bluuebunny/crossref_metadata_2025 huggingface dataset:
Ultrastructural differentiation of stromal and vascular components in early macaque placental villi
Authors: King Barry F.
Published: February 2005

In this study, closely staged placental villi from rhesus monkeys between 19 and 60 days of gestation were used to examine (1) the origin of endothelial cells and the mechanism of angiogenesis in villi; (2) the origin of placental macrophages (Hofbauer cells), and (3) the origin of the reticular cells that compartmentalize the stroma. The results did not support the concept that early stromal cells in the villi were derived by in situ delamination from cytotrophoblast. The extraembryonic mesodermal (mesenchymal) cells at the earliest of ages examined contained considerable granular ER. These cells organized into groups and formed primitive intercellular junctions, thus giving rise to the early angioblastic masses. The angioblastic masses were cellular, not syncytial; and lumen formation was not the result of intracellular vacuolization, but rather was the result of the acquisition of junctionally defined spaces. The earliest capillaries lacked intravascular blood cells and a basal lamina. Later, blood cells were evident in the lumina. At about 45–50 days of gestation, fetal capillaries began to indent the basal surface of the trophoblast. The basal lamina of the fetal capillaries still had not developed by 60 days of gestation. Between 35 and 40 days of gestation, significant morphological changes took place in the villous stroma. Evidence was obtained that the mesenchymal cells differentiated into the reticular cells that subdivided the stroma into fibrilrich and fibril‐free compartments. At the same time, Hofbauer cells were observed for the first time; they occupied the fibril‐free regions of the stroma. We did not observe any clear indications of intermediate stages of differentiation between other stromal cell types and Hofbauer cells. It is suggested that placental macrophages may have an origin independent of other stromal types; one possibility is that they are derived from blood monocytes as in other tissues. It is further suggested that the activities of the macrophages and reticular cells may be important in remodeling the extracellular matrix and may be related to the process of branching morphogenesis in the villi.
Thalamic arterial pattern: An endocast and scanning electron microscopic study in normotensive male rats
Authors: Rieke Garl K.
Published: February 2005

Rat cerebral vasculature serves as a model for study of the pathophysiology of stroke in humans. Human thalamic anteries show a high incidence of stroke. The objective is to describe the thalamic arterial vascular pattern in normotensive male rats as the initial step for quantitative histochemical studies of enzyme activities in the walls of these vessels. Intracardiac injections of methyl methacrylate monomer provide detailed vascular endocasts. The thalamic vascular bed defined by in situ dissection, serial reconstruction, and light and scanning electron microscopy of endocasts contained four groups of vessels: (1) ventral medial thalamic arteries, (2) thalamic branches from the posterior cerebral artery, and (3) ventral lateral and (4) ventral anterior thalamic arteries. Thalamic vessels are muscular arterioles that, after three to four bipinnate branches, feed into a continuous capillary bed (no loops). The parent vessels and their subsequent branches have been evaluated in terms of their mean internal diameters, mean interbranch intervals, and branch angles. The arterial patterns to rat and human thalami are very similar, with the exception of the anterior choroidal artery which is missing in the rat. The branches supplying the thalamus in both the rat and human are closely associated with the circle of Willis; however, the constituent parts of the circle in rat vary from the pattern in human brain. The rat thalamic arteries show morphological features similar to those seen in the stroke‐prone ganglionic arteries in the human basal ganglia.
Rathke's pouch grafts in adult brain sites
Authors: Schechter Joel , Gash Don , Ahmad Nazir
Published: February 2005

Donor tissue containing Rathke's pouch (RP) with its associated mesenchyme and neural lobe was isolated from 15‐day fetal rats and stereotaxically transplanted either to hypothalamic hypophysiotropic sites or to cerebral cortex of adult females for 30 days. Hosts either were intact or had been hypophysectomized 2–4 weeks prior to transplantation of Rathke's pouch. Grafts in the hypothalamus of either intact or hypophysectomized hosts were pleomorphic and large, often as wide as 1–2 mm, and occasionally larger. Grafts in the cortex of either intact or hypophysectomized hosts were nodular and occasionally projected upward in association with the meninges (cortex/meninges grafts).

Certain features were characteristic of the grafts in all experimental groups, i.e., development of histotypic pars distalis with cell cords and fenestrated capillaries. In all experimental groups gonadotrophs and somatotrophs, when present, were localized at the graft margin adjacent to the connective‐tissue interface; mammotrophs, when present, were distributed throughout the graft. Features specific to each experimental group also were apparent. Grafts in the hypothalamus of both intact and hypophysectomized hosts typically were encapsulated by a labyrinthine meshwork of cell processes, whereas cortex/meninges grafts directly abutted dense connective tissue or neural tissue. In hypothalamic grafts in intact hosts, moderately differentiated mammotrophs, gonadotrophs, and somatotrophs could be identified by their cytological features and immunopositivity for prolactin, luteinizing hormone, and growth hormone, respectively. In hypothalamic grafts in hypophysectomized hosts, mammotrophs were absent, and gonadotrophs and somatotrophs were poorly granulated and not abundant. Grafts in the cortex of intact hosts contained numerous, well‐differentiated mammotrophs, gonadotrophs, and somatotrophs. Many of the mammotrophs in these grafts were hypertrophied, and profiles of exocytosis were common. In grafts in the cortex of hypophysectomized hosts, mammotrophs were either absent or very few, whereas gonadotrophs and somatotrophs were numerous. Gonadotrophs in these grafts were dramatically hypertrophied, although exocytosis was rare.

