ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
Filter
  • Inorganic Chemistry  (2,625)
  • Animals  (1,449)
  • Magnetism  (807)
  • Biochemistry and Biotechnology
  • Cell & Developmental Biology
  • EARTH RESOURCES AND REMOTE SENSING
  • Engineering
  • Life and Medical Sciences
  • 2010-2014  (2,258)
  • 1980-1984
  • 1970-1974
  • 1945-1949  (322)
  • 1930-1934  (1,712)
  • 1925-1929  (884)
  • 1920-1924
  • 2013  (2,258)
  • 1994
  • 1949  (322)
  • 1934  (828)
  • 1930  (884)
  • 1926  (884)
Collection
Years
  • 2010-2014  (2,258)
  • 1980-1984
  • 1970-1974
  • 1945-1949  (322)
  • 1930-1934  (1,712)
  • +
Year
  • 1
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The blood of Perophora viridis is found to contain six types of cells: (1) Green cells, which have green-colored fatty bodies embedded in clear cytoplasm. (2) Orange cells, with orange-colored bodies of unknown composition in the cytoplasm. (3) Colorless berry-like cells, with fluid-filled vesicles in the cytoplasm. (4) Granular amoeboid cells. (5) Compartmental amoeboid cells, which have box-like vacuoles containing brownian granules of a fatty substance. (6) Vesicular, signet-ring type of cell having a single large vacuole. The cytological structure of these cells and their reaction to various dyes are described.An effort has been made to homologize the types of cells found in the blood of other ascidians with those found in Perophora.It is concluded that the variety of colors found in the cells of ascidian blood is due to the varying chemical states of the vanadium-containing chromogen present in the cells.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 2
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 42 (1926) 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 3
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 42 (1926), S. 111-141 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Disintegration in killing agents was studied throughout development. In the unfertilized egg and cleavage stages the death gradient runs from animal to vegetal pole. In the late blastula stage the future dorsal surface and future point of gastrulation show heightened susceptibility. The gastrula has a gradient from anterior to posterior end along its dorsal surface, with a slight reverse gradient around the blastopore; lateral and ventral regions are least susceptible.Before and after the appearance of the neural groove, the dorsal surface shows increased susceptibility with gradient in it from anterior to posterior end. The neural tube is highly susceptible, with a death gradient from anterior to posterior end and a slight reverse gradient at its posterior end.During late stages and in the larva the double gradient is present; death begins at the two ends and progresses backward from head, forward from anus; from the former most rapidly. The least susceptible place is near the posterior end. The posterior reverse gradient is less developed in the lamprey than in other vertebrate embryos, due, probably, to its lack of a tail bud.Assuming that death differences indicate differences in rate of activity, it appears that such differences in activity may be causes and not results of developmental processes, for the development of certain parts (dorsal surface, blastopore, central nervous system) is indicated by heightened activity before it is evident morphologically.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 4
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 42 (1926), S. 83-109 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The summary of this paper is as follows:1A critical review of the developmental evidence shows that the branchial pouches are formed in cephalocaudal sequence subsequently to the segmentation of the dorsal mesoderm.2The pouches interrupt a continuous sheet of mesoderm to form the branchial arches.3The arches when formed do not correspond topographically to the dorsal somites.4Branchiomerism does not therefore coincide with somitic metamerism.3The branchial structures do not support the theory of head segmentation.3The nervi trigeminus, facialis, glossopharyngeus, and vagus cannot be regarded as segmental nerves.3There is no evidence that branchial pouches or arches have been elided from the series.3The problem of meristic homology is briefly discussed.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 5
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The claspers of Centrina are adnate with the pelvic fin and bear a spine as in other Spinacidae. Mustelus canis resembles M. lunulatus rather than M. vulgaris. The claspers of Chiloscyllium end in a pointed spike. Pseudotriakis resembles the Carchariidae. The three North American Atlantic species of the genus Raia are considered, and R. laevis and R. erinacea are placed in the pseudogenus containing R. batis, and a new pseudogenus erected for R. ocellata. A gross and histological account is given of the Cowper's glands of Homo, and they are shown to be homoplastic with clasper glands, similar in structure, arrangement, development, and function.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 6
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: In the golden-mantled ground-squirrel, Callospermophilus, a spatulate glandular area has been noted in the skin of the back. It has been found in the following species: C. l. lateralis, C. l. arizonensis, C. l. caryi, C. l. saturatus, C. l. tescorum, C. c. chrysodeirus, and C. bernardinus. Probably it is common to the genus.The individual glands making up this area are modified and enlarged sudoriparous glands. They are divided into a tightly coiled and branched fundus, a large sinus, and a duct which passes caudad and outward to its exit at the surface.The glands secrete a strongly smelling oil, which is probably left on vegetation and other objects in the animal's environment and serves as a source of information to other members of the species. The glands are more active in spring and summer than in winter. They are stimulated by excitement. While present in both sexes, both adult and juvenile, they are best developed in adult males.Callospermophilus has three anal glands. These have flat-topped, straight-sided nipples which are protruded from the anus if the animal is frightened. A milky substance with a very weak odor can be extruded.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 7
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The study is divided into three parts. Part I deals with the chromosome number and morphology in the amniotic cells of rabbit embryos. The number of chromosomes has been found essentially constant in amniotic cells of young, but more variable in older embryos. The somatic number is 44. Part II deals with the chromosomes of race crosses (Flemmish Giant X Polish) in which the homologous chromosomes were found to be alike. Part III deals with spermatogenesis. There are forty-four chromosomes in spermatogonia, and twenty-two in primary spermatocytes. The sex chromosomes are of the usual X-Y type.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 8
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: 1Monovalent cation salts induce reversal in the direction of the stroke of the cilia; bivalent and trivalent cation salts with a few exceptions do not. Some acids induce reversal, others do not.2The duration of reversed action varies with the kind of salt and with the concentration. As the concentration increases, the duration of reversed action increases to a maximum and then decreases to zero.3Bivalent and trivalent cation salts neutralize the effect of monovalent cation salts. The relative amount required varies with the kind of salt used and with the concentration.4The amount of a given salt required to neutralize another salt is not proportional to the concentration of the salt neutralized. Weber's law does not hold.5The results seem to indicate that ciliary reversal is associated with differential adsorption and consequent changes in electric potential, but that there are also other factors involved.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 9
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 41 (1926), S. 427-439 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Webbing of toes or fingers in man is produced by a local arrest of development, causing retention of the normal embryonic webbing. This type of digital fusion involves only the skin, the skeleton being unaffected. The extensor tendons of the toes may sometimes be fused.Webbed digits occur normally in some marsupials, rodents, and insectivores, in a number of lemurs and catarrhines, and in the siamang and gorilla. They also may occur in varying degree in other Primates, notably Hylobates. An analysis of five new pedigrees together with those already published demonstrates that webbing of toes in man may be inherited in either a mendelian or sex-linked manner. In one case this character follows the course of the Y-chromosome.
