bluuebunny/crossref_metadata_2025 huggingface dataset:
Scanning electron microscopy of an elastic fiber network which forms the internal elastic lamina in canine saphenous vein
Authors: Crissman Robert S. , Ross James N. , Davis Terrance
Published: February 2005

Scanning electron microscopy (SEM) was used to study the arrangement of elastic fibers in the canine saphenous vein as the basis for further studies of veins used in by‐pass grafting operations. The elastic fiber arrangement in distended and non‐distended veins was examined in both immersion‐fixed and perfusion‐fixed vessels. Transmission electron microscope (TEM) observation of the SEM samples confirmed the identity of these fibrillar structures as elastic fibers. In addition, specific stains for elastic fibers (Verhoeff's iron hematoxylin and orcein) were used. The elastic fibers forming the internal elastic lamina were arranged in a fishnet‐like pattern. Large‐diameter fibers, running longitudinally along the vascular wall, were interconnected by smaller oblique fibers. Together the fibers formed an elastic cylindrical network between the endothelium and the smooth muscle cells. The thicker longitudinal fibers were the same diameter in distended and non‐distended veins. By contrast, the oblique fibers were thinner and more complexly branched in distended veins. The architecture of the elastic fiber network contributes to vascular flexibility and allows circumferential distension. The interconnecting oblique fibers presumably serve to distribute internal pressure equally around the venous wall.
Fine structure of the rostral pars distalis of the adenohypophysis of the killifish, Fundulus heteroclitus, in fresh and salt water
Authors: Betchaku Teiichi , Douglas W. W.
Published: February 2005

A fine structural study has confirmed earlier light microscopic observations indicating that prolactin cells are the only endocrine cells present in the main body of the rostral pars distalis of the adenohypophysis of Fundulus heteroclitus, a killifish common in New England coastal waters. Some ACTH cells occurred in thin plaques applied to the neurohypophysial trunk in the posterior part of the region. In freshwater‐adapted specimens the volume occupied by the prolactin cell mass was larger than in saltwater‐adapted specimens and contained larger prolactin cells. A paucity of contact specializations between the parenchymal cells may facilitate their spatial rearrangement as the prolactin cell population varies with changes in ambient salinity. Many fine neurohypophysial processes penetrated deeply into the rostral pars distalis and contained Type B (aminergic) nerve fibers believed to modulate prolactin secretion. These fibers ended mainly on the basement membrane that separates the neurohypophysial processes from the parenchyma. Synaptic contacts on prolactin cells were not observed but no prolactin cell appeared to be more than five cell widths from such a nerve terminal. The results emphasize the usefulness of the rostral pars distalis of this easily obtained and maintained teleost for studies of prolactin cell function.
Investigations on the turnover of adrenocortical mitochondria. XIV. A correlated biochemical and stereological study of the effects of chronic treatment with ethidium bromide on the growth maintenance of the rat zona fasciculata mitochondria
Authors: Nussdorfer Gastone G. , Mazzocchi Giuseppina , Rebuffat Piera , Zucchi Sandro C. , Robba Claudia
Published: February 2005

The effects of ethidium bromide (EB) on rat adrenocortical cells were investigated by biochemical and stereological methods. It was found that a treatment with ip. injections of 10 μg/gm of EB every 12 hours induced a persistent inhibition of the incorporation of 3H‐thymidine and 3H‐uridine into the mitochondrial fraction, but not into the nuclear fraction. Chronic treatment with this dose of EB provoked in zona fasciculata cells of rats treated with maintenance doses of ACTH a noticeable decrease in the volume of the mitochondrial compartment (due to the decrease both in the number per cell and in the average volume of the organelles) and in the surface area of the mitochondrial cristae. These findings lend support to the hypothesis that the mechanism underlying the ACTH‐induced maintenance of the growth of adrenocortical mitochondria involves mitochondrial DNA reduplication and transcription.
Ontogeny of the pituitary‐thyroid system in fetal rats: Observations on the fetal thyroid after maternal treatment with goitrogen
Authors: Eguchi Yasunobu , Fukiishi Yonetaka , Hasegawa Yasuhiko
Published: February 2005

The critical time of onset of the reciprocal relationship between the pituitary and the thyroid in fetal rats was assessed by the appearance of goiters in fetuses after maternal treatment with goitrogen, propylthiouracil (PTU), on various days of gestation. The assessment was based on changes in the weight and histology of the fetal thyroids. The day following overnight mating was regarded as day 1 of gestation. Pregnant rats were treated with 40 mg PTU each day for two days and autopsied on the third day. The various experimental periods were days 16–18, 17–19, 18–20, 19–21, and 20–22. PTU given to pregnant rats on days 16 and 17 did not cause any change in the fetal thyroids. PTU given on days 17 and 18 caused only a slight increase of fetal “thyroid weight/body weight” ratio. In all other experimental periods (days 18–20, 19–21, and 20–22), PTU induced conspicuous goiters in fetuses, which was reflected by an increased weight of thyroids, an increased height of follicular cells, and a decreased amount of colloid stored in follicles. The results suggest that in fetal rats, the reciprocal relationship between the pituitary and the thyroid is established on approximately days 19–20 of gestation.
The sensory innervation of primate eyelid
Authors: Halata Zdenek , Munger Bryce L.
Published: February 2005