The results indicate that development of histotypic pars distalis may occur in hypophysiotropic and nonhypophysiotropic brain sites and that the hormonal state of the host as well as implantation site modulate cytodifferentiation of specific pars distalis cell types.
Dynamic histology of the antral epithelium in the mouse stomach: V. Proliferation gradient from the gland base to the isthmus at various times of day
Authors: El‐Alfy M. , Leblond C. P. , Lee E. R.
Published: February 2005

The surface epithelium of the mouse pyloric antrum invaginates into blind‐ended tubules whose proliferative activity was investigated by using light microscopy and 3H‐thymidine radioautography. Adult, male, CD1 mice were habituated to 12 hr of light (0600–1800hr) alternating with 12 hr of darkness. Groups of four were given an injection of 40 μCi of 3H‐thymidine per animal and killed 1 hr later at 0600, 1200, 1800, and 2400 hr. The glands at the base of the tubules and the adjacent isthmi were serially cross‐sectioned, and 0.5‐μm‐thick sections were prepared for radioautography. By using morphological criteria, glands were divided into five levels from their base to the isthmus (which was considered as being a sixth level). Proliferative activity was estimated by measuring the proportion of cells incorporating 3H‐thymidine (labeling index) and the proportion of cells undergoing mitosis (mitotic index).

The labeling index was found to decrease gradually from a high value in the isthmus to a relatively low one in the gland base; and this was observed at four times of the day. Similar gradients were observed in the mitotic index. Moreover, significant circadian variation was disclosed at most levels by comparing either labeling or mitotic index at four different times of the day. The labeling index tended to peak at the transition from dark to light (0600 hr) and drop at the transition from light to dark (1800 hr). In contrast, mitoses usually reached a maximum at the end of the light cycle (1800 hr) and a minimum at 2400 hr.

In summary, the rates of DNA synthesis and cell division showed a sharply decreasing gradient of cell proliferation from the immature cells of the isthmus (level 6) to the mature cells of the gland base (level 1). The existence of some degree of proliferation, even in mature cells, sets apart the renewal taking place in the isthmus‐gland system, since in other renewal sites, cells stop dividing before they reach maturity. Finally, circadian variation has been identified in the proliferative activity of isthmus and gland and appears to be closely related to the light‐dark cycle.
Comparative study of cytoplasmic elimination in spermatids of selected mammalian species
Authors: Sprando Robert L. , Russell Lonnie D.
Published: February 2005

In the transformation of a spermatid into a spermatozoon, cytoplasmic loss occurs, allowing the sperm to swim unhindered. Cytoplasmic loss takes place via elimination of the residual body and through structures known as tubulobulbar complexes. A determination of cytoplasmic loss in several species was undertaken by using high‐resolution electron microscopic morphometric techniques. During the period that tubulobulbar complexes are present, an average 53% cytoplasmic loss was recorded for five species (guinea pig, 48.8±6.2% (SEM); monkey, 60.3±4.3%; opossum, 54.5±4.4%; rabbit, 46.9±2.7%; and rat, 55.7±4.9%), whereas there was essentially no loss or gain in cytoplasm during the same period for round spermatids. Surprisingly, during spermatid elongation an approximate 36% loss of cytoplasm was also recorded for five species (guinea pig, 50.1±6.3%; monkey, 30.0±15.4%; opossom, 25.4±9.0%; rabbit, 42.4±8.6%; and rat, 34.9±11.9%), which is only partially (∼60%) accounted for by fluid pumping from the nucleus during nuclear condensation. A densification of the cytoplasm of elongate spermatids, as compared with round spermatids, suggests fluid is also pumped from the elongating spermatid cytoplasm. Fluid loss from germ cells may contribute to the seminiferous tubule fluid, a fluid previously thought to be solely of Sertoli‐cell origin.
Presence of α‐melanocyte‐stimulating hormone in bovine pituitary intraglandular colloid of intermediate lobe origin
Authors: Boyd William H. , Krogsrud R. L.
Published: February 2005

Alpha‐melanocyte‐stimulating hormone (α‐MSH), one of several peptide hormones originating in the intermediate lobe of the pituitary as proopiomelanocortin, was discovered in bovine pituitary intraglandular colloid by using radioimmunoassay. The quantity of α‐MSH varied from 5 to 368 μg/mg protein in the three pools. The importance of this finding is discussed in light of the possibility that the colloid is a transport medium for α‐MSH and other intermediate lobe hormones.
Ultrastructural demonstration of exocytosis in intact and saponin‐permeabilized cultured bovine chromaffin cells
Authors: Brooks Jack C. , Carmichael Stephen W.
Published: February 2005