    Additional Material: 19 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 10
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 49 (1930), S. 385-413 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The structure of the living blood cells is described and the cells are classified in the following species of ascidians: Phallusia nigra, Ecteinascidia turbinata, Clavelina oblongata, Symplegma viride. Evidence for the genetio relationship of the various types of cells is discussed.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 11
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 49 (1930), S. 455-507 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The history of the cytoplasmic components in the spermatogenesis of Gerris is, in general, like that which has been described in the Pentatomidae. The observations of fixed material have been checked by extensive studies of freshly teased preparations. During the spermatocyte growth period the chondriosomes undergo considerable increase in mass. During the maturation divisions the chondriosomes are remarkably constant in orientation with respect to the centrioles. The nebenkern arises by fusion of chondriosomes differentiated into chromophilic and chromophobic portions. The Golgi bodies of the earlier spermatocytes are vesicular bodies, the peripheries of which are osmiophilic. These are not visible in fresh preparations, but the masses resulting from their fusion in the late prophase of the first division are visible in the unfixed cells. The non-osmiophilic material inside these masses stains with neutral red in fresh preparations. Only the osmiophilic part of the Golgi masses is involved in the fragmentation to form dictyosomes. There is very suggestive evidence that the process of acrosome synthesis largely takes place inside the sac-like acroblast (Golgi apparatus). In the spermatid, material which stains, in fresh preparations, like the acroblast is never seen, except inside or attached to the acroblast, where it appears in the form of small spheres of ‘pro-acrosomic’ material, which fuse to form the acrosome.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 12
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 49 (1930), S. 579-619 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Haemichromis bimaculata is a tropical teleost fish which will produce eggs practically throughout the year at intervals of from three to four weeks. These eggs are of suitable size and character for embryological study, the features of special interest so far discovered being as follows: (1) The egg is oval; (2) it is attached to a substratum by its side, the blastopore being at one end; (3) the embryo always tends to develop along the side opposite that originally next to the substratum.Results obtained by reorienting the eggs previous to cleavage, and by centrifuging them, seem to show that the relation of the embryonic axis to the egg is determined either previous to laying or very soon afterward, possibly by the relation to the substratum, and is not subsequently affected by gravity or other known factors. There may be some tendency for the first cleavage plane and the sagittal plane of the embryo to coincide, but such coincidence is not at all constant or exact.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 13
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 50 (1930), S. 127-142 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Color changes in Palaemonetes had been found to be inhibited in the whole abdomen by occluding the dorsal abdominal artery. Inasmuch as these chromatic responses are brought about by means of circulating hormones, it should be possible, in view of early anatomical findings, for specific substances to reach the abdomen by way of the ventral abdominal artery which has been described for so many decapod crustaceans. This paper reports a degenerate ventral abdominal artery and a ventral continuation of the dorsal abdominal artery, the latter thus being distributed to practically the entire abdomen and therefore chiefly responsible for abdominal color-change phenomena.A method is given for injecting the arteries of small crustaceans, and the entire arterial system of Palaemonetes is described and figured. Several hitherto unreported vascular structures are noted: a plexus of blood vessels surrounding the supra-oesophageal ganglion, certain branches of the ophthalmic artery leading to the eyes, and various branches of the dorsal abdominal artery in the region of the telson and uropods. The forward flow of blood in the ventral portion of the abdomen in decapod crustaceans is held to be unique.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 14
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 50 (1930) 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 15
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Histological changes which occur in the digestive system and its appendages and in the muscular system of the honeybee during metamorphosis are described. Some attention is given to changes which take place in the fat-body, the silk-glands, and the reproductive system. Material of known ages was used. Observations began with the sealing of the larva in its cell and were concluded with the young bee ready to emerge from its cell. Soon after the larva is sealed in its cell, the body tissues begin to undergo a change. Larval epithelial cells lining the midgut are cast into the lumen and they are replaced by cells which proliferate from the imaginal or ‘replacement’ cells. In the fore- and hindgut the lining of the larval cells is replaced by imaginal cells whose points of origin are probably at the anterior and posterior ends, respectively, of the midgut. While the imaginal lining is being formed, the opening from the midgut into the hindgut is closed by a small portion of tissue. A part of the larval muscles are histolyzed and then re-formed from imaginal myoblasts, other larval muscles disappear entirely. The strictly imaginal muscles (e.g., leg muscles) are formed by myoblasts which congregate at the point of muscle formation. There is no evidence of phagocytosis in the honeybee during metamorphosis.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 16
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 50 (1930), S. 341-359 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The growth of chick embryos of heavy and light breeds and the reciprocal crosses between them is described. The embryos of the heavier breed and the hybrids were found to be somewhat heavier than the embryos of the lighter breed from the tenth day of incubation to hatching time. In eggs of the same weight from the two breeds the size difference tends to disappear toward hatching time, probably due to the equivalence of the strictly limited food supply. It is pointed out that the size difference is more probably due to difference in the proportion of cells dividing at a given time than to a difference in duration of mitoses.The mortality of the hybrid embryos was intermediate between that characteristic of the parent breeds, while the percentage of monsters in the hybrids was less than that for either parent breed. There is thus some indication of heterosis.
    Additional Material: 6 Tab.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 17
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 50 (1930), S. 475-495 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Four species of iceryine coccids have been studied cytologically in connection with certain breeding experiments. These are Icerya littoralis, Icerya montserratensis, Echinicerya anomola, and Crypticerya rosae. For the three first-named species the complete chromosomal history has been established, and the evidence on the fourth, Crypticerya rosae, is sufficient to indicate that it differs in no essential respect from the others. The following résumé may, therefore, be considered to apply to all four species. The females are diploid, with a chromosome number of four, and the males are haploid, with a chromosome number of two. Oogenesis proceeds quite normally; two tetrads are formed and two maturation divisions occur in which the chromosomes are reduced to two in each female pronucleus. All eggs undergo this reduction: if the eggs are then fertilized, the diploid number is thus restored and development into females ensues; if the eggs remain unfertilized, whether in the body of a virgin or of a fertilized female, they develop parthenogenetically, with no restoration of diploidy, into haploid males. The spermatogenesis of the haploid males involves a single meiotic division, demonstrably equational in character; the accompanying cytoplasmic division is suppressed, and from each of the binucleate spermatids thus produced two spermatozoa are formed. These conditions are contrasted with the functional hermaphroditism and haploid parthenogenesis of Icerya purchasi.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 18
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 50 (1930), S. 569-611 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: This study is based upon a close series of ontogenetic stages from cleavage until after metamorphosis.The so-called primordial germ cells, first differentiated in the lateral mesoderm, are traced to a definitive position in the genital anlagen. Careful counts of these demonstrated that they exist in larger numbers in the younger stages and that few of them ever reach the genital anlagen where they may form a small portion of the propagative cells.Evidence is presented that the majority of the germ cells are of somatic origin. From the earliest appearance of the indifferent gonad certain cells in the germinal epithelium have been observed which were increasing markedly in size and undergoing the various changes necessary in the transformation of small cuboidal or spindle-shaped peritoneal cells with oval nuclei into large germ cells with immense polymorphic or lobate nuclei. These cells are abundant in all older individuals. All the successive stages in the evolution of a somatic cell into a reproductive cell, involving as it does an increase in size, changes in shape, and a new distribution of chromatin material, are demonstrated.
    Additional Material: 28 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 19
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The various stages in the life history of Cryptocotyle lingua are identified and described. Adults naturally occur in the intestine of fish-eating birds and mammals. They were experimentally obtained in the cat, white rat, and guinea-pig. The development of the miracidium was followed within the egg. Larval stages occur in the marine snail, Littorina littorea. The structure of the redia and cercaria is described in detail, and evidence is submitted to show that the cercaria is identical with Cercaria lophocerca Lebour, described from the same snail on the British coast. Penetration and encystment of the cercaria in the skin of the cunner were experimentally secured. Excystment of the metacercaria was obtained both in experimental animals and in vitro. The metacercariae were maintained in culture media for as long a time as is required for them to attain sexual maturity in the final host. The host relations and specificity of the parasite are discussed on the basis of infection experiments. The cercaria is compared with similar larvae and its taxonomic position determined.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 20
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 50 (1930), S. 497-515 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Our observations confirm the recent findings of Krjukowa ('29) on the specific character of the Golgi material in the salivary glands of the Chironomus larva and are therefore in disagreement with the findings of Parat and Painlévé ('24).The Golgi material in the salivary glands of the Chironomus larva is present as discrete bodies having the form of crescents, rings, and rods. These are evenly deposited throughout the gland and show no makred variation in number at different stages of the physiological activity of the gland.The mitochondria are present in the form of filaments frequently concentrated in the area surrounding the nucleus and at the periphery of the cell.Neutral-red staining was never observed to color the Golgi bodies. It is suggested that the neutral-red bodies may represent the secretory material. However, it is clear that, whatever the significance of the neutral-red bodies, they are not Golgi material. Accordingly, this evidence supports the view that the Golgi apparatus, mitochondria, and neutral-red bodies are morphologically distinct structures in the cells of the salivary glands of the Chironomus larva.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 21
