Paper - On the Development of the Blood-Vessels of the Brain in the Human Embryo

Embryology - 1 May 2024        Expand to Translate
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Mall FP. On the Development of the Blood-Vessels of the Brain in the Human Embryo. (1905) Amer. J. of Anat. 4; 1–18.

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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.

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Cite this page: Hill, M.A. (2024, May 1) Embryology Paper - On the Development of the Blood-Vessels of the Brain in the Human Embryo. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Paper_-_On_the_Development_of_the_Blood-Vessels_of_the_Brain_in_the_Human_Embryo

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