bluuebunny/crossref_metadata_2025_split huggingface dataset:
Argentaffin and other “endocrine” cells of the small intestine in the adult mouse. II. Renewal
Authors: Ferreira M. N. , Leblond C. P. 
Published: February 2005

AbstractArgentaffin and other “endocrine” cells of the gastrointestinal tract were investigated in the mouse jejunum by electron microscopic radio‐autography after administration of 3H‐thymidine either in a single injection or by continuous infusion.One hour after a single injection or after a 24‐hour infusion of 3H‐thymidine, no labeling is seen in the three main types of “endocrine” cells: Type EC (true argentaffin) or biconcave granule cells, Type L or large spherical granule cells, and Type S or small spherical granule cells. Furthermore, no mitosis of these cells may be observed. Hence, they are not capable of division.However, when continuous infusion is prolonged for one and one‐half days, examination of the lower half of the crypts shows labeling in some cells of the three types. The number of granules in these cells is small.By three days, labeled cells of the three types appear in villi, while the number of their granules increases. With time, the percentage of labeled cells rises gradually to reach over 60% after four days and over 80% after six to eight days of continuous infusion.After the infusion is stopped, the number of labeled cells decreases. Thus, eight days after the end of a four‐day infusion less than 10% cells are labeled.It is concluded that the three main types of “endocrine” cells observed in the mouse jejunum arise from unidentified precursors in the lower half of the crypts. They migrate from crypts to villi and are probably extruded from villus tips. Even though the three cell types seem to evolve independently, their turnover time is the same, that is, about four days.
Organ cultures of fetal mouse ovaries. I. Light microscopic structure
Authors: Odor D. Louise , Blandau Richard J. 
Published: February 2005

AbstractOvaries from 16‐day mouse fetuses were cultured as whole organs in a modified Eagle's medium for two through 45 days. In the course of the experiment a single layer of follicular cells resting on a basement membrane surrounded the majority of the surviving oocytes, resulting in unilaminar follicles. A small number lay in multilaminar follicles having two to three layers of follicular cells. No follicles with antra were seen regardless of the length of time in culture. Initiation of zona pellucida formation occurred after three days in culture. In general, the thickness of the zona pellucida was not as great as that around an oocyte of similar size in vivo. Some of the large oocytes attained diameters of 68–73 μ, which is within the normal range for fully grown mouse oocytes in vivo. Only one oocyte in all the cultures examined had a first meiotic metaphase spindle. In many follicles the initial step in degeneration was the migration of macrophages into the follicular epithelium and their attachment to the zona pellucida. The follicular epithelium often was completely replaced by an enclosing layer of macrophages; the oocyte in some such instances still appeared normal. Subsequently, the germinal vesicle became pycnotic and the ooplasm, PAS‐positive. At the end of the degenerative process the zona pellucida appeared as an empty shell with macrophages attached to both its external and internal surfaces.
Gonocytes in fetal guinea pig testes: Phagocytosis of degenerating gonocytes by Sertoli cells
Authors: Black Virginia H. 
Published: February 2005

AbstractIn fetal testes of non‐inbred guinea pigs, virus‐like particles were seen in the primordial germ cells, but not in the somatic cells. Using the particles as a marker for the gonocytes it was possible to trace the phagocytosis of degenerating gonocytes by the Sertoli cells in the fetal testis.
Biochemical, histochemical and ultrastructural studies of thyroid serotonin, parafollicular and follicular cells during development in the dog
Authors: Gershon Michael D. , Belshaw Bruce E. , Nunez Eladio A. 
Published: February 2005

