bluuebunny/crossref_metadata_2025 huggingface dataset:
Three‐dimensional analysis of erythrophagosomes in rat mesenteric lymph node macrophages
Authors: Sasaki Katsunori
Published: February 2005

Erythrocytes extravasated into the sinuses of the rat mesenteric lymph nodes as a result of short‐term clamping of the portal vein were, although autologous, phagocytized markedly by the lymph node macrophages at 1 hr after reopening of the vein. The erythrophagosomes formed in the macrophages were exposed three dimensionally by the cellular matrix maceration method and observed with a high‐resolution scaning electron microscope. These results were compared to those obtained by conventional transmission electron microscopy. The process of degradation of an erythrocyte took about 6 hr. Coated pits were formed on the erythrophagosomal membrane at the early stage, and the erythrophagosomes were degraded by two different pathways: (1) the degradative pathway by invaginations of the phagosomal membrane, through which the erythrophagosome shrank and broke into secondary lysosomes, and (2) the hemolytic degradative pathway, by which it lost its content and formed a ghost.
Variability of measurements of cranial growth in the rabbit
Authors: Alberius Per , Malmberg Martin , Persson Sven , Selvik Göran
Published: February 2005

This study concerns techniques used in experimental cranial growth research: roentgen cephalometry, roentgen stereophotogrammetry, and gross measurements (osteometry). A comparison of the precision of these methods has not been found in the literature. Computation of technical errors is fundamental to the sound evaluation of registered findings, and such a presentation must be obligatory in all biometric reports. We compared the measurement error of roentgen cophalometric and osteometric data with that obtained by roentgen stereophotogrammetry (RSA). RSA demonstrates a superior replicability, and this technique gives possibilities for kinematic and volumetric determinations simultaneously with distance evaluation. Roentgen cephalometry has the advantage of enabling distance and angular measurements between any well‐defined skeletal points or lines. This technique, preferably after implantation of bone markers, is a reliable alternative, but optimal results necessitates calculations of the magnification factor for each bone segment involved. Direct osteometry does not contribute additional information, but problems of image magnification are omitted. Preferably, one individual should perform all measurements regardless of the method used. Growth rates and values calculated by one technique cannot be directly transformed to some other approach. In all probability, assessments of distance changes would gain substantially by using one technical approach consistently throughout actual age intervals. The least variable measurements of sutural growth are made for sutures growing primarily in one plane and with substantial growth rates. One must realize that differences among studies may be due to the limitations of, in particular, the cephalometric and osteometric techniques.
Expression of the epidermal growth factor receptor in developing fetal mouse palates: An immunohistochemical study
Authors: Shiota Kohei , Fujita Shigeuki , Akiyama Tetsu , Mori Chisato
Published: February 2005

Epidermal growth factor (EGF) stimulates the growth of various tissues and, therefore, EGF receptor expression in fetal tissues may play a key role in organogenesis. We have examined immunohistochemically the ontogeny and localization of the EGF receptor in the fetal mouse palate during in vivo and in vitro palatogenesis using the anti‐human EGF receptor rabbit antibody. Immunoreactive products against the EGF receptor were observed in the palatal tissue examined on days 12, 13, and 14 of gestation. On days 12 and 13, the immunoreactive products were predominantly positive on the oral and medial edge epithelia but were minimal on the epithelium of the vertical shelf. The EGF receptor immunoreactivity was less intense in the posterior palate as compared with the midpalatal region. In the fusing palate of day 14 fetuses, the cells forming the midline epithelial seam were continuously positive for EGF‐R immunoreactivity. The mesenchyme of palatal shelves also showed regional heterogeneity and temporal sequence in EGF receptor expression. The localization of the EGF receptor in fetal mouse palates cultured in a serumless medium generally simulated that observed in vivo.
Labeling of hepatic glycogen after short‐ and long‐term stimulation of glycogen synthesis in rats injected with 3H‐galactose
Authors: Michaels John E. , Garfield Sanford A. , Hung Julia T. , Cardell Robert R.
Published: February 2005

The effects of short‐and longterm stimulation of glycogen synthesis elicited by dexamethasone were studied by light (LM) and electron (EM) microscopic radioautography (RAG) and biochemical analysis. Adrenalectomized rats were fasted overnight and pretreated for short‐ (3 hr) or long‐term (14 hr) periods with dexamethasone prior to intravenous injection of tracer doses of 3H‐galactose. Analysis of LM‐RAGs from short‐term rats revealed that about equal percentages (44%) of hepatocytes became heavily or lightly labeled cells increased slightly 6 hr after labeling, and unlabeled glycogen became apparent in some hepatocytes. The percentage of heavily labeled cells had decreased somewhat 12 hr after labeling, and more unlabeled glycogen was evident. In the long‐term rats 1 hr after labeling, a higher percentage of heavily labeled cells (76%) was observed compared to short‐term rats, and most glycogen was labeled. In spite of the high amount of labeling seen initially, the percentage of heavily labeled hepatocytes had decreased considerably to 55% by 12 hr after injection; and sparsely labeled and unlabeled glycogen was prevalent. The EM‐RAGs of both short‐ and long‐term rats were similar. Silver grains were associated with glycogen patches 1 hr after labeling; 12 hr after labeling, the glycogen patches had enlarged; and label, where present, was dispersed over the enlarged glycogen clumps. Analysis of DPM/mg tissue corroborated the observed decrease in label 12 hr after adminstration in the long‐term animals. The loss of label observed 12 hr after injection in the long‐term pretreated rats suggests that turnover of glycogen occurred during this interval despite the net accumulation of glycogen that was visible morphologically and evident from biochemical measurement.
Defective osteoclast differentiation and function in the osteopetrotic (os) rabbit
Authors: Lenhard Sharon , Popoff Steven N. , Marks Sandy C.
Published: February 2005

