome and its anatomical substrates
Authors: Becker Anton E. , Anderson Robert H.
Published: February 2005

The anatomical substrates that underlie the clinical syndromes of preexcitation are still incompletely understood. Regarding the Wolff‐Parkinson‐White syndrome, there is increasing evidence that early ventricular activation is caused by accessory atrioventricular connections. These are muscular connections existing outside the specialized conduction tissue axis, which are almost always composed of working myocardial fibers. Left‐sided accessory atrioventricular connections have been identified with most frequency. They occur in the presence of a well‐developed fibrous annulus, thus contradicting the hypothesis that faulty development of the annulus is a necessary accompaniment. For right‐sided and septal connections, this developmental concept may still hold, since there is marked variability in the formation of the right‐sided annulus fibrosus. Even within these settings, however, the topography of accessory atrioventricular connections may vary considerably. Usually the accessory connection will pass on the epicardial aspect of the annulus fibrosus, particularly when leftsided. The connections are closely related to the fibrous annulus, but in other instances they may be in a superficial location. Multiple connections can occur in one heart. These anatomical features are of paramount significance for successful surgical ablation of accessory atrioventricular connections.
A proposed mechanism for the early development of the human tracheobronchial tree
Authors: Hutchins Grover M. , Haupt Helen M. , Moore G. William
Published: February 2005

The development of the lung in 25 human embryos and early fetuses up to 140 mm crown–rump length was studied by examination of serial histologic sections, morphometry, and selected reconstructions. The proportion of pulmonary tissue consisting of tracheobronchial tree increases during this period. Bronchial cross‐sectional diameter, length of the most distal bronchial branches, and thickness of the distal mesenchyme decline during development. The results are consistent with the concept that the dichotomous branching of the growing tracheobronchial tree occurs because of resistance to forward growth of the bronchial branch by compressed mesenchyme, pleura, or adjacent structures. Division and further growth of the bronchus takes place in areas of lower resistance. This process produces a “filling in” of space available for lung development and brings the epithelial and mesenchymal elements into their definitive relationships.
Regional differences in capillary density and myocyte size in the normal human heart
Authors: Stoker Mark E. , Gerdes A. Martin , May James F.
Published: February 2005

Significant regional morphometric differences are reported for the normal human left ventricle. Epimyocardial capillary density (2,439 capillaries/mm2) is 21% greater than endomyocardial capillary density (2,014 capillaries/mm2). The minimum intercapillary distance is, therefore, increased in the inner region. Endocardial myocytes (617 μm2) have a 53% greater cross‐sectional area than epicardial myocytes (403 μm2).
Femoral mechanics in the lesser bushbaby (Galago senegalensis): Structural adaptations to leaping in primates
Authors: Burr David B. , Piotrowski George , Martin R. Bruce , Cook P. Nong
Published: February 2005

One method used to examine the relationship between behavioral strategies and anatomical adaptation is to study the results of mechanical stress associated with a given behavior and compare this with skeletal adaptations to other behaviors. This comparative approach is appropriate for highlighting combinations of features that are specializations to specific types of behavior. The purpose of this paper is to compare femoral mechanics in Galago senegalensis with previously collected data for macaques and humans as a basis for discussing structural adaptations in the primate hindlimb to leaping. The stiffness and load carrying capabilities of the femoral diaphyses of 27 G. senegalensis were analyzed using the SCADS computer program. The data suggest that the galago femur is well adapted to sustain large sagittal plane compressive loads rather than large bending loads. The straightness of the femoral shaft and large midshaft area moments of inertia prevent buckling from these large compressive loads. Calculations indicate that the ratio of critical buckling load to body weight in galago is 31 times that in macaques and 55 times that in humans. The femur of this saltatory primate is morphologically adapted to resist buckling when subjected to large compressive loads, while those of macaques and humans are better adapted to resist bending moments caused by ground reaction forces acting on the extended limb. The differences between galago on the one hand and macaques and humans on the other suggest that relatively smaller moments about the hip and relatively larger moments about the knee accompany more quadrupedal and bipedal walking, while habitual leaping is associated with relatively larger moments about the hip. These data reinforce the apparent similarity of the mechanical effects of quadrupedal and bipedal locomotion on the femur and dissimilarity with femoral mechanics in habitually saltatory primates.
A quantitative histologic study of bone turnover in young adult beagles
Authors: Kimmel Donald B. , Jee W. S. S.
Published: February 2005

