Ultrastructural anomalies in the fetal small intestine indicate that fetal swallowing is important for normal development: an experimental study

1992 ◽  
Vol 420 (4) ◽  
pp. 305-312 ◽  
Author(s):  
Jeffrey F. Trahair ◽  
Richard Harding
Keyword(s):  
Experimental Study ◽  
Small Intestine ◽  
Normal Development

Further Problems in the Interpretation and Homology of the Insect Ovipositor

1964 ◽  
Vol 96 (1-2) ◽  
pp. 405-417 ◽  
Author(s):  
G. G. E. Scudder
Keyword(s):  
Experimental Study ◽  
Normal Development ◽  
Organ Formation ◽  
Larval Stages ◽  
Insect Phylogeny ◽  
Correct Form ◽  
Developmental Capacity ◽  
Mode Of Development ◽  
Dual Origin

AbstractAn attempt is made to re-evaluate the data on the origin of the ovipositor in insects and to explain its mode of development in living forms. Comparative developmental data from other groups of animals is cited to substantiate the claim that part of the insect ectodermal genitalia is appendicular rather than sternal in origin. It is suggested that the primary abdominal segmental appendages have provided a source of competent tissue which through subtle changes in selection, has evolved along many pathways, to form the gonocoxae, the pleuropodia, the pseudoplacenta and perhaps the prolegs in many different taxa.It is shown, by aid of sections through the insect embryo and larval stages, that the primary embryonic segmental appendages on the abdomen, do not differentiate; there is no loss of tissue and it cannot be proven that such appendages have been lost in insect phylogeny. The fact that they are represented still in the modern embryo, indicates that they have been retained. To explain the observable developmental details, it is suggested that abdominal limb histogenesis is arrested or suppressed in normal development, but this limb tissue retains its competence to differentiate. Thus development may be initiated again at a later time in postembryonic life. In this manner, the original limb tissue is available for organ formation in the maturing insect.The study has suggested that the appendages on the eighth and ninth segments of the abdomen initiate but do not complete their development in the polypod embryo. Possibly the potential limb tissue is arrested in development because it has not undergone some vital change as regards its capacity to respond (competence) to an inductor, perhaps the inductor is not available or perhaps it is not available in the correct form.There is evidence to suggest that the developmental capacity of the limb anlagen are reduced with time, so that full limb formation is not possible in postembryonic life: this can explain the development of abdominal coxae in the Thysanura and hence gonocoxae in higher insects. It is noted that should Gustafson's suggestion that the eversible sacs and gonapophyses are homologous with primary segmental genitalic ampullae prove acceptable, then the female ectodermal genitalia in insects would appear to have a dual origin.It is emphasized that the speculation expressed are being subjected to experimental study in an attempt to verify the suggested ontogeny and phylogeny.

Autotransplantation of the entire small intestine: An experimental study in dogs

1967 ◽  
Vol 2 (1) ◽  
pp. 62-62
Author(s):  
M. Yamashiro ◽  
S. Tsuchiya ◽  
K. Todoroki ◽  
T. Matsumura ◽  
N. Sato
Keyword(s):  
Experimental Study ◽  
Small Intestine ◽  
Entire Small Intestine

Leucylnaphthylamidase in the small intestine of the mouse: Normal development and influence of cortisone and antibiotics

1971 ◽  
Vol 25 (3) ◽  
pp. 398-419 ◽  
Author(s):  
Florence Moog ◽  
Edward H. Birkenmeier ◽  
Howard S. Glazier
Keyword(s):  
Small Intestine ◽  
Normal Development

Pepsinogen gene transcription induced in heterologous epithelial-mesenchymal recombinations of chicken endoderms and glandular stomach mesenchyme

Development ◽  
1988 ◽  
Vol 103 (4) ◽  
pp. 725-731 ◽  
Author(s):  
K. Hayashi ◽  
S. Yasugi ◽  
T. Mizuno
Keyword(s):  
Small Intestine ◽  
Digestive Tract ◽  
Gene Transcription ◽  
Normal Development ◽  
De Novo ◽  
Glandular Stomach ◽  
Northern Hybridization ◽  
Marker Protein ◽  
Chicken Embryos ◽  
Small Intestinal

Proventricular (glandular stomach) mesenchyme of chicken embryos can induce endoderms of some parts of embryonic digestive tract to produce embryonic chicken pepsinogen (ECPg), a marker protein for the differentiation of embryonic proventricular epithelium. In the present study, we investigated the production of ECPg mRNA in the course of epithelial-mesenchymal interactions between endoderms of digestive tract and proventricular mesenchyme. ECPg mRNA was detected by Northern hybridization with ECPg cDNA as a probe. In normal development of the proventriculus, ECPg mRNA was first detected at day 7 of incubation, and it ceased to be produced by day 21. Embryonic esophagus, gizzard and small intestine did not contain ECPg mRNA. When 6-day esophagus, gizzard or proventricular endoderm was associated and cultured with 6-day proventricular mesenchyme, the recombinates formed proventricular-gland-like complex glands and produced ECPg mRNA in almost equal quantity. However, 6-day small intestinal or 3.5-day allantoic endoderm did not produce pepsinogen mRNA under the same conditions, though the recombinates formed complex glands. These results indicate that the proventricular mesenchyme can induce de novo transcription of ECPg gene in esophagus, proventricular and gizzard endoderms, and that ECPg gene in small intestinal and allantoic endoderms fails to react to the inducing signal.

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