AbstractA study was made of the concentration and cellular localization of serotonin in the thyroid gland of the dog. This species is characterized by a low level of serotonin in the adult thyroid gland. Endogenous serotonin consequently cannot be demonstrated by fluorescence microscopy following treatment of frozen‐dried adult thyroid tissue with formaldehyde vapor. In contrast, the thyroid concentration of serotonin was found to be high, in both beagle and basenji (purebred dogs of European or African origin respectively), around the time of birth. The serotonin concentration then fell rapidly as development of the animals proceeded. This pattern also seemed true of the rabbit. When the concentration of serotonin was high, just prior to birth, a yellow fluorophore, probably the condensation product formed between serotonin and formaldehyde could, as in other species, be demonstrated in parafollicular cells after exposure of tissue to formaldehyde gas. Thyroid follicular cells never showed serotonin but instead, a striking accumulation of autofluorescent apical dense bodies (0.3–1.0 μ in diameter), probably lysosomes, occurred during the first year of life.
The anterior abdominal fat body
Authors: Merklin Robert J. 
Published: February 2005

AbstractThe anterior abdominal fat body is a mixture of multilocular and unilocular fat cells. It is found deep to the rectus sheath and immediately beneath the peritoneum of the anterior abdominal wall. It is first seen in the sixth month fetus as thin lobules of tissue arranged on either side of the umbilical vein but receiving blood supply from specific ensiform branches of the superior epigastric or internal thoracic artery and vein. Continued growth results in a coalescence of the bilateral lobules into a single fat body that completely overgrows the supportive blood vessels. In its cytology this body is comparable to the interscapular fat pad. It is unique in that vascular connections develop between it and the liver and in the fact that in a significant number of specimens it attains proportions that appear to represent pathological hypertrophy.
Brunner's glands of the duckbilled platypus (Ornithorhynchus anatinus)
Authors: Krause William J. 
Published: February 2005

AbstractBrunner's glands in the platypus form a lobulated, glandular collar confined to the submucosa of the most distal portion of the stomach. The glands end immediately proximal to the gastrointestinal junction and excretory ducts empty in the region where the stratified squamous epithelium lining the stomach changes abruptly to the intestinal lining epithelium of the duodenum. An individual gland of Brunner is composed of several elongate lobules drained by intralobular ducts which often join to form a single excretory duct.Light and electron microscopic studies have shown the secretory tubules to be comprised of large, pyramidal cells limited basally by a delicate basal lamina. The ergastoplasm, cisternae of which are dilated and contain amorphous material, is associated with numerous ribosomes. In basal and perinuclear regions intercisternal granules and smooth surfaced vesicles are found. Numerous small vesicles found in supranuclear areas apparently form from the smooth membrane portions of ergastoplasm located adjacent to Golgi complexes. Membrane‐bound amorphous granules of varying electron density occupy the apical cytoplasm and show a tendency to coalesce before emptying their contents into the adjacent lumen.The intralobular duct system is lined initially by a columnar epithelium which changes to a simple squamous form before the ducts combine to form a short excretory duct lined by stratified squamous epithelium. The epithelium lining the duct system contains relatively few organelles but appears to be engaged in a limited amount of synthesis and release of secretory material.Histochemical studies indicate that both the secretory tubules and the duct system elaborate a neutral mucopolysaccharide.
The structure of the pulmonary acinus in a child of six years and eight months
Authors: Boyden Edward A. 
Published: February 2005

AbstractSo far as known this is the first portrayal of the detailed structure of a pulmonary acinus as seen both from within its cavities and from without. Some 200 serial sections (× 50) were traced upon transparent plastic plates and then viewed as translucent objects in packets of ten. This method was supplemented by wax‐plate and graphic reconstructions of the whole and of its parts.The pulmonary acinus is a terminal bronchiole and all its branches. In this example there were three generations of respiratory bronchioles and from two to five generations of alveolar ducts ending in saccules. This acinus had a volume of 15.6 mm3, comparable to a cube measuring 2.5 mm on each side. The two halves (medial and lateral semiacini) interdigitated. Only the lateral, forming 53.4% of the whole, was analyzed in detail. It consisted of a roof having three portions with varying patterns (namely a proximal wing, a distal wing extending to the connective tissue septum, and a rudimentary lateral component); a septal portion resting on the septum and consisting of four pairs of alternating small and large clusters of alveolar ducts, to the lower half of which a cluster of vesicles was appended; and a paired lateral envelope of ducts which in one place communicated with an adjacent acinus, thereby revealing a third mode of collateral ventilation.This acinus, reconstructed over a period of three years, is replete with numerous variations such as dilated atria and saccules, supernumerary structures, recurrent ducts, irregular branches and differing lengths of airways. Thus, it records the “fight for space” in earlier periods of growth. Knowing the pattern of this particular acinus, it has been possible to calculate the rate of diffusion of gases between the terminal bronchiole and the peripheral saccules, and vice versa. Yet the impression persists that no two acini are alike in either proximal or distal portions; therefore, it is questionable whether diffusion of gases in the peripheral airways of the living individual are really subject to precise mathematical measurement.
Fine structural observations on cell death in the epidermis of the external gills of the larval frog, Rana pipiens
Authors: Michaels John E. , Albright John T. , Patt Donald I. 
Published: February 2005

