Tenth Day Of Incubation Research Articles

Polyamines and nucleic acid metabolism during development of chick embryo brain.

Abstract— Spermine and spermidine reach maximum concentrations in the chick embryo brain between the 12th and 14th day of incubation. Sucrose‐density‐gradient analysis of polyribosome distribution in the developing chick embryo brain, showed the presence of polyribosomal aggregates in the regions of 147 S and 206 S between the sixth and eighth day of incubation. After the 16th day of incubation the presence of heavier polyribosomal aggregates in the region of 259 S and 280 S was found. The injection of spermine or spermidine into the air space of embryos on the tenth day of incubation leads to a remarkable increase in the incorporation rate of [3H]formate into the ribosomes. Studies under similar experimental conditions, showed an increased radioactivity in the region of 147 S, 206 S, 259 S and 280 S in embryos injected with spermine or spermidine.

Degeneration in the nucleus of origin of the preganglionic fibers to the chick ciliary ganglion following early removal of the optic vesicle.

AbstractExtirpation of the optic vesicle in chick embryos towards the end of the second day of incubation leads to a progressive hypoplasia in the ciliary ganglion and to a secondary, or retrograde transneuronal degeneration, in the accessory oculomotor nucleus from which the preganglionic fibers to the ciliary ganglion are derived. The primary changes in the ciliary ganglion are first observed at about the eighth day of incubation and the resulting cell loss proceeds over the next three or four days to include almost all of the ganglion cells. At the tenth day of incubation (when the volume of the ciliary ganglion is reduced by just over 70%) early signs of cell degeneration can be recognized in both the medial and lateral divisions of the accessory oculomotor nucleus in the form of cell shrinkage, loss of Nissl material and some cell loss. By the fourteenth day of incubation (Stage 40) the nucleus is virtually depleted of neurons with only an occasional shrunken cell persisting in the medial accessory nucleus. After even longer survival periods complete cell loss may occur in the nucleus, but in many of the experiments a small number of cells survive: these are probably related to ciliary ganglion cells which have established aberrant peripheral connections, or in those cases in which the lesion of the optic vesicle was incomplete, to the cells which innervate the surviving ocular tissue.

The ratio of soluble to insoluble collagen in normal chick dermis.

Weiss and Matoltsy (1) reported a total absence of wound healing in chick embryos prior to the tenth day of incubation. The epithelial cells of the wound margin, instead of covering the wound surface as they do in older embryos, penetrate the underlying mesenchymal stroma. We thought that the explanation for this behavior of the epithelium should be sought in the embryonic mesenchyme. The importance of the mesenchyme, e.g., the dermis, for the differentiation of the epidermis and its derivatives during embryogenesis has been well established (2-5). Differentiation and proliferation of epidermal cells in newts was found to be dependent on mesenchymal factors (6). McLoughlin (7) was able to alter specifically the differentiation of embryonic epidermis by combination with mesenchyme from various organs. Epidermal cells cultured without mesenchyme do not differentiate but degenerate, whereas frozen-thawed mesenchyme is able to support epidermal differentiation (8). This property of frozen-thawed mesenchyme, however, is lost after its exposure to trypin (8). This tinding supports the assumption that large molecules are responsible for the inductive action of the mesenchyme. Wessells (9) succeeded in inducing and maintaining cornification of embryonic chick epidermis in the absence of mesenchyme by explanting it on top of a Millipore membrane and supplying it with a suitable concentration of embryo juice. Other subtrate failed to support epidermal differentiation. These findings are reqarded as evidence for the importance of the physical structure of the substrate for epidermal cornification. Collagen is one of the most important structural elements of the dermis. Dodson obtained differentiation of epidermis grown on collaqen gells. Enquist and Adamson (10) stated that “a lack of healing means absence of collagen sqnlthesis.” In view of these data, a correlation between collagen polymerization in granulation tissue and epidermal wound coverage appears plausible. Our investigations, reported in this paper, were concerned with the question of the extent to which changes in collagen polymerization are correlated with changes in wound healing in chick embryos.

