bluuebunny/crossref_metadata_2025 huggingface dataset:
Structural orientation and density in cetacean humeri
Authors: Felts William J. L. , Spurrell Francis A.
Published: February 2005

The cetacean humerus is a short, robust bone without an open medullary cavity. It lies in the base of the resilient, streamlined pectoral limb (flipper) between the only free articulation (the glenohumeral) and approximately the body contour. The humerus is acted upon by muscles of the shoulder complex and receives loadings from the flattened distal portion of the limb as this hydroplane acts against body inertia and water resistance in control of body attitude.

This study is an analysis of development and structure of the humerus in terms of the unique functional role of the flipper of finback, beluga and pilot whales. Gross external and internal architecture are depictued by photographs and by whole bone and frontal section radiographs. Structural density (bone/unit volume of humerus, with mineral content known to be constant) is analyzed indirectly by photodensitometry of standardized radiographs of sawed sections. Results are shown in graphic reconstructions of sections and of the whole bone. By comparison of radiodensity with the actual weight/volume of excised samples, sections are also reconstructed in terms of absolute density distribution.

It is found that the spongy cetacean humerus, from its origin, is without central resorption and that its definitive structure is produced primarily by differential concentration of bone along endoectad gradients of porosity. Thus, the greatest concentration of bone is on medial and lateral sides while bone only half as dense fills the anterior and posterior sides and underlies the most dense regions. The core region is extremely porous. Within the biological context, this is a most reasonable approximation of the engineered box‐beam as employed in some aircraft wings. Whole bone and frontal section radiographs show that, within this overall density pattern, the distribution of bone trabeculae resembles the classic illustrations of trajectories in the loaded beam.

The ontogenetic and phylogenetic factors with possible bearing on this type of bone development and structure are discussed.
John Hunter on spontaneous intersexuality
Authors: Forbes Thomas R.
Published: February 2005

Available information is assembled from published and unpublished accounts and pictures, and from study of surviving specimens, of cases of spontaneous intersexuality, pseudohermaphroditism, and other reproductive anomalies in mammals and birds which were studied by John Hunter (1728–1793). An effort is made to interpret this information in terms of current endocrine theory.
Viability and differentiation of human trophoblast in organ culture
Authors: Tao Tien‐Wen , Hertig Arthur T.
Published: February 2005

Organ culture of 15 immature human placentas — obtained at therapeutic abortion of 5–22 week gestations — was carried out in a medium consisting of: horse serum, 20%; NCTC 109, 15%; and balanced salt solution, 65% to which was added 100 I.U. of penicillin per ml of culture medium. Minced placental fragments were placed on filter paper laid across glass beads within a Petri dish; the medium barely covering the beads. Moist incubation was carried out at 35–36°C in a mixture of 5% CO2 and 95% O2 for 4–6 weeks; the medium being changed every 2–3 days. Radioautographic techniques using 1–2 μc of methyl H3‐thymidine per ml of medium as well as routine histological techniques were employed. These showed that Langhans epithelium or cell masses — cytotrophoblast — differentiated or metamorphosed into a “new” syncytiotrophoblast. Only cytotrophoblastic nuclei took up the radioactive thymidine which appeared later in the new syncytiotrophoblast. Ordinary histologic preparations showed that the “new” syncytiotrophoblast resembled the original syncytiotrophoblast by virtue of its position (between original cyto‐ and syncytiotrophoblast) together with its loss of cell boundaries and its acquisition of intracellular vacuoles and cytoplasmic chromophilia. The cytotrophoblast remained viable for three weeks and then gradually decreased in amount with a corresponding increase in the amount of “new” syncytiotrophoblast. The latter was the predominant though necrotic tissue seen at six weeks. These techniques are tools for investigating the many aspects of growth, differentiation and endocrine function of human trophoblast.
Some efferent connections of the nucleus medialis dorsalis. An experimental study in the cat
Authors: Khalifeh Riyad R. , Kaelber William W. , Ingram Walter R.
Published: February 2005

Single unilateral electrolytic lesions were placed stereotaxically at different loci in the nucleus medialis dorsalis of the cat. The modified Nauta‐Laidlaw silver method for the study of degenerating axons was used. Five animals with satisfactory lesions and staining qualities form the basis of this report. The nucleus medialis dorsalis in the cat sends efferent fibers to gyrus proreus, orbitalis, sigmoides anterior and genualis; also to the globus pallidus and putamen and to other thalamic nuclei. The findings indicated wider areas of projection of the nucleus medialis dorsalis to the frontal cortex than has been previously reported for this species. We were unable to confirm efferent connections from the nucleus medialis dorsalis to the caudate and hypothalamus as reported by others.
Osteolathyrism in mice and inhibition of the endosteal bone reaction in estrogen‐treated mice by aminoacetonitril
Authors: Simmons D. J. , Pankovich A. M. , Budy A. M.
Published: February 2005