Thirty‐six regions of trabecular bone from two 18‐month‐old beagles and transilial biopsies of 25 female beagles aged 28–52 months were studied following in vivo double tetracycline labeling. Turnover rate varied from about 20% per year to 200% per year among the 36 regions. It was highest in the vertebral bodies and the proximal humerus, and lowest in the proximal ulna and foot‐bones. The mineral apposition rate varied from 0.35 to 1.02 μm/day, with a mean of about 0.7 μm/day, tending to be lower in areas of lower turnover. The specific surface varied from 10.9 to 23.8 mm/mm2 with a mean of 17.5 mm/mm2, tending to be higher in areas of high turnover. Specific surface varied only about twofold around the skeleton, while turnover varied by one order of magnitude. The average annual turnover rate for all trabecular bone in the young adult beagle is estimated at 140% per year. The accuracy of this estimate would be improved by knowing the exact mass of trabecular bone at each site.

The annual turnover rate in the ilium of 25 female beagles was 134 ± 94% per year. The iliac trabecular bone turnover rate is two to three times faster in young adult female beagles than in young adult female humans. Using a human to beagle ratio of 1:2.5, the average annual turnover rate for all trabecular bone in the young adult human could be estimated at 40–55% per year. The beagle may be an appropriate model for certain experiments involving the adult bone remodeling system, because it may show a quicker response than humans to various experimental conditions and drugs, due to its faster turnover rate.
Histochennical properties of some jaw muscles of the lizard Tupinambis nigropunctatus (teiidae)
Authors: Throckmorton Gaylord S. , Saubert Carl W.
Published: February 2005

In many vertebrate limb and jaw muscles constituent fibers with differing contractile and metabolic properties are distributed so as to produce distinct intramuscular oxidative and glycolytic regions. The purpose of this investigation was to determine if similar compartmentalization exists in jaw muscles of the teiid lizard Tupinambis nigropunctatus. Nine jaw muscles from two adults and one juvenile were examined, and serial sections from each muscle were analyzed using histochemical techniques to indicate relative contractile, oxidative, and glycolytic capacities of the fibers and their patterns of distribution. Three distinct fiber types were observed. The histochemical profile of type 1 fibers most closely resembled that of tonic muscle fibers, while profiles of type 2 and type 3 fibers corresponded to those of fast‐twitch glycolytic (FG) and fast‐twitch oxidative (FO) fibers, respectively. Three muscles contained only type 2 (FG) fibers, and two muscles contained a noncompartmentalized mixture of all three fiber types. The remaining four muscles were distinctly compartmentalized, having a small, inneroxidative region containing primarily type 1 (tonic) and type 3 (FO) fibers and a larger, outer region consisting entirely of type 2 (FG) fibers. The possible relationships between fiber types, compartmentalization, and jaw function are discussed.
Association between mitochondria and rough endoplasmic reticulum in rat liver
Authors: Montisano Dominic F. , Cascarano Joseph , Pickett Cecil B. , James Thomas W.
Published: February 2005

Mitochondria were isolated from rat liver homogenate by both zonal and sedimentation equilibrium centrifugation. From electron microscopic examination of thin sections it was observed that 81% of the isolated mitochondria were in contact with rough endoplasmic reticulum (RER). Intact, non‐sectioned mitochondria subjected to negative staining procedures appeared to show points of connection between RER and the outer mitochondrial membrane. After treatment of mitochondria with digitonin to remove outer membranes, some of the resulting mitoplasts (intact inner membranes) remained closely associated with RER. Serial section analysis of intact rat liver indicated that RER saccules fit over mitochondria like caps providing broad areas of contact between the two organelles. The RER saccules were also observed communicating with more than one mitochondrion.
Fine structure of the testis in the toad (Bufo arenarum Hensel): A freeze‐fracture study
Authors: Cavicchia Juan C. , Moviglia Gustavo A.
Published: February 2005

The present work reports novel findings in the toad testis using freeze‐fracture techniques. Tight and gap junctions are observed in the nonfenestrated endothelial cells. Numerous gap junctions are present between interstitial cells. Sertoli‐Sertoli junctional specializations in the toad are similar to those described in mammals although they appear to be less elaborate. The appearance of nuclear pores, in the seminiferous epithelium, ranges from a uniformly and apparently random distribution in Sertoli cells to large aggregations of closely spaced pores separated by free areas in the nuclear envelope of spermatocytes. Inasmuch as these features have also been described in mammals, the fact that they are present in amphibia might indicate that they represent a widespread pattern.

