bluuebunny/crossref_metadata_2025_split huggingface dataset:
Structural changes in the murine yolk sac during gestation: Cytochemical and electron microscope observations
Authors: Calarco Patricia G. , Moyer Frank H. 
Published: February 2005

AbstractSpecimens of murine yolk sac prepared for light and electron microscopy at 8, 12, and 18 days of gestational age revealed a changing morphology of the endodermal cells in the visceral layer as gestation progressed. Basophilia increased between 8 and 12 days and decreased slightly between 12 and 18 days. These changes corresponded to the development of a highly organized rough‐surfaced endoplasmic reticulum by 12 days and its partial replacement by smooth‐surfaced elements by 18 days. Staining of frozen sections with tetrazolium dyes revealed a substrate dependent localization of the staining reaction within the cells and suggested an underlying compartmentalization of metabolic activities. Two types of apical granules were observed on the basis of both cytochemistry and electron microscopy. These granules were most numerous at 12 days of gestational age. The observations suggest that although synthesis and absorption doubtless occur simultaneously throughout gestation, the emphasis is on synthesis during the first half of the period and absorption during the second half. It is suggested that the change in fine structure may be due to the rupture of Reichert's membrane and the subsequent establishment of direct contact between the endodermal cells and the uterine wall.
Development of the gonads in Channa punctatus bloch (osteichthyes: Channidae)
Authors: Belsare D. K. 
Published: February 2005

AbstractThe history of the germ cells is traced from the time of hatching. The germ cells are larger in size and have faintly staining cytoplasm, clear cell outline and a distinct nucleus. They migrate by ameboid movement to reach the genital ridge and aggregate to lie against the gonadal epithelium prior to the formation of gonads. The germ cells are distributed along the gonad primordia.The period of sex differentiation occurs between the 5.4 mm to 12 mm stage. The testis formation is recognized by the presence of germ cell nests and the sperm duct cord. The formation of the ovary is noted by the enlargement of the germ cells of uniform size and the development of the ovarian cavity.The ovaries are described in four stages ranging from 21 mm to 135 mm fish. At 21 mm stage the ovarian cavity is continuous but is obliterated at 35 mm stage due to the projection of the ovigerous lamellae. The common opening for both the ovaries develops at 35 mm stage. The testes are described in four stages ranging from 23 mm to 135 mm fish. They differentiate more slowly and the first maturation division is seen at 90 mm stage.
Studies on the embryogenesis of Aulocara elliotti (Thomas) (Orthoptera, Acrididae). II. Developmental variability and the effects of maternal age and environment
Authors: van Horn Saralee Neumann 
Published: February 2005

AbstractThe stages of diapause embryos of A. elliotti reared in the laboratory were described, and the lengths of embryos of stage 19 were compared with a second group of diapause embryos of advanced ages. Collections of diapause embryos of the same species were made from wild populations during the autumn and winter of two consecutive years. The stages of embryos present in these samples were found to vary widely. The mean lengths of embryos in stage 19 from different populations were compared and found to differ with statistical significance. The numbers of retarded embryos in different populations were found to vary significantly between populations of diapause embryos. In two populations, mean lengths of embryos of stage 19 were found to differ from one year to the next.Post‐diapause embryos were collected from wild populations in the spring of two consecutive years and their stages described. No significant difference was found in the incidence of retardation in post‐diapause samples. Results of these studies and those of other authors indicate that there may be wide developmental variation between populations of acridid embryos as well as in one population in two different years.Rearing adult A. elliotti in varying numbers under two different environmental conditions was found to produce significant effects upon the rate of development and variability of their embryonic progeny. Embryos laid by young females were found to be more variable, in general, and to develop more slowly than those laid by older females.
Depletions in the cervical and thoracolumbar sympathetic system following removal of neural crest from the embryo of Chelydra serpentina
Authors: Yntema C. L. 
Published: February 2005

