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Figure 1-34 Schematic drawing of a sagittal section through the body of a 28-day-old human embryo. Foregut, midgut, and hindgut are differentiated. The stomach, however, still presents as an asymmetric tubal segment. The initially elongated body bends, owing to the increasing number of somites and to the prominence of the head. This gives the embryo a C shape. The horizontal line at the left indicates the limits between the branchial derivatives and those of the somites. The dotted area in the gut marks the caudal border of the foregut, which is disproportionately large when compared with the midgut and hindgut. (After Hinrichsen, K.V.: a. ¡ntesünaltrakt, b. peripheres Nervensystem, c. Venen. In Hinrichsen K.V. [ed.]: Human Embryologie: Lehrbuch und Atlas der vorgeburtlichen Entwicklung des Menschen. Berlin, SpringerVerlag, 1990, pp. 105, 449, 516, with permission.)

Figure 1-35 Sprouting of the tracheal bud (1) from the foregut. The primitive pharynx (2), esophagus (3), tracheoesophageal fold (4), and stomach (5) are shown. Although this photograph is of a chick embryo, it strongly resembles the wax plate reconstructions of 3- to 5-mm CR human embryos studied by Zwa-Tun, [ ] who used the material of the Carnegie collection. Sagittal sections. SEM from the external (A) and internal (B) aspects and histologic section (C). (Courtesy of D. Kluth, M.D., Hamburg.)

Figure 1-36 Diagram showing the event of separation of the trachea from the foregut. Following the formation of the primitive foregut, the appearance and downward elongation of the tracheal and lung bud make the trachea and esophagus two different entities. Both structures become intimately positioned but do not fuse. Sagittal sections. The tracheal groove will become the tracheal diverticulum, trachea, and lungs.

Figure 1-36 Diagram showing the event of separation of the trachea from the foregut. Following the formation of the primitive foregut, the appearance and downward elongation of the tracheal and lung bud make the trachea and esophagus two different entities. Both structures become intimately positioned but do not fuse. Sagittal sections. The tracheal groove will become the tracheal diverticulum, trachea, and lungs.

Figure 1-37 Histologic sections, hematoxylin and eosin preparation, 5 pm, through two human embryos of similar age, 44-mm (A) and 46-mm (B) crown-rump length, and similar level, which is at the entry into the chest. A is in the transverse plane, viewed from caudal, and Bis in the sagittal plane viewed from the left. The esophagus is in the posterior position. Both slices show primitive, developing tissues but definite adult organ relationships, such as the Intimate location of the esophagus (1) relative to the trachea (2). 3 = tracheal membrane, 4 = tracheal cartilages, 5 = developing mucosa (note the difference of the cell layers between 1 and 2), 6 = esophageal submucosa (note the dimension of the tissue portion when compared with 7), 7 = muscle coat with large circular and small longitudinal layer, 8 = future Inferior laryngeal (recurrent) nerves (r = right, 1 = left), 9 = primitive mediastinum with undifferentiated tissue of the previsceral and retrovisceral spaces, 10 = pleural cavities (coelom), 11 = primitive vertebral fascia. (From the collection of Liebermann-Meffert.)

Figure 1-38 A-E, Macroscopic view of human stomachs of embryos between 8- and 22-mm CR lengths. Owing to localized cell proliferation, the greater curvature undergoes extensive growth during the 5- through 25-mm stages, which will also form the gastric fundus, the cardiac angulation, and the esophagogastric junction. Both cardia and pylorus are connected by the stalk of the celiac and superior mesenteric vessels. Therewith, growth processes will occur mainly at the free margin of the stomach, at the greater curvature. The lesser curvature does not join this excessive growth stimulation, which, finally, causes the gastric asymmetry. This event is illustrated by the series of human embryos of different CR length (A = 8 mm, B = 14 mm [posterior view], C = 18 mm, D = 19 mm, E = 22 mm).

Figure 1-39 The changes in gastric shape are due to an asymmetric growth process involving mostly the greater curvature by great mitotic activity within the wall.1 ' 1 ' The cardia and the pylorus remain in place anterior to the spine, where they are held because of their firm dorsal attachment (GEJ and Py) and their relationship to the vessel stalks. SSL = Crown-rump length of the embryo, i.e., fetus. GEJ = gastroesophageal junction.