Concomitantly with increasing chromatin condensation, nuclear pores diminish in round spermatids and seem to disappear in the more mature germ cells. The en face freeze‐fracture views of annulate lamellae in the postnuclear cytoplasm and membranous features of the acrosome formation, flagellum, and undulating membrane of elongating spermatids are also described.
Ultrastructural immunocytochemical localization of carbonic anhydrase in normal and calcitonin‐treated chick osteoclasts
Authors: Anderson Richard E. , Schraer Harald , Gay Carol V.
Published: February 2005

Carbonic anhydrase was localized in osteoclasts by light and electron microscopy using a preembedding peroxidase‐antiperoxidase staining method. Osteoclasts on the endosteal surface of the metatarsi of calcitonin‐treated and untreated (control) chicks were studied. A positive staining reaction was seen in the cytosol, in the Golgi apparatus, in and on vesicles, on the plasma membrane of the ruffled border, and on the bone surface beneath control osteoclasts. After calcitonin treatment, positive staining reactions were seen at the same sites except that staining was absent on the plasma membrane and endosteal bone surface. The morphology of osteoclasts from calcitonin‐treated chicks was indicative of cell inactivity. The carbonic anhydrase which was bound to the plasma membrane of the ruffled border is appropriately arrayed for hydrogen ion secretion and subsequent mineral dissolution. The presence of the enzyme within lysosomelike vesicles and on the endosteal surface beneath active cells suggests that it may be released into the resorbing zone along with the lysosomal hydrolases. The function of the extracellular enzyme is also unknown.
Description of the occlusion of the spinal cord lumen in early human embryos
Authors: Desmond Mary E.
Published: February 2005

Previous studies of both chick and human embryos have shown that the brain enlarges rapidly once the neural tube becomes a closed, fluid‐filled system. Prior to such enlargement, the medial walls of the spinal cord appear fused, occluding the lumen. This study describes occlusion of the lumen in terms of its incidence, location along the neuroaxis, time of occurrence, duration of occurrence, and morphology in human embryos. Eighty‐two human embryos (stages 9–15) from the Carnegie Collection were analyzed. Occlusion first occurs (and is most prevalent) in stage 11 embryos and is absent in embryos older than stage 13. In all cases examined, the neuroaxis demonstrated uninterrupted occlusion from the level of the third pair of somites to at least the ninth pair (i.e., approximately 60% of the neuroaxis was occluded). The appearance of the occluded neural tube in cross sections is similar to that of a soda straw that has been pinched between one's fingers.
The chorioallantoic placenta of the spotted hyena (Crocuta crocuta Erxleben): An electron microscopic study
Authors: Oduor‐Okelo Dominic , Neaves William B.
Published: February 2005

The histology and ultrastructure of the chorioallantoic placenta of the spotted hyena have been studied in three specimens obtained in the field and fixed promptly with glutaraldehyde. Observations revealed that the interhemal membrane at its minimal thickness is hemomonochorial, consisting of a continuous layer of syncytial trophoblast, a basal lamina, and fetal capillary endothelium. Cytotrophoblastic cells form a discontinuous layer beneath the syncytial trophoblast and are distinguished by the presence of numerous extracted lipid droplets in their cytoplasm. A network of extracellular spaces, incorrectly identified as cisternae of endoplasmic reticulum by earlier investigators, occurs beneath the maternal surface of the syncytial trophoblast. These spaces contain moderately dense, nonfibrillar material resembling the intrasyncytial lamina previously described only in the hemochorial placenta of certain bats. Hence, these spaces may contain remnants of maternal capillary basal lamina following displacement of the endothelium by extensions of syncytial trophoblast at an early stage of placental development.
Effects of the hypolipidemic drug Nafenopin on the zona fasciculata of the rat adrenal cortex: A correlated biochemical and stereological study
Authors: Mazzocchi Giuseppina , Robba Claudia , Rebuffat Piera , Belloni Anna S. , Nussdorfer Gastone G.
Published: February 2005