AbstractNeural crest and dorsal neural tube of cervical and thoracolumbar levels were removed from embryos of Chelydra serpentina at stages ranging from 8 to 18 somites. Extirpation extended from the levels of the last four somites posteriorly around the neurenteric canal. Deficiencies in sensory and sympathetic ganglia occurred. Motor roots of the associated spinal nerves differentiated. In the absence of postganglionic neurons, the preganglionic fibers form a neuron‐free plexus in the thoracolumbar region. Some observations in the cervical region indicate that the postganglionic neurons depend on preganglionic fibers for their differentiation. The cortex of the adrenal gland formed without related medulla in appropriate experiments.The normal morphology of the sympathetic trunks is illustrated. Superficial and deep cervical sympathetic trunks are described. The latter ascends the neck in a paravertebral position. Along its course are segmental ganglia and rami communicantes; it terminates by joining the medial branch of the superficial sympathetic trunk rostral to the ninth cranial nerve.
Placentation and associated aspects of gestation in the bonnethead shark, Sphyrna tiburo
Authors: Schlernitzauer Donald A. , Gilbert Perry W. 
Published: February 2005

AbstractThe left ovary of the bonnethead shark, Sphyrna tiburo, is rudimentary, and the right ovary supplies both oviducts which share a common ostium situated in the falciform ligament. Preceding ovulation the nidamental gland of each oviduct hypertrophies and the caudal two‐thirds of each oviduct is modified to form a uterus. In the Florida‐Caribbean area Sphyrna tiburo probably mates in March and 3–7 eggs are fertilized in the vicinity of the nidamental gland of each oviduct.The developing embryo is nourished during the first 3–4 months of gestation by yolk stored in its extensive yolk sac. Approximately three and one‐half months after fertilization, the distal portion of the yolk sac becomes convoluted and interdigitates with deep folds in the uterine wall to form a yolk‐sac placenta. As the placenta develops, the maternal uterine epithelium is reduced from columnar cells to squamous cells, and the foetal yolk‐sac epithelium is reduced from columnar and cuboidal cells to squamous cells. Exchange between the maternal and foetal blood systems takes place through maternal endothelium, reduced maternal epithelium, egg‐case membrane, reduced foetal epithelium, and foetal endothelium.
Cardiac glycogen depletion in Amphiuma means during induced anoxia
Authors: Rose Francis L. , Zambernard Joseph 
Published: February 2005

AbstractGiant salamanders, Amphiuma means, measuring 240 to 280 mm from snout to vent, tolerate induced anoxia for six hours. Most of the cardiac glycogen (beta units) is depleted within the first hour of anoxia but a few scattered units remain after six hours. The suggestion that cardiac glycogen is a stand‐by energy source which enhances the energy available to the heart during anoxic strain is reasonable. Beta units are stored in the heart as opposed to the larger alpha units in the liver. The smaller beta units are probably more easily metabolized than the larger alpha units due to their greater surface area per volume ratio and dispersal around the numerous cardiac mitochondria.
Observations on the ultimobranchial gland in small wild and laboratory mammals, with special reference to the histochemical localization of polysaccharides
Authors: Séhe Charles T. 
Published: February 2005

AbstractThis is the last of a series of observations involved in a comparative histological study of the ultimobranchial body in vertebrates. Complete serial longitudinal or transverse paraffin sections were made of formol alcohol, Bouin's, and formalin‐fixed ultimobranchial and thyroid tissues that had been removed from adult specimens of the cat, cotton rat, ground squirrel, Guinea pig, kangaroo rat, bushytailed wood rat, rabbit, and raccoon. The alcian blue‐PAS, aldehyde fuchsin‐alcian blue, mucicarmine, alcian blue‐safranin, Best's carmine, and toluidine blue staining procedures show that the glandular mammalian ultimobranchial tissue is capable of producing considerable amounts of various mucosubstances, particularly the acid mucopolysaccharides, and other carbohydrate‐containing materials. The carbohydrate moiety has been histochemically identified as mucopolysaccharides possessing acidic groups, those having both carboxyl and ester sulfate groups; and as glycogen, muco‐and glycoproteins and other carbohydrate‐protein complexes. The differences in the intensity and localization of a given staining reaction reflect not only individual and species variations but also significant differences in the position of the ultimobranchial tissue in relation to the thyroid gland. An accessory thyroid lobule found near parathyroid IV and thymus IV in a bushy‐tailed wood rat may represent a cystic manifestation of the ultimobranchial body because its follicles varied greatly in size and were lined by a thick stratified squamous epithelium. The possible hormonal mechanisms (TSH, thyroxine) involved in the regulation of ultimobranchial activity are discussed in relation to the gland's production, storage, and release of mucopolysaccharides and other secretory substances.
Tissue dynamics of steady state growth in Hydra littoralis. II. Patterns of tissue movement
Authors: Campbell Richard D. 
Published: February 2005

