The third vascular route of the inner ear or the canal of Cotugno: Its topographical anatomy, fetal development, and contribution to ossification of the otic capsule cartilage.

Three vascular routes to the inner ear are known: (a) through the internal acoustic meatus with the vestibulocochlear nerve; (b) from the endolymphatic duct aperture; and (c) along the canal of Cotugno (CC) inserted into the vestibular part of the ear from the superior or brain side. The third is believed to contain only veins. Examinations of 33 human embryos and fetuses at 6-40 weeks demonstrated that (a) the CC appeared as a recess of epidural mesenchymal tissues at the superior aspect of the otic capsule cartilage in embryos and it was inserted deeply to issue multiple peripheral divisions inferolaterally and posteriorly at midterm; (b) the CC consistently passed through a ring of the superior or anterior semicircular canal and contained both, the arteries from the vestibulocochlear nerve origin at the midbrain and the vein draining into the sigmoid sinus or petrosal sinuses; and (c) the CC appeared not to contribute to ossification of the otic capsule cartilage but, after endochondral ossification of the internal ear, woven bone development occurred along a smooth interface of the CC with the ossified ear. In contrast, another interface between the developing bone and the residual cartilage of the otic capsule was rough and wavy with many short bony columns, called osseous globules. In addition, the endolymphatic duct accompanied veins but no arteries. Our results show that the CC is a major vascular route to the vestibular part of the otic capsule cartilage, but its role appears to be limited after ossification.

Vermiform Appendix During the Repackaging Process from Umbilical Herniation to Fixation onto the Right Posterior Abdomen: A Study of Human Fetal Horizontal Sections.

The anatomical position of the vermiform appendix varies among adults, and these variations are responsible for differences in the symptoms of appendicitis. However, to date no study has examined how and when these variations occur during fetal development. The present study examined horizontal sections of 27 midterm fetuses (crown rump length [CRL] 38-97 mm, gestational age approximately 8-15 weeks). There were 10 fetuses (CRL 56 mm or more) in which the cecum and appendix were in a posterosuperior site near the right kidney (postmigration phase), and 12 fetuses (CRL 39-72 mm) in which the ileocecal junction and appendix remained on the visceral surface of the liver in the anterior or anterolateral abdominal cavity (migration phase, after physiological umbilical herniation). Analysis of the 12 fetuses in the migration phase indicated that the appendix extended inferiorly in eight fetuses and superiorly in four fetuses. Likewise, a "preileal" appendix (a morphology in which the distal part of the appendix was in front of the terminal ileum) was present in eight of these fetuses. Extension of the appendix superiorly or inferiorly during the migration phase seems unrelated to the topographical relationship of the appendix with the terminal ileum at the postmigration phase in fetuses and in adults. Conversely, it seems likely that a retroileal appendix leads to a coiled appendix behind the ileocecal junction. "Guidance" by the liver surface seemed to be important for posterior migration, which ended with the ascent of the liver. Clin. Anat., 33:667-677, 2020. © 2019 Wiley Periodicals, Inc.

Changes in topographical relation between the ductus arteriosus and left subclavian artery in human embryos: a study using serial sections.

At birth, the ductus arteriosus (DA) merges with the aortic arch in the caudal side of the origin of the left subclavian artery (ltSCA). Since the SCA (seventh segmental arteries) were fixed on the levels of the seventh cervical-first thoracic vertebral bodies, the confluence of the DA should migrate caudally toward the lower level. We aimed to describe the changing topographical anatomy of the DA and SCA using serial sections. First, we examined serial sagittal sections of 11 embryos (Carnegie stage 15-18), but the specimens were clearly divided into 2 groups with and without the lower confluence of the DA. Next, we examined serial horizontal sections of 40 specimens (Carnegie stage 14-16) and we chose 5 specimens (CRL 11 mm, 3 specimen; 1, 14 mm; 1, 15 mm) including the DA near (within 1-vertebral segment from) the ltSCA. The final approach of the DA occurred during the heart descent in which the apex of the heart migrated from the level of the first to the fourth thoracic vertebral body. Thus, the DA reached the SCA level before establishment of the heart descent. The right aortic arch maintained its entire course in 2 of the 5 specimens. Therefore, the positioning of the DA along the left aortic arch might occur independently of degeneration of the right arch. Notably, the tracheal bifurcation level was higher when the DA-ltSCA distance was greater. A contribution of the increased pulmonary volume was suggested for the final approach of the DA.

Morphology and relationships of ultimobranchial body with pharyngeal pouches

The ultimobranchial body in humans is still controversial and different theories have been put forward. The aim of this study was to clarify the topographical anatomy of the ultimobranchial body and surrounding tissue during early development. Human embryos at 5-7 weeks of development were used for morphological observation. During the early stages, the sections displayed a ladder-like arrangement of the second to fourth endodermal pouches. The fourth pouch was located in front of the nodosa ganglion. The bilateral fifth pharyngeal pouches protruded anterolaterally to form a Ushaped lumen surrounding the arytenoid swelling. During the middle stages, the third pharyngeal pouch was identified near the fourth pharyngeal artery and the fourth pharyngeal pouch was located anterior to the parathyroid gland IV. We identified a cyst-like structure that is composed of a cell cluster facing to a small lumen as the ultimobranchial body. During the late stages, the lateral thyroid arising from the fourth pharyngeal pouch was located medial to the common carotid artery and joined to dorsal surface of the thyroid gland anlage. The thymus anlage arising from the third pharyngeal pouch was an independent structure that was located lateral to the common carotid artery. However, the ultimobranchial body had disappeared and did not integrate in the thyroid gland. We concluded that (1) the thymus originates from the third pharyngeal pouch; (2) the lateral thyroid originates from the fourth pharyngeal pouch; (3) the ultimobranchial body originates from the fifth pharyngeal pouch

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Pathogenesis of solitary right aortic arch: a mass effect hypothesis based on observations of serial human embryonic sections.