Exocytosis is the release of intracellular vesicular contents directly to the cell exterior after fusion of the vesicular and plasma membranes. It is generally accepted as the process by which transmitters and hormones are released from neurons and neurosecretory cells. There is overwhelming biochemical evidence that exocytosis is the mechanism by which catecholamines are released from adrenal chromaffin cells. With the exception of the hamster, however, there is little ultrastructural evidence to support such a mechanism. We have used a modified in vitro tannicacid method to visualize exocytosis by transmission electron microscopy in intact and saponin‐permeabilized bovine chromaffin cells. When cells are exposed to tannic‐acid‐containing medium, the content of vesicles involved in exocytosis is coagulated in situ as the vesicle opens to the exterior. Numerous exocytotic profiles were observed. The exposed vesicle contents appeared more granular than those of vesicles in the cell interior. Tannic acid also made the plasma membrane more distinct. Small holes were apparent in the plasma membrane of saponin‐treated cells, with little disruption of underlying cytoplasmic structure. Furthermore, when these cells were stimulated with calcium, exocytosis was evident only at regions of intact plasma membrane, not at the holes. Parallel measurements of secretion showed no secretion in the presence of tannic acid. Pretreatment with tannic acid prevented subsequent secretion by intact cells and markedly reduced that of permeabilized cells, indicating a probable change in the nature of the plasma membrane. Our results provide the first ultrastructural demonstration of exocytosis in bovine chromaffin cells with the aid of transmission electron microscopy. It is also clear that exocytosis is the mechanism of release in both intact and permeabilized cells.
Restricted growth at the frontonasal suture: Alterations in craniofacial growth in rabbits
Authors: Babler William J. , Persing John A. , Nagorsky Mathew J. , Jane John A.
Published: February 2005

Apposition of bone at the sutural margin is generally thought to be a compensatory adjustment to growing soft‐tissue organs such as the brain or eyes within the skull. The frontonasal suture which is located at the interface between the cranial and facial skeletons is a site of extremely active growth in the young rabbit. Recently, we showed that premature closure of a cranial suture, the coronal suture, can alter the growth not only at the adjacent frontonasal suture but also of the basicranium and midface. This study examines the effects of restricted growth at the frontonasal suture on both growth at adjacent cranial sutures and linear growth of the basicranium and midface.

Thirty newborn New Zealand White rabbits were subdivided into experimental and sham‐treated groups of equal size and distribution for sex and birth weight. At 9 days of age, the frontonasal suture of each experimental animal was immobilized by bilateral application of methyl‐cyanoacrylate adhesive across the frontonasal suture. Growth and morphometric changes were monitored by radiocephalometric methods through 120 days of age by bilateral implantation of radiopague markers on each side of frontonasal, coronal, and anterior lambdoid sutures.

Results indicate that restricted growth at the frontonasal suture results not only in a significant shortening of the midface but also in significant decreases in growth at the coronal and internasal sutures. Growth at the interfrontal and sagittal sutures is increased. Furthermore, growth at the anterior portion of the nasal bones is significantly increased, thereby offsetting a portion of the decreased nasal bone length resulting from frontonasal restriction.
Quantitative immunocytochemical analysis of the endocrine pancreas of the Nile crocodile
Authors: Rhoten William B.
Published: February 2005

Four major pancreatic hormones were immunolocalized at the light and electron microscopic levels in the pancreas of the Nile crocodile, Crocodilus niloticus. Immunogold was used for electron microscopy, and peroxidase‐antiperoxidase was used for light microscopy. Somatostatin‐positive D‐cells and pancreatic polypeptide‐containing F‐cells accounted for about 60% of the immunoreactive cells in the ventral pancreas. Glucagon‐positive A‐cells were the least frequent cell type in the ventral pancreas, about 15%, but were the predominant cell type, about 40%, in the pancreas that was dorsal in character. An expanded population of D‐cells (relative to mammals and other higher vertebrates) in association with two very different numbers of A‐cells can be expected to have important consequences for the homotropic control of secretory activity of the endocrine pancreas as well as for the function of the acinar pancreas. F‐cells were absent from the dorsal part of the pancreas, whereas insulin‐containing B‐cells were slightly more abundant in this portion of the pancreas. The regional character of the endocrine pancreas was related to the complex looping of the proximal small intestine.

Without immunolabeling, only B‐granules were morphognomonic in electron micrographs. The insulin‐reactive B‐granules were the smallest (370 nm) of the secretory granules and were followed in size by somatostatin‐positive D‐granules (380 nm). The pancreatic polypeptide‐containing secretory granules were the largest (580 nm). Glucagon‐reactive A‐granules (430 nm) sometimes exhibited a protuberance or extension of secretory granule matrix and limiting membrane. Such a morphological feature has previously been associated with secretion of glucagon and the initiation of insulin secretion. Taken together these studies indicate that protuberances have a significant, but as yet undefined, role in pancreatic endocrine cells.
Maturation of myocardial capillaries in the fetal and neonatal rat: An ultrastructural study with a morphometric analysis of the vesicle populations
Authors: Porter Glyn A. , Bankston Patrick W.
Published: February 2005