AbstractIn the column of hydra, tissues continually move away from a region located just underthe whorl of tentacles. Above this subtentacular region, tissues proceed into the hypostome and tentacles; below it tissues pass into the buds or continue down the stalk. These movements represent a steady state pattern of tissue renewal in which column growth is balanced by tissue loss at the body extremities. But the existence of a subtentacular zone in which tissue appears stationary does not necessarily indicate that growth is restrictedto this region, as is commonly stated.The body column of hydra can be viewed as an expanding cylinder whose elongation is balanced by tissue loss at the two ends. In such a body there must be one region from whichtissue appears to emanate, regardless of how growth is distributed along the cylinder. Only the rates at which tissues move will be characteristic of the underlying growthpattern. In Hydra littoralis, the measured rates of tissue movement down the gastric column are consistent with the distributions of mitotic figures, which indicate that growth is spread out along the column.
The microscopic structure of the adult raccoon (Procyon lotor) and woodchuck (Marmota monax) spleens
Authors: Hayes Thomas G. , Eglitis John A. 
Published: February 2005

AbstractHistological serial sections of spleens from the adult raccoon (Procyon lotor) and woodchuck (Marmota monax) were processed for microscopic examination. Observations related to various aspects of the internal vascular pattern in the spleen of the raccoon and woodchuck demonstrated features that were characteristic of the respective animal. The spleen of the raccoon possess well‐developed ellipsoid sheaths, whereas these same structures were not as prominent in the spleen of the woodchuck. The spleen of both mammals examined demonstrated the presence of an anastomosing series of venous sinuses within the red pulp tissue and may be classified as sinusal in nature.
The division and differentiation of Drosophila cystocytes
Authors: Koch Elizabeth A. , Smith Patricia A. , King Robert C. 
Published: February 2005

AbstractLight and electron microscopical studies allow a descriptive account to be given of he morphogenesis of the egg chamber of Drosophila melanogaster. The study demonstrates that the mitotic products of a single cystoblast generate a branching chain of 16 inter‐connected cystocytes. Two specific cystocytes enter meiotic prophase, while the rest become nurse cells. The two pro‐oocytes form synaptinemal complexes in their nuclei. However, one of the two cells later switches back into the nurse cell developmental pathway. The elongation of the synaptinemal complexes is described, and estimates are made of the time involved in their formation. These complexes continue to be synthesized long after the DNA replication which gives the oocyte its 4C DNA content. This finding implies that at least some genetic crossing over follows DNA replication. Evidence is presented that cells undergoing crossing over are most efficient in repairing radiation‐induced chromosomal breaks. Suggestions are given as to the mechanisms by which (1) cell division is inhibited once 16 cystocytes are formed, (2) the future cleavage planes of cystocytes are programmed, (3) the pro‐oocytes are differentiated from nurse cells, and (4) the oocyte is chosen from the twin pro‐oocytes. The contrasting behaviors of the oocyte and nurse cell nucleoli are described. During oogenesis nucleolar synthesis of ribosomal RNAs is suppressed in the oocyte and concurrently stimulated in the nurse cells. It follows that the nurse nuclei are the major sources of the prodigious quantities of ribosomes found in the ooplasm of the mature oocyte.
Mathematical approach to measurements on embryonic chick lens
Authors: Wolpow Edward R. , Marimont Rosalind B. 
Published: February 2005