Some histochemical observations on the effects of chorioallantoic grafts on the spleen, bursa, and peripheral blood of chicken embryos.

AbstractHatching eggs from inbred lines of chickens (inbreeding coefficient exceeds 95%) which show various degrees of resistance and susceptibility to Rous sarcoma, were used for experimentation. Adult tissues were grafted onto the chorioallantois on the tenth day of incubation and tissues of host and control embryos were harvested on the twentieth day of incubation. Enzymes were localized in tissues by histochemical procedures.Small pieces of tissue (thymus or bursa), when grafted onto the chorioallantois, increased the size of the spleen in host embryos although splenomegaly did not invariably occur. Two types of reactions were observed in the spleen, i.e., enlarged spleens with cysts or enlarged spleens which from a morphological point of view were normal. Grafts of either thymus or bursa decreased the size of the host embryo's bursa or were without effect. When weight of the bursa of host embryos was significantly less than that of control embryos on the twentieth day of incubation, this size relationship persisted in chicks four weeks post hatching.Intensity of dehydrogenase and acid phosphatase reactions in cysts of enlarged spleens and in the multinucleated giant cells investing them suggests that they consist of groups of degenerating cells. Intensity of enzyme reaction indicates that enlarged spleens of host embryos in which cysts were absent were normal. Enzyme reactions in the bursae of experimental embryos were more intense than those identified in the same tissues of control embryos. Catabolic reactions were the predominant type in grafts ten days subsequent to implantation. Grafts increased the number of erythrocytes in the peripheral blood of host embryos.

Polyamines and nucleic acids during development of the chick embryo

1. A higher concentration of polyamines (spermine, spermidine, putrescine and cadaverine) during development of the chick embryo was observed between the fifth and tenth day of incubation; the concentrations of nucleic acids showed a parallel increase. 2. When spermine (5mumoles) was injected into the yolk sac of embryos at the tenth day of incubation, a high amine-oxidase activity was noted and the spermine and spermidine concentrations were decreased; also, there was a remarkable decrease in RNA and DNA concentrations and a parallel increase in that of total free nucleotides. 3. On the other hand, when iproniazid (16mumoles) was injected there was an inhibition of amine-oxidase activity and a similar increase in the concentrations of spermine and spermidine and of nucleic acids, whereas that of total free nucleotides decreased. 4. Another group of embryos injected with spermine and iproniazid together showed a remarkable increase in spermine and spermidine concentrations and a parallel increase in those of RNA and DNA, and a decrease in that of total free nucleotides.

Respiratory metabolism during embryogenesis of a diapause species of field cricket, Gryllus pennsylvanicus Burmeister (Orthoptera, Gryllidae)

During the embryonic development of Gryllus pennsylvanicus the rate of respiration continues rising until the fifth day, after which the rate falls off to about one-ninth on the tenth day. This value is maintained for a further period of 10 days. In the post-diapause embryos the rate of oxygen consumption rises continuously throughout the entire period of development. The studies reveal that the diapause in G. pennsylvanicus is obligatory and that the embryos enter a complete diapause condition after the tenth day of incubation at 28°C. The post-diapause embryos take 3 days to reach the maximum rate of respiration of the pre-diapause period.

Wound healing in chick embryos in vivo and in vitro

The faculty of chick embryos for healing skin and corneal wounds varies significantly with age. After lesions in vivo, proliferation of epithelial cells proceeds, but migration over the wound is absent until at least the tenth day of incubation, at which date it automatically starts regardless of how much time has elapsed since the injury. This rules out any of the immediate traumatic effects of wounding as being causally related to migration. When cultivated on a plasma clot in vitro, however, both skin and cornea fragments are capable of migratory wound healing at all ages. This proves that the early failure in vivo is not due to intrinsic immobility of the epithelial cells; nor could it be definitely connected with cell-to-substratum relations. Tentatively, one could consider the critical change to occur in the humoral milieu, as the hormone system becomes active about that time. The remarkable property of dissociating growth and proliferation from migratory activity, exhibited during the first half of the developmental period, makes the chick embryo uniquely suitable for more penetrating analysis of the relative independence of the components of wound healing.