We tested the ability of normal osteoclast progenitors found in neonatal liver and bone marrow to develop into functional osteoclasts when co‐cultured with metatarsals from newborn osteopetrotic rabbits; the latter inherit an osteoclast incompetence resistant to cure by bone marrow transplantation. This system, developed by Burger and colleagous, has been shown to produce normal, functional osteoclasts when used with normal metatarsals. Our study tested the competence of the mutant skeletal microenvironment for differentiation of normal osteoclasts. Mutant and normal metatarsals were cultured alone or with normal liver, spleen, or bone marrow for up to 14 days. All normal cultures possessed a marrow cavity and contained numerous osteoclasts with cytochemical characteristics (tartrateresistant acid phosphatase) of active cells. Mutant metatarsals co‐cultured with normal spleen, liver, or bone marrow failed to develop a marrow cavity (evidence in itself of reduced bone resorption) and had osteoclasts reduced in both numbers and cytochemically detectable activity. Similar metatarsal cultures of an osteopetrotic rat mutation (incisors–absent) curable by bone‐marrow transplantation exhibited marrow cavity development in mutant metatarsals co‐cultured with normal spleen. These data suggest that the skeletal environment of osteopetrotic rabbits contains an inhibitor or lacks a promoter of osteoclast differentiation and function.
Nucleolar structure and synthetic activity during meiotic prophase and spermiogenesis in the rat
Authors: Schultz Michael C. , Leblond C. P.
Published: February 2005

The ultrastructure of nucleoli was examined in developing rat spermatocytes and spermatids, with the help of serial sections. In addition, the radioautographic reaction of nucleoli was examined in rats sacrificed 1 hr after intratesticular injection of 3H(5′)‐uridine and taken as an index of the rate of synthesis of ribosomal RNA (rRNA).

Primary spermatocytes from preleptotene to zygotene have small nucleoli typically composed of fibrillar centers, a fibrillar component, and a granular component, within which are narrow interstitial spaces. During early and mid‐pachytene, nucleoli enlarge to about nine times their initial size, with the fibrillar and granular components forming an extensive network of cords—a nucleolonema—within which are wide interstitial spaces. Meanwhile, there appear structures identical to the granular component but distinct from nucleoli; they are referred to as extranucleolar granular elements. Finally, from late pachytene to the first maturation division, nucleoli undergo condensation, as shown by contraction of fibrillar centers into small clumps, while fibrillar and granular components condense and segregate from each other, with a gradual decrease in interstitial spaces. In secondary spermatocytes, nucleoli are compact and rather small, while in young spermatids they are also compact and even smaller. Nucleoli disappear in elongating spermatids.

In 3H‐uridine radioautographs, nucleolar label is weak in young primary spermatocytes, increases progressively during early pachytene, is strong by the end of mid pachytene, but gradually decreases during late pachytene up to the first maturation division. In secondary spermatocytes and spermatids, there is no significant nucleolar label.

In conclusion, rRNA synthesis by nucleoli is low in young spermatocytes. During pachytene, while nucleoli enlarge and form a lacy nucleolonema, rRNA synthesis increases gradually to a high level by the end of mid pachytene. However, during the condensation and segregation of nucleolar components occurring from late pachytene onward, the synthesis gradually decreases and disappears. The small, compact spermatids arising from the second maturation division do not synthesize rRNA.
A morphologic study of bronchus‐associated lymphoid tissue in turkeys
Authors: Fagerland Jane A. , Arp Lawrence H.
Published: February 2005

Bronchus‐associated lymphoid tissue (BALT) in normal turkeys of ages 1 day and 1, 2, 3, 4, 8, and 18 weeks was examined by light microscopy and by scanning and transmission electron microscopy. Turkey BALT resembled other mucosa‐associated lymphoid tissues; it was made up of a population of lymphocytes covered by a specialized epithelium different from typical pseudostratified ciliated columnar bronchial epithelium. There were distinct age‐related differences in BALT structure. Bronchus‐associated lymphoid nodules were larger and more numerous in older turkeys. In 1‐day‐ to 2‐week‐old turkeys, the primary cell type of BALT epithelium was nonciliated cuboidal; in 2‐week old turkeys it was squamous; and in turkeys older than 4‐weeks of age, the epithelium was primarily ciliated columnar. In 1‐ to 4‐week old turkeys, large numbers of intraepithelial lymphocytes disrupted the normal organization of the epithelium. In older turkeys, epithelial and lymphoid cells were in discrete compartments separated by connective tissue. Lymphocytes in 1‐day‐old turkeys were found in loose aggregates around venules and within the epithelium. In 1‐week old turkeys, lymphocytes were organized into compartments of morphologically similar cells. By 3‐weeks of age, lymphocytes were present in distinct germinal centers. Epithelial cells of BALT did not have large numbers of apical vesicles and thus were not structurally specialized for antigen uptake by endocytosis. However, the epithelial barrier appeared to be disrupted over lymphoid nodules, suggesting that antigen would be readily available to lymphocytes and phagocytes in BALT. Age‐related differences in turkey BALT structure may have functional consequences with respect to the respiratory immune response.
Morphometric analysis of vertebrae and intervertebral discs as a basis of disc replacement
Authors: Aharinejad S. , Bertagnoli R. , Wicke K. , Firbas W. , Schneider B.
Published: February 2005