AbstractThe fine structure of the epidermis of the external gills of the larval frog, Rana pipiens, was observed during the period of gill degeneration. Many of the epidermal cells underwent morbid alterations. In typical degenerating epidermal cells the nucleus became irregular in outline, chromatin formed electron‐dense clumps and the nuclear envelope increased in width. Lysosomes became prevalent in the cytoplasm of these cells and progressively larger autophagic vacuoles appeared. As degeneration continued, apical epidermal cells were found embedded deeper within the epidermis. In some instances cell processes from two neighboring epidermal cells extended partially around the relocated degenerating apical epidermal cells probably contributing to their translocation; phagocytosis was completed by a single cell in other instances. The degree of participation of the phagocytic epidermal cells in the degenerative process was uncertain. The distribution of acid phosphatase activity was followed in specimens treated by the Gomori technique. Profiles of cisterna‐like elements, positive for the enzyme, suggested that perhaps entire Golgi cisternae contributed to the formation of autophagic vacuoles in combination with small vesicles. Heterophils and macrophages observed in the degenerating gills were believed to participate in the removal of the dying cells.
The effects of cortisol and BUDR on cellular differentiation in the small intestine in suckling rats
Authors: Clark Sam L. 
Published: February 2005

AbstractIn suckling rats absorptive cells in the distal two‐thirds of the small intestine ingest colloids by pinocytosis. In the middle third of the intestine pinocytosis ceases 17 to 21 days after birth and can be halted prematurely by glucocorticoids. The adrenal cortex is relatively inactive in newborn rats and begins to secrete glucocorticoids two weeks after birth; this secretion has been suspected to cause the termination of pinocytosis.Glucocorticoids do not stop pinocytosis in absorptive cells already present on the villi but induce the renewing population of cells in the crypts to replace the cells on the villi with new ones that do not engage in pinocytosis. Therefore, glucocorticoids act by inducing a new direction of cellular differentiation.BUDR (5‐bromodeoxyuridine) is reported to inhibit cellular differentiation reversibly in vitro. When injected into 8 to 9‐day‐old rats, simultaneously with cortisol, it inhibited the change in cellular differentiation induced by cortisol; that is, pinocytosis continued unabated. BUDR did not appear to be toxic and did not interfere with cellular replacement in the small intestine, as judged autoradio‐graphically.Thus it appears that BUDR inhibits the initiation of cellular differentiation by cortisol but does not interfere with cellular proliferation or the pre‐established program of cellular differentiation that leads to pinocytosis. The mechanism of action of BUDR is still unknown; it is discussed in light of the possibility that BUDR may after cellular differentiation without acting directly on the genome.
Cerebral cortex of the mouse after prenatal chemical insult
Authors: Langman Jan , Shimada Morimi 
Published: February 2005

