bluuebunny/crossref_metadata_2025 huggingface dataset:
Central projections of spinal dorsal roots in the monkey. I. Cervical and upper thoracic dorsal roots
Authors: Shriver Joyce E. , Stein Bennett M. , Carpenter Malcolm B.
Published: February 2005

A study of the central distribution of cervical and upper thoracic dorsal roots (DR) was made in 18 monkeys subjected to 31 dorsal rhizotomies. Degeneration was studied in multiple spinal and medullary sections stained by the Nauta technic.

Dorsal roots C2 through T7 project fibers to: (1) portions of laminae III and IV, (2) the intermediomedial nucleus, and (3) portions of laminae VII, VIII and IX. DR C5 through T1 project fibers to medial parts of lamina VI. DR fibers reach cell groups of lamina IX via different trajectories, one of which is dominant in the brachial enlargement. Fibers project to the spinal accessory nucleus from C2 through C5 DR, while portions of the dorsal nucleus receive fibers from C5 to T7 DR.

Ascending fibers in the fasciculus cuneatus: (1) arise from C1 through T7 DR, (2) exhibit only general segregation due to overlap, and (3) project somatotopically throughout the extent of the cuneate (CN) and accessory cuneate (ACN) nuclei. Fiber terminations in CN and ACN are: (1) similar for C1 through T1 DR, and (2) distinctive for T2 through T7 DR. The upper five cervical DR project fibers to: (1) the supraspinal nucleus, and (2) both the central cervical and intermediate nuclei. Cytological and degeneration studies suggest that the central cervical and intermediate nuclei constitute parts of the same cell column.
The uptake of ferritin by ileal absorptive cells in suckling rats. an electron microscope study
Authors: Graney Daniel O.
Published: February 2005

An electron microscopic study of the small intestine of rats from birth to 15 days of age has demonstrated a gradient of both structure and function along the length of the small intestine. During this period of development, only the ileum was found to absorb intact exogenous ferritin or colostral proteins. In newborn rats ferritin particles or milk proteins are incorporated by ileal absorptive cells into tubular invaginations of the apical plasmalemma which connect with vacuoles or cisternae in the apical cytoplasm. The ferritin particles are then transported by another vacuolar system to the supranuclear region where several such vacuoles coalesce to form a single supranuclear vacucle. After the first feeding the supranuclear vacuole is established in the ileal cells so that additional ingested proteins, whether ferritin or from milk, are transported from the cisternae directly to the supranuclear vacuole. There was no evidence in the present study to indicate that ferritin is transmitted from the ileal cell to the circulation. The subject of protein transport by the intestinal epithelium is reviewed briefly.
Morphological features of brown adipose cell maturation in vivo and in vitro
Authors: Dyer Robert F.
Published: February 2005

The maturation of brown adipose cells, derived at various time intervals from interscapular brown fat pads of neonatal rats, has been investigated electron microscopically. The major changes in in vivo brown adipose cells are related to lipid accumulation. In older animals, fat droplets are separated by a membrane complex, and membranous fragments are seen within large lipid inclusions. The ultrastructural characteristics of monolayer cultures of brown fat cells, isolated from neonatal brown fat pads by tryptic dissociation, and maintained for one to six days on a reconstituted collagen matrix, have also been investigated. Adipose cells in vitro are morphologically similar to control brown fat cells, and lipid accumulation closely parallels that seen in vivo. In vitro lipid droplet coalescence, impossible to visualize in vivo, has been documented by time‐lapse cinematography, and membrane complexes similar to those observed in vivo are seen. Major changes in cultivated fat cells, compared to in vivo cells, involve extensive glycogen deposition and breakdown of cytoplasmic ribosomal rosettes. Older cultures contain adipose cells exhibiting characteristics of white fat cells. Effects of tissue culture environment upon the brown fat cells, and the possible conversion of the brown fat cell into a white fat cell are discussed.
Studies on the fine structure of ovarian steroid‐secreting cells in the rabbit. I. The normal interstitial cells
Authors: Davies J. , Broadus Carole D.
Published: February 2005

In terms of their light microscopic appearance and fine structure the ovarian interstitial cells of the rabbit are typical steroid‐secreting cells. They are characterized by an abundance of agranular endoplasmic reticulum, spherical mitochondria with closely packed lamellar cristae, lipid droplets which appear to arise independently of the endoplasmic reticulum, conspicuous Golgi areas, a cytoplasm containing ribosomes and variable numbers of glycogen granules. A feature of the differentiation of the cells from the theca interna of atretic follicles or the stroma is the enlargement of the multiple Golgi areas and the progressive accumulation of agranular endoplasmic reticulum, possibly by “budding” from the Golgi cisternae. “Light” and “dark” cells are observed, the latter being characterized by a more closely packed agranular endoplasmic reticulum which tends to be tubular in type, that of the “light” cell being vesicular. Electron dense material (lipid?) is found in the vesicles and tubules of the agranular endoplasmic reticulum and in the Golgi cisternae; it may indicate a role of these structures in the biosynthesis of steroidal hormone. No fine structural changes specifically associated with pregnancy were observed. Degenerative changes are common and are described. The role of the interstitial cells, especially in relation to the production of 20 alpha‐hydroxyprogesterone, is discussed.
Sensory receptor organs of the human nasal respiratory mucosa
Authors: Cauna Nikolajs , Hinderer Kenneth H. , Wentges Robert T.
Published: February 2005

Human nasal respiratory mucosa has a limited capacity for localization of stimuli and discrimination of sensory modalities. In order to obtain morphological data on its receptor organs, histochmeical and electron microscopical studies were undertaken in six individuals ranging in age from 18 to 39 years.

