Aimé Porte

A comparative ultrastructural study of the pars tuberalis of various mammals, the chicken and the newt

SummaryThe pars tuberalis of the rat, mouse, garden door mouse, European hamster, cat, cattle, chicken and newt is composed of two main cell types: specific secretory cells and follicular cells. The specific cells are characterized by comparable morphologic features in the investigated species, despite differences in the diameter of the secretory granulated vesicles; the ultrastructural morphology of these cells is different from that of any of the known cell types of the adenohypophysis. The follicular cells are devoid of secretory granules, they do not only line the numerous follicular cavities of the pars tuberalis but may also be found in the periphery of the cell cords (border cells). In addition, gonadotrophic cells are found; they predominate in the distal portion of the pars tuberalis and are definitely activated by castration or hypophysectomy. Experimental interventions on most of the major endocrine systems did not cause any noticeable ultrastructural changes in the specific cells. It appears certain that the pars tuberalis secretes a specific hormone whose function remains to be determined.

Colchicine effects on neurosecretory neurons and other hypothalamic and hypophysial cells, with special reference to changes in the cytoplasmic membranes

SummaryThe morphological effects of colchicine on the entire neurosecretory (NS) tract and on various hypothalamic nuclei have been studied. The perturbation in axonal flow, indicated by the accumulation of NS material, coincide with fragmentation of the cytoplasmic membranes, i. e. the Golgi apparatus and the endoplasmic reticulum, whereas the neurotubules remain relatively well preserved. Autophagic destruction of NS material is observed along the entire length of the NS fibres. The rapid and systematic changes in the axoplasmic reticulum, known to store calcium, lead us to envisage a role for this system — similar to that of the sarcoplasmic reticulum — in controlling the transport of NS vesicles. The junctional zone between the stalk and the neural lobe seems to play a particular rôle in the transport of NS material to the posthypophysial terminals of the NS axons. Colchicine provokes an increase in dense-cored vesicles in most of the neurons of the other hypothalamic nuclei studied: arcuate, suprachiasmatic, periventricular and ventromedial. Membranous alterations are also observed in these sites. Colchicine administered to animals which were hypothyroid, castrated or adrenalectomized, reveals stimulated neurons, identified by their excessive content of dense-cored vesicles. These neurons display no specific localization, for they occur in all hypothalamic nuclei, irrespective of the stimulation. The frequency of stimulation of neurons of the periventricular nucleus is striking.

Unusual familial cardiomyopathy with storage of intermediate filaments in the cardiac muscular cells

Unusual histological and ultrastructural changes in cardiac muscle cells have been found in 3 brothers with progressive myocardial deficiency. Histologically, this cardiomyopathy was characterized by massive storage of PAS-negative proteinaceous material in most cardiac muscle cells. The electron microscope showed that this material consisted of sinuous filaments, 7–10 nm in diameter, similar to the intermediate filaments normally present in cardiac muscle cells. Filament storage coincided with the disintegration of neighbouring myofibrils, with particular change in Z bands giving rise to rod-like bodies and more complex structures formed by the association of Z band material and sarcoplasmic reticulum (SR) tubules. Filament storage and myofibrillar disintegration always occurred in areas where the SR developed and involuted extensively. Relatively high glycogen accumulation also occurred, in close relation to the SR changes. Discrete SR proliferation, glycogen overload and filament deposits were observed in a few skeletal fibres. These observations suggest that disturbance in the metabolism of desmin (protein subunit of intermediate filaments and a fundamental component of Z bands) might be involved in this type of cardiomyopathy. The influence of a chronic defect in calcium regulation might also be envisaged in view of the marked SR abnormalities.

B-cells of the synovial membrane. II. Differentiation during development of the synovial cavity in the mouse

SummaryStudy of pre- and postnatal development of the metatarsophalangeal joint of the mouse shows that the synovial cavity (SC) forms before any differentiation of the synovial mesenchyme. The primitive cleft results from degradation of a thin vascular mesenchymal layer in direct contact with the chondrogenic layers. Differentiation of the synovial membrane coincides with clarification of the SC (3rd to 6th day of postnatal life). When dilatation of the SC occurs (6th to 8th day), the two intimal cells types (A- and B-cells) are well identified. The B-cells already show typical features at day 6; their content of typical dense secretory vesicles is comparable to that of the adult B-cells at day 13. The specific secretory function of B-cells could be correlated with the particular structure of the intimal interstitial tissue and could account for the origin of some protein(s) of the synovial fluid.

B-cells of the synovial membrane

SummaryAn ultrastructural study of the synovial membrane in mice revealed that, in addition to specific polypeptide-producing secretory cells (B-cells), the intima is characterized by a specific differentiation of the interstitium adjacent to the synovial cavity. Scattered collagen fibrils are embedded in a fine fibrillar material, which often appears as cross-striated strands resembling long-spacing-collagen (periodicity from 90 to 120nm). Similar material was found along the synovial cavity in the rat, guinea pig, rabbit and man. The close relationship between this material and B-cells observed in the mouse suggests that the maintenance of the specialized intimal interstitium may depend on the secretory function of B-cells.