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Each indifferent genital rudiment in the grasshopper embryo is composed of the following: (1) a terminal filament membrane; (2) an epithelial plate of indifferent cells, the dorsal cell mass; (3) the central cell mass containing germ and indifferent cells; (4) the ventral cell strand, and, (5) a delicate, investing membrane, the outer limiting membrane. It is roughly spindle-shaped in transverse section and extends from the first to the eighth abdominal segments.In the sexual differentiation of the genital rudiment the dorsal cell mass is retained as a definite embryonic rudiment in the female, but becomes an indistinguishable part of the central cell mass in the male.Ovarian development is initiated in the dorsal cell mass area, where cell aggregations are formed. Each aggregation is ultimately surrounded by the ingrowing outer limiting membrane to form distinct cellular columns. A latero-ventrad extension of this ingrowing process into the central cell mass continues the column formation process into the latter and results in the formation of a distally tapering structure composed of indifferent cells distad and germ cells and indifferent cells proximad. This structure constitutes the rudimentary ovariole which finally differentiates to form the terminal filament, germarium, and vitellarium.The ovarian portion of the oviduct and the tubular connection between the ovariole and oviduct are differentiated from the ventral cell strand.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 22
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 55 (1934), S. 611-631 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: This paper describes the cellular relations between the prechordal mesoderm and the hypophyseal analage in duck embryos from the first to the eighth day of incubation.At nineteen somites the ectoderm destined to form hypophysis is seen as a plate of cells lying under the mesodermal mass anterior to the notochord. It extends anteriorly in intimate contact with the base of the forebrain, and posteriorly for about the same distance to the oral membrane. Following the lateral growth of the prechordal mesoderm and the rapid overgrowth of the forebrain, Rathke's pouch is definitely outlined. The upward expansion of the pouch, concomitant with the lagging of some of the prechordal mesoderm in the midline, effects a very close relation between these cells and those at the tip of the pouch. With the lateral expansion of the premandibular head cavities, some of the mesoderm adheres to walls of Rathke's pouch in the form of rods or knobs. As development proceeds the inherent growth tendencies of ectoderm and mesoderm express themselves differently and the rods or knobs become constricted off from the pouch, forming in its vicinity vesicles which exhibit a definite lumen.The question of an entodermal contribution to the hypophysis in this form is briefly considered.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 23
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 56 (1934), S. 51-58 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: By treating the clean skeletal tissue of an insect with concentrated KOH at 160° C., the contained chitin is converted to chitosan, and all pigmentation and admixtures are removed. The per cent distribution of chitin, expressed as chitosan, in the exoskeleton of the cockroach, Periplaneta fuliginosa, ranges from 37.65 in the dorsal abdomen to 18.22 in the hindwings. Other regions contain the following per cents: ventral abdomen, 37.11; metathoracic legs, 35.55; mesothoracic legs, 33.28; prothoracic legs, 32.24; pronotum, 31.55; head, 31.07; genitalia, 29.28; dorsal thorax, 29.07; ventral thorax, 28.33; antennae, 27.77; cerci, 25.65; and forewings, 19.99. Regional variations are constant in different individuals of the same species. The crop and gizzard contain 18.69 per cent; the hindgut, 18.15 per cent. The remainder of the alimentary tract contains no chitin. Traces of chitin are found in the trachea. No chitin is found in the egg-cases of this species. No correlation between chitin content and pigmentation or hardness is shown. Based on results from three trials, using thirty insects, the per cent of chitosan in the clean, dry chitinous material from the entire animal is 29.60; the per cent of chitosan based on the weight of the live animal averages 2.01.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 24
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 56 (1934), S. 325-337 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The purpose of this study was to learn something of the nature of the bead-like bodies which occur in the head of the sperm of the fowl since it was found in a previous study that they are apparently affected in a characteristic manner by vitamin E deficiency.Staining tests indicate that these bodies are composed of fats and fatty acids since they respond to osmic acid and Nile blue sulphate. They are also impregnated with silver nitrate and hence may be associated with the so-called Golgi materials of the cell.The beads first appear as a complete single row but subsequently they undergo fragmentation and redistribution. The whole process is probably a final transitory step in sperm transformation.The presence of this fatty material may signify that the sperm of the fowl, in contrast to that of most other animals, carries a store of food material to support its activity after liberation. The sperm may also be the carrier of a definite amount of vitamin E. Furthermore, the presence of this material may offer an explanation of the high resistance of the testis of the fowl to vitamin E deficiency because, since this vitamin is fat soluble, the testis as a whole would probably receive a disproportionately large share of the vitamin E stores of the individual.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 25
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: In sections from livers injected through the vascular system with Carter's carminegelatin or Berlin-blue gelatin masses at known, constant pressures, many cells were observed to contain ovoid or spherical bodies of the colored injection masses, similar to those described by Schäfer and his students, Herring and Simpson, as intracellular blood canaliculi.' In these livers practically all the cells were vacuolated. However, with livers injected with Berlin-blue gelatin mass dissolved in Locke's solution instead of distilled water, there were no intracellular masses and the cells appeared normal, though the sinusoids were completely filled with injection mass. The so-called ‘intracellular blood canaliculi’ described by Schäfer are interpreted as artefacts produced by a combination of factors, the most important of which is the difference in osmotic pressure. This is produced by the hypotonicity of the injection masses that are usually used, augmented perhaps by the effect of mechanical pressure used in administering the injection mass.Following impregnation of liver tissue by Golgi's rapid method, the usual network of intercellular bile canaliculi was revealed, but the presence of a permanent system of intracellular canaliculi was not observed. A few short, knobbed intracellular projections from the intercellular bile canaliculi were noticed; these probably represent the passage of secretion material into the intercellular bile canaliculi at the moment of excretion.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 26
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The early developmental history of Sciuridae (squirrel family), from the ovarian egg to the establishment of the germ layers, was studied in fixed material comprising ova and embryos from six species of five genera. No significant differences were noted in the major processes of development in the six species. Continuous diminution in the size of the ova occurs from the beginning of follicular vesiculation up to the early blastocyst stages. Corpora haemorrhagica are present in most of the recently ruptured follicles of all the species.Cleavage is regular, though adequal, up to the eight-cell stage, the blastomeres clustering into a compact mass. There is desquamation of cellular material from the periphery of the ovum between morula and blastocyst stages. At the same time cells within the blastocyst degenerate to add to the cavity originally formed by confluence of intercellular spaces. The cavity forms among the inner cells, an inner cell mass being left at one pole and an anti-embryonic mass at the other. The anti-embryonic cells produce much of the yolk-sac entoderm and contribute to the implantation mass. The latter mass forms a temporary attachment of the blastocyst to the uterine mucosa in these species. The definitive entoderm arises by migration and delamination of certain of the inner cell mass cells. A transitory notochordal canal, passing in a vertical plane through Hensen's node, is strongly suggested.
    Additional Material: 19 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 27
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 56 (1934), S. 533-575 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The arterial system of Ptyas mucosus (Linn.) reveals the following interesting features: (1) A prominent diverticulum given off from the inner antero-dorsal edge of the left auricle. (2) Ridge-like continuation of the median hanging valve of the sinus venosus lining the ventral edge of the opening of the right precaval vein. (3) Guarding of the opening of the pulmonary vein by a portion of the inter-auricular septum abutting against it. (4) Presence of two longitudinal trunks on either side of the hepatic portal vein formed by the hepatic branches of the hepato-oesophageal arteries, which, uniting with one another, form a peculiar arrangement looking almost like a looped chain. (5) A complete arterial circuit in the female formed by the combination of the genital, supra-renal, and the anterior-most renal arteries of either side. (6) Chain-like arrangement formed by the alternate bifurcation and union of the posterior-most part of the longitudinal fat-body artery and also by its lateral branches, which unite with it here and there after giving off twigs to the fat bodies. (7) A pair of small arteries (or in some cases only one) called ‘arteria complexa’ which take their origin from the dorsal aorta opposite the openings of the iliac veins into the afferent renals.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 28
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 55 (1934), S. 577-609 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: An investigation has been conducted to ascertain the relationship of certain structures in the embryo of the grasshopper known as Melanoplus differentialis with reproductive organs in the adult male.The order of development of these structures was traced through the entire life history.It was determined that they are the rudiments of certain reproductive organs and that the knowledge obtained serves as an aid in more accurately classifying insects.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 29
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 84 (1949), S. 335-363 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 30
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 84 (1949) 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 31
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 84 (1949), S. 459-493 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 32
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 85 (1949) 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 33
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 34
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 85 (1949), S. 483-501 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 35
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 85 (1949), S. 519-531 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 36
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 41 (1926), S. 441-546 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Embryological study of bullfrog tadpoles collected from various parts of the United States has shown the existence of local races which differ markedly in regard to the time of occurrence and character of the developmental processes involved in the formation of the definitive testis of the male individuals. Those races in which the gonads of the two sexes are easily distinguished in early larval stages are called differentiated. Other local races show a peculiar gonadic development chiefly affecting the males, the definitive testis sometimes not appearing until near the end of the second year of larval life. Such races are called undifferentiated, because the morphological features of the definitive testes are not established until late. The larvae first develop a peculiar gonad (progonad) which later degenerates and is replaced by the definitive testis. All male animals of the undifferentiated strains exhibit the gonad cycle.The progonad varies among the local frog races in regard to the length of persistence and degree of differentiation attained before undergoing degeneration. Its germ cells may exhibit a typical male maturation cycle ending in degeneration, or the cells may differentiate along both male and female lines or remain sexually neutral.The development and differentiation of the progonad in the various races are described and a detailed account given of the origin of the definitive testis. The problems of sex differentiation and continuity of the Keimbahn in anurans are discussed.