The ultrastructural morphology of the cellular and extracellular components of the developing myocardial capillary wall—from the 16‐day‐gestation fetus of the rat to the 21‐day neonate—was examined. A morphometric analysis of plasmalemmal vesicles and of coated vesicles and pits of capillary endothelial cells was performed during the same developmental period. As the lateral extensions of the capillary endothelial cells change from irregular to regular in their thickness during development, there is an increase in the number of plasmalemmal vesicles and a progression from clusters of plasmalemmal vesicles to a uniform distribution in the endothelial cell. The ratio of vesicles which are open to the luminal front, which are “free” in the cytoplasm, or which are open to the abluminal front of the endothelial cell was consistent throughout development. The numerical density of plasmalemmal vesicles demonstrates a gradual and significant increase. In contrast, the numbers of coated vesicles and pits are variable within a very narrow range, and no pattern of increase or decrease is discernible during development. Similarly, there is no change in interendothelial cell junctions, which consist of occluding and primitive adhesive junctional types, during development. The lamina densa of the basal lamina gradually develops from discontinuous, patchy densities along the abluminal surface of the endothelial cells to a continuous and distinct layer by 21 days gestation. The presence of the proteoglycan species in the developing basal lamina was assessed with the cationic dye ruthenium red (RR), and the appearance of RR‐marked proteoglycans was found to parallel the appearance of lamina densa material. The RR sites appear discontinuously in patches; and later, the RR sites appear in a continuous and regular planar lattice in the lamina rara interna and externa at 21 days gestation. A complete array of RR‐stainable anionic sites outside a continuous lamina densa near birth indicates that the basal laminae of developing capillaries in the heart are morphologically, and in part biochemically, mature by the end of the first neonatal week.

Our results show that the endothelial cells and the subtending basal lamina of myocardial capillaries gradually mature morphologically during the final days of gestation and the first neonatal week. The finding of tight junctions and small areas of vesicle concentration in fetal endothelial cells could indicate that sites of permeability are limited early in myocardial capillary development and that these vesicular sites increase as gestation proceeds and as the myocardial capillaries mature.
Ultrastructure of the choroid plexus epithelium of pigeons treated with drugs: I. Effect of thyradin, 2,4‐dinitrophenol, and cycloheximide
Authors: Koshiba Kimikazu
Published: February 2005

Possible changes in the epithelial cells of the pigeon choroid plexus induced by administration of thyroid powder (Thyradin), 2,4‐dinitrophenol, and cycloheximide were studied by scanning and transmission electron microscopy. A marked increase in the number of large bulbous and bleblike protrusions on the apical end of the epithelial cells was observed after oral administration of Thyradin for a month. The endoplasmic content of the protrusions consisted mainly of electron‐lucent material. These results provide morphological evidence for the stimulatory effect of Thyradin.

Intramuscular injections of 2,4‐dinitrophenol for 15 days caused the collapse or deformation of the mitochondria and bleblike or bulbous protrusions. This indicates that changes in the surface configuration of the choroid plexus are controlled by an energy‐dependent mechanism. The decrease of protrusions and polyribosomes and increase of the tubular saccules of varying electron density, size, and shape were noted in cells after 15 days of intramuscular cycloheximide injection. The electron density of the protrusions is lower than that of the control pigeons.

The results of this study suggest that a curious pleomorphic structure on the apical surface of the choroid epithelial cell of pigeon is closely related to the functional state of choroidal cells. The study also demonstrates that a secondary ultrastructural response due to diverse physiologic effects is reflected in the architecture of the choroid plexus cells.
Lung growth of the turkey, Meleagris gallopavo: I. Morphologic and morphometric description
Authors: Timmwood Karen I. , Hyde D. M. , Plopper C. G.
Published: February 2005

To describe lung growth qualitatively and quantitatively from prehatch to adulthood of an unselected line of turkey, a precocial a avian species, 36 male turkeys, three in each age group, were killed at 22 and 25 days of incubation, on hatch day, and at 1, 4, 7, 10, 14, 21, 28, 112, and 420 days of age. Body weight and lung volume were measured. A three‐level cascade sampling system was used to prepare lung tissue for morphologic and morphometric observation by light microscopy. Point and intersection counting were used to estimate volume and surface densities of lung compartments relative to lung volume. Absolute volumes and surfaces of lung compartments were calculated. Bilogarithmic regressions provided allometric equations to describe growth of the lung in three phases: (1) Tissue proliferation—explosive growth of lung volume relative to body weight and of the gas‐exchange compartment within the lung. At 22 days of incubation there were few air and blood capillaries and a great deal of tissue that looked like mesenchyme between the parabronchin. Within the 6 days prior to hatch, the surface area of air capillaries increased 11‐fold and of blood capillaries 27‐fold, whereas the volume of interparabronchial tissue decreased 58%. (2) Equilibrated growth—from hatch day to 28 days of age, most lung compartments grew evenly with lung volume. (3) Regulated growth—from 28 days of age to adult, all lung compartments, except large vessels and exchange compartment, grew more slowly than the entire lung. Interatrial septa lengthened and their epithelial covering thinned, infundibula became more apparent, and interparabronchial connective tissue reached a minimal volume density in the adult lung.
Cells of origin of the branches of the facial nerve: A retrograde HRP study in the rabbit
Authors: Baisden Ronald H. , Woodruff Michael L. , Whittington Dennis L. , Baker Duane C. , Benson Amy E.
Published: February 2005