AbstractProfiles of fresh chick lenses of 5, 8, 11, 14, 17 and 20 days embryological age were photographed and from tracings of these profiles, volumes were calculated using a formula for volume of a solid of revolution. Accurate volumes were also obtained by assuming the lens to be two half oblate spheroids of different minor axis, or, better, two half‐solids of profile (x/a)k + (y/b)k = 1. In addition, the k in this equation described well the curvature of the lens profiles and thus provided a quantitative measure of developing lens shape. Lens diameter, depth and shift of equatorial diameter upon lens axis as a function of age were also studied.
Cytological studies of the ductuli efferentes of the opossum
Authors: Martan J. , Hruban Z. , Slesers A. 
Published: February 2005

AbstractDuctuli efferentes in four examined genera of family Didelphidae are organized into highly convoluted tubules, located within a conical body adjacent to the vascular plexus supplying the testis. They have yellowish‐green color in the adult Didelphis virginiana and grey pink color in other genera. The ductuli efferentes in all examined animals are lined by very low columnar cells, covered by microvilli or booth cilia and microvilli.Histochemical analysis reveals several types of cytoplasmic granules in the genera examined. A single sperical body about 1.5 μ in diameter is found in epithelial cells of the four eyed opossum (genus Philander); this body stains positively for RNA and non‐histone protein, and appears granular under the electron microscope, without a limiting membrane. Abundant cytoplasmic bodies in the Virginia opossum show strong reactions for SH groups; these granules may be responsible for the green color of the ductuli in this species. Ultrastructural studies show that the morphology of membrane limited granules in the ductuli of the examined genera is characteristic for each genus. Abundant pinocytotic vacuoles in the apices of these cells and a strongly positive alkaline phosphatase reaction suggest a marked absorptive activity of epithelial cells.
Functional morphology of the head of the anabantoid teleost fish Helostoma temmincki
Authors: Liem Karel F. 
Published: February 2005

AbstractOsteology, myology and motion analysis of the head of the anabantoid fish Helostoma temmincki, a specialized filter feeder, has revealed six functional units: neurocranium, suspensory apparatus, opercular apparatus, hyoid apparatus, branchial apparatus and pectoral girdle. Interactions between the functional units take place through four couplings involved in opening and protruding the jaws. The first coupling is activated in the beginning of the opening cycle by the levator operculi muscle through the opercular apparatus, interoperculomandibular ligament and mandible. The second is activated during feeding by contraction of the sternohyoideus through the hyoid apparatus, interopercular, interoperculomandibular ligament and mandible. The third coupling is active during feeding and “kissing” by contraction of epaxial muscles through mediation of the neurocranium to the jaw apparatus. The fourth coupling is the only one active during air intake and involves contraction of the levator arcus palatini which abducts and rotates the suspensory apparatus forwards, causing the mandible to drop. The retention of isolated ancestral characters during mosaic evolution are explained in terms of the maintenance of couplings which represent functional associations of seemingly remote structures. When natural selection acts on one component of a functional unit or coupling, it essentially acts on all associated elements simultaneously causing character complexes to evolve in common evolutionary trends. It is feasible that functional analysis can separate primary from secondary evolutionary trends.
Correlation of the development of membranous and bony labyrinths, acoustic ganglia, nerves, and brain centers of the chick embryo
Authors: Knowlton Valerie Y. 
Published: February 2005

AbstractDetailed descriptions are presented of morphogenetic and histogenetic events occurring in the membranous and bony labyrinths, sensory areas, acoustic ganglia, and acoustic centers of the hindbrain of the chick embryo, stages 11 to 45. Major morphogenetic changes occur between stage 11 and stage 30. During this period primordial ganglionic neuroblasts are segregated from the otic epithelium and differentiate into the bipolar neuroblasts of the vestibular and cochlear ganglia, neuroblasts of the alar plate in the acoustic region of the rhombencephalon differentiate, migrate, and are organized into acoustic nuclei, and the otic cup closes to form a vesicle which undergoes complicated structural changes to become a labyrinth. Morphological events in neural structures are closely followed by structural changes in the labyrinth. Minor morphological changes continue to occur through stage 44. The histogenetic period, stage 26 to 38, is the same for all parts of the acoustic apparatus. Minor histogenetic events occur up to hatching. In this period, differentiation of ganglionic and central neurones precedes differentiation of sensory cells.
Studies on the neurosecretory system of Ranatra elongata fabricius (Hemiptera: Nepidae) with reference to the distal fate of NCC I and II
Authors: Dogra G. S. 
Published: February 2005

