bluuebunny/crossref_metadata_2025_split huggingface dataset:
Observations on cell lineage of internal organs of Drosophila
Authors: Lawrence Peter A. , Johnston Paul 
Published: April 2021

ABSTRACT
Adult Drosophila mosaics can be used to study cell lineage and to map relative positions of primordia at the blastoderm stage. This information can define which germ layer an organ comes from and can help build models of genetic regulation of development. Here we use the sdh cell marker to map internal organs in mosaics made by nuclear transplantation. We confirm that oenocytes arise from the same progenitors as the adult epidermis, but that muscles and fat body have a separate (mesodermal) origin and that the precursors of epidermis and central neurones are closely intermingled in the ventral, but not dorsal, epidermis. We find that the malpighian tubules are more closely related to the hindgut than the midgut and are therefore ectodermal in origin. We find that each intersegmental muscle in the thorax arises from one specific parasegment in the embryo, but that very small numbers of myoblasts wander and contribute to muscles of inappropriate segments. We present evidence indicating that the visceral muscles of the midgut have a widely dispersed origin (over much of the embryo) while the somatic mesoderm of the female gonad comes from a small number of abdominal segments. The visceral mesoderm of the hindgut develops from a localized posterior region of the embryo.
The role of cell adhesion in the synchronization and orientation of polarization in 8-cell mouse blastomeres
Authors: Johnson Martin H. , Maro Bernard , Takeichi Masatoshi 
Published: April 2021

ABSTRACT
A detailed investigation into the activity of the homotypic, Ca2+-dependent cell-cell adhesion system (CDS) m the early mouse embryo has revealed its involvement in (i) the synchronizing of the time of polarization of 8-cell blastomeres, and (ii) the orienting of the axis of polarization. Since polarization marks an important and early event in the process of cell diversification in the mouse embryo, it is concluded that the CDS provides an important component of the system by which the temporal and spatial elements of normal development are integrated.
The pituitary adrenocorticotropes originate from neural ridge tissue in Xenopus laevis
Authors: Eagleson Gerald W. , Jenks Bruce G. , van Overbeeke A. P. 
Published: April 2021

ABSTRACT
A series of grafting experiments was conducted to determine pituitary origins prior to brain tube closure in Xenopus laevis. Extirpation experiments indicated that the ventral neural ridge (VNR) tissue of stage-18+ embryos was essential for pituitary development. Bolton-Hunter reagent was used to label stage-18+ VNR tissue with 125I, and this tissue was then returned to the donor and its subsequent ontogenesis followed. Labelled tissue was ultimately found in the ventral hypothalamus, the ventral retina, and the anterior pituitary. Using immunocytochemical techniques with antisera to adrenocorticotropin (ACTH), it was found that some of the VNR-derived cells were corticotropes. A region of the nucleus infundibularis which was radioactive labelled also gave ACTH-positive immunoreaction. This might indicate that some ACTH-containing neurones of the hypothalamus are VNR in origin. We suggest that stage-18+ VNR is the site of attachment of brain and anterior pituitary ectoderm. Part of this adherence point is eventually incorporated into the anterior pituitary and will form corticotropes. It is concluded that the ventral retina, the preoptic region of the hypothalamus, some hypothalamic ACTH-immunoreactive cells, and the most anterior portion of the adenohypophysis are all ventral neural ridge in origin.
Some histochemical and ultrastructural observations on the early foetal pig testis
Authors: van Vorstenbosch C. J. A. H. V. , van Rossum-Kok C. M. J. E. , Colenbrander B. , Wensing C. J. G. 
Published: April 2021