The origin of different branches of the facial nerve in the rabbit was determined by using retrograde transport of HRP. Either the proximal stump of specific nerves was exposed to HRP after transection, or an injection of the tracer was made into particular muscles innervated by a branch of the facial nerve. A clear somatotopic pattern was observed. Those branches which innervate the rostral facial musculature arise from cells located in the lateral and intermediate portions of the nuclear complex. Orbital musculature is supplied by neurons in the dorsal portion of the complex, with the more rostral orbital muscles receiving input from more laterally located cells while the caudal orbital region receives innervation from more medial regions of the dorsal facial nucleus. The rostral portion of the ear also receives innervation from cells located in the dorsomedial part of the nucleus, but the caudal aspect of the ear is supplied exclusively by cells located in medial regions. The cervical platysma, the platysma of the lower jaw, and the deep muscles (i.e., digastric and stylohyoid) receive input from cells topographically arranged in the middle and ventral portions of the nuclear complex. It is proposed that the topographic relationship between the facial nucleus and branches of the facial nerve reflects the embryological derivation of the facial muscles. Those muscles that develop from the embryonic sphincter colli profundus layer are innervated by lateral and dorsomedial portions of the nuclear complex. The muscles derived from the embryonic platysma layer, including the deep musculature, receive their input from mid to ventral regions of the nuclear complex.
The Golgi apparatus in the acinar cells of the developing embryonic pancreas: I. Morphology and enzyme cytochemistry
Authors: Pavelka Margit , Ellinger Adolf
Published: February 2005

The Golgi apparatus apparatus of pancreatic acinar cells of rat embryos was studied during development from day 13 through day 20 of gestation. The morphological and enzyme cytochemical patterns varied characteristically in the course of cell differentiation. (1) A pronounced system of “rigid lamellae” characterized the area near the trans face of the Golgi stacks in the protodifferentiated and early phases of the differentiated states; by contrast, “rigid lamellae” were sparse in the terminal period of gestation. (2) Reaction product of acid phosphatase labeled the “rigid lamellae” in the protodifferentiated state, was extended across the majority of the stacked cisternae in the early differentiated state, but was restricted to the trans side again in the later periods of cell differentiation. (3) The early phase of the differentiated state was characterized by the tight association of the endoplasmic reticulum and Golgi cisternae on the trans side; the close spatial relationship of the two compartments was lessened after production of secretion granules had started.

The findings are in line with those of recent studies on the Golgi organization in some other types of cells in different functional states, and they present the embryonic pancreatic tissue as another model for demonstrating the high flexibility of the Golgi complex. In agreement with the patterns previously found in the absorptive cells of the small intestine, the present results show that the close associations of the endoplasmic reticulum and cisternae of the trans Golgi side predominate in the early stages of cell differentiation.
Characterization of filaments within Leydig cells of the rat testis
Authors: Russell Lonnie D. , Amlani Shahira R. , Vogl A. Wayne , Weber James E.
Published: February 2005

Rat Leydig cells were permeabilized and the cytoplasm partially extracted to visualize, describe, and characterize filamentous elements of the cytoskeleton. It was demonstrated by immunofluorescence microscopy that vimentin is abundant within Leydig cells. Ultrastructurally, intermediate filaments in Leydig cells were concentrated at perinuclear sites and comprised bundles that coursed through the cytoplasm. Actin was identified in Leydig cells with the F actin probe, NBD‐phallacidin. Fluorescence was strongest at the cortex of the cell. With myosin S‐1 subfragments, sparse actin was found positioned almost exclusively in cortical regions of the cell associated with coated pits and in Leydig cell processes.
Distribution of myelinated nerves in ascending nerves and myenteric plexus of cat colon
Authors: Christensen James , Rick Gary A.
Published: February 2005

The parts of the colon differ in motor function and in responses to extrinsic and intrinsic nerve stimulation. The distribution of myelinated nerve fibers in the colonic myenteric plexus is not known. Because these fibers might be largely extrinsic in origin, their distribution might indicate the domain of influence of extrinsic nerves and help to explain the different behaviors of the different parts of the colon. Myelinated fibers were examined by electron microscopy in cross sections of the ascending nerves and in myelin‐stained whole‐mount preparations in the colon. The ascending nerves are much like one another. They have the structure of peripheral nerves, not that of myenteric plexus. The proportion of myelinated fibers in the ascending nerves declines rostrad with no uniform change in total nerve fiber number. Cross‐sectional areas of ascending nerves, 3,304 to 7,448 μm2; total number of nerve fibers per profile, 703–2,651; and mean myelin coat thickness, 0.45 ± 0.01 μm, do not change uniformly along the ascending nerves. Myelinated fibers are about 2% of total fibers in the extramural colonic nerves, 7–9% in the ascending nerves in the sigmoid colon, and 2–3% at the rostrad ends of the ascending nerves in the transverse colon. Blood vessels lie at the core of each ascending nerve and on the nerve sheath. Myelinated fibers in the ascending nerves degenerate after section of colonic branches of the pelvic plexus and after section of the pudendal nerves, indicating that myelinated nerves reach the colon through both pathways. Myelinated fibers extend into the myenteric plexus through short lateral branches from the ascending nerves to adjacent ganglia where they turn to run cephalad throughout most of the colon but caudad in the rectum. Myelinated fibers do not extend into the cecum or proximal ascending colon. The nonuniform distribution of myelinated fibers along the colon, many of which are extrinsic in origin, could in part explain the disturbances in defecation that sometimes follow limited distal colonic resection, gynecologic surgery, and obstetric damage to the pudendal nerves in man.
Timing of ovulation and early embryonic development in Myotis lucifugus (Chiroptera: Vespertilionidae) from northern central Ontario
Authors: Buchanan G. Dale
Published: February 2005