It was found that the nasal respiratory mucosa was supplied by non‐myelinated nerves which approached the mucosa in fascicles containing up to 200 axons. These fascicles were devoid of perineurial sheaths. They ramified repeatedly producing only one type of receptor organ — a simple terminal arborization. The finest terminal fascicles of the plexus ended either in the cell free zone of the lamina propria or in the spaces between the epithelial cells next to the basement membrane. The axons in the fascicles and in the endings were only partly insulated from one another by Schwann cell folds. The axoplasm of the terminal and preterminal nerve fibers contained accumulations of fine vesicles, simple granules and clusters of mitochondria. All nerve fibers gave a positive acetyl‐ and a negative butyro‐cholinesterase reaction.

The plexiform endings of the nasal respiratory mucosa are different from any receptor organ of the adult human skin. They are reminiscent of the transitory, yet functional plexiform endings of the fetal skin which are found prior to the formation of the definitive receptor organs.
Electron microscopical studies on axonal degeneration in the rat iris following ganglionectomy
Authors: Roth C. D. , Richardson K. C.
Published: February 2005

Superior cervical ganglionectomy causes a very rapid and complete distintegration of adrenergic axons in the rat iris commencing less than 24 hours after operation. At 48 hours post‐operatively the electronmicroscopical appearance of the iris is normal with osmium tetroxide fixation because the debris has vanished and the abundant surviving cholinergic axons in the autonomic ground plexus give the impression that the total innervation is still intact. However, with permanganate fixation the denervated iris examined 48 hours to one year after operation lacks granular vesicles in its axons and appears in this single respect different from normal. After ciliary ganglionectomy the same kind of degeneration of individual axons begins within 24 hours, but continues for several days, involving a greater number of axons than the previous operation. Removal of both sets of ganglia intensifies the loss of axons and causes some atrophy of the iris tissues. A residue of apparently intact axons persists, however, for as long as ten months. The previously discordant results of ganglionectomy on iris innervation obtained by light microscopy are shown to be dependent on technical inadequacies, combined with the fact that in the earlier literature it was not known that there is a close intermingling of adrenergic and cholinergic axons in all parts of the iris plexuses.
Electron microscopic investigation of the source and direction of movement of lipid granules appearing in the hepatic perisinusoidal space following partial hepatectomy,
Authors: Parks Harold F.
Published: February 2005

The early sequelae of partial hepatectomy were studied at the ultrastructural level in livers of CFW mice that had been maintained on a normal diet or fed a fat‐free diet for four days prior to surgery. Normal‐diet animals showed a marked increase in number of small osmiophilic lipid granules in hepatocytes and the space of Disse during the first post‐operative hour and at all later intervals studied. This observation generally confirmed similar findings on C3H mice by Trotter ('65), but failed to provide conclusive indications of the source or direction of movement (i.e., from extracellular space into hepatocyte by engulfment, or from hepatocyte to extracellular space by secretion) of the granules in the space of Disse. In livers of fat‐free‐diet animals, where small lipid granules synthesized in the hepatocyte are recognizable by their osmiophobia (being derived from lipogenesis they are relatively highly saturated), synthesis and secretion by hepatocytes accounted for substantially all lipid granules appearing in the space of Disse during the first three postoperative hours and continued to occur during the fourth hour. This finding demonstrates the importance of the liver cell as a source of lipid granules (presumably very low density lipoproteins) appearing in the space of Disse after hepatectomy. Osmiophilic granules presumed to be of enteric origin, which were present in the space of Disse in very small numbers during the first post‐operative hours, increased in number during the fourth hour. The exact fate of these granules and their importance, if any, in the “post‐hepatectomy picture” could not be determined from available data.
Blood vessels and tissue space associated with the brain of the rat
Authors: Frederickson Richard G. , Low Frank N.
Published: February 2005

Tissues from adult Sprague‐Dawley rats fixed by perfusion with buffered aldehydes for a combined study of the vascular system of the brain are described in light and electron microscopy. In these preparations lack of shrinkage prevents the formation of perineuronal and perivascular spaces. However, connective tissue stains indicate restricted tissue space along the course of small arteries and veins. In fine structure this space is found within the walls of the vessels. It consists of a tubular extension of tissue space bounded inwardly by the endothelial boundary (basement) membrane and outwardly by the neural boundary membrane. Between these boundaries the formed elements of the media and the adventitia are found. The media consists of a thin layer of smooth muscle cells; each cells being enclosed in its own boundary membrane. The adventitia consists of cells and fibrous elements of the connective tissues which are derived, near the surface of the brain, from the intermingling of pial and vascular leptomeninges. This “neural” portion of the tissue space extends from the depths of the capillary bed (where it is obliterated by the fusion of boundary membranes), along the course of the blood vessels, through the subarachnoid space and into the general tissue space of the body.
Electron microscopical study of relaxation and constriction in frog arterioles
Authors: Phelps Patricia C. , Luft John H.
Published: February 2005