    Additional Material: 100 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 37
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 41 (1926) 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 38
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 41 (1926), S. 333-345 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: In a leech infesting the Alaskan codfish germinal masses in the ovary proliferate secondary groups, comprising about forty cells in which a follicle and central supporting cell early differentiate. Active division results in approximately 500 cells which apparently develop ductules extending to a point on the surface of the egg. Granules of unknown origin then appear in each nurse cell, and are drawn down the ductules into the egg which can now be distinguished. Reasons are given for the belief that the nutritive material is drained from the nurse cells by amoeboid activity of the egg. In early stages the nutritive mateiral forms a loose reticulum which gradually becomes transformed into a more extensive network, persisting until the maturation divisions. In this latest period the follicle and nurse cells, which become shrunken as the ovum enlarges, usually are stripped off and soon disintegrate.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 39
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 41 (1926), S. 547-579 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The pelvic fins of the ancestors of the Chondrosteoidei possessed a metameric musculature and their skeleton consisted of a large number of metamerically arranged cartilaginous fin-rays, to which were attached osseous lepidotrichia. Evolution has involved the concrescence of separate elements to form the basal cartilage, the proximal end of which forms the girdle of the fin; the loss of a number of the fin-rays, and the atrophy of distal elements of the rays. The adult Chondrosteoidei have retained the primitive fin structure which characterized the elasmobranchs of the Palaeozoic period and which has disappeared in recent forms.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 40
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 42 (1926), S. 143-195 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: On the basis of experimental study and observations on the morphology of the legs of spiders, P. Friedrich described a cutting device within the trochanter which would sever that appendage from the body when the leg was stimulated by injury.A reinvestigation of the problem yielded entirely contrary results. Experiments calculated to induce spontaneous amputation through an automatic reflex in the leg were negative on scorpions, harvestmen, and more than a dozen species of spiders. A detailed morphological study of the skeleton and musculature of the arachnid leg showed that no autotomizing device exists, either in the skeleton or in the arrangement of muscles (as is usually supposed). In all species studied, except the scorpion, severance of the leg from the body occurs most readily at some given point. The point at which severance readily occurs is directly correlated with a definite structural weakness in the skeleton and musculature. The spider itself removes an injured leg by grasping the stump with its mouth-parts. No such injured stump falls off spontaneously or without the application of tension. Scorpions do not autotomize appendages under any stimulation, nor do they show any anatomical weakness in the leg skeleton or musculature.Autotomy as an automatic reflex does not exist in the Arachnida.
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 41
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Sixteen species of the genus Scyllium are here considered and arranged in groups according to the accessory structures present on the claspers as follows:1Canicula, sufflans, ventriosum.2Catulus, stellare, capense, variegatum (var. pantherinus), umbratile.3Burgerii, hispida, bivium, anale, natalense, edwardsii.4Marmoratum, laticeps.The structure of the wall of the oviduct and vagina is demonstrated, and it is shown that the epithelium of both is at first columnar, then ciliated in immature specimens; at maturity that of the vagina further undergoes by transitions a change to stratified. The walls are highly vascular, but contain no special glands.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 42
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Amoeba responds to a mechanical shock by a cessation of movement which occurs shortly after the application of the stimulus. The length of the reaction time, the period intervening between application of stimulus and the response, varies inversely with the magnitude of the shock. After stopping Amoeba remains quiescent for a short time, and the length of this period of quiescence varies directly with the magnitude of the shock. A certain amount of time must elapse after a reaction before another can be obtained; during this time the animal reverts to the physiological state which existed prior to the first shock.Partial recovery from the effects of a shock is manifested by a reaction time that is longer than after complete recovery, and a period of quiescence which is shorter. A shock which in itself is too slight to cause a cessation of movement may result in the lack of a response to a heavier one which follows immediately after it, although under other conditions the second shock would have called forth a reaction. If the second shock, however, is made sufficiently heavy, it will bring about a response, despite the effects of the first. This is what would be expected if the reactions take place in accordance with the Weber-Foechner law.
    Additional Material: 4 Tab.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 43
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 42 (1926), S. 523-560 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The different kinds of scales characteristic of the adult sturgeon are described and the facts of ontogenesis which throw light on the history of these structures are presented.The scales of Acipenser are exclusively mesenchymatous and therefore are not morphologically comparable with the placoid scales of elasmobranchs. Salensky ('80) drew erroneous conclusions as a result of failure to study the earlier stages of ontogenesis. Goodrich ('03) has correctly described the ontogenesis of the lepidotrichia.The original form of ganoid scale was that of an elongated rhomb with a longitudinal crest on its external surface. The various forms of scales of the adult sturgeon have been produced by the differentiation of such a scale by change in size, shape, and the fusion of the different elements.The conclusions are extended to the entire family of Acipenseridae.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 44
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The lips of the animal are modified in relation to the act of passing seeds into the sac. The cheek-sacs are invaginations of the buccal mucosa, and their development as diverticula of the vestibulum oris is associated with the establishment of extrinsic muscles, derived from the platysma. The sac is invested by a coat of striated muscle. The epithelial lining of the sac attains a degree of complexity comparable to the epidermis of the skin, except that a stratum lucidum and stratum granulosum are not developed. No glands are developed in the mucous membrane of the sac.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 45
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Three groups of pure lines of diverse clones of Didinium nasutum were maintained in isolation cultures for 778, 786, and 457 generations, respectively, without exhibiting any decrease in fission rate or any increase in encystment rate or death rate. These lines were supplied with Paramecium caudatum in such numbers that a surplus of food was present at all times.Three other groups of lines of the same clones were established simultaneously and cultured in parallel with the preceding groups, but the food of each of these lines was limited to nine paramecia per line daily. The fission rate of these lines fell to zero and the encystment rate increased to 100 per cent after 155, 165, and 113 generations of culture, respectively. The death rate increased appreciably in these lines prior to encystment.Other groups of pure lines were cultured on a diet limited to six paramecia per line daily. These lines encysted after approximately fifteen generations of culture.This evidence indicates that there is nothing in the nature of a definite life-cycle in Didinium and that diminished vitality and encystment do not result from the passage of generations, but from inadequate and unfavorable cultural conditions-specifically, from in-sufficient food. It shows further that it is possible to induce cycles with reference to encystment in Didinium by limiting the food supply and to vary the length of the cycles by varying the quantity of food.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 46
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Chlamydoselachus resembles the Holocephali in possessing no siphon, but a cavity in the proximal portion of the clasper. The cartilages, musculature, and venous sinuses of the clasper are considered. An older specimen of Echinorhinus is proved to have a spine on a soft papilla; Scymnus has no spine; both have the general features of the Spinacidae. Two species of Cestracion are compared with C. philippi. Mustelus lunulatus lacks the pera and pseudosiphon of M. vulgaris. Dicerobatis has a peculiar scaphus, and the claspers end in a fimbriated manner. Pteroplatea resembles Trygon and Benthobatis and Astrape are both like Torpedo.The species are listed below.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 47
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 42 (1926), S. 23-81 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The flagellate, Tetramitus rostratus Perty, appeared in cultures of certain amoebae obtained from the coecum of rats. In a typical life-cycle a cyst, planted in an appropriate medium, gives rise to an amoeba which may divide a number of times, but eventually some of the amoebae transform into flagellates identical with Tetramitus rostratus. These divide frequently through several days, sometimes for weeks or months, and then transform back to amoebae which become encysted.During excystment the smooth cyst wall dissolves. Usually both the amoeboid and flagellate phases pass into a “gel” state during division. A “gel” state sometimes occurs during transformation. The time required for transformations varies from a few minutes to several hours.Many culture media and methods have been tested. In certain cultures the flagellate phase was prolonged for weeks or months. These cultures were characterized by: 1) great variation in size, from minute “dwarfs” to oversized “monsters”; 2) frequent multiple fission; 3) pairing and fusion, and, 4) some evidence for the origin of secondary nuclei from chromidia. In cases of pairing and fusion, the process of maturation and union of nuclei could not be definitely proved, although suggested by the observations.The flagellate phase is more probably the “adult” phase because of its complex organization and possible sexual phenomena. This case is considered an extreme for this type amoeba-flagellate transformation.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 48
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: In the blastula the region of accelerated cell division is on the ventral side of the egg, nearly opposite the site of the future beginning blastopore. The ventral wall of the blastocoele is thicker than the dorsal. In the very early gastrula a new region of accelerated cell division appears in the vicinity of the dorsal lip of the blastopore.A downward movement of material comprising the marginal zone of micromeres and the portion of the wall of the blastocoele immediately above it occurs during all the later blastula stages and continues until this material is carried below the level of the equator and involved in the process of gastrulation. On the dorsal side of the egg, this movement is more rapid than on the ventral side.In the late blastula stage there are evidences of growth in the region of smaller micromeres. In the very late blastula, a vertical groove appears at the dorsal margin of the floor of the blastocoele; this groove is believed to indicate the operation of factors concerned with gastrulation.In connection with the first nuclear division, evidences of cytoplasmic activity leading to the formation of the first cleavage furrow are described. As the blastomeres become smaller, progressive changes take place in the distribution of their cytoplasm.
