bluuebunny/crossref_metadata_2025_split huggingface dataset:
Oogenesis in a thelytokous wasp, Nemeritis canescens (Grav.)
Authors: Speicher B. R. 
Published: February 2005

AbstractIn the fifty generations of reared Nemeritis, males have been totally lacking. Oogenesis is atypical in (1) the occurrence of a pronounced and lengthy prochromosome stage, (2) the partial fusion of the eleven tetrads at early first anaphase, (3) following first anaphase, a return of all dyads from both poles to form a common second metaphase plate consisting of twenty‐two separate dyads, (4) a second division which forms a single polar nucleus and an egg nucleus, each with twenty‐two chromosomes, (5) the parthenogenetic development of the egg nucleus with twenty‐two chromosomes. Oviposition, which occurs at first anaphase, is followed by a pronounced swelling of the egg through osmosis. Oogonia, follicle cells, cleavage nuclei and somatic cells in later embryogeny all show twenty‐two metaphase chromosomes, while pupai tissue shows also tetraploid and octoploid complexes.
The morphology of the hypophysis of amblystoma
Authors: Roofe Paul Gibbons 
Published: February 2005

AbstractThis paper presents an account of the morphology of the hypophysis and adjacent hypothalamic regions of young adult Amblystoma tigrinum. The description deals primarily with reconstructed models made from blotting paper; transverse and sagittal sections are also considered. A new term, hypophysis, pars subdistalis, is used to describe a discrete portion of the hypophysis embedded in the medial and ventral portion of the pars distalis. The other portions of the hypophysis also are described in detail.
Some factors in the morphogenesis of vertebrate embryonic epithelia
Authors: Sauer F. C. 
Published: February 2005

AbstractThis paper correlates the various aspects of the author's previous work on embryonic columnar epithelia and deals especially with the mechanical factors that determine the form of an epithelium. The origin of the terminal bars, the various forms the terminal bars assume, and the significance of the terminal bar net in maintaining the epithelial structure are discussed. The paper also gives detailed consideration to the elongation of columnar cells after division. When this change in shape cannot be attributed to crowding from without, it is suggested that a thrusting action of elongating spindle fibers is the internal force responsible. In either case elongation is influenced by the development of the terminal web limiting the free surface. Further observations on this structure, first described by the author in 1935, are presented. The terminal web, which is generally present in columnar epithelia, is a specialized part of fixed cytoplasm, condensed, and lying in the plane of the terminal bars. It disappears in mitosis, but its reappearance as the new cell elongates limits the area of the free end of the cell. Hence, the terminal web plays an important part in determining the form of columnar cells.
Comparison of the weights of suprarenals of dogs in oestrus, pregnancy and lactation
Authors: Baker Dan D. 
Published: February 2005

AbstractComparisons have been made of the weights of the suprarenals of 525 mature female dogs in dioestrus, oestrus, pregnancy and lactation. Tables and graphs show that there was a slight increase in the size of the suprarenals during oestrus. There was hypertrophy of both the cortex and the medulla in the oestrous dogs. Only slight increase was shown in the weights of the glands of pregnant animals when the net body weight was considered and no increase when the total body weight was used in the study. There was no hypertrophy of the glands of lactating animals.There was only a slight variation in the seasonal occurrence of oestrus. From 34 to 37% of the total numbers of mature females examined in the seasons were found to be in oestrus. From 13 to 16% of the total numbers were found to be pregnant.
The centriole in the parthenogenetic and fertilized eggs of Habrobracon juglandis
Authors: Spotkov Elias Morlenn 
Published: February 2005