AbstractThe purpose of this study was to examine whether a short term chemical insult to neuroepithelial cells (the matrix cells of neurons) causes a clearly defined neuronal deficit in the neocortex and hippocampal region. In the first experiment 15‐day pregnant mice were given a single dose of 5‐azacytidine (4 mg/kg); 30–60 minutes later they were injected with tritiated thymidine (6 μc/g). The fetuses were sacrificed at various hours and days after treatment. No cellular abnormalities were observed one or two hours after treatment with 5‐azacytidine, but at three to four hours abnormal mitotic figures became visible at the lumen. Usually the chromosomes were clumped together, forming commaand circle‐shaped structures. Sometimes chromosome breaks were observed. The number of cells with chromosomal abnormalities increased during the following hours, but ten hours after treatment a few normal mitotic figures appeared again. In the meantime the affected cells moved from the lumen toward the cortical plate. Their number gradually decreased and 48 hours after treatment all had disappeared. Since in the controls many labeled cells reached the cortex but in the experimental animals none, a neuronal deficit resulted from the treatment. It was difficult, however, to pinpoint the type of neuron lacking in the brain of the treated newborn. In the second experiment pregnant animals were given several doses of 5‐azacytidine (2 mg/kg on days 13, 14 and 15 of gestation) and sacrificed at various days after birth. The neocortex as well as the hippocampal region of the treated animals contained fewer cells than the same structures in the controls. In addition many neurons both in the cortex and hippocampus were morphologically abnormal. It is thus concluded that single and repeated shortterm chemical insults to neuroepithelial cells during the later stages of fetal life, result in a shortage of neurons and the presence of morphologically abnormal neurons.
“Sternzellen” in the liver: Perisinusoidal cells with special reference to storage of vitamin A
Authors: Wake Kenjiro 
Published: February 2005

AbstractThe “Sternzellen” (von Kupffer, 1876) in the liver of normal animals and of those injected with excess vitamin A were examined with the light and electron microscopes. These cells were stellate perisinusoidal cells located in the space of Disse and were separated from the sinusoidal lumen by the endothelium. Their cytoplasm contained a number of lipid droplets which reacted intensely with gold chloride. These lipid droplets imparted intense vitamin A fluorescence under the fluorescence microscope. Following the administration of excess vitamin A, these lipid droplets increased remarkably. The “Sternzellen” were identical with cells described as “interstitial” or “fat‐storing” cells by others, and were quite different from the so‐called Kupffer cells of the liver reticulo‐endothelial system.
The brain venous system of the dog
Authors: Armstrong L. D. , Horowitz A. 
Published: February 2005

AbstractThe venous system of the canine brain was investigated by gross dissection and by radiographs. The system was divided into four major groups of vessels: cerebral veins, central veins, cerebellar veins, and pontomedullary veins.The dorsal cerebral veins emptied into the dorsal sagittal sinus and the ventral cerebral veins entered the dorsal petrosal or transverse sinus. The internal system of cerebral veins, and the central veins, were drained by the great cerebral vein which entered the straight sinus. Cerebellar and pontomedullary veins flowed mainly to the sigmoid sinus.The venous system of the dog differed from the human configuration in several ways. In the dog the major dorsal cerebral veins entered the dorsal sagittal sinus by independent lacunae in the same direction as the flow of blood. A middle cerebral vein was not present in the dog but was replaced by a continuation of the caudal ventral cerebral vein. There was a basal vein in the dog but its main flow of blood was to the dorsal petrosal sinus; in man, this vein passes to the great cerebral vein. The entire venous system of the brain was plexiform and collateral circulation was prominent. The larger veins were identified radiographically.
The fusion of dorsal and ventral endocardial cushions in the embryonic chick heart: A study in fine structure
Authors: Hay Don A. , Low Frank N. 
Published: February 2005