Figure 1-40 Anchoring structures above the esophagogastric junction (sagittal section through a 15-mm CR human embryo). The section parallels but does not cut the esophageal and gastric lumen. (1 = diaphragm, 2 = esophagus, 3 = phrenoesophageal membrane, 4 = stomach, 5 = liver, 6 = pleural cavity, 7 = abdominal cavity, 8 = vacuoles in the mucosa.) The small arrows show the differentiating muscular wall.

(Courtesy of Fernandez de Santos, M.D., Madrid.)

Figure 1-41 Tissue origin of the diaphragm and its four sources. (From Moore, K.L.: The Developing Human, Philadelphia. W.B. Saunders, 1988, with permission.)

Figure 1-42 Transverse section through the esophagus in embryos of 8.5-mm (A), 12.5-mm (B), 20-mm (C), and 40-mm (D) CR length. The mucosal epithelium lining the lumen (1) is stratified columnar in the 8.5-mm CR embryo and will become vacuolized between 12.5 and 20 mm CR and multilayered columnar in the 40-mm CR stage. The tissue that surrounds the mucosal epithelium consists mainly of undifferentiated mesenchyme in the 8.5-mm CR embryo. Differentiation of the inner muscle coat is identified by the cell condensation around the mucosal ring seen in A (2). Pale areas of neural cells as precursors to the recurrent laryngeal nerves are seen exterior to the foregut tube (3). In the 12-mm and 20-mm CR stages, the inner muscular layer is further advanced. The outer longitudinal muscle layer and the muscularis mucosae, however, can be identified only at the 40-mm CR length. During this development, the extrinsic innervation, and in particular the recurrent laryngeal nerve, has become of conspicuous size (3). The developmental changes in luminal diameter and shape of the esophagus are seen. (A, B, and D from the collection of Liebermann-Meffert; C from Enterline, H., and Thompson, J.: Pathology of the Esophagus. Heidelberg Springer, 1984, with permission.)

Figure 1-43 Comparison of transverse sections through the esophagus (A) and stomach (B) in the 8.5-mm CR embryo. Consisting of three layers, the esophageal epithelium is stratified and columnar; it shows a basal layer of cells with large oval nuclei. The basement membrane seen here may not yet be distinct in all embryos at this stage of development. The stomach shows an epithelium that has fewer layers and a distinct basement membrane. (From the collection of Liebermann-Meffert.)

Figure 1-44 Transverse section through the upper esophagus of a 12.5-mm CR embryo above the level of the developing tracheal bifurcation with narrowing of the lumen owing to cell proliferation. The arrow shows the differentiating circular muscle layer of the esophagus (1 = primordium of the trachea, 2 = recurrent laryngeal nerve). (From the collection of Liebermann-Meffert.)

Figure 1-45 Transverse section of the middle esophagus at the vacuolated stages of the mucosa in 12.5-mm CR (A), 20-mm CR (B), and 40-mm CR (C and D) embryos. The vacuoles are located between the epithelial cells. Some are large with a diameter occasionally greater than that of the esophageal lumen. Serial sections suggest that some of the vacuoles may even be multichambered (C and D). Small stretched epithelial cells form partitions that separate from the esophageal lumen (C). Some of the vacuoles contain aggregated fiber material (arrows in A and B). (L = esophageal lumen, V = vacuole). (A from the collection of Liebermann-Meffert; B from Enterline, H., and Thompson, J.: Diseases of the Esophagus. Heidelberg, Springer-Verlag, 1984, with permission; C and D courtesy of Fernandez de Santos, M.D., and Tello Lopez, M.D., Madrid.)

TABLE 1-2 -- Prenatal Development of the Mucosa in the Human Esophagus

An interesting aspect of the mechanisms of the developing esophageal mucosa was studied by Menard and Arsenault.1 ' These investigators were able to study expiants of the esophagus from early-stage human fetuses maintained in organ culture. Using this fresh material, they followed the ultrastructural changes that occurred in esophageal epithelialization during maturation of the tissue. They observed that during the replacement of the epithelium, islets of ciliated cells actually developed epithelium.

The stratified squamous epithelium appears in the 90- to 130-mm CR fetus (see Fig. 1-46 C ). Again, this epithelium migrates from the middle third of the esophagus, spreading cranially and caudally until squamous epithelium has progressively and almost completely replaced the ciliated columnar epithelium in the 250-mm CR fetus. Some patches of ciliated columnar cells, however, occasionally remain until birth and are usually found in the proximal esophagus.

