The History of Staining the Development of Cytological Staining

Perhaps no other period has contributed more to our knowledge of the cell than the period 1875-1895. During these years most fundamental cytological phenomena were seen and described. Mitosis, maturation and fertilization, the great cornerstones of cytology, were firmly laid by the remarkable researches of Flemming, Strasburger, Van Beneden, Oscar and Richard Hertwig, Boveri and many others. Upon these researches experimental cytology developed and the significance of the morphological phenomena to inheritance and development was pointed out by such masters as W. Roux, Weismann, O. Hertwig, Boveri and E. B. Wilson.     

A Century of Sea Urchin Development

SYNOPSIS. In the last quarter of the nineteenth century severalinvestigators including Richard and Oskar Hertwig, Theodor Boveri,Hans Driesch, Curt Herbst, T. H. Morgan and others turned theirattention to sea urchin eggs and early embryos. This favorablecombination of outstanding investigators and the sea urchinembryo as an experimental organism contributed to a fundamentalunderstanding of the cell, fertilization and heredity. The advantagesof the sea urchin continued to be recognized as experimentalembryologists used these embryos to develop the concepts ofgradients, regulative development and inductive interactions.Then, as developmental biology arose from chemical embryology,the sea urchin embryo once again emerged as an ideal experimentalanimal, pivotal in the understanding of the molecular and developmentalbiology of eukaryotic organisms.     

Neither a germ line-specific nor several somatically expressed genes are lost or rearranged during embryonic chromatin diminution in the nematode Ascaris lumbricoides var. suum

Ascaris lumbricoides var. suum is a parasitic nematode of pigs. Its embryos undergo chromatin diminution between the third and fifth cleavages, resulting in the loss of about 30% of the DNA from all somatic precursor cells while the germ line DNA stays intact. Most of the eliminated DNA has been shown to be satellite sequences. Theodor Boveri [(1910) In "Festschrift fur R. Hertwig, III," Vol. 3, pp. 131-214, Fischer] proposed that functions essential only to the germ line might be lost from the soma. We have examined this proposal by cloning a gene encoding the major sperm protein (MSP) using a cloned MSP gene from Caenorhabditis elegans as a probe. The MSP appears to be expressed only in the testis of Ascaris, as it is in Caenorhabditis. Actin and alpha tubulin were also cloned to serve as somatically expressed gene controls. By probing Southern blots of somatic and germ line DNA with these cloned genes, it was found that none of them was lost or rearranged during chromatin diminution. Thus at least one germ line-specific gene is neither lost nor rearranged during chromatin diminution. We also found that the two nematode species differ widely in their numbers of both MSP and actin genes. Caenorhabditis has greater than 30 MSP genes, but Ascaris has no more than three; whereas Ascaris has many more actin genes than Caenorhabditis.     

Immunohistochemical investigation of lymphatic vessel formation control in mouse tooth development: lymphatic vessel-forming factors and receptors in tooth development in mice

The presence of lymphatic vessels in dental pulp has recently been controversial, and no conclusion has been reached. In this study, we investigated the control of lymphangiogenesis with dental pulp development in the mouse mandibular molar using VEGF-C, VEGF-D, and VEGFR-3 as indices of lymphatic vessel-controlling factors. In addition, to distinguish blood and lymphatic vascular epithelial cells, we performed immunohistochemical analysis using von Willebrand factor (vWF) and statistical analysis. In dental papilla in the bell-stage non-calcified period, mesenchymal cells positive for VEGF-C, VEGF-D, and VEGFR-3 increased and lumen-forming endothelial cells were noted, but vWF was negative, suggesting that these were actively forming lymphatic vessels. Positive undifferentiated mesenchymal cells, an increase in endothelial cells in dental pulp, and lumen expansion were noted early after birth. Positivity was also detected in the odontoblast layer and sheath of Hertwig after birth, suggesting that these factors also play important roles in odontoblast differentiation and maturation and periodontal ligament and tooth root formation. We embryologically clarified lymphatic vessel formation in dental pulp and a process of lymphatic vessel formation from blood vessels, suggesting involvement of the surrounding tissue, odontoblasts, and sheath of Hertwig in vessel formation.     