In this study measurements were obtained from 359 vertebrae and 215 intervertebral discs in an attempt to classify discs by their size. At the cervical and thoracic levels, this attempt was unproductive because of extensive variations. In the lumbar spine, discs were allocated to six size‐matched groups. The breadth of marginal rims were also measured with a view to provide surgeons operating on the spine with precise data on disc morphology to facilitate dise replacement.
Craniofacial alterations following electrolytic lesions of the trigeminal motor nucleus in actively growing rats
Authors: Byrd Kenneth E. , Stein Stephen T. , Sokoloff Alan J. , Shankar Kavita
Published: February 2005

The objective of this study was to define further the role of the trigeminal motor nucleus (TMNu) in the postnatal ontogeny of the mammalian craniofacial skeleton. To that end, 42 male Sprague‐Dawley rats underwent stereotaxic surgery at 40 days of age; 21 received small electrolytic lesions to their left‐side TMNu (lesioned group) while 21 had TMNu stimulation with no actual electrolytic lesion produced (sham group). Seven rats from each group were killed at 28, 56, and 84 days postoperative to analyze trigeminal motoneuron (TMNe) count, masticatory muscle weight, and osteological growth vector data. At all three time periods, lesioned animals showed significant differences (1) between the surgery and nonsurgery sides, and (2) from sham animals. However, sham animals also demonstrated significant between‐side differences for medial pterygoid muscle weight (56 days), mandibular height (28 and 56 days), and mandibular length data (84 days); these data suggested that even relatively slight damage to TMNe can create morphological changes within the craniofacial complex. Snout deviation in a lesioned rat towards the opposite side from all other lesioned animals was correlated with unique damage to its pontine reticular formation; this suggested that the observed morphological alterations of the craniofacial complex may have been due not only to TMNu damage, but also to changed expressions of the masticatory central pattern generator (CPG). Morphological alterations of the craniofacial skeleton resulting from lesions to the TMNu were likely due to changed neuromuscular activity patterns of the masticatory muscles and their biomechanical effects upon bone.
Blood vascular network of the rat lymph node: Tridimensional studies by light and scanning electron microscopy
Authors: Bélisle C. , Sainte‐Marie G.
Published: February 2005

Many aspects of the blood vascular network of the lymph node are unknown, and others need confirmation. We have studied the blood vasculature of rat peripheral lymph nodes by means of carbon perfusion and vascular cast corrosion techniques. At the hilus of the node, an artery gives off arterioles running in medullary cords towards the cortex. Some reach the peripheral cortex directly, branching there into slender cortical vessels. Other arterioles enter the periphery of the deep cortex units, and then head towards the peripheral cortex. Upon reaching it, they curve part way above the center of the deep cortex units and provide slender branches to the overlying peripheral cortex. Dense plexuses of capillaries arise from arterioles in the medullary cords, in the periphery of the deep cortex units, and in the outermost stratum of the extrafollicular zone of the peripheral cortex. In the cortex, the draining high endothelial venules are restricted to the extrafollicular zone and to the periphery of the deep cortex units. At the cortico‐medullary junction, these peculiar venules transform into regular medullary venules which form the hilar veins. In contrast, the folliculo‐nodules and center of the deep cortex units are little vascularized by a loose capillary network, while no vessels occur in the subsinus layer. These features of the node vascular network are of interest in relation to the node architecture.
The human rhombencephalon at the end of the embryonic period proper
Authors: Müller Fabiola , O'Rahilly Ronan
Published: February 2005

The human rhombencephalon at 8 postovulatory weeks (stage 23) is described and illustrated for the first time with the aid of silver‐impregnated sections and graphic reconstructions. The motor and sensory trigeminal nuclei were among those studied, and the latter was found to be almost contiguous to the dentate nucleus. Fibers to the principal sensory nucleus join the mesencephalic trigeminal tract, which also seems to be connected with the motor fibers. Fine fibers from the sensory root join the tractus solitarius, which appears to receive connections from the facial, glossopharyngeal, and vagal nerves. Main and accessory abducent nuclei are evident. A part (the Kappenkern des Facialisknies) of the nucleus funiculi teretis is particularly prominent. The presence of the pyramidal decussation during the embryonic period is noted for the first time. The arrangement of nuclei and tracts at 8 weeks is shown to be closely similar to that present in the newborn, and it is likely that the rapid growth of the rhombencephalon during the embryonic period proper is associated with correspondingly early functional activity.
Auditory epithelial migration on the human tympanic membrane: II. The existence of two discrete migratory pathways and their embryologic correlates
Authors: Michaels Leslie , Soucek Sava
Published: February 2005