ABSTRACT
Testes of foetal pigs between 26 to 35 days postcoitum (p.c.) were investigated histochemically and ultrastructurally.
Diaphorase and Δ5-3β-hydroxysteroid dehydrogenase activities were studied using, respectively, NADH and pregnenolone and dihydroxy androsterone as substrates.
Ultrastructurally, attention was focused on the development of mesenchymal cells and on the sustentacular cells in the primitive sex cords in an attempt to detect the origin of Leydig cells.
Histochemically there is a concentration of activity toward the interstitium with increasing age. Also the reactions increase in intensity. Ultrastructurally no evidence for Leydig cell development from Sertoli cells could be observed. Mesenchymal cells between the sex cords show a development toward Leydig cells. This is absent in mesenchymal cells in the future tunica albuginea.
Before 30 days p.c. no ‘true’ Leydig cells can be observed morphologically. The role of the rough endoplasmic reticulum/mitochondrial complex, which is present in many mesenchymal and sustentacular cells, is discussed.
Sensory nerve routes in chick wing buds deprived of motor innervation
Authors: Swanson Gavin J. , Lewis Julian 
Published: April 2021

ABSTRACT
To what extent do motor and sensory nerve fibres depend on one another for guidance during the development of peripheral nerve patterns? This question has been examined by looking at the paths taken by sensory nerve fibres growing into the embryonic chick wing in the absence of motor axons. The precursors of the motoneurones were destroyed by irradiating the appropriate part of the neural tube with a focused beam of ultraviolet light, before axons had grown out. The limb nerve patterns seen 5 to 7 days later revealed that sensory fibres followed the usual paths of main nerve trunks and formed cutaneous nerve branches in an almost normal way. However, the sensory fibres did not take the paths where muscle nerve branches are normally seen. Apparently, sensory axons for the most part do not depend on motor axons for guidance, except in the case of proprioceptive fibres, which require guidance from motor axons over the final steps of their path into muscle.
Embryonic differentiation of fibre types in normal, paralysed and aneural avian superior oblique muscle
Authors: Sohal G. S. , Sickles D. W. 
Published: April 2021

ABSTRACT
The influence of innervation on the initial differentiation of muscle fibre types was investigated by using the trochlear nucleus-superior oblique muscle system of duck. The adult muscle is composed of three types of fibres (designated as type I, II, III) as identified with the histochemical techniques for ATPase pH sensitivity. Type I fibre ATPase activity was acidstable, alkali-labile; type II alkali-stable, acid-labile; and type III both acid- and alkali-stable. These types showed variable mitochondrial α-glycerophosphatase dehydrogenase, nicotinamide adenine dinucleotide tetrazolium reductase, and phosphorylase activity. Type I and II fibres are primarily located in the portion of the muscle adjacent to the orbit whereas the rest of the muscle is primarily composed of type III fibres. In the normally developing muscle, type II and III fibres are present as early as embryonic day 9; one day prior to the arrival of nerve fibres in the muscle. Type I fibres are first observed on embryonic day 17. On day 22 the percentages of type I, II and III fibres are 29, 53 and 18, respectively. As the development progressed the percentages of type I and II fibres decrease and after hatching 76 % of the fibres belong to type III, 17 % to type II and only 7 % to type I. In embryos paralysed with daily application of 3 mg d-tubocurarine (d-TC) from day 9 onwards the differentiation of type II and III fibres occurs, but type I fibres were never observed in the paralysed muscles. These muscles also contained significantly fewer myotubes than the normal muscle. By contrast, when the muscle was made aneural by permanent destruction of motor neurones on embryonic day 7 all three types of fibres differentiated. When embryos with aneural muscles were also subjected to d-TC treatment the type I fibres failed to differentiate. It is concluded that the initial differentiation of fibre types is independent of innervation and that primary myotubes are capable of differentiating into all three types of fibres. The absence of type I fibres in curarized muscles may be due to some unique effect of d-TC on the muscle itself.
Cinemicrographic study of the cell movement in the primitive-streak-stage mouse embryo
Authors: Nakatsuji N. , Snow M. H. L. , Wylie C. C. 
Published: April 2021

