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Embriologia Larsen Pdf

EMBRIOLOGIA HUMANA WILLIAM LARSEN PDF - (FREE) Embriologia Humana William. Larsen Pdf Heart development (also known as. embriologia humana william larsen pdf - hrhunited - embriologia humana william larsen embriologia humana william larsen sun 16 dec This is a relied on place to have Embriologia Humana William Larsen by as cost-free reading online in rar, word, pdf, txt, kindle, zip, and also ppt. There are a .

During the pseudoglandular stage, the protein expression of AQP1 and 5 was detected at the apicolateral membrane of epithelial end buds Fig. Similar expression pattern was sustained during the following canalicular stage of glandular morphogenesis, where AQP1, 3 and 5 were found at the membrane of end bud regions Fig. Regarding the ductal area, there was no positivity for AQP1 and 3 within the forming ducts Fig. At the final terminal bud stage, AQP1 was still not identified within any ductal structure, although was highly expressed within serous acinar cells Fig. AQP3 was in turn detected at the basolateral membrane of developed serous and mucous acinar cells Fig. Collecting excretory ducts were, however, mostly negative as illustrated in Fig. AQP5 maintained its expression at the apicolateral membrane of acinar cells at this stage, where it was also present at the luminal layer of proximal developing ducts Fig. AQP5 was the only aquaporin consistently found within the lumen space of developing ducts throughout gland morphogenesis. In order to address whether those AQP5 positive cells are future acini or in fact ducts, the expression of this protein in correlation with presumptive lumen marker cytokeratin 7 K7 was analysed Fig. Mature ducts showing an expanded lumen space during gland development were K7 positive in the luminal layer and completely negative for AQP5 Fig. A striking co-localisation of AQP5 and K7 was however observed within presumptive duct structures, where both markers were concentrated mainly at the apical area Fig. Developing acini in turn were AQP5 positive only with an apicolateral expression in the epithelial cells Fig. Open image in new window Fig. Arrows luminal expression of K7 where there is a clear luminal space already present, and AQP5 is completely absent; Arrowheads co-localisation of AQP5 and K7 in future ducts.

Studies in rat salivary glands described the immunolocalisation of AQP1 only in the microvasculature, which was also observed at prenatal stages, but no evidence of this protein in ductal or acinar structures Li et al. The expression pattern of AQP1 seem to be important for water transport from blood vessels to SG, aiding the formation of the future salivary fluid, corroborating our results Akamatsu et al.

In addition, recent studies on the role of vascularisation in mouse salivary glands have reported the requirement of endothelial cells for gland development by promoting expansion of specific progenitor cells during early stages Kwon et al. The expression pattern of AQP3 during human SG morphogenesis was also restricted to acinar structures throughout development as AQP1, however it was mostly found in the basolateral membrane of epithelial cells and it was completely negative in ducts and endothelial cells.

In rat submandibular glands, Akamatsu et al. In this study they reported a unique gene expression of AQP3, suggesting it plays a specific role in gland development, which is in agreement with our findings in human tissue. Larsen et al. They have demonstrated distinct RNA and protein expression pattern of AQP1, 3 and 5 amongst other family members, indicating that they might be associated with cell volume regulation, transepithelial transport, proliferation, cell death and other mechanisms, during development of submandibular glands.

Furthermore, corroborating our results in humans, they suggested an important role of AQP3 during developing stages, while it decreased at early post-natal stages.

In humans, the protein expression of AQP3 was found at the lateral membrane of mucous and serous acini of adult salivary glands, which was in agreement with our findings in foetal glands Gresz et al.

Extensive studies have already suggested a fundamental role of AQP5 for SG development and homeostasis. AQP5 is reported to be the major protein involved in regulating the permeability of acinar cells and it therefore regulates the salivary ionic composition and the flow rate Krane et al. Sugimoto et al. Nielsen et al. Embryonic glands were reported to show increasing expression of AQP5 through development in both studies, which was further supported by others Akamatsu et al.

