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At least 19 recordsLinked to original sources
PubMed1979

[Hypothalamic influence on differentiation of the immunoreactive ACTH beta-LPH, alpha- and beta-endorphin containing cells in adenohypophysial primordia of rat fetus in organ culture (author's transl)].

Adenohypophysial primordia were isolated in rat fetuses from day 12.5 to day 15.5 of gestation. The organ culture employed for maintenance of the primordia was made up according to Watanabe et al. (1973). The fixation of primordia in Bouin Hollande's solution was performed after 9, 8, 7 or 6 days of culture when the normal duration of pregnancy was achieved. The cultivated primordia were immunologically studied using different antisera: anti-alpha(17-39)ACTH, anti-beta(1-24)ACTH, anti-beta-LPH, anti-alpha and anti-beta-endorphins, with immunoperoxidase or immunofluorescence techniques, including control experiments of the specificity of the antisera. A similar study was performed on pituitaries removed from normal rat fetuses from day 16.5 of gestation and each day up to birth, and fixated immediately. In vivo the first cells reacting with all the antisera used in this study were observed on day 16.5 of gestation; their number increased during gestation (Fig. 1 A, B and C). Immunoreactive cells with the different antisera could be detected in primordia isolated on day 12.5 of gestation after 9 days of culture. Numerous groups of cells were observed in primordia of older fetuses (Fig. 2 A and B). These data indicate that the corticotropic cells in rat fetuses could start to be differentiated without stimuli from the hypothalamus since primordia were isolated before the appearance of this cell type in normal rat fetuses and before the differentiation of the hypothalamus. The presence of ACTH and other peptides such as beta-LPH or beta-endorphin would support the hypothesis of a common precursor in this cell type existing early in gestation. Similar results were obtained in human fetuses.

Adrenocorticotropic Hormone↗
PubMed1977

Contiguous allografts of male and female gonadal primordia in the rat.

Male and femal gonadal primordia from fetal rats were grafted in contiguity under the kidney capsule of normal, castrated and spayed adult host rats. Irrespective of the gonadal status of the host, growth and differentiation of primary overian follicles were suppressed when a fetal testis was grafted close to a fetal ovary. Instead, cystic or tubular structures developed, some of them containing atretic ova in their lumina. The testis grafts, on the other hand, always differentiated extremely well. This is supportive evidence for the concept that the early fetal testis elaborates a substance or substances which are capable or preventing proper development of follicles in ovarian primordia trasplanted next to them.

Animals↗
PubMed1979

The development of mouse spinal cord in tissue culture. I. Cultures of whole mouse embryos and spinal-cord primordia.

Whole mouse embryos were grown in vitro from Theiler stage 12 (1 to 7 somites) to Theiler stages 15 and 16 (25 to 35 somites). This procedure gives experimental access to precisely staged embryos during the early period of neurogenesis. To follow the further development of neurons in vitro, fragments of spinal primordia were set up from these cultured embryos. In such cultures, the proliferation of precursor cells, the formation of postmitotic cells, and, finally, the cytodifferentiation of neurons were observed.

Animals↗
PubMed1978

Production of adventitious root primordia on hypocotyls of castor bean seedling, infected with Agrobacterium tumefaciens.

The development of sterile secondary tumours on hypocotyls of castor bean seedlings, inoculated with any of the ten isolates of Agrobacterium tumefaciens tested, were observed below the site of the primary tumours. Histopathological studies performed in the present work indicate that the observed secondary tumours were adventitious root primordia and not the ordinary type of secondary tumours. According to the available literature such findings are reported here for the first time. All the tested isolates of the present study were also able to initiate well defined roots in conjunction with crown gall (teratomas) on Bryophyllum crenata and Kalanchoe marmorata, but not in tomato.

Ricinus communis↗
PubMed1978

[An ultrastructural study of acid phosphatase activity localized in bud primordia of an organogenic culture of Nicotiana tabacum L. var. P. 19].

Acid phosphatase activity in particularly organogenic strain of tobacco has been localized in two kinds of tissue: the internal bud primordia and the adjacent tissues. Generally the reactions are weaker in the undifferentiated cells. In differentiating cells, the localization of precipitates from the reaction shows up the continuity of membrane systems such as the endoplasmic reticulum, the nuclear membrane and the vacuoles. The relative weakness of the reactions observed in the vacuoles is in agreement with the rareness of hydrolysis. Parenchymatous cells between the meristems and the surface of the tissue culture undergo autolysis, which seems to help the growth of buds produced by neoformation. Specific and often intense reactions occur in the cell walls.

