Lectin histochemistry of enterocytes sugar residues in the gut of the chick embryo and of the newborn

The glycoconjugates sugar residues content, distribution and changes in the enterocytes of different tracts of the developing intestine of the chick embryo and of 1-day-old chick were investigated, using a battery of seven HRP-conjugated lectins (DBA, SBA, PNA, WGA, ConA, LTA and UEAI). The results of the present research have shown the presence of a large amount of glycoconjugates sugar residues in the enterocytes of duodenal, ileal and colonic anlage, starting from the beginning of the second week of incubation. Differences were detected among the three investigated intestinal segments, as to the time of appearance of the glycoconjugates sugar residues in the enterocytes. The duodenal enterocytes showed the most precocious appearance of lectin-reactive material, followed by the ileal enterocytes and afterwards by colonic enterocytes. The duodenal enterocytes were characterised by the presence of SBA binding sites, which were not detectable in the duodenal enterocytes of the adult animal.     

Vasculogenesis drives pulmonary vascular growth in the developing chick embryo.

Formation of the pulmonary vasculature has been described as occurring by outgrowth of existing vessels (angiogenesis), de novo formation of new vessels (vasculogenesis), or a combination of both processes. Uncertainty about the contribution of angiogenesis and vasculogenesis to pulmonary vascular formation is partly due to methodologic approaches. Evidence in favor of angiogenesis stems from studies that used vascular-filling methods. Such methods identify only directly continuous lumina. Evidence for vasculogenesis has been provided by the use of molecular markers of blood vessel endothelium. Use of both methods has not been combined in the same species, however. We hypothesized, based on published evidence from quail and mouse, that chick pulmonary vascular formation occurs by vasculogenesis. To test that hypothesis, we used vascular filling, serial section, and immunohistochemical methods to analyze the developing lungs of chick embryos from Hamburger and Hamilton stages 20 to 43. Vascular filling suggested that the lumen of the pulmonary arteries sprouted from the sixth pharyngeal arch arteries. However, serial sections and immunohistochemical localization of fetal liver kinase-1 protein, the receptor for vascular endothelial growth factor, showed that the pulmonary arterial tree formed from endothelial cell precursors and coalescence of isolated blood vessels in the mediastinal splanchnic mesenchyme centrally to the developing lung tissue distally. Pulmonary veins grew from the left atrium to the developing lungs. Pulmonary blood vessel formation occurred continuously throughout the embryonic period studied. Our results show that vasculogenesis is the main process by which the pulmonary vasculature forms in the developing chick embryo.     

Bidirectional fusion of the heart-forming fields in the developing chick embryo.

It is generally thought that the early pre-tubular chick heart is formed by fusion of the anterior or cephalic limits of the paired cardiogenic fields. However, this study shows that the heart fields initially fuse at their midpoint to form a transitory "butterfly"-shaped, cardiogenic structure. Fusion then progresses bi-directionally along the longitudinal axis in both cranial and caudal directions. Using in vivo labeling, we demonstrate that cells along the ventral fusion line are highly motile, crossing future primitive segments. We found that mesoderm cells migrated cephalically from the unfused tips of the anterior/cephalic wings into the head mesenchyme in the region that has been called the secondary heart field. Perturbing the anterior/cranial fusion results in formation of a bi-conal heart. A theoretical role of the ventral fusion line acting as a "heart organizer" and its role in cardia bifida is discussed.     

Histochemical study of carbohydrate residues in human aortic atherosclerotic lesions by application of lectins

Carbohydrate residues of various cells in human normal aortic intima, fatty streaks and atherosclerotic plaques were studied with 10 kinds of biotinylated-lectins by immunohistochemical techniques in 10 cases. The results showed that: (1) The amount of carbohydrate residues increased along with the progressing of atherosclerotic lesions. (2) The cells in atherosclerotic lesions could be marked by more than one kind of lectins. (3) Decrease of carbohydrate residues on the endothelial membrane might be considered helpful to the formation of fatty streak.     

Histochemical studies on the mucins of the vertebrate tongues. XI. Histochemical analysis of mucosubstances in the lingual glands and taste buds of some birds.