The effect of aminoacetonitrile (AAN) on the skeletons of young mice injected with estrogen was studied histologically and microradiographically. AAN (0.5, 2.5, 5, 10 or 20 mg) was administered daily during the first week of treatment alone or in combination with a single injection of 1 mg estradiol valerate on the first day. The animals were sacrificed at intervals of seven days for a period of four weeks. The bone reaction leading to ossification of the marrow cavities as a consequence of estrogen‐treatment was diminished by 5–20 mg AAN, and the effect was roughly proportional to the dose of the nitrile. The metaphyseal trabeculae (distal femur) of the AAN‐treated mice developed a mosaic appearance. While administration of the nitrile alone induced the formation of periosteal hyperostotic and osteo‐cartilaginous hyperostotic fiber bone tissue over the femoral shafts late in the post‐treatment recovery period, combined treatment with estrogen potentiated these changes during the treatment period itself. The cortical bone tissue was also demineralized by combined treatment, and fused osteocyte lacunae regularly appeared as an apparent sequela of both cell enlargement and degradation of perilacunar matrix. Conversely, estrogen completely protected the epiphyseal cartilages against degenerative changes (abnormal vascular invasion, rents etc.) after low doses of AAN (0.5–2.5 mg) during the treatment period, but the hormone was only partially effective after higher doses of AAN. It was suggested that aminoacetonitrile disrupts both the formation of new bone collagen and the integrity of collagenous structures deposited prior to treatment.
The terminal air sacs and their blood supply in a 37‐day infant lung
Authors: Boyden Edward A.
Published: February 2005

Wax models of a terminal spray of peripheral air passages from the middle lobe of a 37‐day infant lung are presented in three views. Superimposed on drawings of the models are reconstructions of the arteries and veins. The spray begins with a pre‐terminal bronchiole and ends in a trifurcation of alveolar ducts, each giving rise to two clusters of saccules. The third duct and its clusters are markedly under‐developed. So far there is no evidence that new acini are being formed and the possibility of this seems less and less likely.

Terminal arteries do not follow the rigid pattern of Miller (1937), namely, that an artery accompanying an alveolar duct breaks up into as many branches as there are “atria” and each of these into as many branches as there are sacculi. Instead, the six clusters are partially supplied by two rami which branch irregularly and also supply adjacent clusters. Parts of a cluster may be supplied by arteries from distant and alien sources. A long arterial ramus frequently takes a short cut through saccules of other clusters. Conspicuous are numerous small adventitious branches arising from the main artery. Often a peripheral vein is continuous with a pleural vein.
A fluorescence and electronmicroscopic study on certain brain regions rich in monoamine terminals
Authors: Fuxe Kjell , Hökfelt Tomas , Nilsson Ove
Published: February 2005

With the use of both the sensitive fluorescence method of Falck and Hillarp for the histochemical demonstration of monoamines at the cellular level and electron microscopy the synaptic terminals were studied in nucleus caudatus putamen, nucleus tractus solitarii and the substantia grisea periventricularis of the fourth ventricle. In all these regions numerous boutons of a size similar to the varicosities of the monoamine terminal exist. They form mostly synapses with dendrites. The boutons are more or less filled with either small (about 300–350 Å), medium sized (about 450 Å) or — but less commonly — large (about 550–600 Å) agranular vesicles. Larger (about 800–1,000 Å) granular vesicles are found in all three regions studied. In comparison to the agranular vesicles, however, they are practically always few.

In animals treated with a large dose of reserpine or nialamide none of the different types of vesicles showed any obvious changes. It is concluded that the monoamine storage granules are not identical with the large granular vesicles, but that they, with the method used, appear as small, agranular vesicles.
Growth of the rat epiphyseal cartilage plate following partial amputation
Authors: Simmons David J. , Nunnemacher Rudolph F.
Published: February 2005

Following hemi‐resection of the rat distal femoral epiphysis with its growing epiphyseal cartilage, the cut surface of the cartilage is sealed‐off by trabecular bone and the cells fail to undergo further growth and maturation at that site. However, since the peripheral rows of cartilage cells survive and continue to proliferate, the cellular activity gradient causes the epiphyseal remnant to rotate about the fixed cut surface of the cartilage toward the amputated side. In these experiments, the degree of epiphyseal rotation following partial amputation was compared to the longitudinal growth of the contralateral intact femurs in normal and estrogen‐treated rats. While estrogen treatment retarded both the growth of intact femurs and epiphyseal rotation, the ratios of these growth measurements calculated at different time intervals following osteotomy (0–4, 4–7, 7–9 weeks) were identical to those of the control series. It was concluded that partial amputation per se had no demonstrable effect on the vitality of the surviving chondrocytes of epiphyseal cartilages; moreover, these cells were entirely responsive to the growth depressing action of estrogen.
Cytology and histochemistry of the pituitary gland of the five‐striped palm squirrel, Funambulus pennanti (Wroughton)
Authors: Dhaliwal Gurmeet K. , Prasad M. R. N.
Published: February 2005