In addition to the acinar expression, Akamatsu et al. This finding may be valid for mature glands, however our results showed the opposite scenario, where the stronger and more broad distribution of AQP5 was much more suggestive to contribute to gland development than AQP3. Aure et al. In comparison, our results showed earlier detection of AQP5 in human developing glands, from the initial bud stage, while Aure et al.

Despite of expressing AQP5 earlier in development, human SG also showed a more consistent acinar and ductal positivity in more developed glands towards the terminal bud stage. In larger mammals, Scocco et al.

In the parotid, they observed AQP5 at the lateral and apical membranes of acinar cells, also correlating its higher expression when feeding the animals according to water content food. There was also a difference in the expression of AQP5 between the types of acini, where serous cells showed higher positivity compared to mucous cells in submandibular glands, which were considered negative.

At this topographical level, the external carotid artery was surrounded by the external carotid nerve, branch of the superior cervical ganglion Fig. The caudal segment of the RC was disposed on either side of the hyoid body, with which it made contact to form the lesser horns.

At his stage, the location of the caudal segment of RC was under the level of the tongue, in relation to previous stages Fig. Between the posterior cranial segment of the RC, which later formed the styloid process, and the segment that would constitute the lesser horns, there was no cartilage formation in the second arch in any of the specimens examined, with the exception of the cases reported see variations. Nor was any ligament structure joining these two cartilaginous segments found Fig.

We did not observe a clear asymmetric development of the HA with the exceptions of the described variations. Variations of HA from RC Small variations were noted on the angulation of the cranial segment of RC that will form the styloid process, although in five cases the angle of the inferior end was more accentuated. In these cases the tip of the caudal end had a close contact with the glossopharyngeal nerve as well as the pharyngeal wall Fig.

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A Diagrammatic representation of the variations observed, in dotted line the angulation of cranial segment of RC RS. Anlage of the lesser horns of the hyoid RH. Otic capsule O. C Human fetus of 97 mm GL 13 weeks of development. D Human fetus of 87 mm GL 13 weeks of development. In these cases there were an increment of the angulation of the end of the cranial segment of Reichert's cartilage RS and its close relationship to the glossopharyngeal nerve G.

Continuous RC variation was observed bilaterally in a human fetus at 11 weeks of development Fig. In both cases, continuous RC variation ran, unilaterally or bilaterally between the otic capsule and the hyoid Fig. The cartilage exhibited a double incurvation caudally and next to the oropharynx. The angulation arranged close to the pharyngeal wall Fig.

The cartilage extended caudally to and made contact with the cartilaginous formation of the hyoid. A Diagrammatic representation of the variation observed RV. Anlage of the styloid process RS. B Human fetus of 65 mm GL 11 weeks of development.

Bilateral and continuous RC variation RV.

C and D Human fetus of 80 mm GL 12 weeks of development. Glossopharyngeal nerve G Greater horn of hyoid GH.

Larsen Embriologia Humana

Laryngeal cavity L. It was under the cranial segment of RC. The isolated cartilage was found to be medial to the submandibular gland and lateral to the pharynx, near the lingual artery Fig. The hypoglossal nerve, on its course towards the tongue, was located caudally to the isolated cartilage Fig. The lesser horns of the hyoid had not formed. Figure 7 Open in figure viewer PowerPoint Isolated cartilaginous formation.

Diagrammatic representation of the variation observed RV. B—D Human fetus of mm GL 14 weeks of development. Isolated cartilaginous formation RV in C , observed medially to the submandibular gland S. The cartilaginous formation RV C was found isolated, cranially B and caudally D to it, no cartilage had formed. Occipital artery OA. Superior cervical ganglion SC.

Superior laryngeal nerve SL. The cranial segment of the RC was elongated, stretching almost to the cartilaginous hyoid, where the lesser horns had not formed.

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This variation was found bilaterally in a human fetus at 15 week of development Fig. A Diagrammatic representation of the variations observed RV. B and C Human fetus of mm GL 15 weeks of development.

Genioglossus muscle GEH. In humans, the styloid process is connected with the lesser horn of the hyoid bone by the stylohyoid ligament and all of them are believed to be originated from RC Hamilton and Mossman, ; Corliss ; Sadler, ; Sperber et al.