The pathways of movement of dye‐markings on the tympanic membranes of 30 ears of 15 volunteers were investigated by photography with a Hopkin's rod. Two discrete pathways were identified. Movement on the pars tensa was centrifugal in all directions from the edge of the handle of malleus surface. This supported our previous suggestion that pars tensa epithelial migration is based on growth of the meatal plate. Movement on the more central part of the handle surface itself, however, was always upwards to the pars flaccida epithelium and then, with all dye on the latter, in a posterosuperior direction only.

The covering epithelium of the pars flaccida/handle of malleus arises from the fundus of the early embryonic external canal. To explore the possibility that its migration may also commence early, the fundus was examined histologically in 12 embryo ears. It was shaped like an inverted pear to conform to the primordial head of the malleus above and its handle below. There was distinct flattening of the whole fundal epithelium in contrast to the side wall of the external canal, lending support to the concept of a primordial flux of epithelium in the main fundus and its inferior extension. The meatal plate grew from the rim of the fundus producing the pars tensa and deep external canal epithelia. This process, however, was not associated with significant cytologic alterations or increased expression of the human proliferation antigen, Ki‐67, at that rim. This suggests that the pars tensa epithelium grows and moves without the active involvement of the epithelium of the pars flaccida/handle of malleus.
Changes in numbers of pancreatic acinar cell nuclei and in DNA content during raw soya flour feeding in mice
Authors: Ge Y. C. , Morgan R. G. H.
Published: February 2005

Nuclei of pancreatic cells were isolated by trypsin‐detergent digestion of fresh tissue and stained with propidium iodide, and nuclear DNA was measured by flow cytometry. Samples were isolated from mice fed either chow or raw soya flour (RSF) for periods ranging from day to 48 weeks, beginning at 4 weeks of age. In chow‐fed mice, the pancreas contained about 80% diploid (2N) and 20% tetraploid (4N) cells at the start of the study, but tetraploidy gradually increased to about 40% 2 weeks later (6 weeks of age) and remained at this level from that time onwards. Low levels of octaploid nuclei (8N) were also present in some animals after 2 weeks. In RSF‐fed mice, about 20% tetraploid nuclei were also present for 1 and 2 days after starting RSF, but by 4 days tetraploidy had increased significantly to 40% and by 14 days had further increased to 50%. This level was significantly higher than that seen in chow‐fed animals and was maintained for up to 48 weeks. Significantly higher numbers of octaploid nuclei were also present in the RSF‐fed animals. In both chow‐ and RSF‐fed mice, most cells were mononuclear, averaging 70% in chow‐fed and 64% in RSF‐fed animals. This difference was significant. This study shows that the mouse pancreas differs from the rat pancreas in the absence of a large population of binucleate acinar cells and the presence of considerable nuclear tetraploidy. Raw soya flour feeding leads to significant changes in these features, but in this species these changes do not appear to predispose to neoplasia.
Innervation of the guinea pig spleen studied by electron microscopy
Authors: Saito Hiroaki
Published: February 2005

The innervation of the guinea pig spleen was investigated by electron microscopy. Unmyelinated nerve fibers in the capsulotrabecular and arterial systems were found to contain large and small granular and small agranular synaptic vesicles in their terminals and are thought to be sympathetic adrenergic in nature. They influence the contraction of the smooth muscle cells by diffusion innervation in these systems. These nerve terminals were also scattered in both the red and the white pulp. Pulp nerves wrapped by Schwann cells were further enclosed by myofibroblastic reticular cells. This condition revealed that the pulp nerves pass through the connective‐tissue spaces of the reticular fibers, which contain elastic fibers, collagenous fibrils, and lamina densa‐like materials of the usual basement laminae. One of the target cells for the pulp nerves is considered to be the myofibroblastic reticular cell in the reticular meshwork. Neurotransmitter substances released from the naked adrenergic nerve terminals travel through the reticular fibers and may play a role, by both close association innervation and diffusion innervation, in the contraction of reticular cells to expose the reticular fibers. At the exposed sides, connective‐tissue elements of the reticular fibers are bathed with blood plasma, and the included naked nerve terminals, devoid of Schwann cells but with basement laminae of these cells, face free cells at some distance or are in close association with free cells, especially lymphocytes, macrophages, and plasma cells. The close ultrastructural relationship between the naked adrenergic nerve terminals and immunocytes strongly suggests that there is an intimate relationship between the immune system and the sympathetic nervous system through both close association innervation and diffusion innervation. Thus splenic adrenergic nerves of the guinea pig may play a triple role in (1) contraction of smooth muscle cells to regulate blood flow in the organ, (2) induction of the exposure of reticular fibers by contraction of the reticular cells in order to form a close relationship of the nerve terminals with the immunocytes, and (3) subsequent neuroimmunomodulation of the immunocytes.
Fiber type composition of the human male trapezius muscle: Enzyme‐histochemical characteristics
Authors: Lindman R. , Eriksson A. , Thornell L.‐E.
Published: February 2005