Hansemann, Boveri, chromosomes and the gametogenesis-related theories of tumours

Theodor Boveri (1862-1915) is often credited with suggesting (in 1914) the first chromosomal theory of cancer, especially in terms of abnormal numbers of chromosomes arising in cells by multipolar mitoses in adult cells. However, multipolar mitoses in animal cells had been described as early as 1875, and Hansemann (1858-1920), in publications between 1890 and 1919, included this mechanism among various ways by which abnormal chromosome numbers might arise in cells and cause tumour formation. Both theories were conceived in a period when gametogenic ideas of tumour formation were current. Boveri based his theory on the observation that some cells in early sea urchin embryos having abnormal chromosome complements wander from their usual developmental paths. His observation may have been seen by other authors at the time as support for Cohnheim's "embryonic cell rest" theory of cancer. Hansemann's contribution is seen as both the original, and the more significant of the chromosomal theories of cancer.     

Caryological behavior during the first phases of dedifferentiation and habituation inNicotiana bigelovii

Summary Hypocotylar tissues ofNicotiana bigelovii var.quadrivalvis seedlings were induced to dedifferentiate and to habituate after a short treatment with 2,4-D or kinetin.Investigation by cytophotometry and chromosome counts on the nuclear cytology of callus induction and development in minimal medium showed, in addition to diploid cells, an high incidence of aneuploid nuclei. Amitotic phenomena have frequently observed during the culture period. The sequence of nuclear events were not influenced by the hormonal composition of the medium.The origin of these aneuploid cells from nuclear fragmentation processes is hypothesized.The results are discussed in comparison with the cytological status of other habituated and tumorous tissues in plant and animal systems.     

Theodor Boveri and the origin of malignant tumours

As long ago as 1914, Theodor Boveri suggested that there is an inhibitory mechanism in every normal cell that prevents the process of cell division until the inhibition has been overcome by a special stimulus. From his work on abnormal mitoses in the eggs of echinoderms, Boveri also suggested that the inhibitor resided in the chromosomes. The relevance of Boveri's ideas to modern cancer research is discussed in this Retrospective article.     

Staining air dried protoplasts for study of plant chromosomes

The air drying technique used in mammalian cytology was applied to isolated plant protoplasts for study of chromosomes. For cultured celery cells, this technique resulted in good spreads of metaphase chromosomes with high resolution. Mitotic chromosomes of Brassica species are relatively small, poor stained by common stains, and difficult to spread by the squash technique. In this study, however, the chromosomes of B. carinata in callus culture were spread well and stained clearly with Giemsa staining solution. The chromosome preparations by the present techniques should also be amenable to chromosome banding studies in plants.     

Theodor and Marcella Boveri: chromosomes and cytoplasm in heredity and development

The chromosome theory of heredity, developed in 1902-1904, became one of the foundation stones of twentieth-century genetics. It is usually referred to as the Sutton-Boveri theory after Walter Sutton and Theodor Boveri. However, the contributions of Theodor Boveri and his co-worker, Marcella O'Grady Boveri (also his wife), to the understanding of heredity and development go beyond the localization of the Mendelian hereditary factors onto the chromosomes. They investigated the interaction of cytoplasm and chromosomes, and demonstrated its relevance in heredity and development.     

Staining Air Dried Protoplasts for Study of Plant Chromosomes

The air drying technique used in mammalian cytology was applied to isolated plant protoplasts for study of chromosomes. For cultured celery cells, this technique resulted in good spreads of metaphase chromosomes with high resolution. Mitotic chromosomes of Brassica species are relatively small, poorly stained by common stains, and difficult to spread by the squash technique. In this study, however, the chromosomes of B. carinata in callus culture were spread well and stained clearly with Giemsa staining solution. The chromosome preparations by the present techniques should also be amenable to chromosome banding studies in plants.     