The cytology and cytochemistry of the pitiutary gland of the palm squirrel Funambulus pennanti during different phases of reproductive activity are described. Two types each of basophils and acidophils are recognized. The basophils include gonadotrophs and thyrotrophs and acidophils include orangeopils and carminophils. The gonadotrophs which are ovoid, coarsely granulated and mainly located on the sinusoidal borders of the lateral halves of the pars anterior are more numerous in males than in females. They are PAS‐positive and AF‐negative. They cannot be distinguished tinctorially into FSH and LH secreting cells as in the pituitary of the rat. The thyrotrophs which are large, rounded or polyhedral, finely granulated cells are confined to the antero‐median zone of the pars anterior. They are PAS and AF‐positive. The basophils can be tinctorially differentiated by the performic acid‐alcian blue‐PAS‐orange G staining in which the gonadotrophs are stained purple and the thyrotrophs are red. The acidophils are differentiated tinctorially into two types. The orangeophils or STH secreting cells are small, rounded, and coarsely granulated. Carminophils or LTH secreting cells which appear in the pituitaries of females in early pregnancy and increase in number during later pregnancy and lactation, are large and coarsely granulated. The acidophils are specifically stained with mercury‐bromphenol blue.
Studies on the nerve endings in the visceral pleura
Authors: Dwinnell Frank L.
Published: February 2005

The visceral pleura of 12 dogs, eight lambs, nine monkeys and four rabbits was studied by methylene blue immersion. Nerve terminations were found in the pleura of all specimens. The following types of nerve endings and patterns of innervation were observed. (1) Free fiber endings arose from small myelinated fibers and terminated in the caudo‐ventral lips of the lobes. The parent fibers of these and all other endings arose, in the lamb, rabbit and dog, from nerve bundles radiating from the hilus onto the inter‐lobar and diaphragmatic pleural surfaces. In the monkey, parent fibers arose from a complex hilar plexus of nerve bundles before spreading out within the pleural surfaces. (2) Complex unencapsulated endings were seen in all specimens distributed evenly over the inter‐lobar and diaphragmatic pleural surfaces. These arose from myelinated fibers which terminated in two or more complex endings. In the monkey, parent fibers may form an anastomotic network before terminating. (3) In the dog, an “end‐net” formation was found which appears to be a type of complex unencapsulated ending. This “end‐net” is formed by the anastomosis of the terminal branches of several small myelinated fibers.
Fine structure of the surface of mouse hepatic cells
Authors: Heath Trevor , Wissig Steven L.
Published: February 2005

Mouse hepatic cells appear in thin sections as polygons with six or more sides. The plasma membrane covering these sides may contact either bile canaliculi, the narrow intercellular space, the space of Disse or extensions of the space of Disse between adjacent cells. The plasma membrane covering microvilli in bile canaliculi and the space of Disse is thicker than that in contact with the narrow intercellular space. Bile canaliculi, which contact about 6% of the perimeter of each cell, are each separated by tight junctions from the narrow intercellular space. This space contacts more than one‐half the perimeter of each cell and is about 220 Å in width. It is continuous around the occasional studlike junctions which occur, but is interrupted at frequent intervals by circumscribed tight junctions, and occasionally by desmosomes. The narrow intercellular space is in free communication through the space of Disse with the plasma space. An interstitial fluid space, separate from the plasma space, does not occur in the liver lobule. Protein molecules from plasma enter hepatic cells in both coated and pinocytotic vesicles. These vesicles are derived from invaginations of the plasma membrane that borders the narrow intercellular space and the spaces between microvilli in the space of Disse. Pinocytotic vesicles may also incorporate fat droplets into hepatic cells.
Effects of triton WR‐1339 on the rat yolk sac placenta
Authors: Schultz Phyllis W. , Reger James F. , Schultz Richard L.
Published: February 2005

The cytochemistry and ultrastructure of the lysosomal area of the rat's yolk sac placenta was studied at various stages of development. The lysosomal area, located at the apical end of the yolk sac epithelial cell between the microvillous border and the nucleus, consisted of dense bodies that persisted from day 10 of pregnancy through gestation and multivesicular bodies that are present only through day 12. Acid phosphatase activity was restricted to the dense material and to the membranes of this area. Two types of pinocytotic vesicles were present in all stages of development. One was a tubular structure containing dense material and the other, a saccular, clear structure containing a “fuzz‐lining” and membrane remnants. Possible relationships between the pinocytotic vesicles and the dense and multi‐vesicular bodies were considered.

The injection of Triton WR‐1339 on day 11 of pregnancy resulted in a vacuolation of the dense and multivesicular bodies. This vacuolation began 15 minutes after injection and maximum effect was reached within 12‐‐24 hours. A reorganization of the lysosome area occurred on days 15‐‐16 in those animals in which pregnancy continued to term. This reorganization consisted of an increase in the dense material within the vacuoles and a reduction in vacuole size. The vacuoles remained distended in those animals in which death and resorption of the fetus occurred. The first cellular changes associated with death occurred between 48‐‐60 hours post‐injection. The microvilli became shorter, thicker and reduced in number; the pinocytotic vesicles disappeared from the cell surface; the endoplasmic reticulum became dilated and vesiculated; and vesicles were formed from the cristae of the mitochondria.