Female Myotis lucifugus lucifugus, obtained from a hibernaculum in northern central Ontario, were aroused during the week that normal departures from hibernation began, maintained in large cages at 28–30°C, and fed mealworms daily. Some bats ovulated less than 24 hr after arousal, and with one exception, all bats with normal, mature follicles ovulated within 72 hr. Histological examination of reproductive tracts from ovulated bats indicated that oviductal transit was completed in 24–48 hr, and that blastocyst formation and implantation occurred 4 and 10 days, respectively, after fertilization. These time intervals were somewhat shorter than those reported in previous studies; however, the differences appeared to be due to the relative accuracy in determining the time of ovulation, not to differences in rates of development among different populations.
Presence of arginine‐vasopressin in bovine pituitary intraglandular colloid of intermediate lobe origin
Authors: Boyd W. H. , Krogsrud R. , Jichici D.
Published: February 2005

In order to determine whether pituitary intraglandular colloid might contain enough hormonal material to be considered a transport medium for intermediate lobe peptides, arginine‐vasopressin was assayed in three pools of colloid collected from nearly 100 steers. Colloid samples taken from the pituitary glands of freshly slaughtered cattle were pooled, freed of extraneous tissue, and lyophilized. Three such pools were further extracted on octadecylsilyl‐silica and assayed. The radioimmunoassay showed that arginine‐vasopressin was indeed present in the bovine intraglandular colloid at levels ranging from 0.18 to 6.95 ng/mg dry weight. These results indicate that the intraglandular colloid contains a sufficient amount of arginine‐vasopressin to be considered as a transport medium for this and other intermediate lobe peptides.
Mitochondrial migration and Ca‐ATPase modulation in secretory ameloblasts of fasted and calcium‐loaded rats
Authors: Sasaki Takahisa , Garant Philias R.
Published: February 2005

Migration of mitochondria and modulation of Ca‐ATPase activity in secretory ameloblasts were investigated ultrastructurally and ultracytochemically by using lower incisors taken from normally fed, 30‐hr‐fasted, and calcium (Ca)‐loaded rats. In normally fed rats, almost all mitochondria were localized in a narrow infranuclear compartment between the nucleus and proximal cell webs of secretory ameloblasts. In 30‐hr‐fasted rats, a prominent migration of many mitochondria into the supranuclear region of the cells was noted. Mitochondria returned to the infranuclear compartment and seldom appeared in the supranuclear region when fasted rats were Ca‐loaded by transcardiac perfusion with physiological Ca solution. Normally, the mitochondria of secretory ameloblast exhibited moderate Ca‐ATPase activity along their inner membranes. This mitochondrial Ca‐ATPase was decreased by a 30‐hr fast and became prominent again after Ca loading. Plasma‐membrane Ca‐ATPase was demonstrated in the entire cell surface of secretory ameloblasts. An especially abundant reaction was found along the invaginated cell surface of the Tomes process. This Ca‐ATPase also became very weak and was almost abolished from the Tomes process after fasting, but Ca loading caused reappearance of an intense Ca‐ATPase activity on the entire cell surface, including along Tomes's processes.

These results suggest that (1) mitochondrial localization in secretory ameloblasts is influenced by the Ca concentration of the extracellular milieu, and (2) the level of mitochondrial and cell‐membrane ATPase activity is responsive to the concentration of extracellular calcium.
Posthatching development of the rete ophthalmicum in relation to brain temperature of mallard ducks (Anas platyrhynchos)
Authors: Arad Zeev , Midtgård Uffe , Bernstein Marvin H.
Published: February 2005

In posthatching mallard ducks (Anas platyrhynchos), brain cooling improves with growth. To determine whether this may be correlated with growth‐related changes in morphology of the rete ophthalmicum, we studied the development of this rete in immature mallards from hatching to 29 days of age. We found that the number of arteries and veins was fixed at hatching. The rete continued to grow, however, in length and vessel diameter during body and brain growth. The vascular surface area for heat exchange in the rete therefore also increased with body and brain mass. The increase in retial heat‐exchange area was faster than the simultaneous increase in brain mass. The increase in body‐to‐brain temperature difference (δT) described previously occurred nearly in direct proportion to heat‐exchange area, such that the ratio of δT to exchange area was nearly constant at about 0.1°C per mm2 during growth. It is concluded that the increase in heat‐exchange area of the rete ophthalmicum plays a major role in the development of brain cooling capacity of posthatching ducks.
Nonparenchymal liver cells and granulomas during lamprey biliary atresia
Authors: Youson J. H. , Sargent P. A. , Yamamoto K. , Ogilvie D. , Fisher M. M.
Published: February 2005