The effects of Nafenopin, a hypolipidemic drug, on the zona fasciculata of the rat adrenal cortex were investigated by biochemical, stereological, and cytochemical methods. Chronic Nafenopin treatment (5 days) significantly lowered serum cholesterol level, while it did not alter blood corticosterone concentration and 11β‐hydroxylase activity of adrenocortical cells. Stereology showed a significant increase in the average volume of zona fasciculata cells, which was almost exclusively due to smooth endoplasmic reticulum (SER) proliferation. The volume of lipid compartment was significantly reduced, whereas the volume of diaminobenzidine (DAB)‐positive bodies (peroxisomes) per cell displayed a marked increase. Cholesterol administration per os to the treated animals raised the serum cholesterol level and completely reversed the Nafenopin effects. One day of Nafenopin administration provoked a slight but significant lipid depletion in adrenocortical cells, while 3 days of continuous drug treatment induced an extreme lipid depletion and a moderate increase in the SER coupled with a significant decrease in the plasma concentration of corticosterone. Since microsomal fraction and catalase seem to be involved in the cholesterol metabolism and utilization, the hypothesis is advanced that the Nafenopin‐elicited SER and peroxisome proliferation is a compensatory response enabling adrenocortical cells to maintain an adequate level of hormonal output.
An analysis of the variations in position of the greater palatine foramen in the adult human skull
Authors: Westmoreland Edwin E. , Blanton Patricia L.
Published: February 2005

Three hundred dry, adult human skulls, of East Indian ethnic background, and homogenous in arch form and full eruption of third molars, were examined to measure the location of the greater palatine foramen. The greater palatine foramen was found consistently to lie 1.5 cm from the palatal midline and 0.19 cm from the posterior border of the hard palate. This relationship is suggested as a more accurate method of locating the foramen clinically. The usually accepted description (opposite the second molar) of the relative position of the greater palatine foramen to the upper teeth held in only 9.7% of the skulls studied. This study shows the most common position of the foramen to be opposite or distal to the third molar (57%). The direction of opening of the foramen into the oral cavity was observed to be in an inferior or vertical direction in 247 (82%) of the 300 skulls; in 53 (18%) of the skulls the direction was anterior or horizontal. A bony projection, similar to the mandibular lingula, was observed extending from the posterior margin of the foramen in 95 (16%) of the 600 separate foramina examined. The bilateral symmetry between the sides of the skulls studied was remarkable.
Caudal spinal cord of the teleost Sternarchus albifrons resembles regenerating cord
Authors: Anderson Marilyn J. , Waxman Stephen G.
Published: February 2005

The morphology of spinal cord in the caudal‐most spinal segments of normal adult Sternarchus albifrons is different from that of more rostral adult cord. The caudal segments are strikingly similar to the regenerating spinal cord observed after amputation of the tail in Sternarchus. In the caudal‐most vertebral segment of normal spinal cord, ependymal cells are radially enlarged and are more numerous than in more rostral adult cord. Large processes of the ependymal cells extend into the central canal, which also contains a prominent Reissner's fiber. Invaginations of the outer surface of the spinal cord, with the associated basal lamina, are common. Lateral to the immediate ependymal layer, extracellular spaces contain longitudinally oriented neurites. Cell bodies and cell processes filled with dense‐cored vesicles occur throughout the caudal‐most segment of spinal cord, and are especially concentrated in the ventral half, interspersed with numerous capillaries. In all these respects the caudal‐most segments of normal adult spinal cord in Sternarchus closely resemble regenerating spinal cord of Sternarchus. In both regions, at least some of the ependymal cells retain the ability to divide and generate new neurons and glial cells.
A fine structural and cytochemical study of the rhesus monkey yolk sac: Endoderm and mesothelium
Authors: King Barry F. , Wilson Jean M.
Published: February 2005

This study has examined the fine structure and some cytochemical characteristics of the endodermal and mesothelial cells of the rhesus monkey yolk sac between 25 and 66 days of gestation. The endodermal cells were characterized by abundant granular endoplasmic reticulaum, some agranular endoplasmic reticulum, a well‐developed Golgi apparatus, and numerous large mitochondria. During the earlier part of the period studied, endodermal cells had a few acid phosphatase and arylsulfatase‐positive lysosomes and moderate numbers of catalase‐positive microperoxisomes. During the later stages of development, large granules (believed to be lysosomes) with a heterogeneous content were numerous in the cytoplasm. Mesothelial cells showed fewer development changes. Throughout this period they were usually flattened cells with long microvilli, small mitochondria, and limited amounts of granular endoplasmic reticulum. The mesothelial cells had acid phosphatase reaction product in the Golgi region and occasional large vesicles, but were negative for arylsulfatase and catalase. One specimen was incubated at 37°C in the presence of horseradish peroxidase in order to examine endocytosis. Both the mesothelial cells and endodermal cells internalized the peroxidase into a variety of cytoplasmic vesicles. Based on their cytology, the endodermal cells may function in the synthesis of serum proteins during this period, as has been suggested in other species. They may also be involved in lipid metabolism. The mesothelial cells appeared less synthetically active, but evidence suggested that they may be involved in collagen and extracellular matrix production. The endocytic activity displayed by both cell types may indicate a role in fluid and metabolite transfer across the epithelia. The cytology of both cell types was very similar to that described for human yolk sacs, suggesting that the rhesus monkey may be a useful species in which to study the maturation of yolk sac function.
An ultrastructural study of preovulatory apical development in mouse ovanan follicles: Effects of indomethacin
Authors: Downs Stephen M. , Longo Frank J.
Published: February 2005