Mesenteric arterioles of frogs were selected under a dissecting microscope and compact vasoconstriction was induced by local application of a microdrop of epinephrine. Selected arterioles were fixed in situ at maximum constriction by flooding with buffered osmium tetroxide or glutaraldehyde. Fixation was faster than any vasoconstriction initiated by the onset of fixation. The arterioles were embedded in epoxy resin and regions of dilation and constriction were identified optically in the resin block. Ultrathin sections were cut at known levels for examination in the electron microscope. The localized constriction permitted the use of the relaxed, dilated region of the arteriole as a structural control for comparison against the fine structure of the constricted segment of the same arteriole. In constriction there was a dramatic change from the relaxed condition. The endothelial cells assumed a teardrop configuration and their nuclei protruded toward the lumen. The muscle cells and their nuclei became short and thick and demonstrated strongly indented borders, and the elastic membrane assumed a deeply pleated appearance. Both endothelium and smooth muscle cells appeared to adhere tightly to the elastic membrane for they faithfully replicated its convolutions. Bundles of thick (120 Å) and thin (70 Å) filaments were seen in the endothelial cytoplasm. The thick filaments were not contractile although the thin variety may shorten during vasoconstriction.
Ultrastructural and autoradiographic studies of mouse cleavage stages
Authors: Hillman Nina , Tasca Richard J.
Published: February 2005

Studies of cleavage stage mouse embryos are reported, with particular emphasis upon nucleolar fine structural and functional changes. Multiple fibrillar primary nucleoli are present in the early 2‐cell embryo. In late 2‐cell embryos, some of these nucleoli acquire a peripheral zone of granules, while others reticulate, forming nucleoli composed of fibrillo‐granular cortices and fibrillar cores. The nucleoli of early 4‐cell embryos are composed only of fibrils. In the middle of the 4‐cell stage, some of the nucleoli acquire a peripheral granular zone, while others reticulate. The reticulated nucleoli of both the late 2‐cell and 4‐cell embryos can be considered, on the basis of their fine structure, to be definitive nucleoli. Early 8‐cell and morula embryos usually contain only two definitive nucleoli per nucleus. 3H‐5‐uridine‐pulsed embryos contain label localized in the nucleus, particularly over definitive nucleoli. Nucleolar labeling increases at each successive developmental stage. Beginning at the 8‐cell stage, re‐incubation in nonradioactive medium results in a significant decrease in nucleolar labeling and an increase in cytoplasmic labeling suggesting that more ribosomal RNA is transferred from the nucleus to the cytoplasm at the later cleavage stages.
An autoradiographic and morphological investigation of the postnatal development of the pineal body
Authors: Wallace Robert B. , Altman Joseph , Das Gopal D.
Published: February 2005

Cell proliferation in the pineal body of the hooded rat was studied with thymidine‐H3 autoradiography. Animals were either injected at birth and allowed to survive for variable periods or were injected at different ages and allowed to survive for a fixed period. Cell proliferation was high in the neonate (one and six hours of age) and continued at a decreasing rate into adulthood. The final development of the pineal body was believed to be due to cellular hyperplasia in the young animal and cellular hypertrophy in the adult. The morphological evaluation of the autoradiograms indicated that the principal proliferating components were parenchymal cells.
Metaplasia of cartilage into bone – a study by stain historadiography
Authors: Bohatirchuk F. P.
Published: February 2005

Direct redifferentiation of cartilage into bone was studied during callus formation after experimental fractures in rats and rabbits, the combined techniques of histology and x‐rays (stain historadiography) being used. It was showed that in addition to the known osteoblastic bone formation a metaplastic type of bone formation also exists. In this process chondrocytes presumably redifferentiate into osteocytes.
Ultrastructural properties of primary olfactory neurons in fish (Lota lota L.)
Authors: Gemne Gösta , Døving Kjell B.
Published: February 2005

Qualitative and quantitative aspects of the normal fine morphology of the olfactory receptor cells. their cilia, axons, and neighboring cells, were investigated in the burbot. The receptor cells lacked olfactory tubercles and microvilli; they were isolated from each other by supporting and basal cells. The role of cilia and microvilli in chemoreception was discussed. Zonulae occludentes between the epithelial cells sealed off the interior of the olfactory mucosa of this fresh water animal from an environment with low osmotic activity. The number of receptor cells was estimated to be about 73 per 1,000 μ2. Glial cell processes penetrated from the connective tissue, investing small bundles of receptor axons within the epithelium. Formation of the filum olfactorium was described. The average number of axons in the central portion of the olfactory nerve was about 29 per μ2 in areas free of glial cells and connective tissue. The mean diameter of the axons in the nerve proper was 0.136 μ whereas a higher average was found beneath the epithelium. The presence of mitochondria imparted a considerable skewness to the distribution of diameters. The calculated total number of axons in the olfactory nerve corresponded with the number of receptor cells. The convergence of olfactory nerve fibers upon secondary neurons with myelinated axons was estimated to about 1,000:1.
Effects of unilateral ovariectomy on ovulation and cycle length in 4‐ and 5‐day cycling rats
Authors: Peppler Richard D. , Greenwald Gilbert S.
Published: February 2005

Cyclic rats were unilaterally ovariectomized on each day of the estrous cycle and the ovulation rate of the remaining ovary was determined at the next expected ovulation by counting tubal ova.