With the injection regimen used in this study, 25% of the litters were resorbed while the remainder of the pregnant rats delivered viable fetuses at term.
Studies on guinea pig oocytes. II. Histochemical observations on some phosphatases and lipid in developing and in atretic oocytes and follicles
Authors: Adams Eleanor C. , Hertig Arthur T. , Foster Susanne
Published: February 2005

Normal guinea pig oocytes develop in an environment of AMPase within the granulosa cells of the wall, the cumulus and the latter's projections that traverse the zona pellucida to terminate at the surface of the oocyte. Oocytes in developing non‐vesicular and small vesicular follicles have an ATPase activity at their surface, which appears to indicate specialized absorptive mechanisms confined to these early stages of development. Acid phosphatase, present in granules scattered throughout the cytoplasm of all developing oocytes, may be evidence of a mechanism in this species, whereby the oocyte hydrolyzes unidentified nutritional reserves.

Histologically normal appearing oocytes in atretic vesicular follicles may show deviations from the normal histochemical pattern, i.e., clumping and subsequent loss of acid phosphatase activity or a band of AMPase activity at the periphery of the oocyte representing apparent enlargement of the terminals of projections of the cumulus. These deviations may reflect disturbances of granulosa cell‐oocyte transfer as a consequence of beginning atetric processes in the follicle wall. By the eighth day of the estrous cycle the granulosa layer of many medium sized follicles has been invaded by a few long strands of nucleoside polyphosphatase positive thecal connective tissue often carrying a small blood vessel. This early stage of atresia is apparently followed by shedding of the granulosa layer and hypertrophy of the thecal layer which begins the transformation of atretic follicles into interstitial masses.
The interrelation of the digestive and skeletal systems as determinants of tooth position
Authors: Brodie Allan G.
Published: February 2005

In spite of the many differences between teeth and bone in their phylogenetic and embryologic origins, modes of growth, disease and repair processes, the two continue to be equated together in most matters relating to their functioning positions.

On the basis of a variety of studies by others and recent quantitative longitudinal investigations by himself the author seeks to demonstrate that the positions of the teeth are under the control of different body systems, viz., the skeletal and the digestive. The first controls the root apices, the second the crowns.
Microradiographic visualization of structure in bones of the masked shrew, Sorex cinereus
Authors: Felts William J. L. , Spurrell Francis A.
Published: February 2005

Sorex cinereus, the masked shrew, is nearly the smallest of mammals. The femur, metatarsal, phalanges and mandible of wild‐trapped animals were examined by a variation in the technique of contact microradiography. Purpose of the investigation is the exploration of some aspects of the question of size as a factor in structural complexity in bone, as well as the possibilities of the shrew in studies of skeletal aging. Comparison is made with bones of the laboratory mouse and rat.

Limb bones of the masked shrew are avascular. Vascularity of the mandible appears related primarily to maintenance of dental tissues. The femur is comparatively simple, its sparce spongiosa consisting of relatively large trabeculae. Diaphyseal compacta appears to be of maximum thickness for the avascular state. Tubular foot bones are without spongiosa and bone on their articular surfaces is nearly as thick as that in the diaphysis. Metatarsals and phalanges of mice have the same gross structure but are vascular. These bones in the rat have trabeculae in functional patterns.

The simplicity of structure of these minute bones, and the drastic structural modification of bones of apparently starved or stressed animals, indicates potential utility of the shrew in experimental investigations.
Continuous attachment of the periodontal membrane
Authors: Kraw Allan G. , Enlow Donald H.
Published: February 2005

A polychrome stain for differentiating precollagenous and collagenous fibers, and tetracycline for labeling bone changes were used in young rats to trace adjustments involved in movements of teeth within bone. Distinct differences were seen in fibrous attachments on depository and resorptive bone surfaces. These are associated with shifts of the periodontal membrane as the root and surrounding bone undergo drift. Some resorptive areas receive total destruction of fibrous attachment. Other areas involve a process of fibrous conversion as ordinary fibers of the bone matrix become uncovered during bone removal and function as periodontal fibers anchored into the receding bone surface. An intermediate zone of the periodontal membrane functions to progressively shorten distal ends of these same fibers and to relink them with newly formed precollagenous fibrils. These become continuous with mature fibers attached to the cementum. On depository surfaces, outer fibers of the membrane become embedded into new alveolar bone, and former precollagenous fibrils of the inward‐shifting intermediate zone translocate to become the new outer zone. Continuous relinkage is simultaneously maintained between the inner and outer zones. Haversian remodeling occurs beneath resorptive surfaces and re‐anchorage is thereby established in specific areas where total destruction of fibrous connection had previously occurred.
An electron microscopic and radioautographic study of the rat parotid gland after actinomycin D administration
Authors: Han Seong S.
Published: February 2005

Rat parotid glands have been examined by electron microscopy and radioautography (H3‐leucine incorporation) at various intervals following an injection of actinomycin D in the amount of 0.125 μg per gram of body weight. Light microscopic observations confirmed results from previous experiments similar to this. Radioautographs showed a definite drop in number of silver grains in acinar cells of the parotid from experimental animals. This was most pronounced in 7‐day rats which received H3‐leucine four hours prior to sacrifice. Electron microscopic observations revealed a generalized reduction in number and degree of the organization of organelles concerned with protein synthesis. Furthermore, frequent appearances of lipid droplets, cytolysomes and crystalloid structures were noted. Changes of the nucleolus included the reduction of its size and the formation of spherical encapsulated bodies. A brief discussion is made of these results in relation to the biochemical nature of actinomycin effects on protein producing cells.
Central projections of portions of the vestibular ganglia innervating specific parts of the labyrinth in the rhesus monkey
Authors: Stein Bennett M. , Carpenter Malcolm B.
Published: February 2005