The effects of the prostaglandin synthesis inhibitor, indomethacin, on the preovulatory morphology of apical follicle walls have been examind by transmission electron microscopy. Immature mice, superovulated with 5 IU pregnant mare serum (PMS) followed 40 hours later by 80 IU luteinizing hormone (LH) were treated with either 10 mg/kg indomethacin or an equivalent volume of the indomethacin vehicle 10 minutes prior to LH. Follicular apices from both groups were compared at 12 hours post‐LH. Indomethacin treatment suppressed many of the morphological changes normally occurring in the apex during preovulatory development. Whereas apices from vehicle treated animals demonstrated marked deterioration, dissociation, and thinning of tissue, the cell layers of apices from indomethacin‐treated animals remained thickened and tightly packed, with limited signs of disruption. The results presented herein are consistent with the idea that prostaglandins are essential mediators of ovulation and suggest that these lipids augment apical rupture by mobilizing granulosa cells and stimulating the loss of connective tissue elements.
Tracheobronchial epithelium of the sheep: I. Quantitative light‐microscopic study of epithelial cell abundance, and distribution
Authors: Mariassy Andrew T. , Plopper Charles G.
Published: February 2005

Glutaraldehyde‐infused tracheas and airways of five castrated sheep were microdissected following the axial airway of the left cranial and caudal lobes. Airway branches were assigned binary numbers indicating their specific location in the tracheobronchial tree. Samples of known airway generation were resin embedded and examined by light‐microscopy. Based on differences in cell morphology, staining properties, and distribution, eight major cell groups were recognized and quantified: four mucous cell categories (M1, M2, M3, and M4), ciliated, basal, Clara, and serous cells. The last cell category was restricted to submucosal glands. Tracheal epithelium had the most cells per unit length, primarily due to large numbers of basal cells. Basal cells are found in the epithelium of airways without cartilage or glands. The total mucous cell population (M1, M2, and M3) in proximal airways was relatively constant. M4 mucous cells were present in glands of proximal airways and in the epithelial lining of the airways without glands. The most distal airways were lined by Clara and ciliated cells. A small number of the most proximal noncartilaginous airways had mucous (M1, M2, M3, and M4), basal, and Clara cells sharing the epithelial lining. We conclude that in the sheep lung: (1) epithelial cell distribution does not correlate with airway wall components; (2) more than one type of secretory epithelial cell can share the lining of the same airway; and (3) Clara cell distribution is based on airway generation and proximity to alveoli.
Light and scanning electron microscopic study of testosterone‐restored penile papillae in castrated rats
Authors: Taylor George T. , Komitowski Dymitr , Weiss Jürgen
Published: February 2005

Structural changes in various penile tissue from rats with differing circulating androgen levels were analyzed with light and scanning electron microscopy. Adult males were castrated and daily injected for 6 weeks with one of four physiologic amounts of testosterone propionate (TP). Results indicated that epithelium, subepithelial connective tissue, and the papillae protruding from the surface of the glans penis responded, more or less, in a dose‐dependent fashion to the steroid. The least androgen‐sensitive penile tissue was the epidermal stratum corneum, more sensitive was the maligiphian layer, and more sensitive still was the subepithelium. The penile papillae and their follicles were the most androgen‐sensitive tissue. Specifically, the high testosterone, 400 μg and 800 μg TP, males experienced papillae that were thicker, taller, more densely arranged, and more highly keratinized than the lower testosterone, 100 μg and 200 μg TP, males. The function of the papillae may be to provide the female with the mechanical stimulation necessary to ensure a proper hormonal milieu for successful impregnation.
Suppression of adernal cortical growth and differentiation in fetal rats exposed to dexamethasone
Authors: Garvey David , Migally Nabil , Sullivan Jon , Sullivan Lori
Published: February 2005