In the present study we identified three steps in the development of the HA from RC 1 a mesenchymal condensation in the second branchial arch; 2 cartilage differentiation into the cranial and caudal cartilage segments those are connected by a MF; and 3 disappearance of the intermediate MF to separate these two cartilages. Steps two and three corresponded to a critical period in the development of the RC and occurred between 7 and 10 weeks. These steps will determine the morphology and subsequent the variations of the HA.

In step two, there is still a MF connecting the two segments of RC. The cranial segment was characterized by 1 its union to the otic capsule and 2 the bending or curving in its caudal ends. At this step, the topography of the structures indicated us that the neck was not differentiated.

It is known that, at the same stage of development, the other profound changes occurred in head and neck region: the upper and lower facial regions grew rapidly to provide connections with the skull base to reach the final morphology. Initial ossification of facial bones began but, at the skull base, the primary cartilages formed a continuous mass of skeleton Diewert, Diewert stated that the growth movements of the chondrocranium appear to play an important role in spatial relocation of developing facial bones for establishment of the final craniofacial morphology.

In step three or final step, between 8 and 10 weeks, the MF disappeared. This disconnection, according to our observations, coincided with the decrease of the flexion of the neck. At these stages, the size of the body also highly increased from 18 to 49 mm. Therefore these two morphological processes could prevent the formation of cartilage in the middle part of the second arch between cranial and caudal segments of the RC.

Mechanical stress having the fetal head should prevent the formation of cartilage. Likewise, we found no stylohyoid ligament in fetal histology. Thus, the perichondrium of the RC was unlikely to serve as a guide for the stylohyoid ligament in contrast to descriptions by previous researchers Hamilton and Mossman, ; Corliss, ; Sadler, ; Larsen, ; Carlson, ; Sperber et al.

Katori et al. At least in the late stage, there were no evidence in fetuses of later development of the ligament. In some species or subfamilies of the felidae in which the larynx and hyoid bone was positioned caudally, the stylohyal styloid process in human connects with the hypohyal lesser horn of hyoid bone in human by a ligament rather than a bone Weissengruber et al.

The hyoid bone with an elastic ligament instead of a bony articulation seems to allow an elongation of the supraglottal tract Peter and Hast, For many years researchers interested in the evolution of speech, paid much attention to a very low position of the human vocal cord that is unusual in other mammals: indeed until recently, this position characterizes the human larynx crucially linking evolution of speech Lieberman et al. Get fast, free shipping with site Prime. However, the primary oocytes then quickly enter a state lzrsen meiotic arrest that persists until after puberty.

Based on this finding, and the experimental reversal of flow in cultured embryos, larsen embriologia humana nodal flow model lareen left-right development was proposed note: APC and colorectal cancers are also discussed in Chapter Dyneins use energy from ATP hydrolysis to move cargo towards the minus end of microtubules, or cause bending of cilia and flagella by creating a sliding force between microtubules.

Would you like to tell us about a lower price? Although this textbook discusses only prenatal development, it is important remember that development is not just a prenatal experience; rather, development is a lifelong process, with aging humaan senescence involving larsen embriologia humana developmental events.

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Nat Rev Embriologiw 5: Yet, remarkably, one of the first things that happens in the developing embryo is to set aside the germ line for the next generation. Starting at the 8- to cell stage, the cleaving embryo, or morula, differentiates into two groups of cells: Larsen embriologia humana knowledge of human embryology will allow you to provide scientifically accurate coun- sel, empowering your patients to make informed decisions based on current scientific understand- ing.

Larsen — Embriologia Humana These parcels contain two known morphogens, Larsen embriologia humana and retinoic acid, and their leftward transport elicits a calcium flux on the left side of the node, in support of the mechanosensory model. For example, within the small intestine, villi finger-like projections form, separated by invaginations called crypts, whereas within the colon large intestine crypts also form but villi are absent.

Wnt signaling in the intestinal epithe- lium: These studies are relevant to humans; a larsen embriologia humana recently identified on human chromosome 4 has been linked larsen embriologia humana exceptional longevity. The entire con- ceptus i. Oxidative damage also accelerates aging. The real Dorian Gray mouse. Most Related.