bluuebunny/crossref_metadata_2025_split huggingface dataset:
Influence of unilateral ovariectomy on follicular development in cycling rats
Authors: Peppler Richard D. , Greenwald Gilbert S. 
Published: February 2005

AbstractOvarian follicular development was analyzed in intact and unilaterally ovariectomized cyclic rats. Holtzman rats, followed for three successive cycles, were classified as 4‐ or 5‐day animals, with estrus designated as day 1. Intact 4‐ and 5‐day animals were killed on each day of the estrous cycle and one ovary from each animal was saved for histology and examined for normal follicles larger than 352 μ. Cycling rats were unilaterally ovariectomized on day 1 and killed on each of the remaining days of the immediate estrous cycle and day 1 of the next cycle. The follicular population (normal follicles larger than 352 μ) was studied in the remaining ovary.During the estrous cycle of intact rats, there was a gradual increase in the number of follicles with a diameter of 518 to 571 μ and greater; however, the total number of follicles ranging in size from 352 to 571 μ and larger remained relatively constant. At day 5, in the 5‐day cycling rat, the ovaries were depleted of follicles measuring from 395 to 570 μ.Following unilateral ovariectomy on day 1, there was a temporary decrease in the number of follicles larger than 448 μ. This agreed with the finding that animals semi‐spayed on day 1 and injected with 20 I.U. human chorionic gonadotropin on day 2 (PM) did not ovulate, whereas intact animals ovulated an average of seven eggs after the same treatment. The remaining ovary of animals unilaterally ovariectomized on day 1 showed a significant increase by the next estrus in the number of follicles larger than 448 μ.The method of compensatory ovulation in the rat involved doubling the number of large follicles which ultimately matured during the estrous cycle. This resulted from increased proliferation of smaller follicles in the course of the cycle rather than from decreased follicular atresia.
Electron microscopic observations on the morphogenesis of the albino rat lung, with special reference to pulmonary epithelial cells
Authors: O'Hare Karen Hitchcock , Sheridan Michael N. 
Published: February 2005

AbstractElectron microscopic observations of developing albino rat lung provide further evidence for the endodermal origin of the type I and II pulmonary epithelial cells, and for the mesodermal origin of the interstitial pulmonary cells.Cytoplasmic glycogen increased in the fetal endodermal cells from day 16 to the twentieth day of gestation. Further development revealed a decrease of this substance in the differentiating pulmonary epithelial cells, and a concurrent increase in the mesodermal interstitial pulmonary cells, these being cells formerly characterized by their high lipid content. A continuous basement membrane delineated the mesodermal and endodermal components of the developing rat lung from day 16 to the third postnatal day. Tight junctions between adjacent endodermal epithelial cells were present throughout this same gestational period. Lamellar bodies, which are characteristic of the type II pulmonary epithelial cell, may be found simultaneously with large quantities of cytoplasmic glycogen. This feature is considered characteristic of fetal endodermal components.A definite continuum of ultrastructural changes may be traced from the endodermal, columnar epithelial cells to the definitive type I and II pulmonary epithelial cells. Comparable observations for the mesodermal components reveal a progression leading to mature interstitial pulmonary cells.
Ultrastructural aspects of calf submandibular glands
Authors: Shackleford John M. , Wilborn Walter H. 
Published: February 2005

AbstractSubmandibular gland biopsies from four calves were examined by electron microscopy. Most of the parenchyma consists of mucous acini capped by seromucous demilunes. Secretory product of the demilunes reaches the acinar lumen via intercellular canaliculi located between adjacent demilunar cells or by narrow apical extensions of demilunar cells bordering the lumen in common with acinar cells. Intercellular canaliculi are absent between mucous acinar cells, but intercellular space is present at junctions of demilunar cells, acinar cells, and intercalated duct cells. Intercalated ducts are short and connect mucous acini with striated ducts. Striated ducts show more basal infoldings and mitochondria than those of bovine parotid glands. Nuclear bodies are present in most epithelial cell types of the gland but are larger and more easily recognized in nuclei of striated duct cells. Attempts are made to correlate the structure of bovine submandibular glands with its secretion of small amounts of hypotonic saliva relative to the larger volume of isotonic saliva secreted by parotid glands of the same animal.
A comparison of shortening and Z line degradation in post‐mortem bovine, porcine, and rabbit muscle
Authors: Henderson D. W. , Goll Darrel E. , Stromer M. H. 
Published: February 2005