The human trapezius muscle has an origin that is more extensive than that of any other body muscle; it has a complex macroscopic structure with fibers running in different directions. Histochemical analysis of multiple samples, obtained from different parts of the trapezius muscle from five males, showed marked differences in the distribution and the cross‐sectional fiber area of the fiber types among different parts of the muscle as well as among individuals. As revealed by the mATPase activity, after different levels of alkaline and acidic preincubations, the lower third of the descending portion, the transverse, and the ascending portions of the muscle had a predominance of type I fibers (low mATPase activity at pH 9.4), whereas the most superior parts of pars descendens had a higher frequency of type II fibers (high mATPase activity at pH 9.4). The fibers of the most superior parts of the muscle were considerably smaller compared with those in all the other parts. In sections stained for NADH‐TR, motheaten fibers were observed within parts of the descending portion. Their location and their larger fiber area, compared with that of ordinary type I fibers, may be related to frequent and/or continuous use of these fibers. In conclusion, the differences in fiber type composition between the different parts of the muscle probably reflect different functional demands on the trapezius muscle in various head, neck, and shoulder movements. We suggest that the interindividual differences in muscle fiber composition are due, at least in part, to genetic factors.
The eye of the magellanic penguin (Spheniscus magellanicus): Structure of the anterior segment
Authors: Suburo Angela María , Scolaro José Alejandro
Published: February 2005

We undertook a light and scanning electron microscopic study of the eye in the Magellanic penguin (Spheniscus magellanicus). The anatomical peculiarities of the eyeball shape in Sphenisciformes have been previously described by others; here, we show that they are accompanied by several modifications in the organization of the anterior segment of the eye. The main change was found in the portion of opaque sclera extending from the cornea to the anterior border of the scleral ossicles, which was much broader than in other avian eyes. This scleral region was made of a very dense fibrous tissue and was as difficult to cut as the ossicles. The corneoscleral boundary was also different from that of other birds, since the aqueous humor channel and the pectinate ligament were located 1.0–1.5 mm posterior to the cornea. The osseous ring was formed by 13 bones, including three pairs of over‐and underplates. There was a single ciliary muscle, with meridionally oriented striated fibers. They were inserted on a circumference along the boundary between the fibrous sclera and the ossicles, far away from the wall of the aqueous humor channel. On their posterior end, the muscle fibers formed a tendinous structure attached to the inner surface of the sclera and to the outer surface of the ciliary body. Only short zonular fibrils were observed. These anatomical features are probably relevant for the adaptation of penguin eyes to vision on land and in the aquatic environment.
Three‐dimensional cytoarchitecture of the media of arteriovenous anastomoses in the rabbit ear
Authors: Fujiwara Takashi , Iijima Tadahiko
Published: February 2005

Arteriovenous anastomoses in the rabbit ear were examined with scanning electron microscopy to elucidate the structural differentiation of the media of the shunt. Arterial, intermediate, and venous segments in the shunt and two layers of the media in the intermediate segment were differentiated based on cell shape and cell organization. In the arterial segment, smooth muscle cells were spindle‐shaped, either elongated or short, with a few branches, and were arranged circularly or diagonally with respect to the vessel's long axis. There were also stellate muscle cells with radiating processes. In the intermediate segment, the smooth muscle cells of the outer layer of the media were also arranged circularly and resembled the elongated cells in the arterial segments, but they were more irregular in shape and had more processes than those of the arterial segment. The epithelioid cells of the inner layer of the media were oval or polygonal and oriented irregularly with respect to the vessel's long axis, clustering to form longitudinal plicae. The smooth muscle cells of the venous segment were flat with many lateral processes and formed a thin, discontinuous layer. The smooth muscle cells in the arterial segment and those of the outer layer of the intermediate segment exhibited a highly rugged surface texture, indicating their strong contractility; the epithelioid cells and the smooth muscle cells in the venous segment exhibited a generally smooth surface, indicating less contractility. The intermediate segments were supplied with a dense nerve plexus. The intermediate segments, therefore, may be actively involved in the regulation of blood flow under neuronal influence.
Effects of 1,25 dihydroxyvitamin D on osteoclast number and cytochemistry in normal and osteopetrotic (os) rabbits
Authors: Grise Mark A. , Marks Sandy C. , MacKay Carole A. , Popoff Steven N.
Published: February 2005

