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

The development of the ultimobranchial body and its colonizing cells was studied in chick embryos in Hamburger-Hamilton's stages 21 to 46. The most significant observations included the following: 1.-The ultimobranchial body is a separate morphological entity with particular characteristics distinguishing it from the fourth pharyngeal pouch in all developmental stages. 2.-The fifth pharyngeobranchial ducts disappear in Hamburger-Hamilton's stage 27. 3.-From Hamburger-Hamilton's stage 27 on, the left ultimobranchial body is in contact with the caudal end of the left parathyroid IV primordium. 4.-The group made up of the ultimobranchial body and its colonizing cells at no time fuses with the thyroid gland.

Effects of melatonin (aMT) and 5-methoxytryptamine (MT) were studied on the testicular activity cycle of the fresh-water snake, Natrix piscator. The subcutaneous implantation and the injections (morning as well as evening) of these two methoxyindoles prevented testicular recrudescence, retarded the testicular active phase, and accelerated the rate of regression of testes, while having no effect on the inactive testes. Contrary to this, these two compounds increased the pineal gland weight during different reproductive phases. These results revealed that both aMT and MT, whether they were continuously released through silastic capsule implants or administered through daily periodic injections, produced inhibitory effects on the testicular function.

This is a survey of studies on testosterone secretion by the testis of the avian embryo. An unprejudiced critic would not be convinced by existing data. The author is led to conclude that the bird embryo testis does not secrete testosterone.

72 human hearts from necropsies of subjects with an age range from 27 to 83 years have been examined by dissection. The aim of this study was to know the percentage of myocardial bridges (intramural coronary arteries) and to compare with other studies carried on this subject, using the same or different techniques. Myocardial bridges were observed in 25% of cases. The main localization was the middle third of the anterior interventricular artery. The principal characteristics of the myocardial bridges were: The length, from 4 mm to 25 mm, and the thickness, from 0.3 mm to 1.7 mm. Chi-square test have been made in order to verify the relation between the coronary arterial preponderance and the incidence of myocardial bridges, showing the absence of statistical significance.

The various external features of the developing human brain during the embryonic period proper (up to 8 postovulatory weeks) are illustrated as they appear in reconstructions made from embryos of Carnegie stages 8 to 23. This is the first systematic, stage-by-stage account. The appearances are compared with those that can be seen in intact embryos of corresponding stages up to 7 postovulatory weeks. The brain of an early fetus (9 postovulatory weeks) is also included. The medial views will be treated in a subsequent article.

From 16 to 18 days of fetal life (fl) the subfornical organ (SFO) of the rat shows diffuse acetylcholinesterase (AChE) activity. From 21 fl its definitive pattern begins to be organized and is achieved at 30 days of postnatal life (pl). This pattern is characterized by a homogeneous AChE activity in the rostral region, a ring-like distribution in the anterior medial region and a hoof-like distribution in the posterior medial region. The caudal region shows intense, uniform activity. From the rostral region two tracts emerge, ventral and dorsal, that extend to different diencephalo-telencephalic areas. From the SFO caudal region another tract emerges that extends to posterior areas.

The tela choroidea of the prosencephalon in sheep is vascularized by an anterior choroidal artery arising from the rostral branch of the carotid cerebral artery and by a posterior choroidal artery, arising from the caudal cerebral artery, branch of the carotidobasilar system. These two choroidal arteries give off choroidal branches which nourish the capillary networks of the tela. The latter consist of a velar capillary network and of a choroidal capillary network. Together, they drain into choroidal veinules and veins which are tributary of the superficial and of the deep venous systems of the brain.

The most developed and organized lamina running trough the biceps brachii muscle belly forms a well-marked tendinous intersection connecting the proximal tendon with the distal one. Moreover, the lacertus fibrosus arises from this lamina close to the distal tendon and blends with the fascia of the forearm and joins the extensor carpi radialis muscle. The nerve supply for the biceps tendinous intersection arises from the intramuscular rami of the musculo-cutaneous nerve, whereas the lacertus fibrosus is provided with some cutaneous rami of the same nerve. The biceps brachii tendinous intersection and lacertus fibrosus are provided with free and encapsulated nervous endings. The encapsulated corpuscles are represented by rare Pacini, Pacini-like and Ruffini receptors and by numerous Golgi tendon-organs. All these receptors have been studied by a topographical point of view and the role played by the proprioceptors in synchronizing shoulder, elbow and carpal joint movements both in the flexion and the extension of the limb, has been hypothesized.

The ultrastructure of the gland cells associated with the chaetal follicles of the ventral clitellar epithelium is described in the earthworm Lumbricus friendi. Regarding their secretory granules, two cell types (GS1 and GS2) have been identified. Secretory granules of both cell types show a large, electron-dense core which is homogeneous in the GS1 type and irregularly shaped in the GS2 type. Crystalline inclusions embedded in the GS1 granule matrix is characteristic of the GS1 cell type. Both types of secretory granules are directly extruded by exocytosis into the chaetal follicle lumen. The basal regions show the typical cytological features of cells which are capable of synthesis of both protein and complex carbohydrates. The results and the functional significance of the two cell types studied are discussed and compared with that is known in other lumbricids.

The muscular anatomical variations of the thoracic member are recorded in a series of 180 subjects. Two muscles are supernumerary: a bilateral accessory coraco-brachialis and a unilateral accessory palmaris longus. Two muscles have additional tendons: the extensor carpi radialis brevis and the extensor digitorum.