AbstractCyto‐centrosomes containing centrioles but lacking asters originate de novo in great number throughout the ooplasm of Habrobracon eggs during the formation of the first maturation metaphase. These cyto‐centrosomes apparently arise from accessory nuclei which are formed from granules extruded by the germinal vesicle. The accessory nuclei react negatively to the Feulgen nucleal test.Asters similar to those present in artificially parthenogenetic eggs appear around many of the cyto‐centrosomes, thus forming cytasters. These are manifest only after the female pronucleus establishes an association with a cyto‐centrosome, which thus becomes the nuclear centrosome.In the parthenogenetic egg the centriole of the nuclear centrosome is continuous from one cell generation to the next, whereas the centrioles of the cyto‐centrosomes which are unassociated with nuclear material are not perpetuated and disappear during early cleavage.Concerning the origin of the first cleavage centrioles in fertilized eggs, evidence shows that in some ova it is entirely maternal, that is, from two cyto‐centrosomes, one associated with the female pronucleus and occupying one pole of the first mitotic spindle, and the other associated with the male pronucleus and located at the opposite pole; while in other ova it is maternal‐paternal; from two centrosomes, one the sperm centrosome which occupies one pole of the first cleavage spindle, and the other a cyto‐centrosome associated with the female pronucleus and situated at the opposite pole.
Histological and cytological changes in the ovary of Cymatogaster aggregatus during gestation
Authors: Turner C. L. 
Published: February 2005

AbstractViviparity in the teleost fishes is most highly developed in the family Embiotocidae. In Cymatogaster aggregatus, a member of this family, the males are sexually mature at birth. Females born in June and July are inseminated soon after birth and carry the spermatozoa in the ovarian cavity until December when eggs are fertilized. Embryos are retained in the ovarian cavity till the following spring when they are born.The cells of the epithelium lining the ovarian cavity develop internal fluid reservoirs which reach their maximal stage in early gestation when there is an extensive sloughing of epithelial cells. The epithelium returns to its original condition in late gestation and later the cells undergo multiplication. The stroma becomes swollen and contains a large amount of fluid during early gestation and shrinks as the embryos become larger. Many of the eggs, failing to reach maturity at the time of fertilization, degenerate. Degeneration also takes place in numerous smaller ovocytes during gestation but some of them survive to grow during the next season.The cyclical changes in the ovarian tissue of Cymatogaster aggregatus are parallel to those which occur in the ovaries of the Goodeidae and the Jenynsiidae, two other families in which viviparity has been highly developed.
The early development of the avian embryo. I. Endoderm formation
Authors: Jacobson W. 
Published: February 2005

AbstractIn the blastula stage the roof of the subgerminal cavity is composed of an irregular layer of cells, the nuclei of which lie in the upper or middle part of the cytoplasm.On the floor of the subgerminal cavity groups of already degenerating cells occur. They represent the vegetative pole of the blastula. Almost every cell contains glycogen, and mitotic cells show no special orientation.In the gastrula stage the cells of the area pellucida become regularly arranged as a single‐layered, cylindrical epithelium with basally situated nuclei.The yolk endoderm cells are formed from the proliferating upper layer of the area opaca.The embryonic endoderm is formed at the posterior end of the area pellucida by outgrowth of single cells from a circumscribed area, the primitive plate.This plate eventually bends inward to form a typical archenteric canal, through which endoderm continues to invaginate from the epiblast.The endoderm spreads in a cranial and lateral direction until it has formed a complete layer.The epiblast cells lose their glycogen as they invaginate to form endoderm, which is free of glycogen.In the area opaca the upper layer and the yolk endoderm contain glycogen.The mitotic cells of the epiblast of the area pellucida are always orientated horizontally, but in the primitive plate and archenteric canal they are orientated vertically as well.
The early development of the avian embryo. II. Mesoderm formation and the distribution of presumptive embryonic material
Authors: Jacobson W. 
Published: February 2005