Osteoclast‐mediated bone resorption is increased in response to 1,25 dihydroxyvitamin D (1,25[OH]2D or calcitriol). Osteopetrosis is a metabolic bone disease characterized by defective, osteoclast‐mediated bone resorption, which co‐exists with elevated serum 1,25‐(OH)2D levels in some osteopetrotic children and animals. We examined the effects of high doses of calcitriol on osteoclast number and cytochemistry in both normal and osteopetrotic (os) rabbits. Calcitriol was continuously infused at doses of 0.5, 2.5, or 25 μg/kg/day via subcutaneously implanted osmotic minipumps for a period of 7 days. Following treatment, the proximal tibial metaphyses were processed for histomorphometric and cytochemical analyses. Sections were stained for tartrate‐resistant acid phosphatase (TrAP) or acid ATPase (TraATPase). Osteoclasts were significantly reduced in untreated os rabbits compared with age‐matched normal littermates between birth and 3 weeks of age (41–46% of normal). Whereas most normal osteoclasts (85%) stained heavily for TrAP or TraATPase, less than half of os osteoclasts were heavily stained for these acid hydrolases. Infusions of 1,25(OH)2D resulted in elevations of osteoclast numbers in both normal and os rabbits, but the number of osteoclasts remained significantly lower in mutants than in normal littermates at any given dose. Calcitriol infusions also resulted in a significant increase in the percentage of os osteoclasts staining heavily for TrAP and TraATPase. These results suggest that in response to 1,25(OH)2D normal osteoclasts increase their production of acid hydrolases before increasing cell numbers and that, in spite of high levels of endogenous calcitriol, os rabbits can respond to exogenous 1,25(OH)2D as evidenced by increased osteoclast number and cytochemical staining, even though these osteoclasts fail to resorb the excess skeletal matrix. Thus the defect in the mutant skeleton appears to be in the initial cytodifferentiation of osteoclasts, not in their responsiveness to endogenous regulators of bone resorption.
Prenatal development of the human nucleus ambiguus during the embryonic and early fetal periods
Authors: Brown Jerry William
Published: February 2005

The ontogenetic development of the nucleus ambiguus was studied in a series of human embryos and fetuses ranging from 3 to 12.5 weeks of menstrual age (4 to 66 mm crown‐rump length). They were prepared by Nissl and silver methods. Nucleus ambiguus neuroblasts, whose neurites extend towards and into the IXth and rostral Xth nerve roots, appear in the medial motor column of 4–6‐week‐old embryos (4.25–11 mm). These cells then migrate laterally (6.5 weeks, 14 mm) to a position near the dorsal motor nucleus of X. At 7 weeks (15 mm), nucleus ambiguus cells begin their migration, which progresses rostrocaudally, into their definitive ventrolateral position. The basic pattern of organization of the nucleus is established in its rostral region at 8 weeks (22.2–24 mm) and extends into its caudal region by 9 weeks (32 mm), when its nearly adult organization is evident. Cells having the characteristics of mature neurons first appear rostrally in the nucleus during the 8.5–9‐week period (24.5–32 mm), gradually increase in number, and constitute the entire nucleus at 12.5 weeks (65.5 mm). Definitive neuronal subgroups first appear at 10 weeks (37.5 mm) in the large rostral nuclear region. These features suggest that the human nucleus ambiguus develops along a rostrocaudal temporospatial gradient. Evidence indicates that function of nucleus ambiguus neurons, manifested by fetal reflex swallowing, occurs after the cells migrate into their definitive position, establish the definitive nuclear pattern, and exhibit mature characteristics.
Ventricular system and choroid plexuses of the human brain during the embryonic period proper
Authors: O'Rahilly Ronan , Müller Fabiola
Published: February 2005

This morphological study, based on serial sections and graphic reconstructions at 4–8 postovulatory weeks (stages 11–23), is believed to be the first account of the ventricular system in staged human embryos. Closure of the caudal neuropore at stage 12 heralds the onset of the ventricular system and separates the ependymal from the amniotic fluid. After the appearance of the optic ventricle at stage 11, the cavity of the telencephalon medium is discernible at stage 13. At stage 14 the future cerebral hemispheres and lateral ventricles begin, and the rhomboid fossa becomes apparent. The medial and lateral ventricular eminences cause indentations in the lateral ventricle by stage 15. The hypothalamic sulcus is evident at stage 16. At stages 17–18 the interventricular foramina are becoming relatively smaller, and cellular accumulations indicate the future choroid villi of the fourth and lateral ventricies. The areae membranaceae rostralis and caudalis are visible in the roof of the fourth ventricle at state 18, and the paraphysis is appearing. At stage 19 choroid villi are seen in the fourth ventricle, and a mesencephalic evagination (Blindsack) is detectable. Choroid villi are noticeable in the lateral ventricle at state 20. An olfactory ventricle is present by stage 21. At about stages 21–23 the lateral ventricle has become C ‐shaped, so that anterior and inferior horns are visible. Several recesses, e.g., the optic, infundibular, and pineal, develop in the third ventricle during the embryonic period. Features of the ventricular system that do not become apparent until the fetal period include the posterior horn of the lateral ventricle, choroid plexus of the third ventricle, suprapineal recess, interthalamic adhesion, aqueduct, and apertures in the roof of the fourth ventricle.
Morphometric analysis of the surface cells of rabbit corneal epithelium by scanning electron microscopy
Authors: Doughty Michael J.
Published: February 2005

