Archives d'anatomie microscopique et de morphologie experimentale最新文献

Following amputation of the posterior half of Tubifex, all the nerve cells stainable by paraldehyde fuchsin (NF) immediately discharged. Fifteen minutes later, some stained NFs reappeared. Their number increased, reached a peak far above the normal level, then slowly decreased. This peak occurred 8 hours after amputation in the brain, after 3-4 days in the ventral ganglia. A similar cycle took place during the anterior regeneration of Tubifex whose four anterior segments were previously cut away. Following a double amputation (behind the first or fourth segment and at half length), the stimulation of the neurosecretory activity was even clearer, the number of NFs reaching a higher and earlier peak. Correlatively, the regenerative histogenesis was accelerated in the caudal blastema.

A study of primordial germ cells (PGC) of Amphibia Anura was carried out after treatment of sections by different fluorescein isothiocyanate conjugated lectins (FITC-lectins). Specific labelling on the PGC is obtained with lectins, the activity of which is inhibited by D-galactose or N-acetyl-galactosamine. These osidic groups appear to be located more specifically on the PGC. The same labelling pattern is not obtained with lectins possessing major affinity for mannose, glucose, fucose and N-acetyl-glucosamine. Furthermore, changes in labelling pattern are observed during migration of PGC. It is suggested that D-galactose and N-acetyl-galactosamine might be related to membrane activity of PGC during migration. Ultrastructural study of the visualization of cell surface carbohydrates supplies some information on the localisation of these lectins receptors.

After amputation of the posterior region of the body, Hirudinea Helobdella stagnalis is able to regenerate. This faculty, which involves the whole posterior part in the young, still persists in adults but is limited to the posterior ventouse and depends on the presence of the terminal nerve ganglion on the surface of the transsection area. Histologic study in young and adults demonstrates that morphogenesis activity restriction, in this body region, is due to irreparable loss of neuroblastic potentialities of healing epidermal cells.

In the course of development of the mouse embryo prosencephalon, the walls of the dorsal and ventral telodiencephalic sulci fuse along their ependymal surfaces. This study is based on 1 mu semithin sections of the prosencephalon and on ultrathin sections of the fusion zone of mice of 13 days postconception. Ultrathin sections of the rostral part of the fusion zone present two rows of junctions (maculae adhaerentes) in opposition belonging to each of the two walls. On either side of these rows of junctions is found a row of cells, many in various stages of mitosis. In the caudal part of the fusion zone, intercellular spaces are wide and are occupied by numerous cytoplasmic prolongations that present mitochondria, granular endoplasmic reticula, and Golgi apparatus. Many of these prolongations establish contacts between themselves and with the cell bodies.

The importance of cell-matrix interactions during terminal chondrocyte differentiation is to-day accepted by all authors. Na-hyaluronate micro-injections induce an increase of perichondral thickness and maintain mesenchymal aspect in chondrocyte. Cytoplasmic organelles show anomalies which may be bound to disturbance in cellular metabolism. An important decrease of matrix-constituents is observed, a fact showing that high hyaluronate concentration interferes with chondroitin-sulfate synthesis or secretion and collagen organization.

In the pigeon pineal organ studied in vitro, high resolution radioautography was used to visualize the sites of uptake and retention of [3H]-indoles: --incubation of the pineal organ with [3H]-5-hydroxytryptophan ([3H]-5-HTP) during the day and with [3H]-5-hydroxytryptamine ([3H]-5-HT) during the night led to strong selective labelling of the receptor line cells (RLC) which correspond to modified photoreceptor cells (rudimentary photoreceptor cells). No significant radioautographic reactions were found in other cell types. When the 20 min radioactive signal was followed by 20-100 min post-incubation in a cold medium, labelling was still restricted to RLC. The in vitro study of indole metabolism sites might be facilitated by this preparation. --labelling after [3H]-melatonin incorporation was found mainly in RLC but also in interstitial cells. Reactions were less intense than those obtained with [3H]-hydroxyindoles although some erythrocytes were strongly labelled. No definite conclusion can be drawn from the radioautographs, in which artefacts were apparent.

When cultured in combination with testes of the same stage, müllerian ducts from the 7-7 1/2-day-old chick embryo underwent regression, which was nearly complete in the male and less pronounced in the female after a 4-5-day culture period. When a crystal of testosterone was added in the system, the müllerian ducts were maintained in the male, whereas they were even stimulated in the female. Testosterone therefore antagonizes the suppressive action of the anti-müllerian hormone. The exact nature of the interaction of the two hormones at the cellular and molecular level should be the object of further studies.

At the end of intra-uterine life in the rat, hepatic erythron evolution is governed by corticosteroids and it is experimentally possible to prematurely deprive the foetus of a large part of its hepatic erythropoietic tissue by inflicting repeated stress in the pregnant animal. This experimentally induced deficiency of the hepatic erythron leads to an anticipated erythroid activity in the bone marrow. Splenectomy in such fetuses has shown that the spleen does not play a major role in producing circulating anucleated erythroid cells before term.

Administered into the yolk sac of eggs of Lacerta viridis as a single dose of 17 to 40 micrograms, cytosine-arabinoside (Ara-C) was compatible with survival of the embryo, from the sixth day of incubation, for at least 20 to 25 days. The LD50 was 40 to 50 micrograms per egg. Doses of 20 to 40 micrograms of Ara-C introduced in the yolk sac of eggs of the slow-worm (Anguis fragilis) cultured in vitro, at stages of the allantoid bud of 0,5 mm to 2,5 mm long, killed the embryo in 4 to 8 days (possibly due to alterations of capillary blood vessels of allantois and area vasculosa). In the two species, these doses caused cytotoxic effects on embryonic proliferating tissues, growth inhibition and a variety of developmental defects. In young embryos of Anguis fragilis, similar doses of 20 to 40 micrograms of Ara-C caused, in 2 to 4 days, death of many cells in the anlagen of growing organs: neural tube, sensory organs, bronchi, mesoderm of the limb bud, subcutaneous mesenchyme, anlage of dorsal skeletal structures, etc.; followed by growth inhibition and malformations. On the other hand, in the limb bud, the apical ridge was less retrogressed than in control embryos; the limb buds showed slightly better development in treated embryos than in controls, but, Ara-C induced severe damage in their mesoderm. In all embryos of Lacerta viridis, treated at the stage of 6 days or of 10 days of incubation by doses of 20 to 40 micrograms of Ara-C and killed 15 to 35 days later, there was a general reduction of size and of weight and external and internal malformations, more or less severe, were present: modifications of the form of the head, shortening of the lower jaw, labial clefts, microphthalmia, micromelia and other limbs defects, developmental defects of the tail. In some embryos, the only external defects observed were missing fingers and toes; in three of these embryos, the same digits were missing in the four limbs. Modifications of limb morphogenesis induced by Ara-C are compared to structural modifications of the limbs of snake-like Reptilia, and the mechanisms involved in the two series are discussed. These results emphasize the interest of the use of drugs interfering with DNA synthesis, in the field of teratology and in the experimental study of regressive evolution.

The thyroparathyroid complex of house shrews was cut into serial sections. For demonstration of calcitonin cells (C cells) the sections were stained by HE, PAS/haematoxylin, Heidenhain's iron haematoxylin, Mallory's aniline blue, toluidine blue, Davenport's silver impregnation and lead haematoxylin. The C cells are oval to slender in shape and are distributed unevenly (totally lacking from the peripheral, cranial, caudal and isthmus region). They are also encountered in the internal parathyroid gland.