AbstractUltrastructural changes in bovine, porcine, and rabbit muscle have been studied during the first 24 hours post‐mortem. Samples were taken for phase and electron microscopy immediately after death, after 4, 8, and 24 hours of post‐mortem storage at 2° and 37°C, and after 24 hours post‐mortem at 16° and 25°C. The results show that two kinds of structural changes occur in muscle during the first 24 hours post‐mortem: (a) a variable amount of shortening, this shortening occurring via a sliding of filaments in all species and at all post‐mortem storage temperatures examined, and (b) degradation of the Z line, and at higher storage temperatures, of the M line also. Shortening of unrestrained muscle occurs soonest post‐mortem at 37°C in all three species and is completed within four hours post‐mortem in porcine and rabbit muscle and within eight hours post‐mortem in bovine muscle. Post‐mortem short‐ening of unrestrained rabbit and porcine muscle is greatest at 37°C (sarcomere lengths of 1.5 μ); shortening of rabbit muscle is minimal at 2°C (sarcomere lenght of 1.7 μ), but shortening of porcine muscle is minimal at 25°C (sarcomere length of 1.8 μ) and is slightly greater at 2°C (sarcomere length of 1.6 μ) than at 16°C. Post‐mortem shortening of bovine muscle is greatest at 2°C (sarcomere length of 1.3 μ), is minimal at 16–25°C (sarcomere length of 1.8 μ), and increases between 25–37°C (sarcomere length of 1.5 μ at 37°C). Sarcomere length measurements show that some variation occurs in the extent of post‐mortem shortening within the same muscle.Z line degradation occurs sooner post‐mortem and to a greater extent at storage temperatures of 25°C or above than at temperatures of 16°C or below. Also, bovine muscle Z lines are clearly more resistant to post‐mortem degradation than porcine or rabbit muscle Z lines. Loss of fibrillar structure in porcine or rabbit muscle Z lines occurs during the first four hours post‐mortem at 37°C, but eight hours of post‐mortem storage at 37°C are required to cause loss of fibrillar structure of bovine muscle Z lines. After 24 hours at 25 or 37°C, Z lines of rabbit and porcine muscle are usually completely absent; M lines are also frequently absent in this muscle.
Fine structure of the hamster sperm head
Authors: Yanagimachi R. , Noda Y. D. 
Published: February 2005

AbstractThe fine structure of the principal components of the sperm head of the golden hamster (Mesocricetus auratus) is described. The acrosome investing the anterior half of the sperm nucleus comprises two regions, the anteriorly located, enlarged region (acrosome cap) and the posteriorly located, thin region (acrosome collar). The acrosome contains substances which are different in electron density. The less electron‐dense material is present in the anterior part of the acrosome cap. The electron‐dense material is located along the outer acrosome membrane of the posterior part of the acrosome cap and also in the acrosome collar. A cytoplasmic element distributed over the surface of the sperm nucleus is abundant in the regions called perforatorium, subacrosomal ring, and post‐nuclear cap. The perforatorium and subacrosmal ring consist of the densely packed cytoplasmic element invested by the inner acrosome membrane. The post‐nuclear cap is a layer of densely packed cytoplasmic element tightly adhering to the overlying plasma membrane. At the time of sperm death in the epididymis, uterus, and physiological salt solution (Tyrode's) the acrosome cap and plasma membrane tend to undergo drastic degenerative changes. On the other hand, the nucleus, acrosome collar, perforatorium, and post‐nuclear cap remain morphologically unchanged in many spermatozoa during the initial stage of sperm degeneration. Comparisons are made of the structures of the acrosome, perforatorium, and post‐nuclear cap of the hamster spermatozoa with those of other mammalian species.
Morphologic alterations in somatotrophs of the rat adenohypophysis following administration of hypothalamic extracts
Authors: Coates P. W. , Ashby E. A. , Krulich L. , Dhariwal A. P. S. , McCann S. M. 
Published: February 2005