Cytology and clinical spectrum of sexually transmitted infections in Lebanese women as revealed by Pap smear: a cross-sectional study from 2002-2006

To study the cytology profile of cervical smears and the respective prevalence and incidence of certain cervico-vaginal infections detectable by routine Pap smear cytology in Lebanese women from 2002 to 2006. Pap smear cytology results were compiled from the archives of the Institut National de Pathologie for the period extending from 2002 until 2006. This study covered 118,230 cervical specimens obtained from Lebanese women attending clinics and hospitals in all the five districts of Lebanon; prevalence and incidence rates for infections detectable by routine Pap smear examination were determined. A rise in prevalence of these infections by 2.1 percent (2,555) from 2002 to 2006 was revealed. A doubling of Pap smears showing HPV-associated changes was detected (1.4 percent in 2002 to 2.9 percent in 2006), and a simultaneous almost 7-fold increase of Atypical Squamous Cells of Undetermined Significance (ASCUS) cytology was detected during this period; the rise in ASCUS cytology was age-dependent. Moreover, a 60 percent increase in prevalence of bacterial vaginosis (2.3 percent in 2002 to 3.7 percent in 2006) and a more than 3-fold decline in Trichomonas vaginalis infection (1 percent in 2002 to 0.3 percent in 2006) were also noted in this population during this period. An increase in the prevalence and incidence of cervico-vaginal infections detectable by Pap smear cytology in Lebanese women was revealed from 2002 to 2006. Such changes could point to recent modifications of sexual and health behaviours in the Lebanese community.     

Historical roots of centrosome research: discovery of Boveri's microscope slides in Würzburg

Boveri''s visionary monograph ‘Ueber die Natur der Centrosomen’ (On the nature of centrosomes) in 1900 was founded primarily on microscopic observations of cleaving eggs of sea urchins and the roundworm parasite Ascaris. As Boveri wrote in the introductory paragraph, his interests were less about morphological aspects of centrosomes, but rather aimed at an understanding of their physiological role during cell division. The remarkable transition from observations of tiny dot-like structures in fixed and sectioned material to a unified theory of centrosome function (which in essence still holds true today) cannot be fully appreciated without examining Boveri''s starting material, the histological specimens. It was generally assumed that the microscope slides were lost during the bombing of the Zoological Institute in Würzburg at the end of WWII. Here, I describe the discovery of a number of Boveri''s original microscope slides with serial sections of early sea urchin and Ascaris embryos, stained by Heidenhain''s iron haematoxylin method. Some slides bear handwritten notes and sketches by Boveri. Evidence is presented that the newly discovered slides are part of the original material used by Boveri for his seminal centrosome monograph.     

Culture And Staining of Pollen Grains of Ricinus communis

Germinating and growing pollen grains (male gametophytes) of Ricinus communis L. in liquid culture is achieved as follows: Pollen is collected over a 10-15 min period from mature anther clusters which have been removed from the male flowers and which have been kept at 25° C and 40-60% relative humidity. Samples weighing between 2.5 and 5.0 mg are brought as quickly as possible into a Desicote treated vial containing 17% sucrose and 30 ppm H₃BO₃ in boiled distilled water. The proportion (w/v) of pollen to culture solution should be 1:100. Shed pollen is kept in a humidity chamber whenever it is not being handled. The air in the culture vial is replaced by O₂ at the pressure of 1 atmosphere plus 5 lb and the sealed vials are shaken gently for 8-10 hr while partially immersed in a waterbath kept at 30° C. The pollen is fixed by the addition to the incubation suspension of an absolute alcohol-lactic acid (4:1) fixing fluid. The proportion used is 36 parts of fixing fluid to 1 part of culture solution. The fixed pollen can be stored in the fixative. Smears are prepared by applying single drops of the constantly agitated suspension of fixed pollen to a microscope slide. After each drop has spread out and dried, an additional drop is added until 10-20 have been applied. The preparations are stained by adding a drop of 1% acetic-orcein and are sealed with fingernail lacquer. The method is well adapted to the following types of studies: pollen germination, physiology of pollen tube growth, morphology of the male gametocyte, and physiology and cytology of the generative cell and nucleus.     