ABSTRACT
Migration of the mesoderm cells in the primitive-streak-stage mouse embryo was directly studied by cinemicrography using whole embryo culture and Nomarski differential interference contrast optics. Relative transparency and small size of the early mouse embryos enabled direct observation of the individual cells and their cell processes. Seven-day-old mouse embryos were isolated and cultured in a small chamber in a medium consisting of 50 % rat serum and 50 % Dulbecco’s modified minimum essential medium. The mesoderm cells move away from the primitive streak in both anterior and antimesometrial (distal) directions at a mean velocity of 46 μm h−1. They extend cell processes and constantly change cell shape. They do not translocate extensively as isolated single cells, but usually maintain attachment to other mesoderm cells. They show frequent cell division preceded by rounding up of the cell bodies, and accompanied by vigorous blebbing before and after cytokinesis. This study shows that it is possible to examine the motility of embryonic cells inside the mammalian embryo by direct observation if the embryo is small and transparent enough for the use of the Nomarski optics.
Histochemical and autoradiographic study of the cultured rat visceral yolk sac
Authors: Sobis H. , Goebels J. , Vandeputte M. 
Published: April 2021

ABSTRACT
The proliferation and differentiation potentiality of the rat visceral yolk sac was investigated both in organ culture and after grafting in vivo. Using alkaline phosphatase as a marker for germ cells, it was shown that these cells are absent in the 12-day-old visceral yolk sac examined before and after organ culture. Therefore, the only cells that proliferate and differentiate must be of endodermal and/or mesodermal origin. By labelling the cells with [3H]thymidine both the endodermal and mesodermal cells were found to proliferate. After 10 days in organ culture or implantation in vivo differentiated tissues (e.g. squamous epidermis, endodermal cysts and giant trophoblast cells) were regularly detected. Several of these differentiated cells contained the radiolabel indicating that they derived from the initial proliferating endodermal and/or mesodermal cells.
Quantification of the transition from oocyte-coded to embryo-coded glucose phosphate isomerase in mouse embryos
Authors: West John D. , Leask Rosemary , Green J. F. 
Published: April 2021

ABSTRACT
A quantitative electrophoretic analysis of glucose phosphate isomerase (GPI-1) allozymes produced by heterozygous Gpi-1sa/Gpi-1sb mouse embryos has enabled us to estimate separately the contributions of GPI-1 enzyme that were (1) oocyte coded, (2) encoded by the embryonic, maternally derived Gpi-1sa allele and (3) encoded by the embryonic, paternally derived Gpi-1sb allele. The oocyte-coded GPI-1 activity is stable until days and then declines and is exhausted by to days post coitum (p.c.). The maternally and paternally derived Gpi-1s alleles are probably usually activated synchronously but several possible exceptions were observed. This activation was first detected in -day embryos. Total GPI-1 activity falls to a minimum around to days, even though embryonic gene expression has already begun. The profile of oocyte-coded GPI-1 activity is consistent with the suggestion (Harper & Monk, 1983) that there is a mechanism for the removal of oocyte-coded gene products at around days p.c. The method of analysis described is applicable to other dimeric enzymes with electrophoretic variants.
Retinoic acid-binding protein in the chick limb bud: identification at developmental stages and binding affinities of various retinoids
Authors: Maden M. , Summerbell D. 
Published: April 2021

ABSTRACT
The application of retinoic acid (RA) to the developing chick limb bud causes 6-digit double posterior limbs to form instead of the normal 3-digit limb. As an attempt to begin a molecular analysis of this phenomenon we have identified and characterized a soluble cytoplasmic receptor for RA, namely cytoplasmic retinoic acid-binding protein (CRABP), from the cells of the chick limb bud. It is present from stages 20–35 at similar levels and has an apparent Kd of 140–280 nM. In competition experiments with other retinoids Ro 13-7410 was found to be the most effective at competing for sites on CRABP followed by all-trans-RA, 13-cw-RA, Ro 10-1670 and retinal. Retinol, retinyl palmitate, retinyl acetate, etretinate and arotinoid showed low or no affinity for CRABP. Specificity for binding was thus demonstrated since analogues with an acid end group competed effectively, the aldehyde competed less effectively and the ester or alcohol groups did not compete. At the concentration of RA that needs to be administered to cause duplications in the pattern of the limb bud, we estimate that 4 % of the CRABP present in the limb bud has RA bound. The similarities between steroid receptors in the mediation of steroid hormone action and CRABP in the mediation of RA action is discussed. In this regard we note that while there are 104 steroid receptors per cell in other cell types we estimate that there are about 105 RA receptors per cell in the chick limb bud.
A mesoderm-inducing factor is produced by aXenopuscell line
Authors: Smith J. C. 
Published: April 2021