Acid Phosphatase↗
PubMed1976

Immunohistochemical study on adenohypophysial primordia in organ culture.

Rathke's pouches isolated from rat fetuses on day 12 were maintained in organ culture for 9 days and investigated immunohistochemically to test whether or not the hypothalamus is involved in the cytodifferentiation of the adenohypophysis. The unlabeled antibody enzyme method demonstrated that the cultured tissue contains different types of glandular cells, i.e., adrenocorticotropin (ACTH)-, growth hormone (GH)-, luteinizing hormone (LH)-, thyrotropin (TSH)-, and prolactin-producing cells. Indirect evidence was also obtained to indicate the presence of melanocyte stimulating hormone (MSH)-cells. These findings suggest that adenohypophysial primordial cells of rats start to synthesize their respective hormones without stimuli from the neurosecretory substances of the brain which are known to be essential for the maintenance of the secretory activity of the adult gland.

Adrenocorticotropic Hormone↗
PubMed1979

Postembryonic changes in the optic primordia and optic bud in the flesh fly Sarcophaga ruficornis fabr. (Diptera: Sarcophagidae).

Differentiation of the optic lobe anlagen begin in the brain of second instar. Each is an elongated disc of cortical cells placed on the dorsolateral border of each protocerebrum. In the late second instar the disc elongates and its two ends bend inwards which gradually separate from the central region, thus giving three imaginal discs. The protocerebral neuropile extends into these discs and medulla interna and externa are formed. The rudiments of compound eyes (cephalic complex) appear in the early laid larva. These are attached with the brain and pharyngeal wall separately. The posterior portion of cephalic complex (optic bud), after establishing a nervous association with the central optic lobe anlage (lamina ganglionaris), forms the compound eye. Ech optic bud is attached to the brain by a non-nervous stalk. The epiblast cells of the optic bud do not migrate into the brain and the lamina is formed by the proliferation of the central imaginal disc. The reorientation of the optic lobe anlagen starts in the late third instar and the medulla interna divides into two unequal lobes. In 2 day pupa the nerve fibres from the lamina travel into the optic stalk and the optic nerve is formed. The epiblast cells of the optic bud differentiate to form a peripheral epithelial layer which becomes pigmented and gets apposed to the lateral boundary of the brain. The central epiblast cells of the optic bud form several ommatidia. The optic nerve degenerates gradually and various components of the compound eye are formed by the epiblast cells. Chiasm internum is present but chiasm externum is absent.

Animals↗
PubMed1979

[Experimental data on the development of the primordia of the long bones of chick embryo extremities].

By means of various kinds of recombination of the two halves of the chick limb buds transected at the presumptive zeugopod mid-length a continuity was established between the opposite portions of the mesenchymal precursors of heterologous shaft bones of the zeugopod. In later development, both proximal and distal components of the recombined skeletal pieces consistently showed variously marked differences in size and shape in comparison with the corresponding parts of the control bones. Reciprocally, from the opposite portions of the presumptive territory of each zeugopodal bone separated the one from the other so that they could not contact and fuse, hypoplasic pieces developed which failed to attain the size and shape typical of the control segments. Those observations seem to show that morphogenetic interactions reciprocally exerted between the various parts of the presumptive territory of each shaft bone are mandatory to ensure the normal development of these skeletal pieces.

Animals↗
PubMed1978

Observations on the development of the human atrioventricular node and bundle.

This light microscopic study of the cardiac junctional tissues was based on 27 human embryos, fetuses and postnatal hearts. Evidence was presented that superficial and deep portions of the postnatal AV node were derived from two cellular primordia in the posterior wall of the common atrium at the 6-mm stage. The small right primordia was associated with the right venous valve and give rise to the loosely organized superficial AV node that extended posteriorly to the coronary sinus ostium. A larger left primordia formed the more compact deep subdivision of the AV node located against the anulus fibrosus. In most postnatal hearts the two subdivisions are partially or completely fused to form the adult AV node. Failure of the nodal primordia to fuse during cardiogenesis may result in two separate nodal cell aggregates above the anulus. The present observations provide a rational explanation for the two AV nodal masses described in the literature and an additional specimen that is illustrated in this communication. An AV bundle was first identified in a 13-mm embryo and appeared to be derived from large clear cells of the posterior AV canal. At 25 mm the bundle formed a broad band across the top of the IV septum and continued into both ventricles. At this stage multiple cell strands penetrated the endocardial cushion to connect the AV bundle to the two nodal primordia. Failure of normal fusion between the AV node primordia and AV bundle can result in a variety of junctional anomalies including congenital heart block.

