[Anatomic and clinical evidence of intrapelvic pudendal nerve and its relation with striated sphincter of the urethra]. / Evidencias anatómicas y clínicas sobre el pudendo intrapélvico y su relación con el esfínter estriado de la uretra.

OBJECTIVE: To demonstrate that somatic innervation of the urethrae striate sphincter is intrapelvic and not through an internal pudendal nerve, an extrapelvic nerve in its entire path. To study the relationship of the pelvic plexus with genito-urinary organs and its surgical implications. METHODS: 6 embryos and 2 fetuses, sliced and stained with techniques suitable for nervous structures were studied. Sequential observation of the pelvic plexus structures and the internal pudendal nerve was carried out using light microscopy. Three-dimensional reconstruction of the two fetuses was performed to study the relationships of these structures with the genito-urinary organs. RESULTS: A nervous branch was identified in the 19, 25 and 30 mm long specimens that started at the internal pudendal nerve and joined the hypogastric ganglion close to the site of pelvic nerves binding. Hypogastric ganglion efferent branches penetrating the striate sphincter after a short descendent run were seen in the 30 and 39 mm embryos. CONCLUSIONS: Our findings confirm that the urethrae striate sphincter received the autonomous and somatic innervation from the pelvic plexus and, therefore, is susceptible to damage during cancer related surgery of the pelvic organs. An improved knowledge of these structures and the use of nerve preservation surgical techniques can reduce the incidence of post-operative incontinence in this type of surgery.

Evidencias anatómicas y clínicas sobre el pudendo intrapélvico y su relación con el esfínter estriado de la uretra / Anatomic and clinical evidence on intrapelvic pudendal and its relationship to urethrae striate sphincter

OBJETIVO: Demostrar que el esfínter estriado de la uretra recibe inervación somática por vía intrapélvica, y no a través del nervio pudendo interno, un nervio extrapélvico en todo su recorrido. Estudiar la relación del plexo pélvico con los órganos génito-urinarios y sus implicaciones quirúrgicas. MÉTODOS: Fueron estudiados 6 embriones y 2 fetos, cortados y teñidos con técnicas idóneas para estructuras nerviosas. Se efectuó la observación secuencial mediante microscopio óptico de las estructuras que constituyen el plexo pélvico, y el nervio pudendo interno. Se efectuó la reconstrucción tridimensional de dos fetos para estudiar las relaciones de dichas estructuras con los órganos génitourinarios. RESULTADOS: En los ejemplares de 19, 25 y 30 mm de longitud, se identificó una rama nerviosa que partiendo del nervio pudendo interno se unía al ganglio hipogástrico, muy cerca del sitio donde se unen los nervios pélvicos. En los embriones de 30 y 39 mm se apreciaron ramas eferentes del ganglio hipogástrico, que tras un corto recorrido descendente penetran dentro del esfínter estriado. CONCLUSIONES: Nuestros hallazgos confirman que el esfínter estriado de la uretra recibe inervación autónoma y somática a través del plexo pélvico, y por lo tanto, es susceptible de ser lesionada durante la cirugía oncológica de los órganos pélvicos. El mejor conocimiento de estas estructuras y la aplicación de técnicas quirúrgicas de preservación nerviosa, pueden disminuir la incidencia de incontinencia postoperatoria en este tipo de cirugía (AU)

Anastomosis between both hypoglossal nerves in a 30 mm human embryo.

In this paper we present the first description of an anastomosis between both hypoglossal nerves during the embryonic period, a very uncommon anatomical variation. This was observed in a 30 mm crown-rump (C-R) length human embryo (Carnegie stage 23) from the Bellaterra Collection (Prof. Doménech Mateu), stained for nerve fibers. The anastomosis consisted of a large diameter trunk (36.7 microns) situated in front of and slightly below the hyoid cartilage, and clearly distinguishable from the anastomosis found in adults, which has a very fine diameter and is located in the suprahyoid region.

An unusual clinical presentation of bilateral schizencephaly.

We present a case with a characteristic magnetic resonance image (MRI) of bilateral open-lipped schizencephaly and atypical clinical presentation. The patient is still alive and in good health in her forties, she has never presented seizures, and although the motor dysfunction is well correlated with cerebral lobe involvement, neurobehavioral dysfunction is not proportional to the MR image of the cerebral malformation.

Prenatal development of the rat sinuatrial node.