Holtzman rats, followed for three successive estrous cycles, were classified as 4‐ or 5‐day cyclic animals. Control (i.e., intact) 4‐day animals ovulated (2 ovaries) an average of 9.6 ± 0.6 eggs and 5‐day rats ovulated 10.2 ± 0.2 ova. Estrus was designated as day 1 of the cycle. Unilateral ovariectomy on the morning of days 1 to 3 resulted in doubling the number of ovulations (complete compensatory ovulation) by the next estrus in all rats: an average of 10.5 eggs (N = 78 animals). Four‐day animals did not compensate when semi‐spayed after 8 PM of day 3, whereas, 5‐day aniamls continued to double the number of ovulations until 2 AM of day 4.

Unilateral ovariectomy of rats with previous 5‐day cycles between 8 and 12 AM on day 1 shortened the expected cycle length by one day (60/73 rats). In contrast, only 19.4% of intact 5‐day rats, spontaneously shortened their fourth cycle to four days. This effect of unilateral ovariectomy was only apparent in the cycle in which the operation was performed and was preventable by administration of 0.5 to 2.0 mg of progesterone on day 2. This suggests that unilateral ovariectomy on day 1 may have reduced the level of circulating progesterone enough to facilitate the release of LH one day earlier in the estrous cycle.
Some histological features of avian kidneys
Authors: Johnson Oscar W. , Mugaas John N.
Published: February 2005

The avian kidney is composed of cortical and medullary lobules, with the former surrounding branches of the renal vein. Cortical lobule diameters varied intraspecifically according to level of association with the venous system, and interspecifically were greatest in nonpasserines. All cortical tissue examined contained maculae densae.

Each medullary lobule receives collecting ducts and loops of Henle from several cortical lobules. Such a complex may be viewed as a lobe, and the entire kidney as multilobar. The relative diameter of a medullary lobule appears directly related to the number of cortical units with which it is associated. Distally, most lobules vary from 0.3 to 0.5 mm in diameter, and contain 20 to 30 collecting ducts. The latter fuse dendritically as they traverse a medullary unit, and eventually form ureteral branches which drain directly into the ureter.

Intramedullary organization in passerines involves aggregated thin limbs bounded by collecting ducts which in turn are surrounded by uneven layers of thick limbs. While some nonpasserines approach this pattern, others lack apparent organization of intramedullary elements. The turn of Henle's loop was restricted to the thick limb in all birds examined. Avian and mammalian thick limbs are similar in diameter, but avian thin limbs are typically wider.

Small kidneys have short ureteral branches with primary stems clustered in each kidney division. In larger kidneys, where medullary lobules are often remote from the ureter, ureteral branches are long and not clustered.
Splenic megakaryocytes and circulating platelets in pregnant rats
Authors: Marien G. J. , McFadden K. D.
Published: February 2005

A comparative study of the hemopoietic tissues and blood of non‐pregnant and pregnant rats of graded duration of gestation was undertaken and the results were compared with those obtained on postsplenectomized rats at similar stages of pregnancy. The number of megakaryocytes was determined in representative fields of the liver, spleen and bone marrow. Platelet counts were performed on blood collected from the venae cavae of these rats using a modified Rees‐Ecker technique.

The liver of normal adult animals, pregnant or non‐pregnant, does not reveal megakaryocyte production. Although bone marrow is the most active site of megakaryocytopoiesis in the adult animal there is only a slight numerical increase in megakaryocytes during pregnancy. The most dramatic change occurs in the spleen of the pregnant rats and is reflected by increased splenic weight and increases in red pulp and in the number of platelets circulating in venous blood. Splenectomy of the rat produces an abrupt increase in the number of circualting platelets which is not sustained into the later postoperative period when platelet counts below those of control animals are found. When pregnancy occurs in the later postoperative period, the splenectomized rat develops a trend toward increased platelt counts but these never reach the level obtained in nonsplenectomized pregnant rats.
Activation of pain pathways in animals
Authors: Mahan Parker E. , Anderson Kenneth V.
Published: February 2005

In analyzing the anatomy and physiology of sensory systems it is often necessary that one activate the particular system being studied with appropriate stimulation. In experiments where this is necessary, the stimulation presented should be specific to the sensory system under study. With the pain system, however, this is most difficult since most stimuli that activate pain pathways also activate other pathways such as those that mediate touch and pressure sensations. It is also helpful to have available a stimulation technique that can be used in both acute experiments and long term neurophysiological and behavioral experiments. For investigation of the anatomical substrates of pain perception, a technique has been developed for implantation of bipolar electrodes in the teeth of cats that permits one to stimulate the tooth pulp in acute or chronic preparations, and, thus, to activate a pain pathway exclusively and directly. This technique provides a stimulus that is readily quantifiable, easily controlled, entirely nociceptive in character, and which can be used in a wide variety of situations.
Denervation of taste buds in the rabbit
Authors: Naga Ibraheim A. , Sakla Francois B. , Girgis Zaiful A. , State Fathy A.
Published: February 2005