Atrioventricular Node↗
PubMed1978

Facial development in normal and mutant chick embryos. I. Scanning electron microscopy of primary palate formation.

Early facial development in normal chick embryos was studied by scanning electron microscopy, and compared to the abnormal facial development of a mutant in which primary palate formation does not occur, thus resulting in bilateral cleft lip. In both normal and "cleft primary palate" mutant embryos, subsequent to the appearance of the nasal placodes, the surrounding tissues elevate to give rise to the presumptive facial primordia. As the facial primordia grow forward, they gradually assume the configuration of a square which is most pronounced at five days development. In normal embryos, the square configuration is then lost as the facial primordia become aligned in preparation for primary palate formation. The primary palate is formed at six days development by fusion of the "free-ended" medial nasal processes with the combined lateral nasal and maxillary processes across the nasal grooves. Just prior to fusion, long, slender filaments extend from the apposing surfaces of the facial primordia in the regions of prefusion contact. It is speculated that these "prefusion filaments" may function in alignment or adhesion of the facial primordia. In "cleft primary palate" embryos, facial morphogenesis appears to arrest at five days development, so that the square configuration persists. The medial nasal processes never contact the lateral nasal and maxillary processes, but instead remain separated from them by wide nasal grooves. Furthermore, facial primordia of mutant embryos do not exhibit the "prefusion filaments" characteristic of normal embryos.

Animals↗
PubMed1978

The endocrine control of embryonic lung maturation in the chicken. II. Role of the hypophysis.

In order to discover whether the embryonic chick hypophysis acts upon lung maturation directly or via its corticotrophic activity, immature lung primordia were grafted into young hosts, either alone or associated with functional adrenals or pituitaries. When lung primordia were grafted alone, type II pneumocytes did not differentiate. Their differentiation was restored when lung primordia were grafted in association with either adrenals or pituitaries. This last result, which was also obtained in vitro, shows that the hypophysis is able, by itself, to promote the maturation of respiratory epithelium.

Animals↗
PubMed1977

Interference with thyroid histogenesis by inhibitors of collagen synthesis.

Histogenesis of thyroid follicles in the chick embryo begins with a penetration by cells of the mesenchymal capsule into a solid epithelial primordium. Before penetration occurs, slits containing fibrillar material form between the epithelial cells. The fibrillar material is an epithelial cell product as shown by its formation within channels that form in cultures of isolated epithelial primordia. The drugs L-azetidine-2-carboxylic acid (LACA) and alpha, alpha'-dipyridyl, which interfere with collagen synthesis, prevent the formation of fibrils in cultured epithelial primordia and in cultures of whole thyroids. Furthermore, mesenchymal cells do not invade when whole thyroid primordia are cultured in the presence of either drug. The effects of alpha, alpha'-dipyridyl are reversed by washing out the drug; the effects of LACA are reversed by incubation with equimolar or greater amounts of L-proline added to the medium along with the drug. The results are interpreted to mean that the fibrillar material is collagen of epithelial origin, that the collagen in some way plays a role in mesenchymal penetration of the epithelial primordium, and that the epithelium is responsible for the pattern of lobulation within the developing gland.

2,2'-Dipyridyl↗
PubMed1976

The structure and development of the dorsal bristle complex of Oxytricha fallax and Stylomychia pustulata.

Oxytricha fallax and Stylonychia pustulata possess 6 rows of dorsal bristle units. Each dorsal bristle unit consists of a pair of kinetosomes; the anterior kinetosome has a cilium and the posterior kinetosome a ciliary study. The kinetosome pair, located at the bottom of a cortical pit surrounding the cilium and ciliary stub, is surrounded by an asymmetrical fibrillar mass. Future rows 1-4 are formed from 2 sets of primordia originating within mature dorsal rows 1-3. Rows 5 and 6 originate from the anterior regions of both right marginal cirral primorida. Old dorsal bristle units utilized in formation of primordia are presumably maintained in the new rows of the proter and opisthe; those outside the primordia resorbed. The morphogenetic pattern of the Oxytrichidae is similar to those of the Urostylidae and Holostichidae, but quite different from that of the Euplotidae.

Animals↗