In order to study the origin and mode of differentiation of the cells which make up the sinuatrial node, samples of the sinuatrial junction of rat embryos of different ages were studied by transmission electron microscopy. From a seemingly morphologically homogeneous cell population at 11 days, an ultrastructural differentiation occurs from day 12. So, one could see: a) irregular-shaped cells with dark nucleus and medium-sized contractile apparatus which we have identified as ordinary ("working") atrial myocardiocytes and, b) pale cells with a clear spheroidal nucleus and cytoplasm containing few organelles and fine myofibrils which we have classified as nodal cells. Numerous undifferentiated cells of intermediate morphology appear intermingled with nodal and ordinary cells. Throughout development, nodal and ordinary cells progressively enhanced their mutual differences. Ordinary myocardiocytes become increasingly rich in myofibrils and mitochondria, and nodal cells contain scanty organelles and fine myofibrils, whereas undifferentiated cells are few at every stage. At the end of prenatal life, the sinuatrial node shows numerous unmyelinated axons of immature aspect but direct contacts between nodal cells and nerve fibers are not seen. The images we obtained suggest that the sinuatrial node must not be taken as an embryological remnant. Nodal cells are recognized from the 12th day of embryonic life as a particular form of differentiation of the cells which make up the sinuatrial region at the preceeding stages.

[Malformations induced by vitamin A administered in the young chick blastoderm]. / Malformations occasionnées par la vitamine A admnistrée chez le jeune blastoderme de poulet.

The administration of 2250 IU of retinyl palmitate in young chick blastoderm at 4-5 HH stage brings 28% of surviving embryos and 84.5% malformed. The most frequent induced anomalies affect neural tube and/or neural crest which are the most sensible structures to vitamin A teratogenic action. The teratogenic mechanism would be produced by direct effect upon neuroblast and neural crest cells, and thus, this would cause the usual association of neural tube closure defects with facial malformations.

Development of the tendon of Todaro during the human embryonic and fetal periods.

This study covers the development of Todaro's tendon during human embryonic and fetal periods. The tendon primordium first appears when human embryos attain a CR length of 22 mm, but it only becomes well-defined at 24 mm CR length. The tissue that will form the tendon proceeds exclusively from the inferior endocardial cushion. The tendon establishes a close relationship with the base of the septum secundum during its path towards the right venous valve, carrying myocardial tissue out and forming the fasciculus limbicus inferior to muscular tissue. The tendon's relationship with the superior aspect of the atrioventricular node primordium during the first part of its path is of particular interest. The relationship is most intriguing when the node morphology is least defined. This would explain the possible embryogenesis of extra atrioventricular nodes. We also consider Todaro's tendon to be largely responsible for the development of the sinus band which protrudes as a crest inside the right atrium. This band is particularly well-developed in the fetal heart and provides an explanation for the large sub-Eustachian sinus cavity.

Presence or absence of glycogen-beta particles in sinoatrial node cells.

The sinoatrial node is formed by specialized cells, the main ultrastructural differences of which, as compared with ordinary atrial myocardium, are a pale cytoplasm and sparse myofibrils. Moreover, nodal cells have been described to contain large amounts of glycogen particles in their pale cytosol; these glycogen inclusions are often used as the main criterion for identifying nodal cells. Nevertheless, the presence of glycogen cytosolic inclusions has been discussed by several authors. This paradox was solved by the description of some undesirable effects of uranyl acetate when used en bloc. To prove the presence of glycogen granules in nodal cells and the effects of uranyl acetate en bloc, we performed an ultrastructural study of the sinoatrial node in rats of different ages using different staining techniques. Our results do not reveal any beta-particles in nodal cells in tissues processed by either general or glycogen-specific methods. Uranyl acetate staining did not cause any change of appearance in the nodal or ordinary myocardium. From these results, one could conclude that, on the one hand, sinoatrial nodal cells do not show deposits of beta-particles of glycogen which can be detected with ultrastructural techniques, and, on the other hand, that uranyl acetate does not cause any morphological artifacts.

Development of the pelvic plexus in human embryos and fetuses and its relationship with the pelvic viscera.

Development of the pelvic plexus is studied in 15 human embryos and 2 fetuses ranging in size from 4 to 132 mm. C.R. length. A tridimensional reconstruction of the entire pelvic block was made in two specimens (30 and 132 mm. C.R. length) 80 X. The first ganglionic elements appear in Carnegie's stage 16, but the real definition of what in the final anatomy of the plexus is described as the hypogastric ganglion (Lee-Frankenhäuser) is formed in stage 18. Complete development of the plexus occurs in stage 23. Other relevant facts are: the appearance in stage 18 of the pelvic splanchnic nerves, which are formed from S2, S3 and S4, the involvement of S1 and S5 were not observed in any case. In all specimens studied, a close proximity was seen between the pelvic plexus and genitourinary organs. Starting in stage 18, the terminal ureter consistently crosses the posterosuperior part of the pelvic plexus.