ABSTRACTInductive interactions play a major role in the diversification of cell types during vertebrate development. These interactions have been extensively studied in amphibian embryos (usually Xenopus laevis) where the earliest is mesoderm induction, in which an equatorial mesodermal rudiment is induced from the animal hemisphere under the influence of a signal from the vegetal hemisphere. The molecular basis of mesoderm induction is unknown, although Tiedemann has isolated a protein from 9- to 13-day chick embryos that has the properties one would expect of a mesoderm-inducing factor. However, the relevance of this molecule to the events of early amphibian development is unclear, and it is a matter of some importance to discover a Xenopus mesoderm-inducing factor.In this paper I show that the Xenopus XTC cell line secretes mesoderm-inducing activity into the culture medium. Isolated animal pole regions cultured in XTC-conditioned medium differentiate into muscle and notochord, while controls form ‘atypical epidermis’. Three different cell lines - XL, XL177 and KR - secrete no such activity. Preliminary characterization of the XTC mesoderm-inducing activity indicates that the active principle is heat stable, trypsin sensitive, nondialysable, and has an apparent relative molecular mass of about 16000. Work is in progress to characterize the activity further and to discover whether the mesoderm-inducing factor is also present in normal embryos.
Studies on the behavior of mitochondrial DNA: Synthesis of mitochondrial dna occurs actively in a specific region just above the quiescent center in the root meristem of Pelargonium zonale
Authors: Kuroiwa Tsuneyoshi , Fujie Makoto , Kuroiwa Haruko 
Published: April 2021

ABSTRACT
The fate of mitochondrial nuclei (known as nucleoids or mt-nuclei), which contain extremely small amounts of DNA, was followed in thin sections of the root meristem of Pelargonium zonale by embedding of samples in Technovit 7100 resin and double staining with 4′-6-diamidino-2-phenylindole (DAPI) and acridine orange, in combination with light-microscopic autoradiography and microphotometry. The synthesis of cell-nuclear DNA and cell division occurs actively in the root meristem, between 150 μm and 700 μm from the tip of the root. For simplicity, cells in S phase in the cortex were selected for main analysis as the model system for examination of cell proliferation. It is estimated, on the basis of the length of the cells in longitudinal median sections, that the cells in the cortex, which are generated in the area just above the quiescent center (QC) about 150 μm from the tip, enter the elongation zone after at least five divisions. In the entire cortex, individual cells in S phase have approximately 230 mitochondria that each contain one mt-nucleus. The observation suggests that individual mitochondria divide once per mitotic cycle in the entire region of the meristem. By contrast, on the basis of incorporation of [3H]thymidine into mt-nuclei, the synthesis of mitochondrial DNA (mtDNA) occurs independently of the mitotic cycle in a restricted region just above the QC. Fluorimetry, using a videointensified microscope photon-counting system (VIM-PICS), revealed that the mtDNA content per mt-nucleus in the cells just above QC, where the synthesis of mtDNA is active, corresponds to approximately 3000 kilobase pairs (kbp) but, in the meristematic cells just below the elongation zone of the root it falls to less than 170 kbp. These findings strongly suggest that the amount of mtDNA per mitochondrion which has been synthesized in the region just above the QC is reduced stepwise as a result of continuous divisions of mitochondria in the absence of the synthesis of mtDNA. This phenomenon would explain why differentiated cells with a large vacuole in the elongation zone have mitochondria that contain only extremely small amounts of mtDNA.
Formation of the milk fat globule membrane without participation of the plasmalemma
Authors: Wooding F. B. P. 
Published: April 2021

ABSTRACT
In goat mammary tissue under certain conditions perfusion fixation produces a considerable swelling of the rough endoplasmic reticulum and the appearance, in a small number of cells, of intracellular vacuoles which contain lipid globules and casein particles. The morphological evidence suggests that these vacuoles form by fusion of Golgi vesicles. By this process the characteristic structure of the milk fat globule membrane (MFGM) is produced around the lipid globules without any contribution from the plasmalemma. This corroborates the earlier suggestion that normal MFG secretion involves the Golgi vesicles directly.
Stimulation of DNA synthesis by prolactin in rabbit mammary tissue
Authors: Bourne R. A. , Bryant J. A. , Falconer I. R. 
Published: April 2021