Twenty‐five rabbits were used to study the effect of glossopharyngeal nerve transection upon the number, size and cellular constitution of the taste buds. The glossopharyngeal nerve was cut on one side, the other being left undisturbed as a control. The animals were sacrificed in groups of three after 7, 10, 14, 21, and 30 days, and 2 and 4 months after the operation. Seven days after the operation the size and number of intragemmal cells were decreased in the taste buds. The taste pores with hairlets passing through them disappeared. The number of taste buds on circumvallate papillae decreased. After ten days taste buds in both types of papillae showed signs of degeneration. Fourteen days after the operation there was a marked decrease in size and number of taste buds. The circumvallate papillae now possessed no taste buds. After 21 days few taste buds were present in foliate gutters. These consisted of one or two sustentacular cells each. After 30 days there were no taste buds on foliate papillae, and thickness of the epithelium lining the gutters was decreased. Two or four months after denervation, the foliate gutters were shallow and some had become flattened. The importance of the gustatory nerve for development and maintenance of the normal status of the taste buds is discussed.
Electron microscopic observations of the nucleus, glial dome, and meninges of the rat acoustic nerve
Authors: Ross Muriel D. , Burkel William
Published: February 2005

The rat acoustic nerve is separated into central and peripheral portions by an astrocytic glial dome which is convex peripheralward. The long central portion is of typical central nervous system structure with narrow extracellular space (100–200 Å in width), oligodendrocytes and astrocytes. The glial dome is penetrated by acoustic nerve fibers at a node of Ranvier; the basal lamina of the astrocytes is reflected back over the peripheral Schwann cells at this site. Centrally, the myelin is thinner than peripherally.

Acoustic nerve neurons, ranging in size from 25–60 μ, occur in the central portion of the nerve and may be divided into two groups based upon size and density of organelles: large and medium‐sized. All the neurons possess an eccentric nucleus and a peripheral clear zone in the perikaryon beneath which Nissl substance is aggregated, but the medium‐sized neurons have fewer organelles than the large cells. Dendrites and axons are similar in ultrastructure.

While collagenous fibrils, fibroblasts, Schwann cells and extensive extracellular space occur in the peripheral portion of the nerve, no structure corresponding to perineurium or epineurium exists. Instead, dura mater surrounds the acoustic nerve within the modiolus and the pia mater encloses bundles of nerve fibers up to the modiolar foramina where it is reflected back as arachnoid mater. Nerve fibers traversing the modiolar foramina are devoid of a meningeal or perineurial covering; this condition also prevails in the osseous spiral lamina, although wisps of pia‐like cells enclose groups of ganglion cells and nerve fibers in the spiral tract. These findings may help to explain acoustic nerve involvement in pathological processes such as meningitis and encephalitis.
The morphogenesis of the lateral nasal wall in the early prenatal life of man
Authors: Vidić Branislav
Published: February 2005

To study the fetal morphogenesis of the lateral nasal wall and nasal conchae as well as the initial development of the paranasal sinuses, 15 specimens were investigated. Their crown‐rump lengths ranged from 25 to 263 mm. The specimens were fixed in Bouin's solution. Serial sections were stained with hematoxylin and eosin, and Mallory's trichrome stain. The objectives were to ascertain the time and course of development of: (1) ossification in the maxilla and palate, (2) formation of the nasal capsule and the conchae, (3) chondrification and ossification in the nasal capsule and conchae, (4) the maxillary sinus and ethmoidal cells, and (5) glands in the respiratory mucosa. The earliest appearance of the conchae was observed in a 25 mm CR fetus. In a 32 mm CR fetus, ossification in the maxilla and palate was begun and the first maxillary sinus primordium was observed. The glands associated with the maxillary sinus and the inferior concha developed in a 49 mm and in a 90 mm CR fetus, respectively. The ethmoid and three conchae started to ossify in a 160 mm CR fetus. It was concluded that the transformation of mesenchyme into the bony skeleton was accomplished in a 263 mm CR fetus. Both groups of paranasal sinuses and the respiratory glands in the 263 mm CR fetus were morphologically well differentiated. In addition to an extensive survey of the literature, the possible role of the mucosal glands in development of the paranasal system was discussed.
The development of the chorio‐allantoic placenta of the African scaly‐tailed squirrels (family Anomaluridae)
Authors: Luckett W. Patrick
Published: February 2005

The affinities of the isolated rodent family Anomaluridae are unknown. Both sciuromorphous and specialized features characterize its placental morphology. A shallow preplacenta consists of inner cytotrophoblastic and outer syncytiotrophoblastic layers. The early chorio‐allantoic placenta consists of the following zones: a hemochorial zone of interconnected trabeculae, lined with outer syncytiotrophoblastic and inner cytotrophoblastic layers; anchoring trabeculae attached to a zone of decidual giant cells, with the giant cells gradually disappearing in later stages; a zone of acidophilic, PAS‐positive necrotic material underlying the giant cells; and a zone of decidua basalis underlying the necrotic zone and probably contributing to it. An allantoic vesicle lies on the surface of the early placenta; it is reduced in later stages. The bilaminar omphalopleure persists, and it is attached to the margins of the placental disc. The fetal membranes of Anomalurus are most similar to those of sciuromorphs, Pedetes and Ctenodactylus; this may be the result of primitive retentions.
Anchor filament bundles in embryonic skin: Origin and termination
Authors: Kischer C. W. , Keeter J. S.
Published: February 2005

During development and maturation of skin and its derivatives, bundles of extracellular filamentous elements appear, which traverse a cross section of dorsal skin from deep mesenchyme to the basal lamina of the dermo‐epidermal junction. Observations on freshly fixed tissue and on pieces of skin grown in culture for three to five days, especially in areas where the presence of anchor filaments could be predicted, indicate that the filaments most likely originate from fibroblasts which are usually located in a stratified layer of the deeper mesenchyme. The distal end, or termination, appears to be the basal lamina into which the anchor filament blends and is dispersed.