The skin of primate eyelid contains three distinctive sensory nerve terminals. Small down hairs have a collar of lanceolate terminals that are formed by ramifications of the six to eight myelinated afferent fibers. Extensions of Schwann‐cell cytoplasm form masses of cytoplasmic lamellae associated with these terminals. Every large hair or eyelash contains a large pilo‐Ruffini as well as sparse lanceolate terminals. The eyelash Ruffini corpuscle resembles those of monkey facial guard hairs, sinus hairs, and joint capsules of the cat and pigeon. Sparse lanceolate terminals present between the Ruffini corpuscle and eyelash external root sheath resemble those of vellus hairs. On rare occasion Merkel cells are present in the hair follicle external root sheath above the sebaceous gland. Merkel touch spots, or Tastscheiben, are located between contiguous eyelashes as small rete pegs containing several Merkel cell‐neurite complexes innervated by one or two myelinated afferent fibers. The function of this array of sensory terminals is presumed to represent an extensive mechanism of protection for the cornea and globe. On the basis of studies reported to date we can conclude that the Ruffini corpuscles (and related receptors) are the ubiquitous mechanoreceptors of cutaneous and musculoskeletal systems in birds as well as mammals.
The ultrastructure of Ruffini and Herbst corpuscles in the articular capsule of domestic pigeon
Authors: Halata Zdenek , Munger Bryce L.
Published: February 2005

The present study identifies two types of sensory nerve endings in the articular capsule of the shoulder joint of domestic pigeons: Ruffini corpuscles (spray‐like endings), and Herbst corpuscles. Ruffini corpuscles occur in the fibrous membrane of the articular capsule and consist of two to four branched cylindrical segments within a network of fascicles of collagen fibers. At the terminal ends of the cylinders the perineural sheaths of the capsule are deficient and surround the fascicles of collagen fibers. The axon terminals in each cylindrical segment of a Ruffini corpuscle repeatedly ramify, giving rise to delicate neurite profiles. These neurites and associated Schwann cells envelope small fascicles of collagen fibrils. Schwann cells cover only a part of the neurite profiles. The myelinated afferent axon enters the midregion of the cylinder and has a diameter of ∼3 μm. Herbst corpuscles are situated in the subsynovial connective tissue and in the transition zone between the fibrous membrane and the muscular fascia. They appear as elongated ovals in longitudinal section and round in cross section. Small corpuscles measure ∼5 μm × 200 μm in length and large ones ∼100 μm × 600 μm. Each has a myelinated afferent axon (diameter 2.5–7.5 μm) that terminates in one to three inner cores. The inner core contains the nonmyelinated receptor portion of the nerve fiber surrounded by numerous cytoplasmic lamellae, a subcapsular connective tissue space, and a perineural capsule of eight to 12 layers. Avian joint receptors are similar to those present in the skin of various birds and Ruffini corpuscles resemble in fine structure equivalent receptors in joint corpuscles of the domestic cat.
The distribution and mobility of anionic sites on the surface of human placental syncytial trophoblast
Authors: King Barry F.
Published: February 2005

The purpose of this study was to examine the distribution and mobility of anionic sites on the surface of fetal trophoblast in contact with maternal blood using polycationic ferritin (PCF) as a probe. Pieces of human placental villi were washed to remove maternal blood, and fresh, unfixed tissue was expose to PCF for varying times, concentrations, and temperatures to determine the effects on labeling patterns. The major findings were: (1) anionic sites were localized almost exclusively on the microvillous portion of the trophoblast surface; intermicrovillous regions of the surface, including the coated pits, were generally not labeled with PCF; (2) PCF binding was present as small clusters on the microvilli. This pattern was observed in tissue incubated 5–10 sec at 4°C and 23°C. The size of the cluster was increased with increased incubation time, suggesting some aggregation or patching can occur; (3) following the fomation of patches, the anionic sites showed no evidence of being cleared from the membrane by endocytosis during incubation subsequent to labeling; (4) the binding of PCF to the surface was reduced by pretreatment of the tissue with neuraminidase. Tissue fixed in glutaraldehyde prior to PCF exposure showed both clustered and more dispersed labeling. The results indicate that anionic sites on human trophoblast surface have a non‐random distribution and have restricted mobility on the surface. This may be indicative of a segregation of different membrane proteins and functions within different structural regions of the placental cell surface.
Morphology, histochemistry, and distribution of serotonin‐containing cells in tracheal epithelium of adult rabbit
Authors: Dey Richard D. , Echt Robert , Dinerstein Robert J.
Published: February 2005

We have investigated morphologic and histochemical characteristics of serotonin‐containing epithelial cells in tracheas from adult rabbits, using the Falck‐Hillarp freeze‐dried formaldehyde vapor technique. An intracellular formaldehyde‐induced fluorescent substance was identified as serotonin by microspectrofluorometric techniques. Fluorescence microscopy and subsequent histochemical staining of the same sections demonstrated that serotonin‐containing cells were argentaffin‐, argyrophil‐, and ferric ferricyanide‐positive. The serotonin‐containing epithelial cells were more numerous in ventral than in dorsal aspects of trachea. The number of detectable fluorescent cells was reduced after reserpine administration but was not affected by injecting the amine precursor L‐dihydroxyphenylalanine (L‐DOPA). The emission peak of the fluorophore was not significantly shifted after L‐DOPA injections. The cells may regulate tracheobronchial‐pulmonary function by releasing serotonin or other as yet unidentified biologically active substances.
Effects of varying chamber construction and embryo pre‐incubation age on survival and growth of chick embryos in shell‐less culture
Authors: Dunn Bruce E. , Fitzharris Timothy P. , Barnett Bobby D.
Published: February 2005