AbstractWith the help of PF and PAVB bulk‐stained preparations and sections the neurosecretory system of Ranatra elongata has been described. Two medial, each of 9‐10 cells, and two lateral, each of 3‐4 cells, groups of neurosecretory cells have been observed in the protocerebrum. Only the A‐cells have been found to be positive to PAVB histo‐ and cyto‐chemical technique. Axons of the A‐cells after traversing the proto‐ and deuto‐cerebrum emerge from the tritocerebrum as the NCC I. The NCC I after bypassing the corpora cardiaca penetrate the aorta wall. There is no physical continuity between the corpora cardiaca and the NCC I and the two are separable. The NSM from the A‐cells, transported by their nerve fibers, has been observed in the aorta wall. On the basis of large accumulation on NSM in the aorta wall the latter has been considered as the storage‐and‐release organ for the A‐material. Corpora cardiaca are found to be devoid of A‐material. Axons from the B‐cells, after emergence from the tritocerebrum as the NCC II, have been observed to penetrate the corpora cardiaca. On the basis of ample amounts of B‐material the glands have been considered as the storage‐and‐release organ for the B‐material only.Observations are compared with results on related species and it is concluded that two independent organ complexes constitute the neurosecretory systemt of R. elongata. The A‐cells, their pathways, the NCC I, and the aorta wall comprise the first; and the B‐cells, their pathways, the NCC II, and the corpora cardiaca the second. The former is concerned with the elaboration, transportion, storage‐and‐release of the A‐material and the latter with the B‐material. Finally arguments are presented to include the aorta wall in the neurosecretory system.
The structure of the cochlea in chiroptera. III. Microchiroptera: Phyllostomatoidea
Authors: Pye Ade 
Published: February 2005

AbstractThe middle ear and the cochlea have been described in 20 representatives from the superfamily Phyllostomatoidea of the suborder Microchiroptera. Various measurements have been made and the results compared by means of graphs. The ultrasonic pulses used by these bats for echolocation have been recorded and analysed. Generally, the structure of the cochlea does not show extreme modifications as found in some other superfamilies that have previously been discussed.
Electron microscopy of the thymus in two species of snakes, Crotalus atrox and Lampropeltis getulus
Authors: Bockman Dale E. , Winborn William B. 
Published: February 2005

AbstractThe lymphoid cell population of thymus in the rattlesnake and king snake is similar to that of mammals. Lymphocytes occupy the interstices of an epithelial cell framework. An abudance of tonofilaments and desmosomes occupy the cytoplasm of epithelial cells with light, homogeneous nuclei and prominent nucleoli. Other epithelial cells contain phagocytized material in a dense cytoplasm which surrounds an irregular nucleus with heavily clumped chromatin. Small, granular vesicles are found within some epithelial cells.Myoid cells occur in the medullary area. In mature forms, myofibrils are arranged in a concentric fashion around the nucleus and occupy much of the cytoplasmic volume. The presence of developmental stages of these cells suggests their differentiation within the thymus of the adult animal.
Splenomegaly and hemolytic anemia induced in rats by methylcellulose — an electron microscopic study
Authors: Wennberg Emina , Weiss Leon 
Published: February 2005

AbstractParenteral administration of methylcellulose causes massive splenomegaly and hemolytic anemia in rats. The red pulp of the spleen is markedly cellular due mainly to: (1) large numbers of voluminous free macrophages containing methylcellulose‐induced vacuoles, (2) an increase in the number of plasma cells and (3) stasis of blood evidenced by a large number of erythrocytes and platelets in vessels, sinuses and cords. White pulp changes are usually less marked. Here the major change is the presence of macrophages containing methylcellulose‐induced inclusions. The slow circulatory time in the spleen and the increase in macrophages may cause the hemolytic anemia observed in these animals.