In 40 monkeys attempts were made to determine the central projections of cell groups in the superior and inferior vestibular ganglia (SVG, IVG) which innervate distinctive parts of the labyrinth, by: (1) severing peripheral branches of the ganglia, (2) resecting portions of the ganglia, and (3) producing discrete partial lesions in the ganglia. Serial sections of the temporal bones were stained with Sudan black B, and Nauta‐stained sections of the brain stem were cut transversely and horizontally.

Section of peripheral branches of the vestibular ganglia produced no central degeneration and unreliable cell changes in the ganglia. Partial lesions of the SVG, innervating the cristae of the anterior and lateral canals, produced maximal degeneration in the superior and medial (rostral part) vestibular nuclei. Partial lesions of the SVG, innervating the macula of the utricle, produced maximal degeneration in the medial (caudal part) and inferior (mediodorsal part) vestibular nuclei. Some descending fibers related to the utricle entered the accessory cuneate nucleus.

Discrete lesions in portions of the IVG indicate relationships between: (1) the crista of the posterior canal and the superior vestibular nucleus (caudomedial part), and (2) the saccule and dorsolateral parts of the inferior vestibular nucleus. Cells of the vestibular ganglia innervating distinctive parts of the labyrinth have unique, as well as common, central projections within the vestibular nuclear complex.
An electron microscopic study of the modification by monosodium glutamate of the retinas of normal and “rodless” mice
Authors: Cohen Adolph I.
Published: February 2005

Sodium‐L‐glutamate was administered to post‐natal Swiss albino and agouti C3H/HeJ “rodless” mice. In both cases there was at two months a marked reduction in myelinated axons of the optic nerve from about 25,000 to less than 225 axons but Swiss mice had more ganglion cell somas than axons. Glutamate‐treated eyes seemed smaller and the lenses were 65% of the weight of control lenses. The inner nuclear layer of Swiss‐glutamate retinas was reduced from 5–7 nuclei deep to 1–2. In treated Swiss mice the receptor concentration appears unchanged and electron microscopy revealed that both spheroidal and pedicular receptor terminals were contacted by presumed neurites of second order neurons. There was a small, relative increase in terminals of bipolar neurons in the markedly reduced inner plexiform layer. Relative to these findings a description is given of normal synaptic arrangements. In glutamate‐treated “rodless” mice at two months the retina contained two rows of nuclei. Imbricated processes of glial cells of Müller faced the pigment epithelium and the retina contained scattered ganglion cells, bipolar cells, and other neurons less readily characterized. At two months most glutamate‐treated mice, rod containing or “rodless,” had a direct pupillary response and a detectable but obviously weaker consensual response. Preliminary examinations of animals one year after glutamate treatment showed receptor deterioration in albino animals and further retinal deterioration in both groups. The two surviving C3H‐glutamate animals possessed milky cataractous lenses, however full but sluggish direct iris constrictions could be elicited.
Physical, histological and roentgenographic characteristics of the grey lethal mouse
Authors: Doykos John D. , Cohen M. Michael , Shklar Gerald
Published: February 2005

A project was undertaken to investigate the development of dental and osseous abnormalities in the grey lethal mouse. In this study particular attention was focused on the nature of these anomalies and the exact time of onset.

Twenty‐five grey lethal mice, with siblings serving as controls, were sacrificed at two day intervals from the eighth to the twentieth day. Color photographs and lateral full body radiographs were taken at each developmental stage studied. Microscopic sections of the jaws and femurs of each animal were prepared and stained with hema‐toxylin and eosin.

Abnormalities in the incisor region of the grey lethal mouse were demonstrated radiographically at the eighth day. Interference with Hertwig's sheath of the developing first molar tooth was observed histologically at the eighth day. Establishment of molar root bifurcation was not observed in the grey lethal mice. Bone resorption was retarded in both jaws and femurs. Differences between experimental and control animals became more apparent with increasing age.

It was thought that apical root development and osseous apposition in the area of bifurcation of developing molars, as well as resorption of bone occlusal to the crowns of the teeth are constituents in axial movement of developing teeth. Evidence tending to support this concept is presented, since all three functions were shown to be altered in the noneruption dentition of the grey lethal mouse.
Efferent fibers of the subthalamic nucleus in the monkey. A comparison of the efferent projections of the subthalamic nucleus, substantia nigra and globus pallidus
Authors: Carpenter Malcolm B. , Strominger Norman L.
Published: February 2005

A study was made to determine the efferent projections of the subthalamic nucleus in the monkey. Because of the impossibility of producing lesions in this nucleus, not involving adjacent structures, lesions were produced by different stereotaxic approaches. Comparisons were made with degeneration resulting from localized lesions in substantia nigra and globus pallidus. Degeneration resulting from these lesions was studied in transverse and sagittal sections stained by the Nauta‐Gygax method.