[The development of the atrioventricular node and bundle of His in the human embryonic period]. / Desarrollo del nodo atrioventricular y del haz de His en el período embrionario humano.

To study the development of the atrioventricular specific system, together with the closely related mesenchymal tissue (from which the fibrous skeleton of the heart later develops). Thirty human embryos ranging from 3 mm to 30 mm crown-rump length (Carnegie stages 10-23) were used. The primordium of the atrioventricular specific system was observed for the first time in human embryos of 10 mm Crown-Rump length (Carnegie stage 16) as a cellular aggregate located below the inferior endocardial cushion. The primordium cells originate from the myocardium of the posterior wall of the atrioventricular canal. The primordium later forms both the atrioventricular node and the His bundle. The mesenchymal tissue which surrounds these features originates from the endocardial cushions (particularly from the inferior endocardial cushion). Todaro's tendon and the central fibrous body are later formed from the inferior endocardial cushion. The atrioventricular node and His bundle are both formed from the primordium of the atrioventricular specific system. The node is produced from the cranial-dorsal extension of the primordium while the His bundle is produced from the growth of the primordium in a ventral-caudal direction. The central fibrous body is anatomically defined in the stages post-dating morphogenesis of the atrioventricular specific system.

[Anomalies produced by cytochalasin B after 10.5 days of gestation: in vitro study]. / Anomalies produites par la cytochalasine B apres 10.5 jours de gestation: etude in vitro.

124 rats embryos (Rattus Norvegicus sp.) have been cultured for 48 hours period (from 9.5 days to 11.5 days). 24 hours after the beginning of the culture, cytochalasin B (CB) dissolved in 1% dimethylsulphoxide (DMSO) was added to the culture medium in the experimental group (61 embryos), whereas only DMSO was added to the medium in the control group (63 embryos). Survival rate in the control group was 100% whereas in CB-treated embryos the higher the dose, the lesser the survival rate. Embryo growth and morphological score was reduced in CB-treated embryos. The most common gross malformations were delays in axial rotation as well as open neural tube defects.

Study of the development of the atrioventricular conduction system as a consequence of observing an extra atrioventricular node in the normal heart of a human fetus.

We have observed an extra atrioventricular node in the normal heart of a human fetus. It is located in the septal wall of the right atrium, subendocardially, and just where Todaro's tendon leaves this wall to go toward the inferior vena cava valve. In its trajectory, this tendon gives way to a remarkable prominence in the cavity of the right atrium: the sinus band. In order to explain the embryogenesis of this extra atrioventricular node, we have studied the normal development of the atrioventricular specific system and have concluded that the atrioventricular node is formed from a growth and displacement toward the atrium of the primitive atrioventricular specific material, which originates from the myocardium of the posterior wall of the atrioventricular canal. Likewise, during its development, the atrioventricular node keeps in close proximity with the Todaro's tendon. In our view, this accounts for the embryogenesis of the extra atrioventricular node, since a fragment of the atrioventricular node can remain cranial to Todaro's tendon and be displaced by it in a craniodorsal direction. This fragment would then lead to the formation of an extra atrioventricular node like the one present in the heart of the fetus we have examined.

Uncommon number and distribution of the Pacinian corpuscles in a human hand.

We describe some rare findings seen when dissecting the hands of a 65-year-old male cadaver. Very many lamellated (Pacinian) corpuscles were distributed all over the palms of both hands. They were normal in structure, but their size was greater (8 mms. in length and 5 mms. across) than the normal (2 mms. in length and 100-500 microns. across). Each lamellated corpuscle had only one nervous pedicle.

The arterial supply of the human spinal cord: a new approach to the arteria radicularis magna of Adamkiewicz.

The arteria radicularis magna (Adamkiewicz's artery) was studied in 30 human spinal cords after arterial injection. The artery was present in all cases, between T8 and L2, and was identified by its diameter and position. The arteria radicularis magna was the main blood supply to the lowest region of the spinal cord. In one out of three cases it accompanied the ventral root at T9, and in 80% of the cases studied it was found on the left side. The arteria radicularis magna had a posterior component in 63% of the cases. We did not observe specific radiculo-medullary arteries in the conus medullaris region.

The anterior ligament of the human malleus.

The authors have studied the anterior ligament of the malleus (ALM) from a morphological and embryological point of view. Classical textbooks of anatomy stress the correlation between the ALM and the anterior pin of the sphenoid and define the ligament as a residual of Meckel's cartilage. This study demonstrates the y-shaped form of the ligament, one arm of which reaches the capsule of the temporomandibular joint and the other the pin of the sphenoid bone. Meckel's cartilage pilots the fibres of the ligament itself. Several clinical implications may be hypothesised on the basis of this study.

The laryngeal primordium and epithelial lamina. A new interpretation.