Shell‐less cultrure involves culturing chick embryos with associated yolk and albumen outside of the eggshell and shell membranes. The technique allows direct access to and continuous observation of cultured embryos almost to the time of hatching. The plastic wrap/culture tripod technique described in this paper allows normal embryonic growth and differentiation from 48 hours (in ovo pre‐incubation age) through at least 10 days of total incubation. As the duration of in ovo pre‐incubation is decreased below 36 hours, there is a concomitant increase in the percentage of grossly abnormal embryos associated with decreased survival and retarded growth and differentiation. Survival of embryos pre‐incubated for 72 hours through 13 and 18 days of total incubation is greater than 80% and 40%, respectively. The wrap/tripod technique allows substantially better survival and more normal development of cultured embryos than does the petri dish technique of Auerbach et al. (1974). Embryonic growth in 7.8‐cm‐diameter chambers is significantly greater than in either larger (10.6 cm) or smaller (5.2 cm) diameter chambers. Some gas exchange through the culture chamber walls appears necessary for optional embryonic survival and growth. Suspending egg contents in either Safeway® or Handi‐Wrap® plastic wrap (both of intermediate permeability) in 7.8‐cm tripods resulted in superior growth and/or survival compared to suspension in Silastic® sheeting (high permeability), Saran Wrap® (low permeability), glass dishes (nonpermeable), or glass dishes lined with an inner layer of Safeway® wrap(nonpermeable).
Tridimensional study of the deep cortex of the rat lymph node. II: Relation of deep cortex units to afferent lymphatic vessels
Authors: Bélisle C. , Sainte‐Marie G.
Published: February 2005

Recently, we reported that the deep cortex of the rat lymph node is formed of semi‐rounded structures, the “deep cortex units,” contiguous to the peripheral cortex and bulging into the medulla. It was suggested that a unit represents an accumulation of lymphocytes centered on the opening of an afferent lymphatic vessel. To verify the proposal, we carried out a tridimensional analysis of serially sectioned rat nodes, fixed by perfusion and trimmed in such a way as to preserve their lymphatics. The tridimensional analysis revealed that a constant topographical relationship exists between the units and the openings of the afferent lymphatics. The results demonstrated that the topographical organization of the deep cortex of a rat node correlates with the distribution pattern of the opening(s) of its afferent lymphatic(s). The overall observations suggested the following explanation for the shape and topography of the units: factor(s) present in the lymph would spread in a radial manner from the opening(s) of an afferent lymphatic through the underlying cortex. The factor(s) would induce morphological modifications in the stimulated semi‐rounded area which, in turn, would provoke a local accumulation of circulating lymphocytes.
Development of seminal vesicles and coagulating glands in neonatal mice. I. The morphogenetic effects of various hormonal conditions
Authors: Lung Ben , Cunha Gerald R.
Published: February 2005

Seminal vesicles (SV) and coagulating glands (CG) from neonatal mice 1‐ to 7‐days old were observed in whole mount preparations. Untreated, normal SV developed elaborate epithelial branches beginning on day 3 with secondary branches appearing on day 6. Castration (C), estradiol treatment (E), and castration combined with estradiol treatment (C + E) inhibited the morphogenesis of the epithelial branches. Untreated CG formed solid epithelial stalks that developed lateral epithelial buds on day 3 which attained a complex morphological pattern by day 7. Treatment groups (C, E, and C + E) displayed a pattern of retarded growth with few epithelial buds appearing even at day 7. The effects of castration on both SV and CG were reversed by the addition of testosterone. Short term in vitro culture of 1‐day‐old SV and CG glands in control medium or medium supplemented with estradiol did not exhibit visible growth. Culture of SV and CG glands with testosterone or a piece of testis showed pronounced development.
Four hormones in the pancreas of the lizard, Anolis carolinensis
Authors: Rhoten William B. , Hall Carl E.
Published: February 2005

The electron microscopic localization of insulin, glucagon, somatostatin, and pancreatic polypeptide (PP) in the pancreas of the iguanid lizard, Anolis carolinensis was studied by the unlabeled antibody peroxidase‐antiperoxidase immunocytochemical technique. Insulin, glucagon, and somatostatin were localized absolutely to those cells previously identified on the basis of the characteristics of their secretory granules as being β cells, α cell, and D cells, respectively. The secretory granule cores of the PP‐containing cells appeared to be ellipsoidal with a semi‐major axis of 450 nm and a semi‐minor axis of 365 nm. This previously unidentified cell type is named the F cell, in keeping with the localization of PP to the original F cell of the canine pancreas. Without immunocytochemical staining, the qualitative ultrastructural characteristics of the F cell secretory granules were inadequate to permit certain identification of the F cell, especially with regard to the D cell.
Comparative morphometry of the upper bronchial tree in six mammalian species
Authors: Schlesinger Richard B. , McFadden Lynn A.
Published: February 2005