    Additional Material: 35 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 49
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 42 (1926), S. 335-348 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A summary is given of the previous memoirs, and an attempt has been made, upon the three characters of this investigation, to arrange the genera into families, which agree, with two exceptions (Mitsukurina and Dicerobatis), with preexisting families. Some deductions are drawn as to relationships and attention is drawn to Cestracion galeatus and Triakis as connecting links. Separate families are erected for Dicerobatis and Mitsukurina, and the latter is placed near to Notidanus. Resemblances are shown between Chlamydoselachus and the Holocephali. The Trygonidae, Torpedinidae, and Rhinobatidae are singularly uniform families. An index is added both general and specific.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 50
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 42 (1926), S. 453-471 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The activities of the larva and the responses and orientations it makes to external stimulation, and the structural organization by which these activities are produced, are described and figured.Existing systematic confusion of M. citrina with other species (M. manhattensis, M. nana, and M. microsiphonica) is cleared. The duration of the period of larval life is found to vary between 5 and 170 minutes. A proportionally small number retain the larval form a longer time. During larval life, periods of swimming movements alternate with periods of inactivity, the latter, at first of momentary duration, becoming longer and longer until activity ceases.No light receptor exists and no response to light is made. A statolith is found in the sensory vesicle, and frequent geonegative orientations are made during the free-swimming period. These are of short duration and tend to occur, 1) when it emerges from the parent; 2) at the beginning of each of the frequently recurring periods of swimming activity; 3) immediately upon making contacts. Unoriented movements follow each orientation and constitute much the greater part of behavior.The larva lacks definite organs of attachment. The entire surface of the tunic becomes adhesive at the time of metamorphosis. Only those structures that make up the action systems of the larva are fully differentiated, all other parts are embryonic in condition.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 51
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The integument of the vermilion-spotted newt contains three kinds of pigment--yellow, red, and black. The yellow is uniform and continuous over the whole body; the red and black are discrete, and are chiefly in large spots. The pattern does not change measurably in an adult individual.Functional changes in contraction of the scattered dorsal melanophores were uncommon. The only efficient single factors found were a long subjection to low temperature (expansion) and injection of pituitrin (contraction).Removal of skin was followed by a rapid mass migration of dermal elements into the wound area. Melanophores were thus furnished to a dorsal wound, and after several months black spots formed from these. Red pigment never regenerated nor migrated into a wound. Yellow pigment was formed in situ after the wound had completely healed.Auto-, homo-, and heterotransplants lost their pigment patterns and were gradually reorganized so as to conform in gross appearance to the surrounding pattern of the individual host's skin. The transformation was never complete in eight months, but new black spots and new yellow pigment eventually formed.The behavior of melanophores during morphogenesis differed for specific areas of the integument. Their movements and aggregation were highly coordinated among themselves.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 52
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: In the epidermal cells of green-frog tadpoles (Rana clamitans) there are present coarse, conspicuous mitochondrial threads. In the dorsal body regions, epidermal cells of the middle layers also contain pigment granules, grouped in crescentic masses in the distal portions of the cells.Administration of thyroid extract results in permanent disappearance of the mitochondrial threads and disappearance to a large extent of the epidermal pigment granules. Processes of cellular dedifferentiation and proliferation occur rapidly over widespread areas, the mitochondria undergoing intracellular resorption. A new type of epidermis is developed containing many cutaneous glands, adapted for the approaching terrestrial life.Wound infliction induces similar processes of cellular dedifferentiation and proliferation in the epidermis in the immediate vicinity of the wound. Cells in this region lose their mitochondrial threads by intracellular resorption, and there is also some disappearance of pigment granules. The new epidermal cells in the early stages of regeneration produce neither mitochondrial threads nor pigment. This condition is not permanent, however, and in the later stages the larval characteristics appear again, both mitochondrial threads and pigment being redifferentiated.In the hyperthyroid animals there is also a significant mobilization of mesenchymal chromatophores, correlated to some extent with the loss of epidermal pigment.The significance of epidermal changes is discussed with reference to cutaneous abnormalities associated with hyperthyroid and hypothyroid conditions.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 53
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 43 (1926), S. 147-179 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Animal posture cannot be regarded as an actual inheritance, for it constitutes a current physiological interaction between gravity and an organism, according to the structure and physical powers of the latter. Hence, ‘inherited posture’ merely implies that in a given species physical qualifications are congenitally transmitted, which facilitate a certain characteristic position of the body. Evolution of posture, therefore, has inevitably been associated with corresponding evolutionary changes in organic structures.Evidence furnished by the application of biomechanics to studies of ancient and modern primate structures indicates that man's erectly supported body posture could only have originated from a vertically suspended posture (arboreal).The fact that the prehuman stem passed through an earlier arboreal and brachiating period is attested to by the grasping character of his hands, the ratio of arm-body length, the extreme mobility of the shoulder-joints, as well as the extension of his legs on the body.The semierect posture of the great apes is not an advance toward human bipedism, but a modern reversion toward quadrupedism.Postural evidence conforms with the many other lines of testimony which maintain the close relationship of the human and anthropoid stems, and signifies that man has been an erect terrestrial biped since the time of his physical origin.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 54
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 49 (1930), S. 153-221 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A study is made of the morphological types of the second, third, and fourth interdigital patterns of the human palm and their differential occurrence as a basis for determining the morphological significance of the digital triradii and main lines, which are the final remnants of the pattern boundaries. Certain types of patterns show a large preponderance, with a correspondingly large percentage of a certain morphological value for each digital triradius, although other morphological possibilities than the usual one are discovered in each case. Correlated combinations of rare patterns are presented and their hereditary nature discussed.
    Additional Material: 17 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 55
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 49 (1930), S. 251-275 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Intravitam stains were used to determine the functions of several organs in two species of nemas (Rhabditis strongyloides and Rhabditis elongata). The organs were also studied in section. From the results obtained it is concluded that the amphids are not excretory in function, but more probably sensory, for definite connections were observed to extend to the nerve ring. No migratory cells, such as those described by Stefanski, were seen.The phasmids stained with all intravitam stains used. but were never observed to secrete. It seems doubtful that they serve as excretory organs.The excretory system was seen to consist of a typical X system. Actual excretion was observed. Deirids were seen for the first time in both species. Oesophageal glands were also described. A study was made of the structure of the intestinal cells, rectal glands, and anal muscles. Attention was called to the fact that there are two kinds of ejaculatory glands, one of which probably serves as a ‘cement gland,’ while the function of the other is still in doubt.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 56
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 49 (1930), S. 355-383 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The breeding season of Bugula flabellata extends from June 10th to November 15th. The young embryos develop in brood pouches (ovicells) and are finally expelled from the colony as swimming embryos. They come from the colonies at dawn or early morning. After a free-swimming period of four to six hours, each larva becomes attached and after a profound metamorphosis which involves the loss of larval organs, it develops into the bryozoan colony by budding.The larvae at first are positive to light, but become negative before attachment. Their behavior is described in detail and the mode of attachment is explained.After the larva has become attached a period of rapid growth by budding ensues. The rate of growth is given in a table in which it is shown that the first individual of the colony is completed in two days and that a new series of buds is formed every two days. There are eight or ten individuals after one week and over a hundred in two weeks. In one month the colony is half-grown and becomes sexually mature. A colony becomes senescent in three months, when it measures 112 to 134 inches in diameter.Younger colonies hibernate successfully and resume growth in early May, when new polypides are formed.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 57
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The germ cells in human embryonic ovaries arise by proliferations from the germinal epithelium. These cells pass through the early maturation phases, including synizesis, beginning at about the third month. Four distinct periods may be distinguished in ovogenesis, each having its own peculiar characteristics: the early embryonic period from seven weeks to three months, the middle embryonic period from three to five months, the late embryonic period from five to seven months, and the adult period. The early embryonic period shows only growth and multiplicative phases; the middle embryonic period is distinguished by maturation phases, among which phases are interpolated which do not appear elsewhere in the species; the late embryonic period is charcterized by phases similar to those of the adult male germ cells, and the adult period by the omission of early maturation phases preliminary to the maturation divisions.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 58
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 50 (1930) 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 59
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The first of a series of studies on the comparative histology of the digestive tubes of fishes selected, on the basis of their feeding habits, from the teleost group: a study of the microscopic anatomy of the digestive tube of a predaceous teleost, the sea bass (Centropristes striatus (L.)). Based on studies of sections, with details of gross anatomy from both fresh and preserved material. Includes a short survey of previous work. Deals with the histology of the various regions of the tract, their tunics and tissues, together with details of cell structure and arrangement. Approach is made from the physiological side, with particular reference to the adaptation of histological elements to functional activity. Parts treated in detail are esophagus, cardiac and pyloric limbs of the stomach, intestine, and pyloric caeca. Particular stress is laid on the histological structure and arrangement of the tunica mucosa, especially in relation to digestion and absorption. Topics given particular emphasis are: condition of mucosal folds with reference to the amount of food present in the lumen; transformation between adjacent epithelia of different types; structure of cardiac and pyloric glands; origin and differentiation of intestinal goblet cells; comparisons between histology of pyloric caeca and that of adjacent intestine, together with general conditions found in the caecal mucosa.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 60