In general, solitary right aortic arch carries the left-sided ductus arteriosus communicating between the left subclavian and pulmonary arteries or the right-sided ductus connecting the descending aorta to the left pulmonary artery. Serial sections of fifteen 5- to 6-week-old embryos and ten 8- to 9-week-old fetuses suggested that the pathogenesis was unrelated to inversion due to dysfunction in gene cascades that control the systemic left/right axis. With inversion, conversely, the ductus or the sixth pharyngeal arch artery should connect to the right pulmonary artery. The disappearance of the right aortic arch started before the caudal migration of the aortic attachment of the ductus. Sympathetic nerve ganglia developed immediately posterior to both aortae, with a single embryonic specimen showing a large ganglion at the midline close to the union of the aortic arches. These ganglia may interfere with blood flow through the distal left arch, resulting in the ductus ending at the descending aorta behind the oesophagus. In another fetus examined, a midline shift of the ductus course resulted in the trachea curving posteriorly. Therefore, solitary right arch is likely to accompany abnormalities of the surrounding structures. The timing and site of the obstruction should be different between types: an almost midline obstruction near the aortic union needed for the development of the left-sided ductus and a distal obstruction near the left subclavian arterial origin needed for the development of the right-sided ductus. A mass effect of the sympathetic ganglia may explain the pathogenesis of any type of anomalous ductus arteriosus shown in previous reports of the solitary right arch.

Analysis by Light, Scanning, and Transmission Microscopy of the Intima Synovial of the Temporomandibular Joint of Human Fetuses during the Development.

Objective. To characterize morphologically and ultrastructurally using light microscopy, the scanning electron microscopy and transmission electron microscopy the intima synovial of the temporomandibular joint (TMJ) of human fetuses between the 10th and the 38th week of development. Materials and Methods. The TMJ was dissected bilaterally in 37 human fetuses belonging to the Institute of Embryology of the University Complutense of Madrid and of the Federal University of São Paulo. Results. The outcome by light microscopy showed the morphology of the TMJ and that the formation of inferior joint cavity precedes the superior joint cavity and the presence of blood vessels in the synovial. Conclusion. By scanning and transmission electron microscopy we observed the presence of two well-defined cell types in the intima layer of synovial of the TMJ of human fetuses, macrophage-like type A cell and fibroblast-like type B cell, and the presence of the a third cell type, defined by the name of intermediate lining cell in the intima layer of the synovial.

Early fetal development of the medial canthal ligament and Horner’s muscle: a histological study

Horner's muscle is a well known structure that accelerates lacrimal drainage. However, the fetal topographical relationship between this muscle and the medial canthal ligament (MCL) seems to differ from the adult morphology because a fetal connective tissue band toward the eyelids has never been demonstrated.We examined horizontal and frontal sections of 15 specimens (20-30 weeks of gestation) from the large collection of human fetuses stored at the Complutense University in Madrid (Spain). Frontal sections demonstrated the orbicularis oculi muscle inserting to a raphe-like structure along the horizontal parts of the lacrimal canaliculi. In horizontal sections, the raphe-like structure corresponded to a fibrous tissue mass sandwiched by the superior and inferior lacrimal canaliculi. The tendons of Horner's muscle were divided into 1) the so-called "reflection tendon" that included the typical myotendineous junction at the insertion into the maxilla, and 2) the so-called "direct tendon" in the roof of the lacrimal sac. However, Horner's muscle did not insert into the canaliculi, but was simply attached to, or embedded in, the fibrous sheath around them. Notably, none of these connective tissue structures was attached to the tarsi. Horner's muscle and its tendon might contribute to formation of the bony attachment of the future MCL, but the main part of the MCL most likely originates from the raphe-like structure. The connection between the MCL and the tarsi seems to be established after birth due to the growth of connective tissue along the lacrimal canaliculi. Although congenital entropion is a rare condition among Westerners, the present study demonstrated that the tarsus is unlikely to be fixed at a late stage in Western fetuses (AU)

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[Morphogenesis and clinical anatomy of the petrotympanic and petrosquamosal fissure]. / Morfogénesis y anatomía clínica de las fisuras petrotimpánica y petroescamosa.

Petrotympanic and petrosquamosal fissures are located in the temporal bone, in a complex area of the base of the skull, closely related to the evolutionary development of mammals. However, until now we do not have a comprehensive descriptions about how the formation of these fissures were formed. Recent researches have allowed us to determine the factors involved in their development, and consequently how the closure of the middle takes place and its separation of the temporomandibular joint. The mechanisms and structures involved in their morphogenesis determine the variability and anatomoclinical implications.

Giant Aortic Arch Aneurysm and Cardio-vocal Syndrome: Still An Open-surgery Indication.

The Cardio-vocal Syndrome (Ortner's syndrome) is described as hoarseness due to the left recurrent laryngeal nerve palsy, caused by a specific cardiovascular pathology. In this case, we present a patient with a giant aortic arch aneurysm with an initial clinical presentation of Cardio-vocal Syndrome. The conventional open-surgery, instead of endovascular approach, was useful to control the morbidity from the compressive effect of adjacent structures, also preventing the aortic rupture. We strongly recommend analyzing carefully the individual case and the clinical targets to resolve, because the new technologies are not always the most effective therapeutic response.