Transmission (thin sections and freeze‐fracture replicas) and scanning electron microscopy were used to describe the nonparenchymal liver cells during the seven (1–7) stages of metamorphosis in the sea lamprey, Petromyzon marinus L., when bile ducts and canaliculi degenerate. The biliary atresia is accompanied by an increased diameter of fenestrae in the endothelium, an active phagocytosis by Kupffer cells in the sinusoids, and large lipid inclusions in perisinusoidal lipocytes (fat‐storing or Ito cells). Plasma‐like cells and foci of nonparenchymal cells (granulomas) are present in the liver interstitium during at least four stages of metamorphosis. The fenestrae in the sinusoidal wall are wider (up to 2.8‐μm diameter) than normally reported for vertebrate livers but are likely a reflection of the morphogenetic and physiological events and consequences of the biliary atresia. Kupffer cells are involved in an extensive erythrophagocytosis, the storage of iron, and perhaps the incorporation of cellular components from hepatocytes. Lipocytes are the vitamin A‐storing cells of the transforming liver and may be responsible for some perisinusoidal fibrosis. Granulomas are present during stages 3–6 and are focal areas where mononuclear leukocytes (lymphocytes and plasmalike cells), macrophages, and neutrophils have infiltrated the hepatic parenchyma. The function of the granulomas is not known; but their presence may be related to the porous nature of the sinusoidal wall, the tissue degeneration, and/or the physiological change (e.g, bile stasis) during biliary atresia.
Passive Heymann nephritis induced by rabbit antiserum to membrane antigens isolated from rat visceral yolk‐sac microvilli
Authors: Leung Christopher C. K. , Cheewatrakoolpong Boonlert , O'Mara Tom , Black Mercedes
Published: February 2005

Passive Heymann nephritis (PHN) is an animal model of immune‐complex‐induced renal disease resembling human membranous glomerulonephritis. It was induced in rats by injecting rabbit antiserum directed against glycoprotein antigens isolated from rat embryonic visceral yolk‐sac microvilli (VYS‐MV). The glycoprotein antigens were isolated by extracting the VYS‐MV with detergent Nonidet P‐40 followed by gel filtration in Sephacryl S‐300 and finally by lectin affinity chromatography with Ricinus communis agglutinin I. In vitro immunofluorescent localization studies demonstrated that the nephritogenic antibodies were localized along the apical region of the visceral yolk‐sac endodermal cells and the brush border of the proximal tubular cells of the kidney. Rats injected with a single dose of the antiserum manifested proteinuria. Indirect immunofluorescent studies showed that the injected rabbit IgG was localized in vivo along the capillary walls of the glomerulus in a granular fashion. Electron microscopic examination of the same kidney glomeruli revealed numerous electron‐dense deposits along the lamina rara externa of the glomerular basement membrane. Fusion of the epithelial foot processes was also present. These findings represent the typical immuno‐pathological characteristics of Heymann nephritis. Furthermore, with the aid of Ouchterlony analysis, the antiserum against the isolated VYS antigens exhibited an immunoprecipitin band which was in common with that formed by the antiserum against the homogeneous nephritogenic antigen (gp330) of renal brush border origin. Thus, the nephritogenic antigens which have been found to be associated with the brush border of the renal proximal tubules may also be present or cross‐reacted in the microvilli of the rat embryonic visceral yolk‐sac.
Innervation of mouse lymph nodes: Nerve endings on muscular vessels and reticular cells
Authors: Villaro A. C. , Sesma M. P. , Vazquez J. J.
Published: February 2005

Lymph node nerve endings have been studied in 1‐ to 48‐day‐old mice. Serial sections of Epon‐embedded lymph nodes were observed under the electron microscope to find the nerve endings. Most lymph node nerve fibers finally reach the smooth muscle cells of arterioles and muscular venules. Both kinds of vascular endings are similar, although endings are less numerous on venules. Nerve endings consist of one or more nerve processes surrounded by a usually incomplete Schwann cell sheath; frequently, axons show wide areas directly facing the muscle cells. The distance between such a naked axon and a myocyte ranges from 100 to 800 nm. Small granulated and clear vesicles are especially abundant in varicosities of nerve processes that are located very close to muscle cells. Nerve endings of lymph node vasculature probably correspond to vasomotor sympathetic adrenergic endings, regulating the degree of contraction of vessels which have a muscular layer. Other kinds of nerve endings also exist in lymph nodes: some axons appear free in the stroma and contact the surfaces of reticular cells; the latter also extend delicate cytoplasmic processes that surround the axons. The functional significance of nerve cell–reticular cell contacts is unknown.
Quantitative morphology of the primate peripheral retina (Macaca irus)
Authors: Krebs Wolf , Krebs Ingeborg P.
Published: February 2005

By using electron microscopy to study the quantitative morphology of the retina, it was possible to determine the spatial density of all principal retinal cells at a defined retinal location. In two retinas of cynomolgus monkeys at a position of 30° nasal of the fovea centralis, the following cell densities were determined from composite electron micrographs: retinal pigment epithelium: 3,400 cell/mm2; rod cells: 115,000 and 168,000 cells/ mm2; cone cells: 8,200/mm2; horizontal cells: 7,000/mm2; bipolar cells: 50,000/mm2; amacrine cells: 11,500/mm2; Müller cells: 16,000/mm2; and ganglion cells: 5,350 and 6,750/mm2.
Opossum adrenal medulla: I. Postnatal development and normal anatomy
Authors: Carmichael Stephen W. , Spagnoli Daniel B. , Frederickson Richard G. , Krause William J. , Culberson James L.
Published: February 2005