The effects of maternal dexamethasone (DEXA) administration during the last days of gestation on fetal adrenal growth and differentiation were studied. Timed pregnant rats were divided into three groups: (a) 21d DEXA‐3 received DEXA in drinking water (5 μg/ml) from days 18 to 21 of gestation; (b) 21d DEXA‐6 received the same dosage of DEXA from days 15 to 21 of gestation; and (c) 21d control received tap water throughout gestation. On gestation day 21, pregnant rats were decapitated and ble into heparinized tubes; their fetuses were excised, weighed, decapitated, and bled. Fetal adrenals were prepared for electron microscopy or weighed and frozen until assayed for corticosterone. Control adrenals were also collected on day 15 of gestation and processed for electron microscopy only. Fetal adrenals were fixed in 2.5% glutaraldehyde in 0.5 M cacodylate buffer, postfixed in 2% osmium tetroxide (OsO4), dehydrated, and embedded in Epon 812. Twenty‐one day (21d) fetal adrenal weights were 44% and 68% lower than control values for DEXA‐3 and ‐6, respectively. Fetal adrenal corticosterone levels were decreased by 70% and 89% for the respective groups. These observations correlated with ultrastructural findings of decreased mitochondrial number and size, altered orientation of the inner mitochondrial membrane, decreased lipid, and dilation of smooth endoplasmic reticulum (SER) in cortical fascicular cells of DEXA‐exposed fetuses. Ultrastructural changes in the 21d DEXA fetal adrenals resembled 15d day control fetal adrenals. The results suggest suppressed adrenocortical differentiation probably due to DEXA inhibition of the steroidogenic influence of the fetal pituitary on the developing adrenal gland in DEXA‐exposed fetuses.
Three‐dimensional reconstruction of the rat incisor by means of computerized histomorphometry
Authors: Steigman S. , Michaeli Y. , Weinreb M. , Zajicek G.
Published: February 2005

A detailed, quantitative, three‐dimensional reconstruction of the adult rat lower incisor is presented. The mandibles of 12 male adult rats were dissected and radiographed. The outline of each incisor was traced and the center of the arc formed by the lower, or labial, border of the tooth was geometrically determined. The sector of the bone‐embedded part (mean length 20.70 ± 3.5 mm) of the tooth was divided into six equal segments by radii drawn through the arc center. The dividing radii were transposed onto the specimens and three consecutive 100‐μm transverse ground sections were cut from the incisal side of each segment, parallel to their bordering radii. The distance between each section and posterior wall of the alveolar socket was measured and the information stored in the computer. The outlines of all the dental structures were traced and fed into a computer with the aid of a sonic digitizer. The circumference of the tooth (5.91 ± 0.002), and the mesiolateral and labiolingual widths (1.36 ± 0.001 mm and 2.18 ± 0.01 mm, respectively) remained constant at all tooth levels. The decrease in width and cross‐sectional area of the pulp and the corresponding increase in dentin were represented by the best fitted second order polynomials. These changes were not uniform, being more pronounced in the proximal part of the tooth. The polynomials also served for calculation of the total volumes of pulp, dentin, and enamel (13.93 mm3, 18.05 mm3, and 4.43 mm3, respectively). The three‐dimensinal measurements included the periodontal ligament (PDL), which was significantly wider on the lateral side than on the mesial (0.16 ± 0.006 mm and 0.12 ± 0.004 mm, respectively). The volumes of the enamel‐bordering PDL and of the cementum‐bordering PDL were 7.77 mm3 and 8.67 mm3, respectively. In the latter, the tooth‐related compartment constituted 42.7% of the total volume. The data presented can serve as a basis for future quantitative studies of the rat incisor.
Effect of estradiol on ultrastructure of granular ducts in submandibular glands of female rats
Authors: Flynn Evelyn A. , Yelland Kenneth T. , Shklar Gerald
Published: February 2005

The effects of estradiol on the granular ducts in submandibular glands of female albino rats were studied. Twenty‐five‐milligram pellets of 17 β‐estradiol were implanted subcutaneously in the experimental animals, and their glands, as well as controls, were examined after 2, 4, 7, and 10 wk using light and electron microscopy. During the course of the experiment an increasing proportion of the granules in the granules ducts appeared more lightly stained in the experimental animals. In the estradiol‐treated rats the granular ducts increased in relative cross‐sectional area at a faster rate than in the controls, which exhibited maturation changes. In addition, the average number of granules per granular duct cell decreased significantly in the treated animals. Our results indicate that estradiol caused a change in the cytology of the granular ducts suggesting an alteration in protein synthesis. These results might occur through a change in structural proteins or in other hormones and growth factors which are known to influence the submandibular gland.
Noradrenergic innervation of the penis in control and streptozotocin‐diabetic rats: Evidence of autonomic neuropathy
Authors: Felten David L. , Felten Suzanne Y. , Melman Arnold
Published: February 2005