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 49 (1930) 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 61
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 49 (1930), S. 139-151 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: In Trichamoeba sp two types of inclusions are recognized on the basis of reaction to vital dyes and tomethods of osmic and silver impregnation. Globular inclusions, which are stained selectively with neutral red, may be blackened under direct observation by exposure to osmic vapor in hanging-drop preparations and demonstrated by osmic and silver impregnation. Rod-like and granular mitochondria, stainable vitally with Janus green, may be distinguished from the neutral-red globules in preparations stained with a mixture of Janus green and neutral red, and are demonstrated by Regaud's chondriosome method.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 62
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Spining in Galleria begins shortly after hatching and continues throughout larval life. The gland cells secrete continuously, irrespective of the act of spinning.The nucleus plays a direct and an importnat rôle in silk secretion by the migration of nucleoli into the cytoplasm, where they enlarge and synthesize a fatty material in the center; the fatty material is transformed into a non-soluble basophllic substance, which then changes into the secretory product in its final form. The processes of converting the fat into non-soluble substance and of converting the latter into the secretory product progress inwardly from the periphery of each secretory body. The secretory bodies or masses of secretory material break up into smaller and smaller masses and eventually into a fine dispersed state before their entrance into the lumen of the gland.The mitochondria are granular in the cells of the conductive portion and filamentous in those of the reservoir and secretory portions of the gland. In the secretory portion they are orientated with the long axis toward the gland lumen. Their rǒle in silk secretion is negligible or at most a minor one.The Golgi apparatus is in the form of discrete ring- and half-ring-shaped bodies and remains so during all stages of secretion. If it plays any rǒle in silk secretion, the fact has not been detected by the author.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 63
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 50 (1930), S. 453-473 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Ovaries of adult albino rats were studied, the following phases being considered: Eleven to twenty and one-half days pregnant, shortly after fertilization, oestrus, not pregnant, young sterile, old, and senile. Some new ova are produced from the germinal epithelium during pregnancy and oestrus, but it is in the ovaries of non-pregnant animals between oestrous periods that the germinal epithelium is most active. There can be no question of the formation of new ova during adult life, for there is a correlation between the activity of the germinal epithelium and the number of oocytes and young follicles present in ovaries. Also one can trace the origin of ova in the surface and follow their transformation and movement into the ovary proper. In some sterile young animals little new formation took place, in others a good deal. In old and senile animals the germinal epithelium continued to be active, especially in producing ingrowing cords of cells, but frequently these were anovular. The germinal epithelium may form different types of cells by ingrowth: ova, follicle cells, and interstitial cells, but the formation of anovular follicles at one period does not prevent a later production of normal ova and follicles.Some new ova are produced from the germinal epithelium of ovaries during pregnancy and oestrus, but it is in the ovaries of non-pregnant animals between oestrous periods that the germinal epithelium is most active. There can be no question of the formation of new ova during adult life, for there is a correlation between the activity of the germinal epithelium and the number of oocytes and young follicles present in ovaries. In some sterile young animals little new formation took place; in others, a good deal. In old and senile animals the germinal epithelium continued to be active, especially in producing ingrowing cords of cells, but frequently these were anovular. The germinal epithelium may produce different types of cells by ingrowths - ova, follicle cells, and interstitial cells - but the formation of anovular follicles at one period does not prevent a later production of normal ova.
    Additional Material: 17 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 64
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A study of the cytological changes occurring in the larval oenocytes of Galerucella nymphaeae Linn., correlating those changes with the molting cycles. Preceding each larval molt, vacuoles, apparently of nuclear origin, are found in the cytoplasm from which they are eliminated at the time of the molt. The accumulation of vacuoles is not so striking at the times of pupation and the emergence of the imago, but occurs nevertheless. Beginning with pupation or just previous to it, the larval oenocytes seemingly undergo a process of deterioration, decreasing in size and presenting a ragged appearance.The fat-cells are closely associated morphologically with the larval oenocytes, and it seems that there is a probable physiological relationship also, since the fat-cells undergo a series of changes at the same time the oenocytes are exhibiting their cyclic behavior. Furthermore, it has been observed that in many instances there is a greater accumulation of vacuoles in that part of the cytoplasm of the oenocytes which is adjacent to the fat-cells than elsewhere.
    Additional Material: 23 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 65
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 49 (1930), S. 415-453 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The male and female germ cells of Polygra appressa were found occurring together in the acini from the time the snails were 5 mm. in width onward, and their development traced backward to the gonial stage, in which the aspect of the female cells, present in small numbers in the acinus wall, and the male cells, in greater numbers in the lumen, seems identical.In oocytes, differentiation involves the enormous increase in volume of cell, nucleus, and plasmosome; the appearance of yolk and of a secondary nucleolus attached to the first one, and, in some cells, various other nucleoli, attached to the chromosomes. Meanwhile the chromosomes become diffuse and spread into the interior of the nucleus, finally condensing again on the periphery. The employment of various technical methods produced interesting variations in the aspect of oocyte chromatin and nucleoli.The appearance of the Nebenkern in spermatocytes during the growth period was noted, but no indication of its presence discovered in oocytes until the fairly late growth period.The chromosome forms were noted in spermatogonia, first spermatocytes and oocytes, and their numbers found to be 61 63, 31, and 31, respectively, but no clear dividing oogonia were found, on which similar observations could be made.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 66
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 50 (1930), S. 71-126 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: An extensive survey of the anatomy of the endolymphatic organ (i.e., endolymphatic sac and duct) has been made on thirty-four species of amphibians.1The histological structure is similar throughout the group; the sac being formed of cubical cells, which grade into the columnar cells of the duct. A part or the whole of the duct is formed of peculiar ‘ependyma-like’ cells.2The organ typically arises from the sacculus, extends to the endolymphatic foramen by which it enters the endocranial cavity. Here the sac-like expansion of the organ lies in the extradural space.3Six morphological types of endolymphatic organ may be recognized in the Amphibia.4The development of the endolymphatic organ of four of these types has been followed. The structure in each case may be considered to have reached its definitive condition at the time of metamorphosis.5The types of sac structure cannot be readily correlated with any habit of the animals possessing them.6A discussion is given of the homology, comparative morphology, and function of the organ throughout vertebrates.
    Additional Material: 28 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 67
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 50 (1930), S. 259-293 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A study of the development of the ear of the common dogfish from the 3.5-mm. stage to the adult, with a brief review of the literature and comparison with related forms.The study includes the following topics: First indications of vesicles. The beginning of specialization. The separation of component structures. The sensory epithelium. The structure of the adult ear, including a description of the sensory areas, the innervation, the lagena.The position of the future canals is first indicated in 15- to 20-mm. stages. The sacculus and utriculus were first noted in the 22-mm. stage. Complete separation of the canals, the sacculus, utriculus, the recessus utriculus, and the lagena has occurred by the time the 33-mm. stage is reached. Definite innervation of the ampullae is found at this stage.The article contains twenty-seven figures; eight of them are drawings made from wax reconstructions of various stages.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 68
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 50 (1930), S. 361-392 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: This ontogenetic study shows the following facts: (1) the presence of a vidian artery homologous with that of reptiles, which serves visceral elements of the jaw; (2) there exists a transitory occipital artery arising from the stapedial which contributes to the vascular supply of the occipital region; (3) the presence of a transitory fifth arch intimately associated with the sixth arch; (4) there is evidence of at least two presegmental branches of the aorta; (5) in the development of the adult pulmonary stem the right artery forms very little of the common vessel; (6) a single cephalobrachial trunk forms the culmination of arch development; (7) arterial development of the head and neck falls into three phases: (a) a temporary arterial pattern designed to carry nutriment to primitive head structures, (b) a plan of arterial distribution adapted to supply the rapidly forming cartilage and muscle of the jaws, and, (c) a readjustment period when the arterial plan is readjusted due to the increased heteronomy of the head.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 69
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 50 (1930), S. 413-451 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The process of ‘chromatin diminution’ may be said to be a casting off of chromatic material from the chromosomes earlier or later in the course of mitosis. A study of the phenomenon as it occurs in Ephestia and Ascaris shows it to be comparable in only the broadest and most general sense.In Ephestia the diminution substance is not formed in the nucleus, but is due to a later differentiation of the chromosomes long after their discharge from the nucleus. This can be made apparent by the use of differential stains and by other methods.In Ascaris diminution is found not to occur until the third cleavage, and then in all three cells that are destined to be somatic. The diminution process in this instance is apparently comparable to the casting out of residual substance which occurs when the nuclear vesicle breaks down in other cells.