AbstractThe first mesoderm cells, and therefore the primitive streak, originate from the epiblast in an axial zone of the third quarter of the area pellucida.The primitive streak grows by epiblastic proliferation only, without any forward movement of the epiblast.Presumptive mesoderm cells invaginate during the existence of the streak.The endoderm plays no part in forming the mesoderm and head process.The epiblast cells lose their glycogen when invaginating through the primitive streak or node, to form the mesoderm or head process, both of which are free of glycogen.When invaginating, the epiblast cells show an increase of lipoids (probably sterols) which decrease as they become mesoderm cells, but are retained in the head process. The higher lipoid content is correlated (1) with the organizing effect of the primitive streak, node and head process; (2) with the behavior of Nile blue marks, which when reaching the streak, node or head process are retained and no longer follow the movements of the individual cells.The shortening of the primitive streak is effected by the approximation of the epiblast from either side, which begins at the cranial end of the streak and spreads caudally. There is no backward migration of the cells of the primitive node.The arrangement of the presumptive embryonic material in the epiblast at the end of the blastula stage is described.
The changes in the central nervous system during the life history of the beetle, Passalus cornutus fabricius
Authors: Cody Frances Perle , Gray I. E. 
Published: February 2005

AbstractIn early embryonic stages of Passalus there are, in addition to the brain and suboesophageal ganglion, three thoracic and ten abdominal ganglia; one ganglion to each body segment. Before hatching the tenth, ninth and eighth abdominal ganglia coalesce. During the three larval instars the terminal ganglion remains in the sixth abdominal segment and only minor changes occur. By the end of the third day of pupal life the adult form of the nervous system is practically assumed. All abdominal ganglia are fused into a single, solid, elongated ganglionic mass. Connectives have disappeared between meso‐ and meta‐thoracic and between metathoracic and abdominal ganglia; and with exception of the brain, sub‐oesophageal and prothoracic ganglia, the entire ventral chain has come to lie in the mesothorax. The peripheral nerves still arise from the ganglia and ganglionic mass in their same relative positions and still supply the same segments in which they were originally located.
The development of the imaginal eye in the larva of Drosophila melanogaster
Authors: Enzmann E. V. , Haskins C. P. 
Published: February 2005

AbstractA study has been made of the growth of the eye anlage, and of the increase in number of the elements of the dioptric system of larvae of Drosophila melanogaster.In newly hatched larvae the eye rudiment grows fast, but slows down later and becomes nearly stationary during the second half of larval life. The increase in number of elements in the eye disc parallels the growth of the whole anlage and reaches a maximum about 70 hours after hatching. The imaginal disc cells increase in number but not in size, in contrast to other larval cells which increase in size but not in number.
The comparative morphology of the vertebrate spinal column. Its form as related to function
Authors: Rockwell Helen , Evans F. Gaynor , Pheasant Homer C. 
Published: February 2005

AbstractThe form of the vertebral column is definitely related to its function as a supporting rod, a base for attachment of body and limb muscles, and a protection of the spinal cord and nerves. Primitively composed of a series of simple undifferentiated blocks, it progressively becomes complicated through development of articular processes giving added strength and greater mobility. Simultaneously, the centrum and the neural arch become adapted to withstand tension and compression stresses which vary with the movements possible in different regions of the column. These movements are partially determined by the plane of the zygapophyses and the nature of the intercentral articulation, together with the action of the axial muscles and ligaments.In fish and primitive tetrapods the axial musculature serves as the chief locomotor organ and consists of a series of myomeres extending with little interruption from the head to the tail. In tetrapods the locomotor function is taken over by the limbs and the axial muscles become progressively differentiated into long flexors and extensors of the column and gradually lose their external segmentation.
Sexual differentiation of urogenital ducts of Ambystoma tigrinum
Authors: Rodgers Leland T. , Risley Paul L. 
Published: February 2005

AbstractAdult salamanders of Ambystoma tigrinum show a high degree of sexual dimorphism. The normal growth of the urogenital ducts system in relation to the development of the gonads is traced from the sexually indifferent period preceding metamorphosis to sexual maturity at 1 year. Differentiation and growth of secondary sex characters is correlated with spermatogenesis in the male and with growth of ovocytes in the female.Testicular hormone manifests its initial appearance in male differentiation of the wolffian and urinary collecting ducts following metamorphosis. Growth of ovocytes and oviducts begins before metamorphosis and may be assumed to indicate the initial appearance of the ovarian hormone. Females retain the larval arrangement of wolffian and urinary ducts. The oviducts of the male regress during the period of rapid male differentiation. This suggests the possibility of antagonistic activity of the male hormones in Ambystoma.
Blood‐cell changes during experimental nutritional deficiency anemia and recovery in the newt, Triturus viridescens, with special reference to the erythrocytes
Authors: Jordan H. E. 
Published: February 2005