The anatomy and histology of the adrenal gland in the adult opossum were found to be typical for mammals. The development of the adrenal medulla was also found to follow the typical mammalian pattern. Primitive sympathetic cells were found in both intra‐ and extra‐adrenal locations in the newborn at a time when chromaffin precursor cells were migrating to the adrenal anlage. Pheochromoblasts first appeared within the forming medulla where at a later stage chromaffin cells could be observed forming columns of cells between adjacent sinusoids. Unlike in other mammals, much of this development takes place postnatally when the neonate is in the mother's marsupium. The value of the developing opossum adrenal medulla as an experimental model is stressed, since a significant amount of development takes place in an environment that is accessible to experimental manipulation.
Paracervical ganglia of the female rat: Histochemistry and immunohistochemistry of neurons, SIF cells, and nerve terminals
Authors: Papka R. E. , Traurig H. H. , Klenn P.
Published: February 2005

The paracervical ganglia of the female rat were studied to elucidate the variety of neural elements in the ganglia. Light and electron microscopy, histochemistry, and immunohistochemistry were employed to reveal subtypes of neurons; small, intensely fluorescent (SIF) cells; and nerve terminals and to examine the relationships between these elements. On the basis of their histochemical markers, four subtypes of principal neurons were identified: acetylcholinesterase (ACHE)‐positive, noradrenergic, neuropeptide tyrosine‐immunoreactive (NPY‐I), and vasoactive intestinal polypeptide‐immunoreactive (VIP‐I). The NPY‐I neurons appeared to be the most numerous and the noradrenergic the least common type of neuron. Four subtypes of chemically coded SIF cells were revealed: catecholamine‐containing, NPY‐I, and those immunoreactive for calcitonin‐gene‐related peptide (CGRP‐I) and cholecystokinin‐octapeptide (CCK‐8‐I). The SIF cells were present (1) as single cells among and adjacent to principal neurons and (2) as large clusters near the edges of the ganglia or in nearby nerve trunks. Synaptic contacts on SIF cells, or between SIF‐cell processes and neurons, were not observed. Seven subtypes of nerve terminals were stained: ACHE‐positive, CGRP‐I, CCK‐8‐I, VIP‐I, substance P‐I, enkephalin‐I, and atrial na‐triuretic factor‐I. Nerve terminals enwrapped the neurons as perineuronal plexuses in synaptic‐like relationships.

These results demonstrate that the paracervical ganglia of the female rat are a complex system of neural elements. For example, several classes of chemically coded neurons, SIF cells, and terminals exist in the ganglia. Each of these components contains a number of substances, some of which are putative neurotrans‐mitters, which could influence activity in the ganglia or in the effector organs innervated by the ganglia.
Ultrastructural, histochemical, and freeze‐fracture evaluation of multilamellated structures in human pulmonary alveolar proteinosis
Authors: Takemura Tamiko , Fukuda Yuh , Harrison Maria , Ferrans Victor J.
Published: February 2005

Ultrastructural, histochemical, and freeze‐fracture studies of material recovered by bron‐choalveolar lavage from patients with pulmonary alveolar proteinosis revealed four types (A, B, C, and D) of multilamellated structures (MS). Type A, the major component, consisted of concentric, trilaminar structures which were composed of two electron‐dense layers and a central lucent layer (5.7–7.5 nm in overall width) alternating with wider (25–30 nm) electron‐lucent intervening layers. Type B MS were formed by concentric lamellae with a 5–5.3‐nm periodicity. Type C MS were composed of wavy, electron‐dense lamellae with a 4–4.5‐nm periodicity. Type D MS were conglomerated masses of intricately arranged double or triple electron‐dense layers (7.5–13.5 nm wide) alternating with wider (30–40‐nm) electron‐lucent layers. The electron‐dense lamellae of type A, type C, and type D MS were stained with ruthenium red, the Thiéry method, and concanavalin A, indicating the presence of carbohydrate components. Freeze‐fracture studies revealed smooth inner and outer surfaces in type A MS, with the fracture planes passing through the central parts of the trilaminar structures; the intervening layers contained 10‐nm particles, which probably are proteins. Type B MS had smooth surfaces, and type C MS had slightly particulate surfaces; while type D MS showed tubular or polygonal structures, 350 nm wide, with rows of particles 7–8 nm in diameter. It is concluded that type A and type D MS contain proteins and carbohydrates, probably in the form of glycoproteins, as well as phos‐pholipids, and are related to tubular myelin. Type B and type C MS are considered to contain mainly phos‐pholipids; type C MS are also considered to contain carbohydrates and to be related to lamellar bodies of type II alveolar epithelial cells.
Neuropeptides in sensory perikarya projecting to the rat ovary
Authors: McNeill Daniel L. , Burden Hubert W.
Published: February 2005

Afferent perikarya in dorsal root ganglia (DRG) at the T13 and L1 segmental levels projecting to the rat ovary were identified by utilizing the fluorescent retrograde tracer true blue (TB). Subsequently, TB‐labeled ovarian afferent perikarya in DRG were examined for vasoactive intestinal polypeptide (VIP), substance P (SP), cholecystokinin‐8 (CCK‐8), neuropeptide Y (NPY), and somatostatin (SOM) immunoreactivity and for the presence of fluoride‐resistant acid phosphatase (FRAP) enzyme activity. Of the ovarian afferent perikarya at the T13 and L1 segmental levels, 20.5% displayed VIP immunoreactivity, 23.8% displayed SP immunoreactivity, and 43.1% were immunoreactive for CCK‐8. No ovarian afferent perikarya contained SOM or NYP immunoreactivity or FRAP activity. It is suggested that different neuropeptides may participate in modulation of specific ovarian functions.