Efferent fibers from the subthalamic nucleus pass through the internal capsule into the medial pallidal segment; a few fibers are distributed to the lateral pallidum. Some subthalamic efferent fibers pass to the contralateral globus pallidus via the dorsal supraoptic decussation, but none projection to the thalamus.

Nigral efferent fibers project to parts of the ventral anterior (VAmc) and ventral lateral (VLm) thalamic nuclei. The medial pallidal segment gives fibers to: (1) ventral anterior (VA), ventral lateral (VLo) and centromedian (CM) thalamic nuclei, and (2) the pedunculopontine nucleus. The lateral pallidal segment projects exclusively to the subthalamic nucleus. Thalamic projections of the substania nigra and globus pallidus are distinctive. Subthalamic projections to the globus pallidus are more profuse than those of the substantia nigra.

The following hypothesis is presented: Subthalamic dyskinesia, due to lesions in the subthalamic nucleus, is a consequence of removal of inhibitory influences acting upon the medial segment of the globus pallidus.
The adrenergic nerve supply to the female reproductive tract of the cat
Authors: Rosengren E. , Sjöuberg N.‐O.
Published: February 2005

Pilot studies on the fluorescence histochemistry of the adrenergic innervation to the female reproductive tract in different mammals revealed a conspicuously well developed innervation in the cat. Moreover, the female genital tract of the cat is studied extensively with regard to the pharmacology of adrenergic mechanisms. An exact knowledge of the adrenergic innervation apparently would make the cat a particularly suitable model for functional studies on the involvement of neuronal adrenergic mechanisms in the reproductive tract.

Fluorimetrically, noradrenaline was the only catecholamine occurring in measurable amounts in nonpregnant cats. The amine seemed to have an exclusively neuronal distribution, although a comparatively small fraction may be also located in “chromaffin” cells present in relation to ganglion formations.

A considerable number of adrenergic nerve terminals were found in all organs of the reproductive tract. Consistent numbers of these terminals were directed to various structures forming the ovarian parenchyma and to the smooth muscle coats of the oviduct, uterus, and vagina. The rest of the innervation seemed to be of vasomotor nature. The histochemical results agree well with the high level of noradrenalin, 1.22–4.93 μg/gm, found in the different organs.

Denervation experiments revealed that the postganglionic sympathetic innervation reaches the oviduct, uterus, and vagina partly by way of the hypogastric nerves, and partly by way of short adrenergic neurons originating from adrenergic ganglia that could be directly visualized in the region of the uterovaginal junction. The ovarian adrenergic innervation seemed to arise more proximally, probably directly from the sympathetic chain.
The fine structure of neurons and satellite cells in the trigeminal ganglion of cat and monkey
Authors: Pineda Anselmo , Maxwell David S. , Kruger Lawrence
Published: February 2005

Neurons and satellite cells in the trigeminal ganglion of cats and monkeys fixed by aldehyde perfusion were examined in the electron microscope. The fixative employed and its tonicity appear to be critical factors in accounting for some of the differences noted in earlier descriptions. With satisfactory preservation, only one variety of neuron is seen on the basis of cytoplasmic and nuclear features, although there is a substantial size range. Interdigitating processes of neurons into the satellite cell capsule probably accounts for the axon terminals and intracapsular nerve nets reported in early metallic impregnation studies. Axonal glomeruli are encased in satellite cells and become myelinated by Schwann cells as the axon leaves the region of the neuron soma.

Satellite cells reveal layers of attenuated processes forming unusual membrane complexes around the axons. The external surfaces of the satellite cells are completely invested with a prominent basal lamina, which is continuous with that surrounding the Schwann cell at the first “internode.”
Catagen in the hairless house mouse
Authors: Orwin D. F. G. , Chase H. B. , Silver A. F.
Published: February 2005

A morphological and histochemical study was made of some aspects of the catagen phase of the first hair cycle in hairless (hr) mice.

The histochemical tests used included those for sulphydryl and disulfide groups, collagen, and periodic acid‐Schiff‐reactive materials. Measurements were made of skin thickness, follicle length and for follicles in catagen VI and VII, epithelial column length, length of hair shaft in the skin, the width of glassy membrane and connective tissue sheath, and the width of collagen in the glassy membrane. The results showed that:

The mutant epithelial column shortens at a slower than normal rate so that at catagen VII, the total follicle length is greater than normal. The position of the mutant hair shaft in the skin is normal at this stage.

The keratinization sequence of the mutant club appears normal. The failure to form an anchoring brush is associated with a morphological variation in the cell shapes and fibrils of the club.

The inner root sheath of the mutant follicle, although apparently keratinizing in the normal sequence, extends further up the follicle than normal and also further down, enclosing the club.