The length, diameter, and angle of branching of all airways through the sixth level of branching below the trachea were measured on corrosion casts prepared from the lungs of two animals whose bronchial geometry has not previously been studied, namely the donkey and the rabbit. These measurements and morphometric data for the rat, hamster, dog, and human obtained from other sources were analyzed and compared. The cast prepared from human lungs exhibited an airway geometry that was clearly distinct from that shown by the nonhuman species. The human upper bronchial tree was the most symmetrical with respect to airway diameter and angle of branching. In all species studied, airway length was the most irregular parameter. The reasons for differences in branching geometry are not clearly understood. However, when attempting to determine whether a particular species may be used as a model for man in inhalation toxicology, and in the subsequent interpretation of animal data, an appreciation of differences in airway morphometry is essential.
Changes in rat palatal epithelium during neonatal growth
Authors: Hill M. W.
Published: February 2005

The epithelium of rat palatal mucosa was examined from 2 to 30 days after birth and changes in epithelial thickness, cellularity, average cell volume, mitotic activity and the turnover time of the nucleated cell layer were determined from histological sections. The mean epithelial thickness, which was 35.3 ± 1.5 μm at 2 days, remained constant for the first 9 days and then progressively increased, reaching 91.7 ± 1.7 μm by 30 days. This change in thickness was partly bought about by a doubling of the number of nucleated cells per mm2 of the surface, from 90.4 ± 2.81 × 103 to 187.63 × 5.654 × 103, and partly due to a change in the ratio of cells in the progenitor and maturing cell compartments, as assessed by the change in volume of an “average” epithelial cell. Mitotic activity also remained constant for the first 9 days and then increased, reaching levels five times greater than initial levels by 30 days. It is suggested that these changes are brought about by frictional stimulation associated with the initial intake of solid food as well as systemic influences related to general growth mechanisms.
Sequential events in the formation of collagen secretion granules with special reference to the development of segment‐long‐spacing‐like aggregates
Authors: Cho Moon‐Il , Garant Philias R.
Published: February 2005

The formation and maturation of collagen secretion granules in periodontal ligament (PDL) fibroblasts of young male Balb‐C mice were studied by electron microscopy and cytochemistry. The Golgi apparatus was composed of several dictyosomes, each consisting of a stack of five smooth‐walled cisternae. Each cisterna was connected at both ends to a dilated saccule. The cisternae, with their associated pairs of saccules, underwent progressive maturational changes from the immature to mature face of each dictyosome. The most immature saccules (type 1) were large, spherical, and filled with loosely arranged short filamentous structures. These saccules were continuous with the first and second Golgi cisternae (counting from the immature side). Golgi saccules type 2 were ellipsoidal, associated with the third and fourth cisternae, and contained parallel, elongate filaments. The most mature saccules, type 3, were more rectangular and connected by a short fifth cisterna. They contained aggregated filamentous material in the form of eight segment‐long‐spacing (SLS)‐like crystallites, one in the center and seven at the periphery, to form a basic secretory unit. As type 3 saccules matured, the interconnecting cisterna progressively shortened until the two saccules were nearly juxtaposed. At this time the shortened fifth cisterna split to give rise to two independent presecretory granules. By progressive condensation, presecretory granules matured into secretion granules that contained a densely packed SLS‐ like aggregate, within which individual crystallites were no longer discernable. Maturation of cisternae and saccules involved removal of membrane, apparently by the formation and detachment of coated vesicles. The staining reaction with silver methenamine and phosphotungstic acid increased over the procollagen as the saccules matured, indicating addition of carbohydrate moieties and possible crosslinkages. It is concluded that the formation and maturation of collagen secretion granules in PDL fibroblasts involves the packaging and further modification of eight SLS‐like crystallites, which are secreted as a basic unit.
Morphological organization and contractile properties of the wrist flexor muscles in the cat
Authors: Gonyea W. J. , Marushia S. A. , Dixon J. A.
Published: February 2005

A comparison of the anatomy, fiber type profiles, and contractile properties of the wrist flexor muscles was undertaken in the cat. Isometric contractile characteristics were measured for each muscle. Three muscle fiber types, FG, FOG, and SO, were differentiated by staining cross sections of each muscle for ATPase, NADH diaphorase, SDH, and α‐GPD activities. The wrist flexor muscles ranged from less than 1% to 49% SO fiber content; with two of the five heads of the flexor digitorium profundus (FDP) having 1% or less SO fibers (FDP1—1.07%, FDP5—0.81%) and the humeral head of the flexor carpi ulnaris muscle (FCUh) having the greatest content of SO fibers. The mean contraction time (CT) plus one‐half relaxation time for an isometric twitch was correlated with the percentage of SO fibers and ranged from 40.5 to 111.8 ms. Except for the FCU (37 ms), the CT was less than 25 ms for the wrist flexor muscles. The uniarticular wrist flexor muscles, the flexor carpi radialis (FCR), and the FCU had the highest percentage of SO fibers and were more fatigue‐resistant that the multiarticular muscles. Considerable differences exist in muscle structure, fiber type proportions, and contractile properties between the FCR and FCU, which may be related to functional differences between the two sides of the wrist that may exist during the placement of the foot during locomotion.
Histochemical patterns of dehydrogenase activity in the development of free muscle grafts in the rat
Authors: Magon Davindra K. , Basson Marc D. , Carlson Bruce M.
Published: February 2005