    Additional Material: 49 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 70
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 50 (1930), S. 517-525 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The fertilized hen's eggs of known origin were incubated under predetermined, standardized, and uniform conditions of all physical factors except air, the composition of which in respect to the carbon dioxide and oxygen varied in each experiment. The growth and mortality of the embryo were studied daily, with, on an average, four observations.The experimental data show that the continuous exposure to about 0.4 per cent of carbon dioxide in the air of the incubator stimulated growth during the first part of embryonic life. A high content of carbon dioxide and at the same time a slightly reduced content of oxygen resulted in diminishing of the size and increasing of mortality of the embryo. The maximum combined proportions of these gases possible for growth of the embryo were about 22.0 and 16.3 per cent, respectively. A temporary exposure (twenty-four and forty-eight hours) to a large amount of carbon dioxide resulted in diminishing the size of the embryo without apparent deformities or increase of mortality.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 71
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The segregation of the germ cells is related in time and differentiation to the ectoderm (ventral plate), the inner germ-band layer (lower layer) and the mesenteron (entoderm) rudiments. The inner germ-band layer is formed by invagination of cells from a median blastoporic groove and by cellular proliferations among the invaginating cells and from the median line of the ectoderm immediately caudad of the blastoporic groove. The mesenteron material is derived from inner germ-band layer material associated with the internal ends of the stomodaeum and proctodaeum. The germ cells are segregated from the lateral margins of the abdominal lobe ectoderm in the region of the amnion attachment as segmentation of the abdominal lobe is initiated. They ultimately become separated from the ectoderm cells of the lateral wall and from the amnion and migrate in a passive manner onto the coelomic sacs where they become associated with the inner walls of the sacs. When the coelomic sacs unite the germ cells and the splanchnic wall mesoderm cells form two continuous cell strands from the first to the eighth abdominal segments, inclusive. These strands form the indifferent genital rudiments. An endeavor is made to correlate the segregation of the germ cells in the grasshopper with that of various other insects.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 72
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 56 (1934) 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 73
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 56 (1934), S. 21-49 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The literature relating to the flexor and adductor muscles of the thigh and their nerve supplies, in Sphenodon, the lizards, crocodiles and mammals was correlated and new dissections made of animals belonging to the last three groups. All of these muscles can be traced as individual entities from animal to animal without loss or addition to their number, although splitting may occur. The attachments of the muscles and their relationships to one another and to the two heads of the gastrocnemius are the same in all the reptiles studied. In the mammals one group, including the adductor longus and magnus and the retractor femoralis, has migrated from the tibia between the two heads of the gastrocnemius onto the femur, and another from the ilium onto the vertebrae, the one migration being caused by expansion of the gastrocnemius, and the other by expansion of the gluteal muscles. A new lateral flexor mass has been formed from part of the reptilian ilio tibialis by migration down the fibula. The nerve supplies of the various muscles are not constant when traced from group to group, and it is suggested that a muscle receives its nerve supply from the nerve nearest to it in embryonic development, so that when a muscle has migrated the nerve supply is no longer a reliable guide to its homology.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 74
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Histological studies of testes of both immature and mature individuals show that the peritoneal epithelium does not give up its proliferative capacities with the completion of testis differentiation. Certain regions of the antimesorchial surface retain their activity and continue to contribute cellular elements during testis growth. Stromal cells, germ cells, and sections of or entire seminiferous tubules originate from the peritoneum in the form of cord-like ingrowths. In this form, the proliferations of the germinal epithelium of the testes are similar to and homologous with the continuous proliferations of the germinal epithelium of the ovary.In Sternotherus, both testis and ovary differentiate out of a bisexual primordium in which the deeper parts of the germinal epithelium form an ovarian cortex. Since the germinal epithelium persists as an active part of both ovary and testis, it must be responsive to the same physiological factors of female or male differentiation respectively. It is indifferent sexually and once the direction of sex differentiation is established, the response of the germinal epithelium is in the determined direction. Its activity is then to produce either seminiferous tubules or ovarian follicles, and is directly dependent upon the processes of embryonic sex differentiation and determination.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 75
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 56 (1934), S. 295-323 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The primordia of the thymus bodies in Necturus begin to form in 7-mm. embryos. These structures arise as clumps of entodermal cells on the posterior dorsal portion of the first four visceral pouches; the first or last pouch, being rudimentary, fails to form such a primordium. All except the first of these primordia lose their connection with their respective pouches in the 16-mm. stage and lie free in the surrounding connective tissue. The primordium on the first pouch begins to show degenerative changes during that stage, losing connection with its pouch in the 23-mm. stage, finally to disappear altogether in 30-mm. specimens.The three remaining bodies continue to grow, but the second and third outstrip the fourth in development and begin to form Hassall's corpuscles in 32- to 34-mm. stages. Sections of 30-mm. Necturi show a few of these corpuscles fairly well developed and containing a faintly staining secretion. The fourth body remains relatively small a long time, not showing the Hassallian cysts until the animal is 60 mm. long. By shifting of positions and increasing in size, the three bodies come to lie in proximity, one behind the other, to form the definitive thymus gland of the adult. The gland lies embedded in the heavy musculature on top of the head in front of the gills.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 76
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 56 (1934), S. 339-359 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The effects of vitamin E deficiency in the fowl were observed in Rhode Island Red males over a period of approximately 2 years.Mating experiments showed that after 1 year on the E-free diet all of the males were capable of fertilizing ova, but that after 2 years some of the males were sterile.Sperm smears showed that shortly after the beginning of the experiment, many of the mature spermatozoa exhibited an abnormal condition of the nuclear material of the head, while others remained normal.In histological sections of the testes made at the end of the 2 years, conditions varied from almost normal to complete atrophy, the latter being a condition that has already been described in the male mammal. Moreover, the conditions in any given section were not uniform for even in an advanced stage of E deficiency there were small islands of apparently normal tissue. However, in this case, as in the mammal, the process of degeneration affects the mature sperm cells first and gradually works to the outside of the seminiferous tubule thus attacking the youngest maturation stages last.The results of the experiment point definitely to destruction of the testis under prolonged E-deficient conditions but it is also quite apparent that the testis of the fowl is extremely resistant to vitamin E deficiency.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 77
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: This paper is an attempt to clear up the confusion concerning the osteological relationships among the Haplomous fishes.The osteology of Novumbra hubbsi was worked out by the dissection of numerous specimens. The various skeletal features found were compared with the osteology of Umbra limi, U. pygmaea, U. crameri, and Dallia pectoralis.A description of each skeletal element of Novumbra was made, followed by a description of the chief differences between it and the same structures in Umbra and in Dallia. No constant osteological differences were found between Umbra limi and U. pygmaea, and very few between these two species and Umbra crameri. Novumbra and Umbra have more in common with each other than either does with Dallia or Esox. The presence of postorbitals, postcranials, and the shape of the secondary shoulder girdle in Novumbra show it to be also closely related to Dallia and Esox.The relationships of the various forms are summarized in a synoptic key which lists the following groups: Order Haplomi. Superfamily I, Dallioidea; Family Dallidae; Genus and species, Dallia pectoralis. Superfamily II, Umbroidea; Family 1, Umbridae; Genus and species, Umbra limi, U. pygmaea and U. crameri; Family 2, Novumbridae; Genus and species, Novumbra hubbsi. Superfamily III, Esocoidea; Family Esocidae; Genus, Esox.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 78
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 56 (1934), S. 445-475 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: This paper deals with the morphology of all the so-called gustatory and olfactory organs of blowflies, and describes tests conducted to determine whether these insects taste with their tarsi and smell with their antennae and palpi. Antennae bear two types of so-called olfactory hairs, while palpi bear only one. With the aid of an olfactometer it has been shown that antennae and palpi do not bear the olfactory organs.In order to explain the proboscis response, described by Minnich, it is not necessary to assume that tarsi bear gustatory organs, because: (1) a tarus bears no sense organs, except nine olfactory pores; (2) it is almost impossible to wet the tarsi with water or sugar water; and (3) when flies were in the proper nutritive condition and liquids were about 3 mm. from the tarsi, the insects were induced by a special method to exhibit the proboscis response. It was further clearly demonstrated by a similar method that tarsi can easily distinguish between chemically pure saccharose water and distilled water when these liquids are about 3 mm. from the tarsi. The responses, obtained by any method, are caused by two stimuli, one mechanical and the other olfactory. The act of touching the feet produces the initial stimulus and brings the liquids almost in contact with the olfactory pores on the tarsi.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 79