The noradrenergic sympathetic innervation of the penis of control and 4‐month streptozotocin‐diabetic rats was examined with the glyoxylic acid histofluorescence method. Noradrenergic varicosities were found in the corpora cavernosa in a dense subtunical plexus and in the perisinusoidal and trabecular regions of the erectile tissue, in the corpus spongiosum in perisinusoidal tissue, around large arteries and veins, and around small tortuous arterioles and small draining veins of the corpora cavernosa and spongiosum. Noradrenergic varicosities were diminished in number and fluorescent intensity in all regions of the penis of diabetic rats compared with controls. The subtunical plexus was absent, perisinusoidal and trabecular varicosiities were sparse, and only occasional intermittent, discontinuous, dull fluorescent fibers or plexuses were found around the vessels. Quantitation with highperformance liquid chromatography revealed a significant reduction of norepinephrine in the penis of diabetic rats compared with controls. The present study suggests that long‐term streptozotocin diabetes in the rat is accompained by sympathetic autonomic neuropathy of the penis that seems to parallel changes in the noradrenergic content of penile corpora of men with diabetes and erectile impotence. The streptozotocin‐diabetic rat merits further study to explore the relationship between noradrenergic innervation of the penis and erectile tissue.
The development of specific antibody‐containing cells and the localization of extracellular antibody in the follicles of the spleen of rabbits after administration of free or liposome‐associated albumin antigen
Authors: van Rooijen N. , Kors N. , van Nieuwmegen R. , Eikelenboom P.
Published: February 2005

In order to study the localization pattern of specific antibody‐containing cells and extracellular antibody in the spleen during a primary immune response, the antigen human serum albumin (HSA) was injected intravenously in rabbits, either free in solution, or associated with the surfaces of liposomes as a model of membrane‐associated antigens. Demonstration of specific antibody‐containing cells was performed by incubation of sections of spleen with HSA‐HRP conjugates, followed by peroxidase cytochemistry.

Specific anti‐HSA antibody‐containing cells were detected already at 4 days after injection of the antigen. The bulk of these cells localized initially in the outer parts of the periarteriolar lymphocyte sheaths (PALS) and around the terminal arteriolar branches. Both extracellular antibody and specific antibody‐containing cells were also found in the follicles of the spleen. Arguments are given that extracellular antibody precedes the development of specific antibody‐containing cells in the follicle. This extracellular antibody probably represents antigen‐antibody complexes trapped in the follicles as soon as the antigen in the circulation is complexed by the first antibodies produced during the immune response. The localization pattern of specific antibody‐containing cells and extracellular antibody did not differ markedly when rabbits injected with free or liposome‐associated antigen were compared. Results are discussed particularly with respect to the role of follicles in the immune response.
Envirnmental conditions prerequisite for complete limb regeneration in the postmetamorphic adult land‐phase salamander, Ambystoma
Authors: Young Henry E. , Bailey Claudia F. , Dalley Bernell K.
Published: February 2005

Historically, postmetamorphic adult land‐phase salamanders have been shown to exhibit minimal to nonexistent limb regeneration. Hence, it has been generally accepted that these forms have lost the intrinsic capacity to regenerate a limb. Due to the experimental protocols used, an alternate explanation is also possible: that this intrinsic capacity cannot be expressed when the salamanders are maintained under adverse laboratory environmental conditions. Therefore, this study addresses two questions: (1) What are the optimal environmental conditions for long‐term survival of adult land‐phase salamanders; and (2) will complete limb regeneration occur in these salamanders if they are maintained under survival conditions. A mixed population of adult Ambystoma were tested under varying conditions of habitat, temperature, humidity, photoperiod, and food source. Complete limb regeneration was possible in 100% of four species of adult postmetamorphic land‐phase Ambystoma salamanders given the proper environmental laboratory conditiions of a peat moss and potting soil habitat with a controlled temprature of 25°C ± 5°C, 70% or greater humidity, a 12/12 light/dark photoperiod, a diet including nightcrawlers released into their respective terraria, and an extended observation time of up to 370 days postamputation (dpa). Regeneration was completed during the following range periods for the adult salamanders: A. annulatum, 324 to 370 dpa; A. maculatum, 255 to 300 dpa; A. texanum, 215 to 250 dpa; and A. tigranum, 155 to 180 dpa.
Isolation by flow sorting of cytokinetic and morphological heterogeneity in late‐passage cultures of human diploid fibroblasts (IMR‐90)
Authors: Kelley Robert O. , Perdue Bradley D. , Uruchurtu‐Valdivia Richard A.
Published: February 2005