Patterns of activity of six dehydrogenase enzymes were studied histochemically in 42 free muscle grafts in the rat. Within hours, the surviving peripheral muscle fibers can be distinguished from the central ischemic muscle fibers. The surviving muscle fibers retain their characteristic pattern of staining throughout the post‐transplantation period. The central ischemic muscle fibers stain abnormally and by five or six days they lose their enzymatic activity. The zone of regeneration, between the surviving and the ischemic muscle fibers, initially shows little dehydrogenase activity, but as the regenerating muscle fibers mature, they develop first a homogeneous staining pattern and, later, differences in staining intensity among different types of muscle fibers.
Change in intramembranous particle distribution in epididymal spermatozoa of the boar
Authors: Suzuki Fumie
Published: February 2005

Membranes of boar spermatozoa from different regions of the epididymis and after ejaculation were studied by the freeze‐fracture replica technique. The ordered pattern of the intramembranous particles of spermatozoan plasma membranes was different in the five arbitrary zones of the epididymis and in the semen. A distinctive ordered pattern was absent in zone 1, which is the proximal segment of the epididymis. In zone 2, paired parallel rows of the particles were present in the plasma membrane over the acrosomal region. This parallel arrangement was not present in zone 3 spermatozoa. Anterior to the posterior ring, cords formed by packed particles were apparent in zone 2 spermatozoa and reached their maximum prominence in zone 3, and persisted in zones 4 and 5 and in the semen. The plasma membrane over the marginal ridge of the acrosome had a hexagonal array of particles only in zones 4 and 5 spermatozoa. A similar pattern appeared on the post‐acrosomal region of spermatozoa in zone 5 and in the semen. The plasma membrane of the middle piece had a rectilinear arrangement of the particles in zone 2 spermatozoa in which the migration of the cytoplasmic droplet was complete. Rudiments of the rectilinear arrangement persisted in spermatozoa in zones 4 and 5 and in the semen. These changes are discussed in relation to sperm maturation in the epididymis. The acrosomal membrane had a hexagonal arrangement of particles in the equatorial segment. The marginal ridge of the outer acrosonal membrane had parallel rows of intramembranous particles. The organization of the acrosomal membrane particles did not change during the epididymal passage of boar spermatozoa.
Membrane dynamics in the parotid acinar cell during regranulation: A stereological study following isoprenaline‐induced secretion
Authors: Williams M. A. , Cope G. H.
Published: February 2005

Recently weaned male rabbits were injected either with 150 μg/kg isoprenaline in saline containing 0.01 M ascorbic acid or simply with the drug vehicle. Groups of drug‐injected animals were killed at various time after injection. Parotid gland tissue samples from all animals were fixed, embedded and thin sectioned, and micrographs were prepared at standard magnification. Estimations of membrane areas of each membrane type in parotid acinar cells were made. It was found that in animals killed 2 hours after induced secretion apical area was larger than in controls. In animals killed at sucessively later times the apical area was progressively less. No elevation of any internal smooth membrane areas was ascertained at any sampling time, though the areas of rough endoplasmic reticulum in 2–12 hour samples were larger. It is suggested that excess apical membrane, though probably removed by interiorization, is afterwards disassembled inside the cell to create fresh macromolecular building units (protein molecules), perhaps after passing through the Golgi apparatus. This cryptic pool of building units can provide about 900 μm2 of secretion granule membrane per cell, the supply apparently being exhausted in the first eight hours after degranulation, whilst granule numbers are being increased. Thereafter, apparently, limited granule fusion occurs, so that ultimately the cellular complement of secretion granule membrane comes to enclose a greater volume of secretory product, though the average granule number per cell is smaller.
Cellular composition of the rostral pars distalis of the anterior pituitary gland of the alewife, Alosa pseudoharengus, during the spawning run
Authors: Betchaku Teiichi , Douglas W. W.
Published: February 2005

The rostral pars distalis of the anterior pituitary gland of the marine alewife, Alosa pseudoharengus, during its annual spawning run to fresh water was examined histologically. The rostral pars distalis is composed of many interconnecting follicles of various sizes. Contrary to earlier reports, the follicular epithelium contains not only prolactin (PRL) cells but corticotropic (ACTH) cells and thyrotropic (TSH) cells (in addition to two nonendocrine cell types). Basally all three endocrine cell types make direct contact with the basement membrane which separates the follicles from the neurohypophysial processes. Apically, however, only the prolactin cells, the largest of the three, protrude into the follicular lumen by means of the small ciliated apical protruberance. All other cellular elements are sealed from the follicular lumen by a layer of covering cells which have properties of transitional epithelial cells. In the follicular epithelium, the slender TSH cells are intercalated between the large conspicuous prolactin cells. The ACTH cells, the smallest of the three endocrine cells, lie in deep invaginations in the basal regions of the individual PRL cells in such a way that on cursory examination they can be mistaken for the nuclei of the latter. Only a small portion of the cellular surface of the ACTH cell escapes the enveloping prolactin cell to make contact with the basement membrane of the follicle. In teleosts, prolactin, ACTH, and TSH have all been implicated in the regulation of hydromineral metabolism and reproductive development. The intimate spatial relation between the three endocrine cells in the alewife rostral pars distalis thus raises the possibility of some functional interactions at the adenohypophysial level, perhaps as an adaptation of this anadromous teleost whose reproductive development and behavior is associated with large changes in ambient salinity. The functional significance of the follicular lumen is discussed together with possible sensory functions of the PRL cells.
Pituitary tumorigenesis in aging female C57BL/6J mice: A light and electron microscopic study
Authors: Schechter Joel E. , Felicio Leda S. , Nelson James F. , Finch Caleb E.
Published: February 2005