The corneal surface of female New Zealand white rabbits (1.9–2.6 kg) was examined at × 500 magnification by scanning electron microscopy. A total of 112 micrographs, taken as sequential sets from the center to the edge of the corneal surface from 8 different animals, was analyzed using a digitizer pad. Each cell was identified by the number of immediately bording cells and by the nature of its electron reflex (light, medium, dark). Analysis of areas of the cells by number of bordering cells (number of cell sides) reveals a wide range of areas and skewed distributions especially when the number of sides is 5 or less. Overall, the cell‐surface area increases as the number of cell sides increases. However, analyses of the mean surface areas for cells with different numbers of sides and additionally grouped by electron reflex suggests the existence of three separate populations of cells at the corneal surface. The possible etiology and dynamics of this complex cell mosaic are discussed in relation to circadian rhythms and to resurfacing of the cornea following mechanical trauma, ultraviolet radiation, and toxic chemical exposure.
Toward the origin of the secondary palate. A possible homologue in the embryo of fish, Onchorhynchus kisutch, with description of changes in the basement membrane area
Authors: Shah Ravindra M. , Donaldson Edward M. , Scudder Geoffrey G. E.
Published: February 2005

The oral cavity of embryos and larvae of the teleost Onchorhynchus kisutch was examined. Tissues were obtained at different ages prior to and after hatching and processed for transmission and scanning electron microscopy. A bilaterally symmetrical bulge developed from the superolateral aspect of the oral cavity and projected toward its floor, along the sides of the tongue. The bulge extended from behind the primary palate to a position midway below the eye, anterior to the gill arches, and it is suggested to be the homologue of the secondary palate of higher vertebrates. Ultrastructurally, the epithelium differentiated as the stratified squamous type and it contained mucous cells. However, the features of programmed cell death seen during palatogenesis in mammals were absent in fish. The fish palate mesenchyme, unlike that of higher vertebrates, was chondrified. Also in contrast to higher vertebrates, alterations were seen in the fish palatal basement membrane. A transient appearance of adepidermal granules in the lamina lucida region was followed by organization of collagen fibrils, first into an orthogonal pattern and then into a herring‐bone arrangement, in the lamina reticularis region. There was no further advancement in the morphogensis of fish palate. It is suggested that the differences in the morphogenesis and structure of the secondary palates of various vertebrates may reflect environmentally enforced adaptation, resulting in different programming of cells.
Development of the musculoelastic septation complex in the avian truncus arteriosus
Authors: Rosenquist Thomas H. , Fray‐Gavalas Charlotte , Waldo Karen , Beall Arthur C.
Published: February 2005

It is now well established that cells from the cardiac neural crest (CNC) are essential for normal conotruncal septation. The truncal septation complex consists of the aorticopulmonary (AP) septum and the myocardial sheath of the truncus. The principal role of the CNC cells during septation appears to be their differentiation into the elastogenic smooth muscle that forms the AP septum proper. The objective of this study was to integrate serial reconstruction and specific histochemical markers in order to provide a unified analysis of the relationship between the CNC and the other components of the truncal septation complex. The development of the septation complex was compared normal embryos vs. embryos from which the CNC had been surgically ablated. Embryos from each group were harvested after incubation periods of 4–8 days (Hamburger‐Hamilton stages 23–34). Histochemical procedures were performed for positive identification of the elastic matrix and smooth muscle alpha‐actin; the presence of these proteins was used as the criterion for “septal cells” and to define the boundaries of the septum. The results indicate that the shape, components, boundaries, and degree of organization of the septation complex may be different from previous descriptions. Furthermore, all of the components of the truncal septation complex are dysgenic in the absence of the CNC. Of special significance in the absence of CNC are: (1) the failure of the myocardial sheath to retract; (2) the apparently random distribution of surrogate ectomesenchyme; and (3) the impairment of truncal elastogenesis.

These results indicate that the cells of neural crest origin interact with the surrounding mesenchyme during septation and that the entire septation complex depends upon the presence of the neural crest cells for normal development.
Analysis of the sternotrachealis muscle fibers in some anseriformes: Histochemistry and sex differences
Authors: Lalatta‐Costerbosa G. , Scapolo P. A. , Barazzoni A. M. , Petrosino G. , Clavenzani P. , Lucchi M. L. , Bortolami R.
Published: February 2005

Histochemical characteristics and sizes of the fibers of the sternotrachealis (ST) muscle have been investigated in some Anseriformes (mallard, Pekin duck, Muscovy duck, and goose) of both sexes. A sexual dimorphism has been shown in the muscle of the species examined. In the mallard and Pekin duck, the male ST muscle shows type IIIA fibers in addition to the type I, IIA, and IIB fibers observed also in the female. In the Muscovy duck, the male muscle has only type I and IIA fibers, whereas the female muscle presents type I fibers and both types IIA and IIB fibers. Moreover, the mean frequencies for each fiber type were significantly different between males and females. In the goose, both male and female muscles present only type I and IIA fibers. In all the species examined, the mean areas of each fiber type are significantly different between male and female, being always larger in the male muscles. The anatomical sexual dimorphism observed in the ST muscle is discussed in relation to function.
Fine structure of the elasmobranch renal tubule: Neck and proximal segments of the little skate
Authors: Lacy E. R. , Reale E.
Published: February 2005

This is the first in a series of studies that examines the renal tubular ultrastructure of elasmobranch fish. Each subdivision of the neck segment and proximal segment of the renal tubule of the little skate (Raja erinacea) has been investigated using electron microscopy of thin sections and freeze‐fracture replicas.