The anchor bundles are composed of long thin filaments in close aggregation and they demonstrate cross‐striations separated by approximately 400 Å in the midportions, and up to 600 Å near their origin and termination. The diameters of the bundles average approximately 0.33 μ at their thickest part. However, at or near their origin, they measure 0.2 μ or less in diameter.

The analogy of the filaments to a growing tree is suggested in that, the roots, or origins of the filaments are thin, tortuous and in many cases widely separated. In certain areas they converge into one main trunk which tapers toward their termination in the basal lamina. The observations also suggest that some bundles may have several roots or rootlets, while others have only one or two.

Although collagen is often seen close to the bundles, the data indicate that the latter are distinct from, and not derived from collagen.
Protein absorption by the guinea pig chorioallantoic placenta
Authors: King Barry F. , Enders Allen C.
Published: February 2005

Previous experiments have suggested that the guinea pig chorio‐allantoic placenta is a barrier to the maternal‐fetal passage of proteins. The means by which the placenta exercises this barrier function were investigated by electron microscopy after injection of peroxidase, ferritin, and Thorotrast. Uptake of protein was by coated vesicles which formed at the trophoblast surface, pinched off, and migrated deeper into the cytoplasm. Some vesicles emptied into multivesicular bodies; others migrated across the trophoblast, emptying their content into the underlying compartment. Peroxidase and ferritin were observed in basement membranes within 10–20 minutes after injection. At longer intervals, the proteins were increasingly difficult to demonstrate in basement membranes, although increased amounts were present in the trophoblast. Neither the basement membranes nor the fetal capillary endothelium constituted an effective barrier to proteins which crossed the trophoblast. The results suggest that the trophoblast is the major barrier to maternal‐fetal protein transfer across the labyrinth. The trophoblast appears to exercise this barrier function by (a) having a low rate of protein absorption and (b) having multivesicular bodies and lysosomes which sequester and possibly degrade absorbed proteins. However, the trophoblast is not a complete barrier to the passage of these exogenous proteins which may indicate a normal, albeit minor, pathway of maternal‐fetal protein transport.
The fine structure of developing cartilage in the chick embryo
Authors: Olson Mark D. , Low Frank N.
Published: February 2005

The fine structure of developing cartilage is described in the area of the future vertebral bodies in the cervical region of chick embryos. Incubation ages range from 36 hours, when the sclerotome of the somite begins to break up, to the thirteenth day. In the 36‐ to 72‐hour interval cells of the sclerotome become free and assume stellate form. Polyribosomes nearly fill the largely undifferentiated cytoplasm. Microfibrils and amorphous material appear in the connective tissue space

The extent of the connective tissue space is determined by boundary (basement) membranes; externally by those of epithelium facing the geometric exterior of the organism and internally by those of endothelium, mesothelium, muscle, nerve and fat. The true contents of the connective tissue space are the connective tissues. As used in this paper “connective tissue space” refers to the extracellular portion, in which the fibrous and amorphous components exist.

by the end of the third day. From the fourth through the sixth day both cellular contours and contents suggest fibroblasts. Microfibrillar diameter increases from 50 to 150 Å. Periodicity does not occur. Matrix granules appear and establish contact with microfibrils. From the eighth through the eleventh day the predominating cell types are chondroblasts and chondrocytes whose fine structure is typical. Microfibrils become more numerous and matrix granules larger. During days 11 through 13, chondrocytes show degenerative changes including lucid areas of nucleoplasm and cytoplasm with fragmentation of endoplasmic reticulum. Microfibrils and matrix granules are heavily concentrated in the connective tissue space and lucent osteoid appears.
Blood supply of human fetal teeth
Authors: Tobin Charles E.
Published: February 2005

Injection studies were made of the blood vessels of developing human teeth, using 114 unfixed aborted fetuses and new‐born infants ranging in gestation age from three through nine months. These specimens were injected with India ink‐formalin, Micropaque‐formalin, Microfil, or vinyl acetate solutions via the umbilical vessels; in cases where an autopsy had been performed, injection was made through the carotid artery. After further fixation by immersion in 10% neutral formalin, the head was bisected in the sagittal plane. One half was dissected and tissue obtained for microscopic study; the other half was radiographed, dissected or dehydrated and cleared. These techniques revealed that the plexus of vessels which surrounds the developing dental organs is derived mainly from the inferior alveolar and palatine arteries, respectively. However, branches from vessels in adjacent tissues also supplied this plexus. The teeth growing most rapidly, and which usually erupt the earliest, receive the largest blood supply.