AbstractA batch of fifty newts was subjected to complete food deprivation for a period of 4 months. During the experiment twenty‐two individuals died and twenty‐eight were killed at intervals. From the end of the second month the erythrocytes began to show in increasingly greater numbers a progressive alteration in the nucleo‐cytoplasmic ratio. The nucleus of these atypical erythrocytes gradually enlarged and ultimately occupied the entire cytosome. Meanwhile the nuclear reticulum became extremely fine and closely meshed, eventually appearing practically homogeneous and relatively chromophobic. The end result was complete dissolution. The leukocytes became greatly reduced in number, the eosinophils disappearing completely. The neutrophils and basophils were agranular in the blood smears. The erythrocyte transformations represent late results of a chain of factors: cytoplasmic hypotonicity, nuclear endosmosis, attenuation and fenestration of nuclear membrane. The subcapsular lymphogranulocytopoietic tissue of the liver had almost completely disappeared. The spleen was greatly reduced in size; it was essentially lymphoid in character and erythrocytopoietic activity had ceased practically completely. Complete restoration of normal conditions in blood, liver and spleen was effected by the end of 2 weeks by feeding with earthworms. The regenerating blood showed many naked nuclei of disintegrating atypical erythrocytes, many immature erythrocytes in mitosis, increased number of small lymphocytes (lymphoid hemoblasts), large but variable numbers of microcytes, many giant thrombocytes and normal granulocytes.
The absorption of colloidal carbon from the body cavity of Ammocoetes. A study of the structure and function of the larval kidneys and blood forming tissues
Authors: Torrey Theodore W. 
Published: February 2005

AbstractColloidal carbon injected into the coelom of the larval lamprey, Ammocoetes, is taken up directly by the pronephric tubules. Due to the absence of nephrostomes the mesonephric tubules do not function in a similar way. The tubules of neither show any intracellular deposition of carbon. The reticular elements which support both these kidneys exhibit pronounced phagocytic and hemocytopoietic activity. Carbon in either a free or included form reaches all the other organs both as a result of direct invasion or secondary distribution by the vascular system. The liver is the only organ whose vascular endothelium exhibits cytopoietic properties. To the diffuse spleen as a site of blood cell formation thus should be added the reticular tissue of the pronephros and mesonephros and the vascular endothelium of the liver. Playing a minor role in a similar way are the intestinal mucosa exclusive of that in the typhlosole and the spongy tissue dorsal to the neural tube.
A cytological study of the pleuropodia of Melanoplus differentialis (Orthoptera, Acrididae) which furnishes new evidence that they produce the hatching enzyme
Authors: Slifer Eleanor H. 
Published: February 2005

AbstractIn an earlier paper (Slifer, '37) experiments were reported which showed that in Melanoplus differentialis eggs the hatching enzyme, which destroys the white cuticle, is secreted by the pleuropodia (appendages of the first abdominal segment of the embryo) during the last few days of incubation. In the present report the development and differentiation of the pleuropodia, together with the cytological changes which occur in them before, during and after they become functional, have been followed. The time at which the secretion granules are discharged from the pleuropodial cells was found to be closely correlated with the time at which the tough, white cuticle begins to disintegrate. The cytological evidence, then, supports the author's earlier conclusion, based upon experimental work, that the pleuropodia secrete the hatching enzyme.
The follicular cycle in the sexually mature thirteen‐lined ground squirrel (Citellus tridecemlineatus Mitch.)
Authors: Pliske Edward C. 
Published: February 2005