Spontaneous pituitary tumors have been studied by light and electron microscopy in female C57BL/6J mice at 2½, 11, 15, 22, 23, 24 and 30 months. Tumors were evident macroscopically in greater than 50% of mice 22 months or older, and greater than 80% on microscopic evaluation. Active and hypertrophied mammotrophs were the predominant cell type within the tumors at 22‐‐30 months, often totally filling large portions of the tumor mass. Exocytosis of secretory granules was extensive from the mammotrophs, but much less abundant from other parenchymal cells. Somatotrophs and gonadotrophs were also present, and appeared active and often strikingly hypertrophied. The tumors were characterized by disruptions of parenchymal and capillary integrity which resulted in the formation of large vascular lakes lined solely by tumor cells, generally mammotrophs. Apparent metastasis of tumor cells into the vascular lakes was also observed. In 11‐ and 15‐month mice small tumors or pretumor foci were evident in some mice on microscopic evaluation, although they were not visible macroscopically. Their degree of development was somewhat variable, but they had essentially the same features as more advanced tumors in older mice. Pretumor foci were characterized by more moderate disruptions of parenchymal cell and capillary integrity; cellular hypertrophy, particularly of somatotrophs and gonadotrophs; and the presence of small vascular lakes. In 2½‐month mice tumors could not be localized macroscopically or microscopically, and the pituitary was composed of well‐defined cell cords and an intact capillary bed. However, small focal zones of capillary and tissue disruption were apparent occasionally in 2½‐month mice. These findings indicate that the process of pituitary tumorigenesis in female C57BL/6J mice is initiated by midlife, with subsequent progressive development into large, mammotroph‐dominated tumors.
Growth of the turtle Chrysemys scripta under constant controlled laboratory conditions
Authors: Sarnat Bernard G. , McNabb Elizabeth , Glass Michael
Published: February 2005

The purpose of this study was to determine (1) growth of the turtle shell and change in weight under constant controlled laboratory conditions and (2) whether under these constant conditions there were seasonal changes. Fifty unfed refrigerated eight‐week‐old hatchling turtles Chrysemys scripta were received in October and maintained in aquaria with 16 hours of artificial light and eight hours of darkness, at 24–27°C and a humidity of 30% and fed twice weekly. Gross linear measurements of the width and length of the plastron and carapace, and total body weights, were taken at eight weeks and thereafter at about six‐week intervals. During the two‐year period the mean increase of the plastron length was from 30.79 ± 0.19 mm to 68.32 ± 1.58 mm, plastron width from 24.23 ± 0.20 mm to 50.43 ± 1.03 mm; carapace length from 32.47 ± 0.24 mm to 75.21 ± 1.82 mm, carapace width from 31.81 ± 0.28 mm to 67.12 ± 1.29 mm, and body weight from 6.94 ± 0.15 gm to 80.63 ± 5.02 gm. Calculated daily percent changes revealed that as the turtles aged, the rates decreased. At 56 days of age, weight was the most strongly correlated with its value at 786 days of age. No seasonal differences in growth were noted between the summer and winter periods when turtles would enter winter dormancy in certain natural environments. Environmental factors are reflected in the growth of the turtle.
Morphology of a two‐headed piglet
Authors: Partlow Gary D. , Barrales Dorothy E. , Fisher Kenneth R. S.
Published: February 2005

A live‐born, one‐day‐old diprosopic piglet was presented to the Ontario Veterinary College. The piglet had a normal body with two heads, joined in the occipital region. There were two complete snouts, four eyes and three ears. The lower jaws were immobile because of overlapping mandibular rami. Although there was only one vertebral column, the bodies of the vertebrae, but not the neural arches, were doubled from the axis to T8. There was one thyroid gland and one larynx and hyoid apparatus. The two tongues were joined at their base just rostral to the single epiglottis. The palate was completely split in the right head but only partially split in the left. The cranial nerves were normal and doubled except for IX, X and XI. The brains were fused at the pons‐medulla junction. An anomalous midline tag of neural tissue resembling remnants of the medial halves of two nervous systems extended from this point to the level of T8. Possible developmental mechanisms and rates of incidence are discussed.
A freeze‐fracture study of avian epiphyseal cartilage differentiation
Authors: Borg Thomas K. , Runyan Raymond , Wuthier Roy E.
Published: February 2005