Metabolism and Glycogen Formation in the Liver of the Chicken Embryo

ABSTRACT In the liver of the chicken embryo the earliest stage at which glycogen was regularly found was a group of embryos of which the eye diameter was 4·3-4·9 mm. The mean incubation time of these embryos was 6·9 ± 0·14 days. The appearance of glycogen was associated with changes in the metabolism of the isolated liver in a glucose-containing medium; mean values for the rate of respiration fell from 1·02 to 0±53 μl. oxygen/c.mm. tissue/hr., and the mean values for the respiratory quotient from 0·84 to 0·68. In both cases the lower level had undergone no further significant alteration by the tenth day of incubation. Observations in a medium to which glucose had not been added showed that before the appearance of glycogen omission of glucose caused a decrease in the mean rate of respiration and in the mean value for the respiratory quotient. These changes were not observed after glycogen had appeared. From these changes it is concluded that the appearance of glycogen in the liver of the chicken embryo is associated with the loss of enzymatic activity necessary for the respiratory catabolism of glucose. After the appearance of glycogen in the liver cells the respiratory quotient of the isolated liver suggests that uric acid formation occurs. This possibility has been discussed.

Radioiodine metabolism in the chick embryo.

Many studies have been made of the histology of the thyroid gland at various stages in the development of the chick embryo. These studies, as well as several to detsrmine the age of the chick embryo at which biochemical differentiation or thyroid function begins, have recently been summarized by Moore (1950). Methods used to determine thyroid function in the chick embryo include measurement of the total iodine in the thyroid glands (Sun, 1932), demonstration of the presence of the thyroxine in the chick thyroid by tadpole test (Hopkins, 1935), and demonstration of organic binding of radioiodine in the thyroid gland by autoradiography (Hansborough and Khan, 1951). Using these methods, it was not possible to detect any evidences of thyroid function or biochemical differention prior to the tenth day of incubation, which is the time colloid has been reported to appear in the thyroid gland (Bradway, 1929; Hopkins, 1935; Venzke, 1949).

Development of the thyroid gland in the chick embryo

Abstract1. The developing chick thyroid consists of epithelial plates or cords suspended in a sinus, probably lymphoid. These cords in cross section have the appearance of follicles.2. Growth in size is accomplished by fusion of follicles. Growth in number of the latter by proliferation of inter‐follicular epithelial cells.3. Colloid first appears on the tenth day of incubation. The tadpole test indicates the beginning of functional activity at this time.4. During development there is a progressive decrease in the cytoplasm‐nucleus ratio from 3.3: 1 on the third to 1.5: 1 on the nineteenth day, as measured in area, not volume.5. Not only is chromophobe and chromophile colloid present in different cells of the same follicle at the same time, but both are occasionally present in the same cell at the same time.6. Evidence of heightened activity in the chick thyroid are as Uhlenhuth (′28) describes them in salamanders: namely, high columnar cells, apically located secretion granules, and vacuoles of chromophobe colloid.7. Follicles in late developmental stages have, at some time during their functional cycles, tubular exits, which are thought to represent one path through which colloid reaches the circulatory spaces.8. Vital staining indicates that elements of the reticulo‐endothelial system are present in the developing thyroid. Phagocytic cells in the gland of one embryo were observed phagocytosing entire erythrocytes.

The effects of breed on the growth of the chick embryo

AbstractThe growth of chick embryos of heavy and light breeds and the reciprocal crosses between them is described. The embryos of the heavier breed and the hybrids were found to be somewhat heavier than the embryos of the lighter breed from the tenth day of incubation to hatching time. In eggs of the same weight from the two breeds the size difference tends to disappear toward hatching time, probably due to the equivalence of the strictly limited food supply. It is pointed out that the size difference is more probably due to difference in the proportion of cells dividing at a given time than to a difference in duration of mitoses.The mortality of the hybrid embryos was intermediate between that characteristic of the parent breeds, while the percentage of monsters in the hybrids was less than that for either parent breed. There is thus some indication of heterosis.