The laryngeal primordium is present in both the laryngotracheal sulcus (LTS) and the primitive pulmonary sac (PPS). Its early period of development may be subdivided into two phases. The first phase (Stage 11) is represented by what is traditionally referred to as the LTS, located directly beneath the PP4 on the ventral wall of the foregut (primary segment), and by the PPS which is situated at its caudal end. The LTS will represent the primordium of the upper or membranous infraglottic cavity region; whereas the PPS, will give rise not only to the bronchial tree, but also to the primordium of the trachea and the lower or cartilaginous region of the infraglottic cavity. The second phase (Stages 13 and 14) is distinguished by the cranial growth of the LTS above the PP4 and therefore by its absorption into the floor of the primitive pharynx in the mesobranchial area (secondary segment), which will develop into the primordium of the vestibule of the larynx. Similarly, we observed that in the development of the laryngeal cavity there are two temporally and spatially separate epithelial structures: the epithelial septum and the epithelial lamina. In this respect we differ from other authors who are of the opinion that there is a single structure (the epithelial lamina). The epithelial septum is a primary structure responsible for the final configuration of the LTS, as it contributes to the development of the lower end of the primary segment of the LTS and also to the creation of the secondary segment. The epithelial lamina is a secondary structure which appears inside the LTS as a result of pressure exerted by the mesenchyme on its lateral walls, without having any effect on the morphogenesis of the LTS.

Effects of L-asparaginase on rat embryonic development and yolk sac membrane in vitro.

A comparative analysis of the teratogenic effects of L-asparaginase on 10.5- and 11.5-day rat embryos after 24 and 48 hours of exposure in vitro, respectively, were performed. Several medium concentrations of L-asparaginase (0.05, 0.25, and 1.5 IU/ml) were tested in both embryo series. Resulting embryos were submitted to morphological studies in a search for a specific route of pathogenesis. Morphological alterations of the visceral yolk sac were also studied to investigate its contribution to L-asparaginase teratogenicity in rats. Main embryonic malformations (open truncal neural tube, open encephalic vesicles, anophthalmia, lack of inversion, abnormal frontolateral protrusions, great vascular dilations at the cephalic level) and developmental retardation were already generated after the first 24 hours of culture (embryos of 10.5 days) and presented a dose-response relationship. Vascular dilations and neurulation disturbances seemed to be related to an early mesenchyme deficiency. Reduced number of mesenchymal cells was more evident in embryos of 10.5 days than those of 11.5 days, suggesting the existence of a later compensatory mechanism of cellular proliferation in the older embryo. Visceral yolk-sac endodermal cells at both embryonic stages were greatly deformed and enlarged by an increase of the high electron-dense vacuolar system. Therefore, both a blockage of the processes of lysosomal digestion and derived trophic deficiencies probably existed. A double teratogenic mechanism for L-asparaginase is postulated: a direct action mainly in younger embryos (before invagination of the embryo into the yolk sac) and a yolk sac-mediated one.

Anterior spinal arteries. Origin and distribution in man.

This study was designed to extend our present knowledge of the origin and distribution of anterior spinal arteries and was carried our using 31 human cadavers with arterial injections of natural latex. The conclusions reached are that there are always one or two anterior spinal arteries (right or left), which proceed from the intracranial segment of the vertebral arteries. These arteries have a descending course, with distribution into the ventral face of the medulla oblongata and the first cervical segments of the medulla spinalis. In cases where there are two anterior spinal arteries, they anastomose with each other to form the common, unpaired and median anterior spinal artery. The different observed locations of the origins of anterior spinal arteries may be systematised into three types. Each of these types has differential characteristics: bilateral origin (type I; 77.4%), unilateral origin (type II; 9.7%) and origin in an intervertebral transversal anastomosis (type III; 12.9%). We do however subdivide the bilateral origin group, according to the calibre of the arteries, into the subtypes 'balanced' (type Ia; 22.6%), 'right dominated' (type Ib; 32.2%) and 'left dominated' (type Ic; 22.6%). The collaterals of the anterior spinal arteries which distribute into the ventral face of the medulla oblongata are described.

Association of tracheoesophageal anomalies with visceral and parietal malformations in a human embryo (Carnegie stage 21).

A human embryo (Carnegie stage 21) with tracheoesophageal malformations (esophageal atresia and tracheoesophageal fistula) and anomalies at the caudal end of the embryo (anorectal atresia, rectovesical fistula, vertebral and notochordal defects, and agenesis of the metanephros) was studied. Other anomalies observed were: absence of right umbilical artery, fusion of spinal ganglia, and absence of cloacal outlet of mesonephric ducts. The possible pathogenesis of these associated malformations is discussed.