Odontoblasts were supplied by vessels which course through the dental pulp to their deeper surface. The ameloblasts were adjacent to vessels in the capillary plexus on the outer surface of the enamel organ. A venous sinus was located at the base of the dental organ.
Effects of a bacterial vaccine on the marginal zone of the spleen
Authors: Clark Junius M. , Weiss Leon
Published: February 2005

The effect of systemic administration of a typhoid vaccine (T.A.B.) on the marginal zone of rat spleen has been investigated by light and electron microscopy. This bacterial preparation damages granulocytes in the circulating and marginated pools and the damaged cells are sequestered in the spleen, particularly in the marginal zone. The activities of the vaccine are attributed to its endotoxic properties. Terminations of arterial vessels in the marginal zone are also described.
Cell replication of mesenchymal elements in adult tissues. II. Replication of smooth muscle cells in the colonic muscularis externa of adult rabbits
Authors: Kaye Gordon I. , Siegel Linda F. , Pascal Robert R.
Published: February 2005

Autoradiographic determination of the number and distribution of replicating cells in the colonic muscularis externa of adult rabbits was carried out, using animals sacrificed between 11 minutes and 14 days after a single‐dose‐pulse of 3H‐thymidine; or using animals sacrificed between two hours and 21 days after a multiple‐dose‐pulse of 3H‐thymidine. Labeling of smooth muscle cells was seen as early as 11 minutes after injection. By two hours after a multiple‐dose‐pulse more than 0.3% of the cells of the colonic muscularis externa were heavily labeled. Both the number of labeled cells and the number of labeled pairs, triplets and nests of cells increased with time after injection of 3H‐thymidine. There was a very regular reduction in grain count per nucleus during the 21 day period. No regular migration away from the site of division was observed.

This tissue, like the tunica media of blood vessels and the panniculus adiposus, exhibits independent replication and no migration. The colonic muscularis externa can be classified as a slowly renewing population.
Ultrastructure of the corpus luteum of the white‐tailed deer during pregnancy
Authors: Sinha Akhouri A. , Seal Ulysses S. , Doe Richard P.
Published: February 2005

The fine structure of corpora lutea from 14 white‐tailed deer was studied from early through near‐term pregnancy. The corpora contained both thecal and granulosal lutein cells. The small, elongate and cylindrical thecal lutein cells contained many lipid droplets, juxtanuclear Golgi elements, abundant agranular endoplasmic reticulum, and other cytoplasmic organelles. These cells were observed throughout pregnancy. Some of the thecal lutein cells became modified during early to midpregnancy. The modified thecal lutein cells possessed many lipid droplets, several lysosomes, packets of PAS‐positive glycogen granules, and numerous small membranous whorls of agranular endoplasmic reticulum. The granulosal lutein cells had highly folded and/or ruffled plasma membranes, abundant tortuous tubular and cisternal agranular endoplasmic reticulum, numerous rod‐shaped to round mitochondria with tubular and lamellar cristae, Golgi elements, and a few packets of granular endoplasmic reticulum. Many granulosal lutein cells became modified during mid‐ to near‐term pregnancy by the addition of numerous small membrane‐bound osmiophilic droplets and variable numbers of large nonmembrane‐bound lipid droplets. The granulosal and thecal lutein cells appeared more active in steroid biosynthesis than the modified granulosal and thecal lutein cells.
The fine structural localization of acetylcholinesterase activity in the rat parotid and sublingual glands
Authors: Bogart Bruce Ian
Published: February 2005

The fine structural localization of acetylcholinesterase activity was studied in the rat parotid and sublingual glands. In both glands, reaction product was found in association with the axolemmae of stromal axons invested by Schwann cells and between the contact with effector cells. In the sublingual gland, reaction product was also found in association with surface vesicles and pits and the rough endoplasmic reticulum of myoepithelial cells.
Autoradioraphic studies on 14C‐leucine incorporation into motor neurons of the spinal cord of X‐irradiated mice
Authors: Olkowski Zbigniew
Published: February 2005

The incorporation of 14C‐leucine into the cytoplasm and nuclei of the motor neurons in the spinal cords of control mice and of mice given total‐body X‐irradiation was studied with the use of autoradiography. A decrease in isotope incorporation into the cell cytoplasm of the motor neurons in the spinal cords of irradiated mice was observed. The incorporation of 14C‐leucine into the nuclei of the motor neurons of spinal cords of irradiated animals was increased significantly as compared to the appropriate control values.
Influence of some endocrine glands, hormones and blinding on the histology and porphyrins of the Harderian glands of golden hamsters
Authors: Hoffman Roger A.
Published: February 2005