The morphological features of avian epiphyseal cartilage have been investigated by freeze‐fracture techniques. Progressive changes occurred in both the cells and the matrix during differentiation. Chondrocytes changed in shape from small flattened cells with few, short cellular processes, to enlarged ovoid cells with numerous long processes often associated with extracellular vesicles. In the matrix these vesicles appeared first in the cellular lacunae, then in the extralacunar matrix, becoming larger and more numerous. Large membrane‐associated particles (MAPS) were seen on the p faces of the plasmalemma. These became progressively concentrated on and around the cellular processes, with few large MAPS being seen on the e face. Similar distribution of MAPS was seen in the matrix vesicles. Domains of hydrated proteoglycan aggregates were manifest as regular fracture patterns in the extralacunar matrix of the upper regions of the plate. Collagen fibrils progressively increased in size and state of aggregation, often being associated with matrix vesicles and in the end, with long plate‐like mineral crystals. These findings, while in basic agreement with patterns observed with TEM, reveal important new features concerning cellular and matrix structure during cartilage differentiation.
Role of microtubules in the organization of the Golgi complex and the secretion of collagen secretory granules by periodontal ligament fibroblasts
Authors: Cho Moon‐Il , Garant Philias R.
Published: February 2005

Fibroblasts of the periodontal ligament (PDL) of the mouse exhibit a high degree of cytoplasmic and functional polarity. This polarity is dependent upon an elaborate system of microtubules. The location of the microtubular arrays and the observed effects of colchicine administration suggest that microtubules play an important role in maintaining the organization of the Golgi complex and its functional relationship to the rough endoplasmic reticulum. Smooth‐walled intermediate vesicles, apparently derived from the rough endoplasmic reticulum, are aligned along microtubules at the immature face of the Golgi apparatus, and mature secretory granules are closely related to microtubules at the mature face of the Golgi apparatus. In distal cell processes the granules are closely parallel to microtubules and on occasion bridge‐like attachments from granules to microtubules were noted. This relationship of secretory granules to microtubules, the lack of granule storage, and the effects of colchicine on granule secretion suggests that microtubules are part of a mechanism for collagen granule translocation from the Golgi complex to the cell periphery.
A stereologic analysis of collagen phagocytosis by fibroblasts in three soft connective tissues with differing rates of collagen turnover
Authors: Svoboda E. L. A. , Shiga A. , Deporter D. A.
Published: February 2005

The purpose of this study was to assess the importance of the phagocytic mechanism of collagen resorption in the normal turnover and remodelling of soft connective tissues. Collagen phagocytosis by fibroblasts in rat skin, attached gingiva, and periodontal ligament was quantitated using the methodology of electron microscopic stereology. Periodontal ligament contained five and 15 times as much phagocytosed collagen as attached gingiva and skin respectively. Also, for each tissue examined, a positive correlation was observed between the amount of collagen phagocytosed and the known rate of mature collagen turnover.
Circadian rhythm in mitotic index of corneal epithelium: Presence of ehrlich ascites carcinoma and treatment with saline or hydroxyurea
Authors: Burns E. Robert
Published: February 2005

A study of the circadian rhythm in the mitotic index (MI) of the corneal epithelium was completed in non‐tumor‐bearing mice and in mice bearing the Ehrlich ascites carcinoma (EAC). All mice were standardized to a light‐dark cycle with 12 hours of light from 0600 to 1800 CST alternating with 12 hours of darkness from 1800 to 0600 CST. Treatments included injection with saline (SAL) or hydroxyurea (HU) at different circadian times. This investigation demonstrated that: (1) Data from untouched animals cannot serve as proper controls because treatment with SAL altered the level of the MI, but only during the diurnal, not the nocturnal, phase of the circadian cycle; (2) the presence of the EAC depressed the level of the MI, but this inhibition was only detected during the diurnal period; (3) treatment with 500 mg/kg HU injected at 0500 caused more perturbation in this rhythm than did treatment with 500 mg/kg HU at 1700; (4) when 500 mg/kg HU was given at 2000 and 0100 and 0500, the perturbation of the rhythm was greater than when 500 mg/kg HU was given at 0900 and 1400 and 1700; (5) when 3000 mg/kg HU was given at 1700 and compared to 500 mg/kg HU at 1700, little difference in the overall circadian profiles of these rhythms was observed, indicating that the circadian control mechanisms operating on the MI exerted a greater influence than did a dosage change from 500 to 3000 mg/kg HU; and (6) a comparison of the practice of plotting experimental and control data as “hours after treatment” versus using a “time of day” plot for the same data demonstrated that the “hours after treatment” plot is very misleading because it fails to account for the significant circadian oscillation in this in vivo system.
Morphological profiles of cryptorchid XXY mouse testes
Authors: Huckins C. , Bullock L. P. , Long J. L.
Published: February 2005

