|
|
| (57 intermediate revisions by the same user not shown) |
| Line 1: |
Line 1: |
| {{Header}}
| | #REDIRECT [[Paper - On the development of the blood-vessels of the brain in the human embryo (1905)]] |
| Mall FP. [[Paper - On the Development of the Blood-Vessels of the Brain in the Human Embryo|On the Development of the Blood-Vessels of the Brain in the Human Embryo]]. (1905) Amer. J. of Anat. 4; 1–18.
| |
| | |
| {{Historic Disclaimer}}
| |
| | |
| =On the Development of the Blood-Vessels of the Brain in the Human Embryo=
| |
| | |
| By
| |
| | |
| Franklin P. Mall.
| |
| | |
| From the Anatomical Laboratory of the Johns Hopkins University.
| |
| | |
| With 3 Double Plates and 4 Text Figures.
| |
| | |
| During the past year, while studying sections through the heads of the embryos in the collection at this laboratory, it was noticed that in some of the specimens the blood-vessels were unusually well marked, for they were well distended with blood. This natural injection made it possible to reconstruct the blood-vessels in a satisfactory manner down to the capillaries. At the same time I obtained from Mr. Brudel a number of embryos’ brains in which the arteries had been injected with Prussian blue, which, together with numerous embryo pigs injected alive or immediately after death, form the basis of this study.
| |
| | |
| ===Table of Embryos Studied===
| |
| | |
| I
| |
| I Length Thickness of Direction of I
| |
| | |
| Number. in mm_ section in ,,_ section_ From Whom Obtained.
| |
| 2 7 15 Transverse Dr. C. 0. Miller.
| |
| | |
| 163 9 20 ‘- Dr. D. 8. Lamb.
| |
| 109 ll 5!) "‘ Dr. Harvey Cushing.
| |
| 144 14 40 Sag-ittal Dr. Watson.
| |
| | |
| 74 19 50 “ Dr. Irving Miller.
| |
| 145 83 50 “ Dr. W’. T. Watson.
| |
| 225 46 . . Injected Dr. Wegefarth.
| |
| 237 L8 . . "‘ Dr. Todd. (Brbdel Collection).
| |
| 235 59 .. “ Dr. Linthicum. “ "'
| |
| 234‘) 66 . . “ Brodel Collection.
| |
| . . . . 80 . . “ Brodel Collection.
| |
| 234- 80 50 Transverse Dr. Ash by (Brbdel Collection)
| |
| 233 90 . . Injected Dr. Smart “ “
| |
| 236 92 "‘ Dr. Wilson “ “
| |
| | |
| The blood-vessels of five human embryos were reconstructed from serial sections, and eight older embryos which had been injected were dissected. The brains of pigs which had been injected with India ink proved to be of great value to control the studies of the human. It is quite easy to make single or‘ even double injections of young embryos by injecting them either before or after death, or both. In case India ink is injected into the liver of -a live pig with a hypodermic syringe, the
| |
| | |
| very much with the sharpness of the arterioles and_making it impossible to define the veins, or embryonic sinuses. So constant is this extravasation in position and degree that it often seems as if the arachnoid spaces communicate freely with the veins, but, as will be shown presently, this is not the case.
| |
| | |
| | |
| In the smallest specimen (No. 225, 46 mm. long) the middle cerebral artery and the arteries to the mid-brain are well injected, but in no case does the injection extend into the brain substance. The arachnoid spaces are filled evenly with the blue injecting fluid, but there is none within the ventricles. Since the fluid does not reach the capillaries, it is evident that the extravasation took place from the arterioles, and this seems to be the case, for the arterioles are easily torn at the point they enter the brain substance. In the early stages the brain is attached only slightly to the embryonic pia mater, and it is practically impossible to remove the brain with its pia mater intact, as can be done in older embryos or in the adult. At the point the vessels leave the pia mater to enter the brain substance the blood-vessels have but a single endothelial wall, and it is here that the rupture and extravasation take place when these arteries are injected.
| |
| | |
| | |
| In an embryo a little older, No. 237, Fig. 1, the injection of the artery is practically perfect, and I have therefore given a drawing of it. The brain was peeled out with its pia mater only with difficulty and over the region of the lateral cerebral fissure (Sylvius) some of the vessels separated and remained attached to the dura. This portion was drawn inverted -and redrawn upon the brain, and the point at which the main trunks are torn off is indicated in the drawing in the region of the island. The injection is practically a complete arterial injection with but little extravasation into the arachnoid and none into the ventricles. An extravasation is over the region of the island, on both sides, and to a slight extent over the mid-brain on one side. The arteries divide and subdivide in regular fashion until the terminal branches are reached, when they turn at right angles to enter the brain substance. There are from five to ten of these cortical arteries to each square millimeter of brain surface. Around some of them there is some extravasation of Prussian blue, indicating the way the blue enters the arachnoid spaces.