Considerable structural, metabolic, and proliferative heterogeneity develops in populations of cultured diploid cells which have reached advanced levels of population doubling. Isolation of noncycling cells from late‐passage cultures would permit more definitive investigation of the structure and behavior of individual senescent cells. In this paper, we report the viable sorting of late‐passage cultures of human diploid fibroblasts (IMR‐90) into two subpopulations of cells with different proliferative potentials. Sorting is based on cellular light‐scattering properties and autofluorescence. Structural and behavioral features of the subpopulation exhibiting increased forward‐angle light scatter are more characteristic of senescent cells than the subpopulation sorted by decreased forward‐angle light scatter.
Hepatic sinusoidal endothelium in sheep: An ultrastructural reinvestigation
Authors: Wright Peter L. , Smith Kathryn F. , Day William A. , Fraser Robin
Published: February 2005

Following perfusion fixation of livers from fetal, neonatal, and adult sheep, the ultrastructure of the fenestrated sinusoidal endothelium was examined. In contrast to an earlier report which utilized immersion fixation, we found the fenestrae to be unoccluded by diaphragms or basal lamina, thus offering only a discontinuous barrier between the blood and the space of Disse and hepatocytes. This observation was confirmed by perfusing the liver with marker particles. The fenestrae appear, therefore, to have a sieving function, regulating the metabolism of particulate matter such as lipoproteins in sheep in a similar manner to that which has been shown to occur in rats.
Ontogeny of Peyer's patches of the rat
Authors: Sminia T. , Janse E. M. , Plesch B. E. C.
Published: February 2005

The development of lymphoid and nonlymphoid cells in Peyer's patches (PP) of the rat was investigated using light microscopical methods (routine histological techniques, enzyme histochemistry and immunohistochemistry). In newborn rats PP were mainly populated by T lymphocytes and Ia‐positive nonlymphoid cells, which most likely are interdigitating cells. At about 12 days after birth the B and T cells were localized in defined regions, the follicular (FA) and interfollicular area (IFA), respectively. Compartmentalization within the FA started about 14 days after birth. The first signs of the development of secondary follicles were seen from about 18 days onward. PP obtained their mature structure at about 4 weeks after birth. It is suggested that after PP had developed fully, cells having cytoplasmic IgA migrate via the high endothelial venules (HEV) to the lamina propria of the intestine; cIgM and IgG cells seem to develop locally within the FA.
The preparation of human cross sections
Authors: Boushey Dallas Richard , Stultz Walter Alva
Published: February 2005

Technical advances in the field of radiology, especially computerized axial tomography (CAT) scanning, have made gross anatomical crosss‐sections increasingly important in understanding the relationships of internal structures. Since 1940, the Anatomy Program at the University of Vermont has developed and used cross‐sections of the entire human body in teaching predoctoral, postdoctoral, and allied health professionals. This paper describes in detail the process through which specimens are selected, embalmed, frozen, sectioned, and displayed. Kaiserling's Method is used for fixation and preservation of the specimens, which are then housed in appropriate display containers. Specimens prepared over forty years ago in the manner described in this paper are still in use.
Gross anatomy of the respiratory system of the bowhead whale,Balaena mysticetus
Authors: Henry Robert W. , Haldiman Jerrold T. , Albert Thomas F. , Henk William G. , Abdelbaki Yahya Z. , Duffield Dennis W.
Published: February 2005

Components of the respiratory system from seven bowhead whales have been examined. The paired and laterally curved external nares are passively closed by a valve‐like mass located in the rostral, lateral, and ventral walls of the nasal vestibules. Nasal septal cartilages are paired smooth plates rostrally changing to accordion‐like folds caudally. The epiglottic and arytenoidal protuberances of the larynx are typically cetacean, but blunt. The cricoid cartilage is not a complete ring, but an elongated, inverted, troughshaped structure. The thyroid cartilage is trough‐shaped with elongated cranial cornua curving dorsocaudally from each thyroid lamina. A conical mass of skeletal muscle serves as the floor of the short trachea and also surrounds the termination of the laryngeal sac. The trachea is dorsoventrally compressed, lacks a tracheal bronchus, and its width equals its length. The principal bronchi give rise to lobar bronchi at obtuse angles. Large segmental bronchi branch extensively from lobar bronchi near the mediastinal lung surface. The lungs are rectangular and of nearly uniform thickness throughout, without external or internal lobulation.