ABSTRACTThe capacity of mammary gland tissue slices to incorporate [3H]thymidine into DNA was studied at intervals after intraductal injection of prolactin. Prolactin markedly increased the rate of incorporation of thymidine into DNA (as extracted by HClO4 or by sodium dodecyl sulphate). The increase in incorporation rate occurred within 6 h of prolactin injection. Autoradiography of mammary tissue, after administration of [3H]thymidine in vivo, showed that the increased rate of incorporation of thymidine was caused by an increase in the number of alveolar cells entering 5-phase. These results are discussed in relation to current theories concerning functional differentiation of mammary tissue.
Patterns of incorporation of [3H]galactose by cells of Zea mays root tips
Authors: Dauwalder Marianne , Whaley W. G. 
Published: April 2021

ABSTRACT
[3H]galactose shows a selective pattern of uptake distribution in the apical portion of the root tip of Zea mays. In cells entering division it is incorporated into the Golgi apparatus within 10 min and is transferred from that organelle to the forming cell plate.
The pattern of uptake suggests a specific biochemical activity on the part of the Golgi apparatus at the time of division so far as the incorporation of galactose is concerned. Apparently little galactose is converted to glucose in the most apical portion of the root. In normal secretory cells, the heaviest uptake is found in the sieve tube elements, epidermal cells and the outer cells of the root cap.
Cytochalasin B and embryonic heart muscle: Contractility, excitability and ultrastructure
Authors: Sachs H. G. , Mcdonald T. F. , Springer M. 
Published: April 2021

ABSTRACT
The effect of cytochalasin B (CB) on beating, electrical activity and cytological ultrastructure of embryonic hearts and tissue-cultured heart preparations was investigated. The inhibition of spontaneous pulsation and the subsequent recovery after drug washout were found to be dosedependent and to be a function of the type of preparation. In the presence of CB, spontaneous action potentials can be recorded from all three (intact hearts, isolated myocytes, reaggregated cells) after cessation of all visible contractions, although the action potential duration is reduced. CB at 0·5–10 μg/ml was found not to uncouple heart cells electrically nor to prevent cells from aggregating and establishing new electrical coupling. In all 3 systems, however, CB does result in disruption of myofibrillar organization. After 30 h in CB (2 μg/ml) bundles of myofilaments are found to be randomly oriented, with Z-band material condensed into amorphous bodies, no longer aligned with the myofibril, but remaining in register between the A-bands. Within the bundles the normal hexagonal cross-section of thick and thin filaments is maintained. The unaligned Z-bodies, however, demonstrate attached thin filaments of very reduced length. Following washout of the drug, normal sarcomeric organization is restored in parallel -with resumption of spontaneous beating. The present data, therefore, are consistent with the hypothesis that one major effect of CB is an alteration in myofibril (myofilament) stability, and that this effect alone is sufficient to account for the observed inhibition of contractility.
Fine-structural identification and organization of the epidermal proliferative unit
Authors: Allen T. D. , Potten C. S. 
Published: April 2021

ABSTRACT
Mouse dorsal interfollicular epidermis has a vertical organization consisting of approximately 1400 units/mm2. Each unit is identified by its uppermost 4 to 6 layers of roughly hexagonal flattened cornified cells or squames, which are stacked in a precise vertical column. Beneath each column of squames there are 3 differentiating cells and a group of 10 or 11 basal cells, which provide cells to replace those lost by desquamation at the top of the squame column. The whole unit is termed an epidermal proliferative unit or EPU. In the central region of the basal layer of each EPU is a single dendritic Langerhans cell, devoid of desmosomes, but held in position by the surrounding keratinocytes. The dendrites radiate outwards between the keratinocytes to the periphery of the unit. Keratinocyte migration into the spinous layer takes place from the edge of the unit. In the squame column itself, a modified cell-to-cell attachment (squamosome) runs around the edge of each cornified cell, and attaches it to the overlapping region of cells from adjacent squame columns.