AbstractHypothalamic extracts injected intravenously into rats produced morphologic alterations in somatotrophs of the pars distalis as observed with light and electron microscopy. Histological changes were correlated with pituitary growth hormone content as determined by bioassay by the tibia test in the same tissue samples. Statistical analysis of data derived from fine structure (number of secretory granules/somatotroph profile) was useful as an index of granule storage and release. Increased numbers of secretory granules, hypertrophy of the Golgi complex, and increased granule extrusion which were observed within five minutes after injection of hypothalamic extract supported the concept that growth hormone‐relasing factor in the hypothalamic extract was effective not only in releasing growth hormone but also in stimulating its biosynthesis. Significant increases in both growth hormone content and granule counts agreed with this concept. Extremes of granulation and variable organelle morphology were apparent 15 minutes after injection with hypothalamic extract, although overall granule counts and bioassable growth hormone were within normal limits. By 30 minutes somatotrophs depleted of granules were common, suggesting granule release of major proportion which was consistent with significant decreases in number of granules and growth hormone content. Granules remaining in somatotrophs were aligned peripherally. Vesicular Golgi complexes were prominent. Increased numbers of presumed lysosomes may be related to membrane and/or secretory product accumulation which may result from granule synthesis and release. Somatotrophs from control rats appeared normal.
Prenatal growth in the albino rat: Effects of number, intrauterine position and resorptions
Authors: Barr Mason , Jensh Ronald P. , Brent Robert L. 
Published: February 2005

AbstractData from 103 litters of albino rats were analyzed for the effects of the number of fetuses in the litter and in each uterine horn, resorptions, and intra‐uterine position on variations in fetal weight. The right uterine horn tended to contain more fetuses than the left. There appeared to be systemic control over both the number of fetuses in the litter and their distribution between the horns. The number of fetuses per litter and the number per horn had separate and different effects on fetal weight. The number of fetuses in the horn was a more important determinant of fetal weight than was the number in the litter. Fetal weight was higher and the effect of the number of fetuses in the horn was stronger in horns with early resorptions than in horns without resorptions. Resorptions had no effect on the weight of adjacent fetuses or on fetal weight variation in the horn which suggests that resorptions influence fetal growth systemically rather than locally. Fetal mortality was highest in the lower one‐third of the uterine horn and lowest in the upper one‐third. Fetal weight variation increased as the number of fetuses per horn increased and as mean fetal weight decreased. Intrauterine position was a significant determinant of fetal weight. The heaviest fetuses occupied the middle of the uterine horn while the lightest fetuses were at either end. The importance of these findings in prenatal growth and teratologic studies is discussed.
The early pattern of cardiac innervation in the fetal guinea pig
Authors: Hoar Richard M. , Hall James L. 
Published: February 2005

AbstractEmbryonic hearts were obtained from 78 guinea pig embryos at 20–40 days of gestation. They were frozen quickly, freeze‐dried and prepared by the Falck catecholamine fluorescent method for demonstration of adrenergic fibers. Other hearts were fixed in 10% formalin and examined after silver impregnation with the Holmes technique. The results of the two methods were correlated to visualize the total neural pattern as well as the specific adrenergic elements of the developing hearts.The present study indicates that vagal fibers, accompanied by the primordia of the cardiac ganglia, reach the atrial wall on the twenty‐fifth day of gestation in the guinea pig. They penetrate the wall and are distributed by individual branches throughout the atrial wall from days 26 to 29 inclusive. From day 30 to parturition, the basic pattern of atrial distribution is elaborated by the lengthening, thickening, and branching of individual fibers. Sympathetic fibers pass to the atrial wall from the twenty‐fifth to twenty‐ninth day, those coursing with the vagus nerve arriving on the twenty‐fifth day, while the remaining fibers arrive on the twenty‐sixth to the twenty‐ninth days.A ventricular ground plexus of sympathetic fibers is present just deep to the epicardium on the twenty‐sixth day, and from this point until 30 days of gestation the ground plexus penetrates the ventricular myocardial wall. The sympathetic fibers at first course along the edge of a muscle bundle, but not between muscle fibers. The nerves become thicker at 29 days but do not exceed 2 μ. They branch slightly at 27 days, and at 30 days they are well branched and appear to overlie the surface of the muscle bundles simulating a perimysial plexus. At 40 days a very dense perimysial plexus is visible which contains some fluorescent nerves.Complete autonomic innervation is established by the thirtieth day of gestation.
The satellite cell bud and myoblast in denervated mammalian muscle fibers
Authors: Hess A. , Rosner S. 
Published: February 2005