Culture And Staining of Pollen Grains of Ricinus communis

Germinating and growing pollen grains (male gametophytes) of Ricinus communis L. in liquid culture is achieved as follows: Pollen is collected over a 10-15 min period from mature anther clusters which have been removed from the male flowers and which have been kept at 25° C and 40-60% relative humidity. Samples weighing between 2.5 and 5.0 mg are brought as quickly as possible into a Desicote treated vial containing 17% sucrose and 30 ppm H₃BO₃ in boiled distilled water. The proportion (w/v) of pollen to culture solution should be 1:100. Shed pollen is kept in a humidity chamber whenever it is not being handled. The air in the culture vial is replaced by O₂ at the pressure of 1 atmosphere plus 5 lb and the sealed vials are shaken gently for 8-10 hr while partially immersed in a waterbath kept at 30° C. The pollen is fixed by the addition to the incubation suspension of an absolute alcohol-lactic acid (4:1) fixing fluid. The proportion used is 36 parts of fixing fluid to 1 part of culture solution. The fixed pollen can be stored in the fixative. Smears are prepared by applying single drops of the constantly agitated suspension of fixed pollen to a microscope slide. After each drop has spread out and dried, an additional drop is added until 10-20 have been applied. The preparations are stained by adding a drop of 1% acetic-orcein and are sealed with fingernail lacquer. The method is well adapted to the following types of studies: pollen germination, physiology of pollen tube growth, morphology of the male gametocyte, and physiology and cytology of the generative cell and nucleus.     

Comparative study of cytology and punch biopsy in cervical intraepithelial neoplasia during pregnancy. A preliminary report

To elucidate the accuracy of cytology in diagnosing cervical intraepithelial neoplasia (CIN) during pregnancy, cytologic screenings for uterine cervical cancer in pregnant women were reviewed for a five-year period. Of the 967 pregnant women screened, abnormal cytologic findings were recorded for 15 (1.6%). Only nine of these were subsequently examined by colposcopy and punch biopsy, which demonstrated CIN in all cases, for an incidence of documented CIN during pregnancy of 0.93%. Including two referral cases also examined by colposcopy and biopsy, cytology and histology agreed on the degree of CIN in four cases and disagreed by one degree in four cases, by two degrees in two cases and by three degrees (mild dysplasia versus carcinoma in situ) in one case. Review of the specimens from these cases did not readily explain the poor concordance between cytology and punch biopsy; some findings suggest that overestimation of the punch biopsy sample may be the explanation.     

Fixation and Staining of the Bacterial Nucleus

An examination of some early methods in bacterial cytology shows that technics for demonstrating the nucleus of the Eubacteriales were available for at least twenty years before the current era of investigation, which began in 1942. Although the bacterial nucleus reacts in many respects like the chromatin elements of higher plants, it shows certain peculiarities in its staining reactions. For example, hematoxylin, methyl green, and several preparations used to stain chromosomes, apparently do not exhibit the same affinity for the bacterial nucleus that they do for chromosomes in higher plants. Not only is the selection of a fixative important in nuclear studies, but also the manner in which the fixation is obtained. For example, when bacteria are fixed and processed in a completely wet state it is generally impossible to stain their nuclei. None of the special fixatives studied revealed any unusual organization in the bacterial cell or exhibited any advantage over the fixatives now in common use by bacteriologists. In view of the properties of osmium tetroxide vapor, particularly its relative lack of interference with positive nuclear staining, there can be little doubt of its superiority as a nuclear fixative. It appears that the basophilic material removed from the bacterial cell by hydrochloric acid is not only in the cytoplasm, but that a very significant amount of it is in close contact with the cell wall.     