The glassy membrane and connective tissue sheath of the mutant are abnormally narrow due mainly to a marked reduction in collagen, and to a narrower band of PAS‐positive material.
Fine structure of nerves in the regenerating limb of the newt Triturus
Authors: Lentz Thomas L.
Published: February 2005

The structural integrity of some tissues and the regeneration of extremities in some vertebrates depends upon the nervous system. To investigate the structure of nerves exhibiting trophic function, nerves in regenerating forelimbs of adult newts, Triturus viridescens, were studied with the electron microscope. Nerve fibers sprout from the transected axons, 2–3 days after amputation of the limb, and invade all portions of the blastema and epidermis in large numbers. Regenerating nerve fibers contain a greatly increased amount of smooth‐surfaced channels of endoplasmic reticulum containing moderately dense material, an increased number of microtubules, and large (1000 Å) membrane‐bounded dense granules. The latter were not observed normally and could be distinguished from synaptic vesicles and dense‐core vesicles thought to contain catechol amines. In larger nerves, the organelles are distributed in the peripheral axoplasm around a central zone containing neurofilaments.

The relationship of the fine structural changes occurring during regeneration to the trophic action of nerves and the regeneration of nerve fibers is discussed. The tortuous membranous tubules of endoplasmic reticulum could serve as channels for the transport of substances, either trophic material or materials necessary for growth of the nerve, down the axon. Microtubules may play a role in the regulation of form of the growing axon and also be related to axoplasmic flow or migration of particles (e.g., granules) along their length. The large membrane‐bounded dense granules appearing during regeneration resemble neurosecretory granules, which have been associated with regeneration in some invertebrates. These structures could, therefore, contain a trophic substance or hormone that is transported down the axon, released into the intercellular spaces, and controls subsequent regeneration of the limb.
The structure of the proximal tubule: A morphological study of basement membrane cristae and their relationships in the renal tubule of the rat
Authors: Waugh Douglas , Prentice Robert S. A. , Yadav D.
Published: February 2005

The basement membrane of the proximal tubule of the rat has a smooth outer surface and a series of closely spaced, transversely arranged inner ridges or cristae. By determining the specific plane of section in light and electron micrographs, the basal architecture of the tubule cells and its relationship to cristae can be elucidated. Toward the base of the cell, there are well defined linear cytoplasmic compartments parallel to the basement membrane cristae. From these, emanate terminal cytoplasmic villi which make final contact with the inner surface of the basement membrane. The arrangement appears well suited to the dual functions of adhesion between cell and basement membrane and large volume fluid transport.
Protein synthesis studied by autoradiography in the epidermis of different species
Authors: Fukuyama Kimie , Epstein William L.
Published: February 2005

This paper reports autoradiographic studies of protein synthesis related to epidermal cornification in several different species. A high concentration of injected histidine appeared in granular cells of man, the monkey, guinea pig, hairless mouse, and newborn rat, indicating that synthesis of relatively histidine‐rich protein is involved in formation of keratohyalin granules. Two steps in the cornification process: synthesis of this histidine‐rich protein, in addition to protein synthesized in the lower layers of the epidermis are postulated in epidermis containing keratohyalin granules. In the epidermis of the turtle, which does not contain keratohyalin granules, concentration of histidine is not observed, suggesting that protein of the cornified layer in this species seems to be synthesized as a 1‐stage process.
A comparative morphologic study of the cardiac innervation in domestic animals II. The feline
Authors: McKibben John Scott , Getty Robert
Published: February 2005

Detailed morphological studies of the cardiac innervation of the cat were reported. Sympathetic cardiac nerves arose from the thoracic, cervicothoracic, vertebral, and intermediate ganglia. Parasympathetic cardiac nerves arose from the vagi, both cranial and caudal to the origin of the recurrent laryngeal nerves, and from the right recurrent laryngeal nerve. Left cardiac nerves passed primarily to the caudal and right surfaces of the left chambers while right ones ramified on the right chambers and left portion of the left chambers. Left cardiac nerves are more prominent around the coronary sinus and atrioventricular node, while right ones contribute more to the area of the sinoatrial node. Both sympathetic and parasympathetic nerves were followed to each chamber. Interconnections through the cardiac plexus facilitated overlapping of nerve distributions.
Central projections of spinal dorsal roots in the monkey. II. Lower thoracic, lumbosacral and coccygeal dorsal roots
Authors: Carpenter Malcolm B. , Stein Bennett M. , Shriver Joyce E.
Published: February 2005

A study of the central distribution of lower thoracic, lumbosacral and coccygeal dorsal roots (DR) was made in 11 monkeys. Degeneration resulting from 17 individual dorsal rhizotomies was studied in multiple spinal and medullary sections stained by the Nauta technic.

At the rhizotomy level all DR project fibers to: (1) portions of laminae III and IV, (2) the intermediomedial nucleus, and (3) portions of laminae VII, VIII and IX. Lower thoracic, lumbar and the first sacral (S1) DR project in overlapping fashion to particular portions of Clarke's column; ascending and descending fibers terminate in a spatially organized manner. Lower lumbar DR project to medial lamina VI throughout the lumbar enlargement. DR fibers reach cell groups of lamina IX via two trajectories, one of which is dominant in the lumbar enlargement.