The first superficial glands have been observed during the 160-mm CR stage (see Table 1-2 ). They contain acini. These glands are numerous in the esophagus of 210-mm CR fetuses and are located mostly at the level of the cricoid cartilage and at the lower end of the esophagus.[ ] [ ] During the last 3 months of gestation, the downgrowth of the surface epithelium begins to generate submucosal glands ( Fig. 1-47 ).

The formation of the esophageal lumen is greatly influenced by the development of the mucosa. Owing to cell proliferation and to the appearance of the vacuoles between the 10- and 21-mm CR stages, the initially slit-like (see Fig. 1-42 and Fig. 1-44 ) or elliptic lumen becomes narrow and asymmetric and then assumes a bizarre configuration (see Fig. 1-42^ to C). This phenomenon is more pronounced at levels between the esophageal opening and the tracheal bifurcation and is caused by cell proliferation (see Fig. 1-44 ). As the process of vacuolization

Figure 1-47 During the last trimester of fetal development, downgrowth of the surface epithelium begins to generate future submucosal glands. A few ciliated cells are present on the surface above the squamous epithelium. (From Enterline, H., and Thompson, J.: Diseases ofthe Esophagus. Heidelberg, Springer-Verlag, 1984, with permission.)

Figure 1-48 Sagittal sections through the esophagus of a 15-mm CR embryo at two consecutive levels. A, The esophageal musculature is cut at its peripheral limits. The lumen appears to be obliterated by musculature mimicking a solid structure. B, A deeper slice through the esophageal wall displays the vacuolated but patent esophageal lumen. (A = aorta, E = esophagus, D = diaphragm, p = pancreas, S = stomach.) (Courtesy of Fernandez de Santos, M.D., and Tello Lopez, M.D., Madrid.)

Figure 1-49 Schematic drawing of a sagittal section through the foregut. As shown, two of the three main sources of the adult blood supply are derived from branchial arch arteries. These are the esophageal branches from I, the later thyroid arteries, and from II, the tracheobronchial arteries. The third source (III) derives from the gastric and splenic branches of the celiac artery. (Modified from Moore, K.L.: The Developing Human, Philadelphia, W.B. Saunders, 1988, with permission.)

Figure 1-50 The esophagus in the fetus and its topographic development. Structures above the line of the tracheal bifurcation (vessels, nerves, and lymphatics) originate from the tissue of the branchial arches and pharyngeal pouches. Below this line, the structures derive from the lateral plate of the body mesenchyme. This border, located at the level of the tracheal bifurcation, permanently defines the direction of vascular flow. (1 = head, 2 = oral cavity and pharynx, 3 = esophagus, 4 = stomach, 5 = bowel.)

Figure 1-51 Schematic illustration of the saccular lymphatic system at the 30-mm CR stage, eighth week of gestation. The branchiogenic part into which the upper foregut drains is far more voluminous than that of the lower foregut, midgut, and hindgut. The saccus jugularis (1); the jugular vein (2); the suprascapular (3); supraclavicular (4); and axillar lymphatic protrusions (5); the thoracic duct (6); and the bronchoesophagomediastinal lymphatics (7) are seen. (After Gaudecker, B. von: Lymphatische Organe. In Hinrichsen, K. V. [ed. J: Human Embryologie: Lehrbuch und Atlas der vorgeburtlichen Entwicklung des Menschen. Berlin, Springer-Verlag, 1990, p. 340, with permission.)

Figure 1-52 The parasympathetic and sympathetic nervous systems in relation to the foregut in a human embryo of 18 mm CR. (From Hinrichsen, K.V.: a. Intesünaltrakt, b. peripheres Nervensystem, c. Venen. In Hinrichsen, K.V. [ed.]: Human Embryologie: Lehrbuch und Atlas der vorgeburtlichen Entwicklung des Menschen. Berlin, Springer-Verlag, 1990, pp. 305, 449, 516, with permission.)

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Herbal Remedies For Acid Reflux

Herbal Remedies For Acid Reflux

Gastroesophageal reflux disease is the medical term for what we know as acid reflux. Acid reflux occurs when the stomach releases its liquid back into the esophagus, causing inflammation and damage to the esophageal lining. The regurgitated acid most often consists of a few compoundsbr acid, bile, and pepsin.

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