AbstractSatellite cells, rarely seen on normal muscle fibers, are located between the sarcolemma and the basement membrane of a muscle fiber. Limb muscles and the extraocular muscles of adult guinea pigs were denervated and studied from two to seven days after operation. Satellite cells are now frequently seen. A nucleus surrounded by a small amount of cytoplasm separates from a denervated muscle fiber and forms a satellite cell. A series of clefts and membranes forms in the periphery of the muscle fiber to make separation channels and pinch off the muscle cell nucleus and its cytoplasm from the parent fiber. This cell, now called a satellite cell bud, can be seen in the process of splitting off from the parent muscle fiber, with portions of the same cell separated from and still part of the muscle fiber. The sacs of endoplasmic reticulum in the satellite cell bud dilate markedly. Centrioles and a cilium form in the satellite cell bud. The bud elongates, and concentrations of ribosomes and polyribosomes appear in its cytoplasm. Small points of contact, with membrane thickenings, between bud and parent fiber allow the elongating bud to be kept longitudinally oriented under the basement membrane of its parent fiber. Muscle filaments form in the elongating bud, which is now a myoblast. Hence, satellite cells arise from portions of denervated muscle fibers themselves, elongate, and become myoblasts.
The fate of isologous, homologous and heterologous ferritin molecules in the rat
Authors: Han S. S. , Han I. H. , Johnson A. G. 
Published: February 2005

AbstractThe fate of heterologous, isologous and homologous ferritin‐I125 injected into rat footpads was compared by determination of radioactivity in sera and organs, and by radioautography and electron microscopy. The clearance of heterologous ferritin‐I125 from circulation was significantly faster than that of isologous or homologous ferritin‐I125. This was supported by measurement of radioactivity in various organs, and by radioautography and electron microscopy of popliteal lymph nodes which reveled structural details of macrophages undergoing antigen uptake.These observations permit the following conclusions. (1) In most reticuloendothelial cells there is some nonspecific pinocytosis of antigen which is not related to immunogenicity. (2) The induction of massive immunologically specific pinocytosis by macrophages may be due to specific antigen recognition by receptors located at the cell surface. (3) Heterologous ferritin ingested by macrophages are mostly found in vacuoles or scattered in the ground cytoplasm. However, some appear in the nucleoplasm, usually in association with loose strands of chromatin materials. (4) Ferritin molecules are conspicuously absent from mitochondria, the rough‐surfaced endoplasmic reticulum and Golgi apparatus. (5) The fiber‐associated reticular cells of the primary nodule and germinal centers may correspond to “dendritic reticular cells” or “dendritic macrophages,” capable of long‐term retention of antigens.
Protein absorption and transport by the guinea pig visceral yolk sac placenta
Authors: King Barry F. , Enders Allen C. 
Published: February 2005

AbstractThe cytological basis for protein transport across the guinea pig visceral yolk sac at 36–44 days of gestation was studied by means of electron microscopy following injection of horseradish peroxidase and ferritin. These results were compared with those obtained after administration of colloidal thorium dioxide. Distribution of the tracer molecules was studied at 2, 10, 20, 40, and 160 minutes after injection into the uterine lumen. All three tracer molecules were rapidly absorbed by endoderm cells. Although most of the protein appeared to be retained in droplets in endoderm cells, some protein was transmitted. Peroxidase was found to be rapidly transmitted across the yolk sac, ferritin somewhat more slowly, and colloidal thorium was not transmitted at all. Protein which had exited from the endoderm cells followed any of three pathways: (1) it crossed the visceral basement membrane and entered the vitelline capillaries; (2) it crossed the mesodermal compartment, crossed the mesothelial cells and entered the exocoelomic cavity; or (3) some of the protein was sequestered by macrophages in the splanchnic mesoderm. The pathways observed are consistent with those suggested by previous authors for the passage of maternal antibodies and serum proteins to the guinea pig fetus.
Morphology and cytochemistry of the Golgi apparatus of rat salivary gland acinar cells
Authors: Hand Arthur R. 
Published: February 2005