Herring Bodies Reexamined: An Ultrastructural Experimental Investigation of the Rat Neural Lobe1,2

In 1970 (a), DELLMANN/RODRIGUEZ gave a detailed account of the ultrastructure of mammalian Herring bodies and subdivided them into three main types. Type I Herring bodies are characterized by the presence of numerous neurosecretory granulated vesicles and a few mitochondria, Type I1 Herring bodies contain many dense lamellar bodies, a very extensive axoplasmic reticulum and only a few neurosecretory granulated vesicles, and Type I11 Herring bodies possess a still more extensive axoplasmic reticulum together with numerous mitochondria and a varying number of neurosecretory granulated vesicles. Based upon these morphologic characteristics it was hypothesized that Type I Herring bodies are nothing else but an accumulation of neurosecretory granulated vesicles, the excess of which is being disposed of through a process of involution in the Type I1 Herring bodies, (in 1970 the term degeneration was used to characterize localized catabolic events which usually do not entail interruption of the axonal continuity: see conclusions) followed by restitutional events in the Type I11 Herring bodies. As the first part of this hypothesis was based upon the observed similarity between the morphologic pictures of degenerating amphibian neurosecretory axons (DELLMANN/RODRIGUEZ, 1970 b) and Type I1 Herring bodies, i t was felt that an investigation of degenerating mammalian neurosecretory axons might

Evolution des glandes prothoraciques de larves permanentes de Locusta migratoria obtenues par irradiation sélective du tissu hématopoïétique

SummaryIt has been shown in previous studies that the endocrine control of molting is blocked by selective X-irradiation of the hemocytopoietic tissue of young last instar larvae of Locusta migratoria, the treated animals surviving as larvae for months without ever initiating a molt. The aim of the present study is to determine, on both a morphological and a physiological basis, if the block is related to a precocious functional involution of the prothoracic glands, known to elaborate a molting hormone.The prothoracic glands of normal animals clearly show morphological signs of functional involution during the late fifth (last) larval instar and degenerate completely some days after the imaginal molt. In the prothoracic glands of X-ray treated animals (selective irradiation of the hemocytopoietic tissue, the prothoracic glands being shielded), the signs of intense secretory activity persist up to 40 days following the irradiation. No signs of involution could ever be noticed in the prothoracic glands of such larvae. The irradiation of the hemocytopoietic tissue thus not only blocks molting, but also prevents the normal involution of the prothoracic glands.Extirpation of the prothoracic glands in young larvae of Locusta is known to result in the inhibition of the subsequent molt. Implantation of prothoracic glands from normal donors of the same age restores molting in fifth instar larvae previously deprived of their own glands. Using these results in physiological assays for the implanted prothoracic glands, we chose as donors irradiated animals of different ages and young normally developing adults. The prothoracic glands of irradiated animals fully retain their physiological activity after the X-ray treatment and are able to induce molting in larvae deprived of their own glands.It appears that the radiosensitive cells of the hemocytopoietic tissue of Locusta produce a substance which, while having no overt influence on the functioning of the prothoracic glands, is necessary for molting and probably acts in synergy with the prothoracic factor (molting hormone).

Morphological evidence of a polypeptide-like secretory function of the B cells in the mouse synovial membrane

In the synovial membrane of the mouse, morphological features associated with acitve secretion are unusually well developed in cells immediately subjacent to the lining layer (in the position of B cells), comparable to those of cells known to elaborate polypeptides.

Storage of proteins in the rough endoplasmic reticulum of human hepatocytes in a patient with normal blood proteins, on oral contraceptives.

Aspects of protein storage in the rough endoplasmic reticulum of hepatocytes, comparable with those reported in α1-antitrypsine (AAT) deficiency, have been observed in the course of jaundice in a woman presenting no evident abnormality in AAT or other blood proteins. In light microscopy, most hepatocytes contained characteristic globular inclusions but they were PAS negative and did not react with anti-AAT antibodies. This storage of protein ceased at the time the jaundice disappeared. Prolonged treatment with high doses of contraceptive steroids may have been involved in this peculiar reaction of the hepatocytes.

Light and electron microscopic study of ear cartilage in a case of relapsing polychondritis evolving under corticoid treatment.

Light and electron microscope studies of the ear cartilage in a patient with relapsing polychondritis (RP) under corticoid treatment are reported. Unilateral auricular deformation evolved without inflammatory episodes and the lesions consisted mainly of marginal erosions filled with fine collagen fibrils and containing degenerating perichondrial cells in their basal parts. Degenerative cells were scattered throughout the perichondrium, but cartilage erosions only occured when numerous cells were affected in a same area. Cartilage outside the eroded zones did not seem to be modified. Cartilage lesions thus appear to be a result of a chondrocyte renewal defect leading to loss of proteoglycans and elastic fibers, with only collagen remaining. These data suggest that inflammation is probably not the initial pathogenic process responsible for cartilage injury in RP, but that a metabolic defect in perichondrial cells might be involved.