Archives d'anatomie, d'histologie et d'embryologie normales et experimentales最新文献

The tela choroïdea of the fourth ventricle of the dog is vascularized principally by the principal and accessory caudal cerebellar arteries but also by the middle cerebellar arteries and dorsal network of the medulla oblongata. The choroïdal branches arising from these arteries supply the capillary network of the choroïd plexus. The latter drains towards the sigmoïd sinus, either directly or through the dorsal plexus of the medulla oblongata. The choroïd plexus drains also partially towards the cerebellar veins and the ventral petrosal sinuses.

Determination of gonadal weight, seminiferous canalicule diameter, thickness of ovarian cortex and medulla, as well as of gonadal cell counts in 20-day chicken embryos exposed to gonadotropin (FSH and LH) or TSH at 15 days of pre-hatching life has shown that the examined hormones were able to evoke gonadal response also prenatally. TSH was found to overlap gonadotropin effect in causing increase of seminiferous canalicule diameter, testicular weight and gonocyte counts. In respect of the latter two parameters TSH was even more active than an identical dose of gonadotropin. This indicates that the interstitial and germinal cell receptors of the embryonic testis are not able to differentiate between chemically related, but - in adulthood - functionally different hormones. The ovarian effect of TSH was significant in respect of enhancing organ weight and oocyte mitosis, but not significant for the other parameters.

Binucleated cells and constricted nuclei have been observed in the polymorphic follicles during certain developing stages in both the intermediate and the pyriform cells. The formation of binucleated follicle cells may increase RNA synthesis and/or another function may be assumed which is the migration of these nuclei to the ooplasm. The migrated nuclei have been seen during certain stages in the ooplasm and are apparently taken into the ooplasms by phagocytosis, or through cytoplasmic bridges, but there is a great possibility that these nuclei enter the oocyte by the fusion of both cell membranes (the oocyte and the follicle cell cytoplasmic membrane). The number of these nuclei is not very large and often too small in each oocyte to permit a true nutritive function but it does enable DNA and RNA material to enter the ooplasm.

The vascularization of the different layers of the jejunum and the ileum was studied in 35 human intestins between the 23d foetal week and the first postnatal year. The vascular systems in all 35 cases were injected with gelatinous inda ink. During the perinatal period the submucosal layer is a true vascular crossroad formed by an intricate plexus of blood vessels, both arterial and venous, similar in structure and whose density increases with the development of the intestinal wall. The vascularization of the muscularis, essentially a tributary of the submucosal layer, is assured by long and short muscular arteries whose structure and number vary with age. The venous system of the muscularis is a satellite of the arterial system. The arteries of the serosa originate essentially from straight arteries and accessorily from the intervascular mesenteric arches. Their terminal and collateral branches form an anastomotic network caracteristic of the perinatal period. Drainage is assumed by veins of the serosa, which are tributaries of straight veins, and similar to the arteries, undergo progressive densification parallel with development. The arteries of the mucosa are tributaries of the submucosal network and abandon precapillary arterioles and two capillary networks: one surrounds the Lieberkühn glands, the other is destined for the intestinal villus. These dense networks and the vascular networks of the other layers help preserve the intstinal villus and glands during development. Finally, the venous drainage of the mucosa flows into the submucosal venous network.

This is a survey of previously published data and some new ones. The target organs studied were chick and mouse wolffian ducts and mullerian ducts. The following statements can be made: 1. The anti-mullerian hormone of the chick embryo testis is active on both the avian and mammalian mullerian ducts. Testosterone on the contrary will stimulate them. 2. Testosterone will stimulate both the avian and mammalian wolffian ducts, the chick embryo testis will not. It is concluded that there is no testosterone secretion by the chick embryo testis or in too low a quantity to be effective. Thus, the chick embryo testis and testosterone exert quite different actions on all four target organs studied.

This work which is based on the study of eight human embryos of 4,5 to 13,6 mm from the Madrid collection, and also on six plastic reconstructions made by the BORN method, and on experiments on chick embryos (ligature of the left vitelline vein in embryos, 3 days of incubation) enables us to reach the following conclusions: no true rotatiorial movements take place during normogensis. Only ventromedial rotation of the right ventricle is observed in stages 12 to 14. This rotation will place the right ventricle, and therefore the vestibulum pulmonalis in front of the aortic infundibulum. We consider that the initiation of cardiac septation is to a great extent due to hemodynamic. causes. During normogenesis in all cases, from the earliest stages of development the presumptive pulmonary outflow tract is always anterior and to the right of the presumptive aortic tract. We do not agree with the statement of GOOR and EDWARDS and VAN PRAAGH R. and VAN PRAAGH S. (1965), that in some stages the presumptive coni of the aorta and pulmonalis are arranged inversely to the way in which they will arranged later.

Light- and electronmicroscopical observations are made on the pancreas of 18 rats after 4 weeks of B1-avitaminosis. The B1-avitaminotic animals show a definite decrease in bodyweight and in the weight of their pancreas. The mitochondria of the acinar cells are swollen and invaded by numerous vacuoles. Single cells die by eosinoplilic necrosis. The islets of Langerhans demonstrate a definite hyperplasia (polynesis) and hypertrophy (macronesis). The mitochondria are swollen and also transformed into vacuoles. There is a lysosomial granulolysis. Only occasional lesions are observed in the A1 and A2 cells of the islets.

The present paper describes the modifications induced in Malpighian tubules of Locusta migratoria by uranyl nitrate. These modifications are observed only if doses injected are approximately a hundred times higher than those which affect the renal epithelium of Vertebrates. The elimination of the uranyl salts seem to occur by apical excretion of dense metallo-proteic granules. When strong doses are used, metallic particles are seen on the basal membrane and in the extracellular spaces. Such intracytoplasmic particles are rarely observed.

Our purpose is to bring a contribution to a better understanding of the role played by the condylar cartilage in children's mandibular growth. In the newborn, microradiographical analysis of frontal (fig. 1, 2 and 3 A) or sagittal sections (fig. 4 A) has been used to locate trabecular bone of endochondrial origin. This trabecular bone contains islets of calcified cartilage easy to identify in the microradiograph (fig. 3 B) or in the section itself after methylen blue staining (fig. 4 B) and resulting from the activity of the condylar cartilage (fig. 4 C). At four month of age, the condylar cartilage is still in activity (fig. 5 A and 5 B). From both morphological and physiological points of vue, this work leads to suggest that the condylar cartilage must be compared to a growing epiphyseal nucleus or to a so-called infertile extremity of a small long bone rather than with a true growing cartilage.

Arterial collateral ways are reviewed correlatively with five differents levels of obliteration : aortic, iliac, ilio-femoral, femoro-popliteal, dista. A double visceral and parietal supply system caracterize each obliterated level; the importance of this double system varies considerably with the site of obliteration.