| |
| | |
| | |
| Over the surface of the brain of an embryo 65 mm. long (No. 234*’) there are numerous blue spots, about one to each square millimeter. Where the spots are larger there is a tendency for them to run together, but in general the brain is only spotted rather than being covered evenly with an extravasation. There is no extravasation in the ventricle. In another brain of about the same age (No. 235, 59 mm. long) the extravasation is complete, filling all the arachnoid spaces and the whole ventricle. After the extravasation was brushed off, the brain substance was still found to be spotted, showing that the extravasation penetrated the brain substance.
| |
| | |
| | |
| In an embryo of the beginning of the fourth month (80 mm. long) the whole brain was evenly spotted, about one spot to each square milli- meter. Another specimen of the same age and of the same general appearance (No. 234“, 80 mm. long) (Fig. 2) was cut into serial sections in order to study the relation of the spots to the surrounding tissues and to the cortical arteries. Around the large cortical arteries (possibly the medullary arteries) there is an extravasation which encircles the vessel as a small spherical body. There is no rupture of the vessel. It indicates that at this point the vessel is at least very pervious. There is no extravasation into the ventricle.
| |
| | |
| | |
| In specimen No. 238 (90 mm. long) both the arteries and the veins were injected without injecting the capillaries. There was no injection of the brain substance, and there is no extravasation of the cortex nor into the ventricles. At the base of the brain and in the falx there is considerable extravasation, apparently coming from the veins. In an embryo of the same age (No. 236, 92 mm. long) the arterial injection is complete again, with the usual spots of extravasation in the cortex of the cerebral vesicle. The extravasation fills all of the arachnoid spaces as well as the cavities of the ventricle. The injection passes through the medial opening into the fourth ventricle (Majendie), and apparently the ventricles are injected through this opening from the arachnoid.
| |
| | |
| | |
| It is apparent from the description of the injected embryos that as a rule the extravasation into the arachnoid spaces takes place from the arteries as they penetrate the cortex of the brain, and that in case the veins are injected the extravasation is directly from them. This conclusion was reached in part by making corresponding injections of embryo pigs, many being constantly at my disposal. In general the extravasation is the same in the pig as it is in the human embryos. It frequently appeared, however, as if the India ink injected leaked with even greater case from the veins and sinuses of the pig’s brain. In embryos in which the heart had just stopped beating the injected fluid would first fill the jugular veins, then the sinuses, from which the arachnoid spaces filled as readily as did the capillaries.
| |
| | |
| | |
| When the arachnoid spaces were filled by injecting directly into the lateral ventricles of perfectly fresh embryos, the injected fluid would not pass over into the veins. I made this test repeatedly with live embryos from 3 to 8 cm. long, always with the same result. It is best to injectordinary India ink into the ventricle of a live embryo with a hypodermic syringe. The ink spreads at once throughout the central canal of the brain and cord and escapes through the medial opening of the fourth ventricle and fills the spaces of the arachnoid of the whole brain and cord. From the cord the ink extended for a short distance along the main trunks of the spinal nerves. In the larger embryos the ink invariably flowed freely fro-m the mouth of the pig as soon as all of the arachnoid spaces had been filled. After hardening the specimens in formalin, razor sections showed that it had reached the mouth through the Eustachian tube. It had entered the middle ear along the trunks of the seventh and eighth nerves. In younger embryos (5 cm. long) the fluid came out of the mouth in only half of the tests, while in the smallest ones injected (3 cm. long) it did not come out of the mouth at all.
| |
| | |
| | |
| In all of these tests the India ink or the Prussian blue should have passed over into the veins were the communications with them free. In all instances the pigs were still alive or just dead when the tests were made, for it is known that extravasations take place with the greatest of ease after the embryo has been dead for some time. While in these tests injections could be made with ease from the veins into the arachnoid spaces, but not in the opposite direction, in embryos still alive it Was found that in no instance would an injection into the artery pass into the arachnoid spaces. The live embryo may be injected using its own heart to inject the India ink. If the uterus is kept warm the embryo will remain alive for an hour or longer, giving ample time. The ink is to be injected directly into the liver with a hypodermic syringe and then by means of gentle massage or by gravity it is forced into the heart, which gradually pumps it all over the body. The arteries to the brain fill slowly and the granules pass over into the veins. If at this time the embryo is cooled the heart will stop, thus giving a single injection of the arteries. If it is continued, the veins will fill through the capillaries, which confuses more or less. Yet this double injection is desired in this test, for the result is always the same: in no instance is there an extravasation into the arachnoid space. In case too great a quantity of ink is injected into the liver, it is forced directly into all of the veins of the body and then the ink granules will leave the veins and enter the arachnoid spaces. If the injection of the arteries and veins of the brain is made through the arteries, using the embryo’s heart to do the pumping, all of the granules remain within the blood-vessels, showing conclusively that there are no free communications between the vessels and the arachnoid spaces. When the granules do leave the spaces by injecting them directly into the veins, we must conclude that artificial openings are
| |
| | |
| | |
| | |
| {{Footer}}
| |
| | |
| [[Category:Cardiovascular]][[Category:Neural]]
| |
| [[Category:1900's]][[Category:Franklin Mall]]
| |