Two mice with an XXY karyotype and cryptorchid testes appeared spontaneously in a colony. The animals were H‐Y antigen‐positive, and had elevated serum levels of follicle‐stimulating (FSH) and luteinizing (LH) hormones. Testes of the affected mice were atrophic, containing a few solid seminiferous cords surrounded by vast amounts of compact interstitial material. The cords were delimited by a broad tunica propria in which the basal lamina was irregularly thickened and stratified into a number of alternating dense and less dense layers. Most sex cords were populated by mature Sertoli cells and small pleomorphic elements resembling monocytic‐derived macrophages. Within some cords, the macrophages aggregated into a central mass with which identifiable Sertoli cells and (PAS) periodic acid Schiff‐positive fragments of basal lamina were associated. In more severely damaged cords, the basal lamina and peripheral carpet of Sertoli cells were totally missing. Such cords were populated only by the central macrophages with fragments of basal lamina and degenerating Sertoli cells. Finally, a few collapsed remnants of cords contained compact nodules of macrophages surrounded by what appeared to be the outer part of the tunica propria. The interstitial area, as well as the outer walls of the seminiferous cords were also heavily infiltrated by macrophages. Overall, the morphological picture was one of severe immunological injury. We do not know what role, if any, the genetic constitution and/or intra‐abdominal environment may play in the expression of these bizarre pathologies. However, such severe changes have not been reported in either Klinefelter's syndrome or the undescended testes of any human or subprimate species.
The mammary gland of the weddell seal, Leptonychotes weddelli (Pinnipedia). I. Gross and microscopic anatomy
Authors: Tedman R. A. , Bryden M. M.
Published: February 2005

The Weddell seal cow possesses two subcutaneous, ellipsoidal, abdominal mammary glands with a volume of two to three liters when lactating. Corrosion casts reveal that approximately ten large ducts radiate from a gland cistern at the base of the nipple, and end in a complex system of terminal branches. Each gland has a separate arterial supply, mostly from the caudal deep epigastric with a minor contribution from the deep circumflex iliac. Histologically, lactating, nonlactating (resting), and immature glands resemble those of other eutherians. Sinusoidal blood vessels, not observed in the mammary glands of other mammals, are present within lactating but not in resting lobules in the seal. The terminal pouch and lactiferous sinuses possess circular smooth muscle and elastic fibers in the walls, and accumulations of lymphocytes immediately beneath the epithelium. Sebaceous and sweat glands open into the walls of the nipple and the apex of the terminal pouch. There are extensive networks of blood vessels and longitudinal smooth muscle and elastic fibers in the walls and base of the nipple. The possible functions of these morphological observations are discussed.
Sympathetic innervation of murine thymus and spleen: A comparative histofluorescence study
Authors: Williams John M. , Felten David L.
Published: February 2005

Fluorescence microscopy of thymus and spleen from four strains of mice (C3H and ICR controls, AKR spontaneously leukemic and NZB autoimmune) revealed varicose noradrenergic (NE) fibers in perivascular and parenchymal regions of both organs. Thymic innervation was largely perivascular, but isolated islands and strings of free NE fibers were noted among thymic parenchymal cells. A morphological proximity between NE fibers in the thymus and mast cells was noted in all strains studied, but was exceptionally prominent in the NZB thymus. Perivascular plexuses within the splenic white pulp sent single NE fibers between the surrounding lymphocytes. Catecholamines and histamine have been shown to modulate lymphocyte development and activity in vitro. The present study provides morphological evidence that both NE and histamine are available to lymphocytes in thymus and spleen, and thus provides morphological evidence for neurla modulation of immune activity in vivo.
Ultrastructural study of the embryonic development in the rat pineal gland
Authors: Calvo J. , Boya J.
Published: February 2005

The ultrastructure of the albino rat embryo pineal gland was studied from day 13 of development through birth. In the first stages (13–16.5 days of development) the pineal evagination presents a barely differentiated epithelium. From 17 days onward the transformation of the pineal gland from a tubular evagination into a compact organ occurs. The obliteration of the recess takes place by means of two mechanisms: (a) multiple foldings of the epithelium which determine an approximation and fusion of the walls of the recess, and (b) occupation of the lumen by cells extruded from the pineal epithelium. Embryos of 18–21 days of gestation still show remains of the pineal recess.

Frm day 16.5 onward elements of the pineal parenchyma have been found outside the pineal epithelium contour. They contact with the mesenchymal cells without a basal lamina separating both elements.

Day 20 marks the beginning of recognizable differentiation of pineal cellular types. However, in the newborn rat these types are not yet clearly established.
The three‐dimensional cytoarchitecture and pattern of motor innervation of branched striated myotubes
Authors: Ontell Marcia , Feng K. C.
Published: February 2005

Three‐dimensional reconstructions of “regenerating” myotubes in the “degeneration‐regeneration” regions and in the “regenerative” foci of the extensor digitorum longus muscle of the C57BL6J/dy2J myopathic mutant mouse were made from spaced serial ultrathin section. Complex branching and recombination occurred, involving myotubes which for extensive regions along their length appeared to be independent. No accumulation of specialized organelles occurred at the branching site. Continuous branches displayed multiple discrete motor endplates.
The presence of proximal tubulelike cells in the kidney parietal epithelium in response to unilateral nephrectomy
Authors: Andrews Peter M.
Published: February 2005

Five months following unilateral nephrectomy, the parietal epithelia in the remaining kidneys of Sprague‐Dawley rats were examined by light and electron microscopy. Compared with controls, the kidneys from uninephrectomized rats exhibited a dramatic increase in mass characteristic of compensatory hypertrophy. Approximately 20% of the renal corpuscles in the hypertrophied kidneys had parietal epithelia lined by tall cells which possessed a brush border and other morphological characteristics of proximal tubule cells. In some instances proximal tubulelike cells made up over half of the cells lining the parietal epithelium. The possible significance of this finding is discussed.