The tongues of six birds were investigated histochemically to determine the distribution and nature of mucosubstances in the lingual glands and taste buds. The anterior lingual glands in sparrow, kingfisher, parrot and pigeon hawk contained only one type of cells (seromucous) elaborating a mixture of neutral mucosubstances, sialomucins and sulfomucins. The anterior lingual glands in fowl and owl contained three distinct types of cells elaborating separately neutral mucosubstances, sialomucins and sulfomucins. The posterior lingual glands in most of the birds investigated except fowl contained only seromucous cells identical to the cells in the anterior lingual glands, while in fowl two distinct cell types were identified: one elaborating sulfomucins and the other sialomucins. Taste buds were found to be restricted in the glandular areas of the tongue in all the birds and always in close association with the gland ducts. Special adenomere cavities were seen only in the tongue of sparrow.     

Metabolic control of pulmonary ventilation in the developing chick embryo

In birds, during the period from the breaking of the air cell by the beak (internal pipping) to hatching, pulmonary ventilation (VE) begins and gas exchange is jointly provided by the lungs and the chorioallantoic membrane (CAM). We asked to what extent, during this phase of two concurrent gas exchange organs, changes in the embryo's metabolic needs were accompanied by changes in VE. The carbon dioxide and oxygen exchange rates (VCO2, VO2) through lungs and CAM were separately, but simultaneously, measured in chicken embryos at 20-21 days of incubation, while VE was calculated from the measurements of pressure oscillations in the air cell during breathing. During the last 24 h of incubation, lung VO2 and VCO2 gradually progressed as the corresponding CAM values declined. An increase in egg temperature (T) from 33 to 39 degrees C increased the embryo's total metabolic rate, especially when the lungs were the predominant gas exchange route. Whether metabolism increased because of the embryo's development or because of the increase in T, VE was linearly proportional to lung VO2 and VCO2, and not to the embryo's total metabolic rate. Hence, in the developing chick embryo, VE control mechanisms sense the peripheral tissue requirements via the gaseous component of cellular metabolism.     

The fine structure of developing cartilage in the chick embryo

The fine structure of developing cartilage is described in the area of the future vertebral bodies in the cervical region of chick embryos. Incubation ages range from 36 hours, when the sclerotome of the somite begins to break up, to the thirteenth day. In the 36- to 72-hour interval cells of the sclerotome become free and assume stellate form. Polyribosomes nearly fill the largely undifferentiated cytoplasm. Microfibrils and amorphous material appear in the connective tissue space

1 The extent of the connective tissue space is determined by boundary (basement) membranes; externally by those of epithelium facing the geometric exterior of the organism and internally by those of endothelium, mesothelium, muscle, nerve and fat. The true contents of the connective tissue space are the connective tissues. As used in this paper “connective tissue space” refers to the extracellular portion, in which the fibrous and amorphous components exist.

by the end of the third day. From the fourth through the sixth day both cellular contours and contents suggest fibroblasts. Microfibrillar diameter increases from 50 to 150 Å. Periodicity does not occur. Matrix granules appear and establish contact with microfibrils. From the eighth through the eleventh day the predominating cell types are chondroblasts and chondrocytes whose fine structure is typical. Microfibrils become more numerous and matrix granules larger. During days 11 through 13, chondrocytes show degenerative changes including lucid areas of nucleoplasm and cytoplasm with fragmentation of endoplasmic reticulum. Microfibrils and matrix granules are heavily concentrated in the connective tissue space and lucent osteoid appears.     

Mucopolysaccharide histochemistry of the avian tongue. Histochemical features of the lingual glands in Larus ridibundus (L).

From the histochemical analysis carried out on the tongue of Larus ridibundus (L.), it has been possible to establish that it is covered by thick stratum corneum on the dorsal surface and shows both in the anterior and posterior portions lingual glands, which histologically consist of aggregates of branched tubules. These glands exhibit identical histochemical reactions which show the presence of neutral mucopolysaccharides, sulfated and unsulfated acid mucosubstances and hyaluronidase-resistant sulfomucins. The acid mucosubstances have no connection with sialic or hyaluronic acid. The seeming absence of sialomucins which may probably not be due to the feeding habits of the animal, could be referred to the phylogenetic aspects of some markedly heterogeneous glycoproteins.     

Distribution of adenosine triphosphatase activity in the developing brain of the chick embryo

The development and distribution of ⁺-K⁺-stimulated and Mg²⁺-dependent ATPase activity in different parts of the chick embryo brain were investigated. Maximal changes in the Na⁺-K⁺-stimulated ATPase activity in the hemispheres and optic lobes took place between day 15 and 17 and in the cerebellum and brain stem between day 17 and 19 of incubation. Most of this activity was localized in the membranous fraction of the chick embryo brain. An attempt was made to correlate the rapid rise in the activity of this enzyme with the development of electrical properties of the chick embryo brain.