Ascending DR fibers in the fasciculus gracilis: (1) arise caudal to T7, (2) exhibit only general segregation due to overlap, and (3) project in an overlapping somatotopic fashion throughout the rostrocaudal extent of the nucleus gracilis. Zones of the nucleus gracilis receiving fibers are organized, so that: (1) DR of the lumbar enlargement project to a central core region, (2) lower thoracic and upper lumbar DR project to narrow oblique laminae lateral to the core, and (3) S1 and Co1 DR project to crescent‐shaped dorsomedial regions. Less autonomous terminal representation of DR fibers was found in the nucleus gracilis than in other posterior column nuclei.
Ultrastructural changes in the sperm head during fertilization in the rabbit
Authors: Bedford J. M.
Published: February 2005

Spermatozoa have been observed with the electron microscope at various stages of their approach to and penetration of the rabbit ovum. No significant change in fine structure is observed in uterine sperm, or in many of the sperm at the periphery of the granulosa investment around the ovum. By contrast, a majority of sperm lying between the granulosa cells or on the surface of the zona pellucida display various stages of the “acrosome reaction”; this involves fusion and vesicle formation between the plasma membrane and the outer membrane of the acrosome. Loss of these vesicular elements, and content of the acrosome cap, takes place before sperm begin to penetrate the substance of the zona. The constricted posterior “equatorial” segment of the acrosome cap does not take part in the acrosome reaction and remains with its content intact during penetration of the zona; neither does the content of the apical sub‐acrosomal region (perforatorium) or post‐acrosomal region appear to change in traversing the zona. The hypothetical zona lysin is thus presumed to be closely associated with the persistent inner membrane of the acrosome, which now becomes the limiting membrane around the anterior part of the sperm nucleus.

No “penetration filament” has been observed, but sperm within the zona pellucida of ageing eggs are often preceded by a straight or curved fissure in the substance of the zona. The possible nature of capacitation and its relation to the acrosome reaction and to the process of penetration, are discussed briefly.
Fluid flow in the liver demonstrated with horse radish peroxidase
Authors: Papadimitriou J. M. , Walters M. N‐I.
Published: February 2005

Using horse radish peroxidase as a tracer for fluid flow, rapid diffusion was demonstrated between sinusoidal lumina and the interhepatocytic spaces of the murine liver. The marker passed rapidly between adjacent sinusoidal cells and filled the space of Disse. Appreciable amounts of peroxidase were also seen in pinocytic and phagocytic vacuoles within sinusoidal cells. Many junctions in the wall of bile canaliculi impeded the passage of the marker, but in some sites this hindrance did not occur. This provides a path for the direct exchange of material between vascular and biliary contents. Such a mechanism may be physiologically controlled. Junctions in bile ductules prevent diffusion of horse radish peroxidase.
Marginal zone and germinal center development in the spleens of neonatally thymectomized and nonthymectomized young rats
Authors: Pettersen James C. , Rose Robert J.
Published: February 2005

Spleens from neonatally thymectomized and nonthymectomized young rats were studied histologically and histochemically to elucidate the development of the splenic immune system with and without thymus.

In intact animals primitive germinal center activity could be elicited with antigen as early as 13 days of age. More definitive germinal centers lacking tingible body macrophages were observed at 18 days of age. Germinal centers containing tingible body macrophages did not develop until 35 days of age in response to antigenic stimulation. This coincided with maximal development of the marginal zone of medium‐sized lymphocytes and the mature development of nodular macrophages possessing strong acid phosphatase activity.

Neonatally thymectomized rats developed marginal zones and germinal centers similar to control littermates when the young animals were maintained on tetracycline. Thymectomized animals not given tetracycline showed disturbances in splenic development. These are discussed.

The results suggest that the thymus may be critical to the immune system in rats from birth to about 30 days of age but is not essential to its function beyond this period. Marginal zone lymphocytes and germinal center cells proliferate normally and mature to the plasma cell stage in the absence of a thymus if the animals are maintained on tetracycline beyond this critical age.
An electron microscope study of differentiation of the molting muscles of Rhodnius prolixus
Authors: Warren Robert H. , Porter Keith R.
Published: February 2005

The abdominal intersegmental molting muscles of Rhodnius prolixus undergo a repeated differentiation and dedifferentiation correlated with the molting cycle of the insect. In the dedifferentiated phase, the muscle fibers lack myofibrils but contain a few bundles of 50–60Å filaments associated with amorphous dense plaques on the sarcolemma. Differentiation of the muscle fibers begins when a starved Rhodnius nymph takes a blood meal. The first morphological signs of differentiation at ten hours after feeding are a dispersal of ribosomes from the nuclear envelopes and a formation of polysomes in the sarcoplasm. The initial myofilaments appear within 10 to 15 hours after the blood meal and are preferentially deposited in the cortices of the muscle fibers in association with the 50–60Å filament bundles and the dense plaques on the sarcolemma. Striated myofibrils are present after five days of differentiation. Developmental continuity between Z‐band segments and sarcolemmal dense plaques is suggested. The formation of cross‐bridges between thick and thin myofilaments appears to be the primary mechanism of myofibril organization. Disruption of microtubules with colchicine does not significantly alter myofilament deposition and organization during early stages of differentiation. Dyads, consisting of smooth sarcoplasmic reticulum and invaginations of the sarcolemma, are present in the dedifferentiated muscle fiber, and increase in number as differentiation proceeds.