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 56 (1934), S. 513-531 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: A study of the male reproductive organs of a hemipteron, Leptocoris trivittatus, has been made. The genital system, which consists of fan-shaped testes; the vasa deferentia, to which a single pair of accessory glands are attached; ejaculatory ducts and the copulatory apparatus, is described and photomicrographs of consecutive parts presented.Then an analysis of the method of aggregation and turning of the sperms is made by means of intravitam technic. Aggregation and turning commence in the early spermatid stage. A spherical cyst forms, the tails first grow centripetally and then push out toward the lower end of the cyst. This line of growth in the cyst moves the head ends of the spermatids to the upper end where aggregation gradually takes place.The cysts spiral up and across the follicles, the moving force being, probably, the elongating tails. Later they spiral down the follicle, development progressing rapidly. The descending bundles are mature sperm, held together by a cytoplasmic cap.The accessory gland secretes a milky substance which probably activates the sperm at a later stage. Peristalsis occurs in the wall of the gland and duct.The process of massing sperm into bundles before copulation insures effective translocation. Then peristalsis and movement of tubular fluids carry the sperm down the duct to the copulatory apparatus.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 80
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 84 (1949) 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 81
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 84 (1949), S. 1-30 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 82
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 83
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 84 (1949), S. 145-183 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 84
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 85
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 84 (1949), S. 525-534 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 86
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 87
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 88
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 89
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 90
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 84 (1949), S. 401-409 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 91
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 84 (1949), S. 427-457 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 92
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 93
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 42 (1926), S. 253-305 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The testis is differentiated from the indifferent gonad in embryos of fourteen days. The indifferent gonad and the sex cords contain large and small cells, both of which are derived from the coelomic epithelium. The large cells have generally been called primordial germ cells, they increase by mitosis and reach their maximum in embryos of seventeen days. But all the large cells degenerate and have completely disappeared by nine days after birth. The large cells, therefore, do not contribute to the formation of cells in the tubules of the adult testis. After the disappearance of the large cells, the solid seminiferous tubules are composed of indifferent epithelial cells of a uniform type, which are descendants of the small cells of the genital ridge, and which later form both the germ cells and the Sertoli cells of the seminiferous tubules of the adult testis.Definitive spermatogonia begin to form fifteen days after birth, when the solid cords are becoming hollow tubules; spermatocytes occur at twenty-three days, when the testes are entering the inguinal canals; spermatids are first observed about thirty-three days, when the testes enter the scrotum, and perfect spermatozoa at forty-eight days. Sertoli cells cannot be clearly distinguished until almost puberty; these cells may be only indifferent epithelial cells. During the development of the seminiferous tubules, a good many cells of all stages of spermatogenesis degenerate.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 94
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 42 (1926) 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 95
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 42 (1926), S. 371-439 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The prochordal plate in the chick is a thickening of the entoderm in the anterior part of the area pellucida. It consists at first of several layers of yolk-charged cells, which finally lose their yolk and form a thin layer of entoderm.The prechordal plate (an area of mesodermal proliferation immediately anterior to the notochord) arises immediately anterior to the primitive streak (and head process when the latter appears) in a part of the region once occupied by the prochordal plate. Later the prechordal plate comes to lie upon the dorsal wall of the foregut.The premandibular cavities arise in condensations of the prechordal mesoderm. The cavities seem to appear during the rapid expansion of the prechordal mesoderm which occurs in response to a release from constraint imposed by surrounding structures. They are connected with one another across the midline by a usually solid bridge of mesoderm.Later, the cavities are replaced by a mesodermal condensation which serves as a mold, on the surface of which the oculomotor muscles appear, arising before the disappearance of the premandibular head cavities.Differences in the relations of notochord and hypophysis in the chick and robin may be explained by an analysis of the growth of the two forms. The analysis furnishes a basis for understanding the relations of the anterior end of the notochord in the mammal.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 96
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 43 (1926) 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 97
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 43 (1926), S. 81-103 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Paramecium trichium varies from 50 μ to 105 μ long with most individuals between 80 μ and 90 μ. The width varies from one-third to one-half the length. It is somewhat depressed dorsoventrally. The broad buccal groove extends from the anterior left border diagonally across the ventral surface to the mouth, which is usually slightly anterior to the middle and to the right side of the median line. The mouth leads into a relatively long cytopharynx containing an undulating membrane. The cytopyge is subterminal and the small caudal tuft of longer cilia is subapical. The plastic ectosarc contains numerous trichocysts. A contractile vacuole apparatus occurs near either end. Each is deeply located and stains more intensely than surrounding protoplasm. In life there appear to be two alternately contracting vacuoles with smaller ones adjacent. Contractions are from fifteen to twenty-five per minute. The macronucleus is medium in size and the single micronucleus is of the ‘caudatum’ type.Binary fission appears to be initiated by a metaphase-like condition of the micronucleus. This is followed by great enlargement and the eventual separation of the chromatin threads into two anaphase groups. The metaphase thus appears to precede the changes which correspond to a prophase in other cases. During division of the body, the two old contractile vacuoles persist as the posterior ones for the daughters, new anterior ones being developed.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 98
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 49 (1930), S. 333-353 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The current view in mammals is that ova are formed in the embryo in large numbers and stored in the ovary as a reserve to be drawn on through adult life; they may persist for long periods ina latent condition, a few resuming active development at each recurring oestrous period; new ova are not and cannot be added.An alternative hypothesis has been presented by several authors: New ova are formed throughout life, from the embryonic period through the time of sexual maturity; each ovum so produced must at once begin its growth and development of die; long latency of oocytes and primary follicles is not possible and does not occur. There is a constant degeneration of most follicles, and only a few come to ovulation. A study of the albino rat presents evidence which is consistent with the second view and supports it more strongly that it does the older hypothesis. Similar evidence is found in other mammals. It seems probable that the newer hypothesis is the correct one, at least in some mammals; further investigation may show it to be of general application.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 99
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 49 (1930), S. 223-249 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: During the course of a hydrobiological survey of Monterey Bay, California, a series of pelagic organisms was taken at a depth of approximately 350 M., which appears to be a link connecting the Echiuroidea (Gephyrea armata) on the one hand and the polychaetes on the other. The range in body length is from 5 mm. to 27 mm.; and in an extended condition the anterior end of the body, with its palps and cirri, bears a close resemblance to a nereid. The supra-oesophageal ganglia and the ventral nerve cord, with eleven pairs of ganglia, are also strikingly annelidan in character. On the other hand, the spacious coelom, communicating with the exterior by a pair of anterior nephridia, allies it with the gephyreans. The same is likewise true of the gonad, which arises from the coelomic epithelium surrounding the genital vessel. The various systems are described in detail, and their resemblances to those of other annelids are indicated. This new species, Poeobius meseres, is made the representative of a new family, the Poeobiidae, which, provisionally at least, is included in the Echiuroidea.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 100
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    Journal of Morphology 49 (1930), S. 277-331 
    ISSN: 0362-2525
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: The entire ovary, including its germ cells, is produced by a local proliferation of peritoneal cells. The germ cells of the embryonic ovary grow, divide, become grouped into nests, pass through synaptic changes, and become primary follicles by three days after birth. At that time, growth of all the ova and follicles begins, and this results in a normal maturation, then a degeneration of all the ova by about thirty-two days after birth; few, if any, of the original germ cells remain after this degeneration. About twenty-three days after birth, there begins a great activity of the germinal epithelium in forming new ova, reaching its maximum between thirty-six and thirty-nine days, but continuing into the adult animal.The definitive ova of the adult are transformed peritoneal (germinal epithelial) cells formed anew during the late youthful and adult life. This occurs chiefly by a local enlargement of single germinal epithelial cells which become surounded by follicle cells and push into the ovary; there is also the production of ova from ingrowing cords of the surface layer of the ovary. The original germ cells pass through synapsis and other meiotic changes in late embryonic and early postnatal periods, but these all degenerate; synapsis cannot be distinguished later than three days after birth. But it is possible to follow, in young and adult ovaries, the transforming germinal epithelial cells into ova which pass through normal maturation and ovulation; therefore, these must be considered as true ova, which they are in fact, even though synapsis cannot be observed in their history.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...