Harderian glands of female or castrated male hamsters contained scattered luminal pigment deposits and a single cell type. Two cell types were found in the glands from intact males. Glands from both male and female animals showed abundant cytoplasmic lipids. Pigment formation appeared to be endogenous and in some cases occurred by extrusion of cells from alveolar walls and their subsequent transformation. Holocrine secretion was demonstrable. Porphyrin concentrations in the glands from females were increased three weeks after bilateral blinding and decreased following hypophysectomy, ablation of one Harderian gland, unilateral blinding, treatment with thiourea or exposure to an environmental temperature of 8°C. Ovariectomy or ovariectomy plus treatment with 17‐α‐estradiol for three weeks had no effect on the Harderian glands nor did pinealectomy. Porphyrin concentrations in the glands from male hamsters were extremely low. Castration increased these concentrations over 100‐fold and modified the morphology toward that of the female while testosterone proprionate treatment prevented these changes. Administration of H3‐thymidine and subsequent radioautography revealed a peak in mitotic activity between 9:30 PM and 12:30 AM at the end of the light period or the beginning of the dark period. Longterm blinded or blinded, castrated males had Harderian glands which were microscopically “lacelike” due to intense steatogenesis.
Collagen distribution in the rat demonstrated by a specific anti‐collagen antiserum
Authors: Engel M. B. , Catchpole H. R.
Published: February 2005

A specific anti‐collagen antiserum was prepared in rabbits using as antigen a rat tail collagen preparation free of serum protein reactants. This antiserum reacted with several forms of isolated collagen and with rat urine, but not with rat serum. It was coupled to fluorescein and used to label sites of collagen in frozen and dried cryostat sections of rat tissues. The indirect method, with uncoupled serum, was also used routinely.

Tubular and glomerular basement membranes, Bowman's capsule, basement membrane of skin and lung, reticular fibers of spleen and the connective tissue framework of muscle were strongly stained, as was also new bone on trabecular borders and around osteocytes.

The supporting fibers of normal hyaline cartilage, calcified bone, most tendons and the deeper fibers of skin were less stained or unstained under identical conditions and are presumably masked or blocked in situ.

Cytoplasm or cytoplasmic processes in some fibroblasts of skin and tendon, cytoplasm of osteocytes and some cartilage cells in elastic cartilage were stained.

Reaction and masking in fibers are presumably related to the modes of collagen linkage both within the fiber and externally with the ground substance matrix. Activity could be elicited in tendon by a brief heating at 60°C sufficiently to abolish the collagen birefringence. These collagen linkages are believed to be of importance in determining its behavior in overall processes of tissue disaggregation.
The fine structure of progressive stages of myocardial mitosis in chick embryos
Authors: Hay Don A. , Low Frank N.
Published: February 2005

The fine structure of mitosis in myocardial cells possessing myofibrils from embryonic chick hearts (4.5–6 days incubation age) is described. In these cells during prophase, chromosomes appear, but the nuclear membrane, Golgi complexes, and Z bands mostly disappear. In metaphase, lipid droplets and large quantities of membranous cisternae localize around the centrioles, while sarcomeric lengths of myofibrils (largely without Z bands) are found disoriented in the periphery, mainly in the polar zones. In anaphase the cisternae collect near the chromosomes, as reconstruction of the nuclear membrane commences. An intact nuclear envelope and well‐formed Golgi complexes characterize telophase, but Z bands still are not present. During all of the mitotic stages, junctional complexes between dividing cells and adjacent resting cells persist.
The permeability of the guinea pig parietal yolk sac placenta to peroxidase and ferritin
Authors: King Barry F.
Published: February 2005

The permeability of the guinea pig parietal yolk sac placenta late in gestation was investigated by means of electron microscopy using the tracer proteins ferritin and peroxidase. The parietal yolk sac consists of a layer of trophoblast, a thick extracellular lamina (Reichert's membrane) and a layer of endoderm. After injection into the maternal vascular system, the proteins crossed the trophoblast by means of small pinocytotic vesicles. Both proteins readily permeated Reichert's membrane and then moved by an intercellular pathway between endoderm cells to reach the uterine lumen. After injection of ferritin into the uterine lumen, the protein was observed between endoderm cells and throughout Reichert's membrane. Presumably the marked permeability of the endodermal epithelium to the tracer molecules is due to the absence of zonulae occludentes around the endoderm cells. Parietal endoderm cells exhibited limited pinocytotic activity regardless of the site of injection. The results indicate that the parietal yolk sac placenta of the guinea pig is permeable to relatively large molecules and therefore it may be an important pathway in overall maternal‐fetal exchange in this species.
Cellular growth in hypophysectomized or diabetic adult rats during protein repletion
Authors: Leathem James H. , Koishi Hideo
Published: February 2005

The influence of hypophysectomy or alloxan diabetes on the capacity of the adult male rat to replete organ protein composition was studied. Adult male rats that were fed a protein‐free diet for 30 days exhibited a loss of protein in the liver, kidney, gastrocnemius muscle and heart and of RNA. Total DNA and cell size (P/DNA) changes varied with the organ studied. Hypophysectomy followed by protein refeeding moderated the increase in liver protein and cell size and prevented the increase in RNA observed in normal rats. Diabetes had no effect on liver repletion. Hypophysectomy completely prevented the normal increase in kidney mass, total protein and cell size associated with refeeding, whereas diabetes moderated only the cell size increase. Diabetes effectively blocked the anticipated increase in protein synthesis in the gastrocnemius muscle associated with refeeding, whereas hypophysectomy was followed by an increase in total muscle protein. Repletion of the heart was prevented by hypophy‐sectomy but not by diabetes in which an increase in total protein and in cell size occurred. Neither endocrine deficiency prevented a gain in body weight nor in nitrogen retained but distribution of the retained amino acids was markedly modified. Thus organ responses to endocrine deficiencies are influenced by body protein reserves.