AbstractThe ultrastructure and cytochemistry of the Golgi apparatus was studied in acinar cells of the parotid and von Ebner's glands of the rat. The Golgi apparatus was composed of four to six stacked cisternae, numerous small vesicles, and condensing vacuoles. The latter appeared to form as dilatations of the innermost Golgi cisterna, and their irregular membrane suggested fusion with or fission of small vesicles. Nucleoside diphosphatase and thiamine pyrophosphatase activities were localized to the inner Golgi cisternae. Acid phosphatase activity was localized to condensing vacuoles, coated vesicles, and an irregular, narrow cisterna found in the internal region of the Golgi apparatus and termed the internal Golgi lamella. The morphology and relationships of the Golgi apparatus indicate that it plays an important role in secretory granule formation. The presence of nucleoside diphosphatase activity may reflect the role of the Golgi apparatus in the addition of carbohydrates to the secretory proteins. It is suggested that the internal Golgi lamella develops from the inner Golgi cisterna after secretory granule formation is completed. Acid phosphatase activity in condensing vacuoles may be a mechanism for lysosomal regulation of the secretory process.
Regeneration of rat submandibular gland following partial extirpation. A light and electron microscopic study
Authors: Hanks C. T. , Chaudhry A. P. 
Published: February 2005

AbstractA wedge of parenchymal tissue was excised from the left submandibular gland of six week old male Sprague‐Dawley rats. The animals were randomly grouped by body weight and killed at intervals of one day to five weeks following the operation. Tissue from and adjacent to the site of injury was removed and prepared for routine light and electron microscopy. Light microscopic findings consisted of degeneration and necrosis of the parenchymal tissue during the first 24 hours, followed by hyperemia and endothelial as well as epithelial proliferation from one to three days. Extensive epithelial proliferation occurred during the next two weeks, followed by regeneration of new lobules, beginning at the periphery of the injured lobes.Ultrastructurally, the new parenchymal tissue appeared to have regenerated from residual duct cells. Dedifferentiated epithelial cells gave rise to two different cell lines: one line which transformed into terminal tubules and acinar cells, and another which became striated ducts. These differentiating cells were organizing into lobules as early as three weeks after the operation. Because of their proximity to cells of regenerating striated ducts as well as intercalated ducts and acini, the myoepithelial cells appeared to be of epithelial origin.
Action of metabolic hormones on the fine structure of rat liver cells. I. Effects of fasting on the ultrastructure of hepatocytes
Authors: Cardell Robert R. 
Published: February 2005

AbstractThis report provides information on the ultrastructure of liver parenchymal cells from rats fasted 2, 15–21, and 21–40 hours. Fasting rats from 2 through 40 hours provokes alterations in the quantity and patterns of glycogen, amounts and forms of the rough endoplasmic reticulum, and the quantity of smooth endoplasmic reticulum in hepatocytes. After two hours of fasting glycogen occurs as clumps of α particles in restricted areas of the cytosome, the smooth endoplasmic reticulum is relatively sparse, and the rough endoplasmic reticulum is displayed as parallel cisternae comprising the characteristic basophilic bodies of the hepatocyte. Fasting the rat for 15 hours and longer decreases the amount of hepatic glycogen which appears predominantly as β particles in restricted regions of the liver cell. The prolonged fast provokes a dramatic proliferation of smooth endoplasmic reticulum in the liver parenchymal cell. The tubules of this organelle are continuous with the cisternae of rough endoplasmic reticulum and extend deep into the glycogen areas of the hepatocyte. Arguments are presented to support the concept that the smooth endoplasmic reticulum develops from rough endoplasmic reticulum and that its membranes provide a site for the location of enzymes involved in glycogen metabolism.