AbstractFusion of atrioventricular endocardial cushions begins during Hamburger‐Hamilton stage 27 and is completed during stage 28 (5 to 6 days incubation age). Connective tissue cells of these cushions are derived from the proliferating endocardial cell layer. The character of the organelles in cells of these cushions changes progressively as the cushions approach, meet and fuse: granular endoplasmic reticulum accumulates; Golgi complexes become extensive, and nuclei develop irregular shapes. These occur first in the connective tissue cells of the cardiac jelly and later in the endocardial cells. Fusion apparently is accomplished by liberation of the endocardial endothelial cells into the cardiac jelly, where, along with pre‐existing connective tissue cells, they become cells of the membranous interventricular septum. Gradually the cells appear to merge into one morphological population and thus become indistinguishable from each other. Both endocardial cells and connective tissue cells exhibit uptake of tritiated thymidine and undergo mitosis before, during and after fusion of the cushions. An outstanding characteristic of these cells is their continuing vitality throughout the entire process of fusion.
Olfactory and non‐olfactory epithelia in the nasal cavity of the mouse, Peromyscus
Authors: Adams Donald R. 
Published: February 2005

AbstractThe nasal cavities of 14 deer mice, Peromyscus maniculatus, were examined histologically to determine the variability in surface area of the olfactory epithelium and its correlation with nasal cavity volume, area of non‐olfactory epithelial surface, and body size.Forty‐four per cent of the nasal cavity surface of P. maniculatus is covered by a non‐olfactory epithelium with an area of 129.8 mm2; the epithelial surface consists of gradations in type from keratinized stratified squamous rostrally to ciliated pseudostratified columnar caudally. An extensive portion of this epithelium is non‐ciliated and devoid of goblet cells. Situated dorsocaudal to the non‐olfactory epithelium is the olfactory epithelial surface measuring 166.8 mm2 in area.The areas of total, non‐olfactory and olfactory epithelial surfaces are highly variable in a sample of mice containing two subspecies, both sexes and various ages. Surface area measurements of non‐olfactory and olfactory epithelia are correlated significantly with body length, body weight and volume of the nasal cavity. A relatively constant epithelial area to volume ratio is present in the nasal cavity of P. maniculatus. It is surmised that a stable ratio of molecules in the air to epithelial area may occur within a species.
Morphology of adipose cells in lambs at birth and during subsequent transition of brown to white adipose tissue in cold and in warm conditions
Authors: Gemmell R. T. , Bell A. W. , Alexander G. 
Published: February 2005

AbstractLight and electron microscopy were used to study the morphology of adipose cells in newborn Merino lambs (Ovis aries). Postnatal changes in morphology were also examined in naturally fed Merino lambs held at 26°C or at 3°C for up to 32 days from the time of birth, and in lambs fasted for up to three days at 26°C or at 3°C since birth.All adipose cells examined in the newborn lambs showed the morphological characteristics of brown adipose cells; no white adipose cells could be found. The brown adipose tissue in normally fed lambs was replaced progressively by white adipose tissue during the first two or three weeks of life, and this replacement was retarded in the lambs held at 3°C. During replacement a continuous spectrum of cells with morphological characteristics between those of brown and white adipose cells were seen. No degenerating brown adipose cells were observed; and, apart from brown adipose cells, no cells were identified that could have been precursors of white adipose cells. This evidence suggests that in various body regions of lambs white adipose cells are derived from brown adipose cells.Lambs fasted at 3°C or under conditions that approached thermoneutrality (26°C) showed rapid depletion of lipid from brown adipose cells; hence brown adipose tissue of the lamb differs from that in the newborn rabbit in which this tissue is not readily depleted of fat during starvation under thermoneutral conditions.
Adrenergic innervation in ovaries of the rat and guinea pig
Authors: Burden Hubert W. 
Published: February 2005

AbstractThe ovarian adrenergic innervation of rats and guinea pigs was studied using a fluorescent technique. In both species, catecholamine‐containing nerves entered the ovary via hilar perivascular plexuses and extended into adjacent medullary and cortical tissue. The interstitial gland of the rat ovary was well innervated; however, cortical components of the ovary in this species, including corpora lutea and developing and mature follicles, were sparsely innervated. The interstitial gland and theca folliculi of developing and mature guinea pig follicles contained a dense network of beaded preterminal nerves. It is suggested that ovarian adrenergic nerves facilitate ovulation, either directly by stimulating perifollicular smooth muscle to contract or indirectly by influencing the steroid output of the interstitial gland.