AbstractThe germinal epithelium was studied in an effort to determine its role in postpubertal ovogenesis. Active and inactive areas of epithelium were observed regardless of the oestrous periods. The active areas, exemplified by numerous mitoses and a frequent stratification of the epithelium, are foci for egg cell production.Egg cells are produced from the germinal epithelium by: activation, migration and transformation of single germinal epithelial cells; migration and differentiation of nests of cells; ingrowths of cords of cells.Young ova in the cortex of the ovary are at first surrounded by a single layer of flattened follicular cells of germinal epithelial origin. In the subsequent development of the follicle stratified layers make their appearance. The zona pellucida appears as a well‐defined structure coincident with the stratification of the follicular layers.The follicular cavity develops as a split between the follicular cells at one side of the follicle. In the mature follicle the cavity is broad and contains liquor folliculi. The theca interna and externa are not distinguishable until the follicle is highly cellular.
Studies on the structure of nucleolusforming regions and related structures in the giant salivary gland chromosomes of Diptera
Authors: Poulson D. F. , Metz C. W. 
Published: February 2005

AbstractSalivary gland nuclei in Chironomus regularly show large, conspicuous nucleoli. In Sciara no true nucleoli have been found, but sometimes certain particular chromosome regions expand greatly, forming ‘puffs’ or ‘bulbs,’ somewhat nucleolus‐like in nature. Detailed study has been made of the chromosome structure in the affected regions in both genera.In the nucleolar regions of Chironomus the banded structure of the chromosome is distinctly modified. In the case of the large nucleolus the chromosome breaks up into a heavy network in which solid discs are replaced by interconnected chromatic spheres and granules, extending out somewhat into the clear nucleolar substance. In the case of the smaller nucleolus, Balbiani's ring, the banded structure is less disturbed. A chromatic network, resembling a system of rootlets, runs out from the chromatic bands into the clear nucleolar substance.In Sciara ocellaris the ‘puff’ regions are at times normally banded, but at other times in the condition described as ‘puffed.’ The same is true of the ‘bulb’ regions. The relation between nucleoli, puffs and bulbs is discussed. Also that between ‘heterochromatin’ and ‘euchromatin.’ Evidence seems to indicate that the latter are merely extremes in a continuous range involving different relative amounts of chromatic and achromatic materials. The ‘puff’ regions appear to be structurally similar to the chromocenter in Drosophila.
The postpartum formation of egg cells in the cat
Authors: Kingsbury B. F. 
Published: February 2005

AbstractThe summary of this paper is as follows:
From an examination of 108 ovaries from eighty‐nine individuals it was apparent that, in the cat a certain but variable amount of degeneration of primary follicles occurs in all life epochs.
The primary oocytes undergo the degeneration, while the follicle cells remain for an undetermined time.
The most profound instances of such degeneration were encountered in kittens of 6 to 9 weeks, accompanying or follwing the resolution of the egg cords into primary follicles and the establishment of the cortical or marginal zone. A sporadic degeneration of young oocytes occurs at earlier periods.
No evidence was seen of a new formation of egg cells from the residual follicle cells after the degeneration of the oocytes. The degenerations of the 6 to 9 weeks epoch are not believed to be of universal occurrence.
No adequate evidence was encountered of a new formation of egg cells from the surface epithelium, either before or after sexual maturity.
No evidence linking the degeneration of primary follicles with the estrous cycle was seen.
The stock of primary follicles established in the first few weeks after birth is believed to be adequate for the growth of graafian.
On a new law of the bi‐triangular medial concentration of the cephalic appendages in the chilopoda and the insecta
Authors: Roonwal Mithan Lal 
Published: February 2005

AbstractA law of the “bi‐triangular medial concentration of the cephalic appendages” in the Chilopoda and the Insecta is propounded. According to it, the cephalic appendages lying in front of and behind the intercalary pair of appendages undergo a concentration, both in phylogeny and in ontogeny, toward the median line. In this way, two hypothetical triangles, termed the ‘anterior or procephalic triangle’ and the ‘posterior or gnathocephalic triangle’ are formed, having a common base in the level of the intercalary appendages. The cephalic appendages occupy roughly either the sides or the apices of the triangles and the degree of their final medial concentration is in direct proportion to their distance from the triangular base. Before the final bi‐triangular condition is achieved by the appendages, varying types of transitory shiftings are passed through.