Flagellar cells, characterized by long, wavy, flagellar ribbons, were observed in both nephron segments. They were found predominantly in the first subdivision of the neck segment, which suggests that propulsion of the glomerular filtrate is a primary function of this part of the renal tubule. In the non‐flagellar cells of the neck segment (subdivisions I and II), there were bundles of microfilaments, a few apical cell projections, and, in subdivision II, numerous AUtophagosomes.

In the proximal segment, the non‐flagellar cells varied in size, being low in subdivision I, cuboidal in II, tall columnar in III, and again low in IV. Apical cell projections were low and scattered in subdivisions I and IV and were highest in III where the basolateral plasma membrane was extremely amplified by cytoplasmic projections. Furthermore, in these cells the mitochondria were numerous with an extensive matrix and short cristae. A network of tubules of the endoplasmic reticulum characterized the apical region of the non‐flagellar cells in subdivisions I, II, and IV. In the late part of subdivision II and the early part of III, the cells were characterized by numerous coated pits and vesicles, large subluminal vacuoles, and basally located dense bodies, all of which are structures involved in receptor‐mediated endocytosis.

Freeze‐fracture replicas revealed gap junctions restricted to the cells of the first three subdivisions of the proximal segment. The zonulae occludentes were not different in the neck and proximal segments, being composed of several strands, suggesting a moderately leaky paracellular pathway.
Brain growth and differentiation in two fetal bats: Qualitative and quantitative aspects
Authors: Pirlot Paul , Bernier Réjane
Published: February 2005

The development of the main brain components in two fetal bats (one insectivorous and one frugivorous type) is studied quantitatively and comparatively. The telencephalon, cerebellum, and diencephalon grow faster in the frugivorous bat. The brainstem maintains a greater relative volume throughout in the insectivorous type. The morphology and density of neurons in the cerebellum, cAUdate nucleus, olfactory, mitral stratum, and neocortical layer II suggest that there exists an initial delay in development in the frugivorous bat; through subsequent reordering, however, it becomes more advanced in development in accordance with the more progressive status of the adult forms in its category. In this there may be a certain ontogenetic recapitulation of a possible chiroptera phylogeny. These comparisons also point to the precociousness of the functional determination of those structures that are related to future behavior in a purely deterministic, non‐teleological sense. The qualitative differentiation appears to be more significant than might be expected in comparison with the quantitative proliferation. Technical problems in volved in the study of brain morphogenesis are discussed, especially the difficulty of distinguishing the respective effects of cell multiplication, cell death, and artificial increase in cell density through tissue shrinkage.
Pathogenesis of bromodeoxyuridine‐induced cleft palate in hamster
Authors: Shah Ravindra M. , King Katherine O. , Feeley E. J. Elizabeth
Published: February 2005

In the present study, the morphological, histochemical, biochemical, and cellular aspects of the pathogenesis of bromodeoxyuridine (BrdU)‐induced cleft palate in hamster fetuses were analyzed. Morphological observations indicated that BrdU interferes with the growth of the vertical shelves and thus induces cleft palate. At an ultrastructural level, BrdU‐induced changes were first seen in the mesenchymal cells. Eighteen hours after drug administration, the initial alterations were characterized by swelling of the nuclear membrane and the appearance of lysosomes in the mesenchymal cells of the roof of the oronasal cavity. During the next 6 hr, as the palatal primordia developed, lysosomes were also seen in the overlying epithelial cells. The appearance of lysosomal activity, which was verified by acid phosphatase histochemistry, was temporally abnormal and was interpreted as a sublethal response to BrdU treatment. Later the cellular alterations subsided; 48 hr after BrdU treatment, they were absent in both the epithelial and mesenchymal cells of the vertically developing palatal shelves. Subsequently, unlike controls (in which the palatal shelves undergo reorientation and fusion), the BrdU‐treated shelves remained vertical until term. Biochemical determination of DNA synthesis indicated that although there was an inhibition of DNA synthesis at the time of appearance of palatal primordia, a catch‐up growth during the ensuing 12 hr may have restored the number of cells available for the formation of a vertical palatal shelf. It was suggested that BrdU affected cytodifferentiation in the palatal tissues during the critical phase of early vertical development to induce a cleft palate.
Size and shape of human cranial sutures–A new scoring method
Authors: Hauser Gertrud , Manzi Giorgio , Vienna Alessandro , de Stefano Gian Franco
Published: February 2005

A method for the differentiation of sutural patterns of the human cranial vault is introduced. Three criteria of differentiation are considered, one for size and two for shape: (1) maximal shape extension; (2) basic configuration; (3) secondary protrusion. The method is illustrated here for the coronal and lambdoid sutures of 70 recent Italian skulls (35 adult males and 35 adult females). Differences between coronal and lambdoid sutural size and shape can be detected analytically; for example, the coronal suture commonly shows lesser degrees of shape extension, a simpler basic configuration, and an absence of secondary protrusion. Heterogeneity within each suture, as well as a relationship among corresponding sections and between the three criteria adopted, have been also observed; symmetry predominates for both the sutures, and sexual differences are slight.