Finding treasures in frozen cells: new centriole intermediates

Centriole duplication has been an area of interest since the late 1800s when Boveri suggested that these structures were central organizers for mitosis and cell division. Two groups12 have delineated a linear pathway for centriole assembly. In C. elegans, Pelletier and coworkers1 have identified intermediates in the pathway using cryo-electron tomography. Surprising, the first intermediate is a hollow tube of 60 nm that increases in diameter and then elongates before acquiring microtubules. Similar structures have not been observed to date in other centrioles.     

Boveri's long experiment: sea urchin merogones and the establishment of the role of nuclear chromosomes in development

Theodor Boveri's major intellectual contribution was his focus on the causality of nuclear chromosomal determinants for embryological development. His initial experimental attempt to demonstrate that the character of the developing embryo is determined by nuclear rather than cytoplasmic factors was launched in 1889. The experimental design was to fertilize enucleate sea urchin eggs with sperm of another species that produces a distinguishably different embryonic morphology. Boveri's “hybrid merogone” experiment provided what he initially thought was empirical evidence for the nuclear control of development. However, for subtle reasons, the data were not interpretable and the experiment was repeated and contested. At the end of his life, Boveri was finally able to explain the technical difficulties that had beset the original experiment. However, by 1902 Boveri had carried out his famous polyspermy experiments, which provided decisive evidence for the role of nuclear chromosomal determinants in embryogenesis. Here we present the history of the hybrid merogone experiment as an important case of conceptual reasoning paired with (often difficult) experimental approaches. We then trace the further history of the merogone and normal species hybrid approaches that this experiment had set in train, and review their results from the standpoint of current insights. The history of Boveri's hybrid merogone experiment suggests important lessons about the interplay between what we call “models”, the specific intellectual statements we conceive about how biology works, and the sometimes difficult task of generating experimental proof for these concepts.     

Reappraisal of the Hansemann–Boveri hypothesis on the origin of tumors

Cancer is now known to be a genetic disease. In tumor development, cell nuclei undergo mutations, which can result in cytologically visible chromosome aberrations. The aneuploid errors may involve amplification or deletion of whole chromosomes or segments thereof. David Hansemann [1858–1920] and Theodor Boveri [1862–1915] were major contributors to early debates on the relationship between chromosomal defects, tumorigenesis and malignancies. In 1890, Hansemann observed asymmetrical nuclear divisions in human epithelial cancers. In these abnormal, but bipolar, divisions, a fraction of the chromosomes fails to segregate properly. Hansemann carefully documented the occurrence of asymmetric divisions in a wide variety of tumors. However, he remained a lifelong skeptic with regard to whether such events could be considered the underlying cause of tumors. Almost a quarter of a century after Hansemann's initial observations, Boveri considered the origin of tumors based on his earlier recognition of the functional specificity of each chromosome. He also explicitly drew on Hansemann's observations in proposing a model for tumorigenesis. Its central tenet was that a tumor typically originates from a single cell that has inherited a defined, but incorrectly combined, set of chromosomes. The rare occurrence of a pluripolar spindle represented Boveri's paradigm for a type of abnormal mitosis that can produce a host of random chromosomal combinations. He suggested that some of these combinations will induce tumorous transformation, and will inevitably arise occasionally. Since pluripolar and unbalanced bipolar divisions fail to distribute the hereditary chromatic material correctly, both of these mechanisms can give rise to tumor progenitors.     

Dye Exchange in Bacterial Cells, and the Theory of Staining

Bacterial cells were stained in sequence, and at various pH's, by 22 different basic dyes. It was found that any dye could replace another already present in the bacterial cell. This replacement was shown to act according to mass action laws for reversible reactions, and hence was influenced by concentration of reagent and time of application. Since basic dyes are also known to react at carboxyl group sites, the phenomena of staining of bacterial cells by ordinary basic dyes must be a chemical adsorption exchange reaction.