Biomedical subjects
Publications and source records attributed to J van Limborgh.
In this case report a patient with multiple duplications in the cervical spine, skull-base and oral cavity is described and a discussion on the possible origin of the duplications is presented.
In 12 adult rabbits, according to the pull through technique a strip of muscular fascia was implanted in the wall of the femoral vein. Of 11 of these animals, sacrificed at intervals varying from 0 days to 3 months after the operation, the area of implantation was removed and histologically studied. Two cases showed wound infection and one case, moreover, venous thrombosis. Among the other 9 cases, in 2 specimens the end of the strip was found to lie within the venous wall, while in the remaining 7 specimens the strip protruded into the venous lumen. In the latter cases, the strip proved to be firmly attached to the venous wall within 4 days; within the same time the protruding part of the strip became completely covered by venous endothelial cells. Loose connective and fatty tissue adherent to the strip only disappeared, when the end of the strip freely floated in the streaming blood.
In an effort to verify the supposition that a normal development of the lower face and the hyoid apparatus is dependent on the availability of a sufficient number of cells derived from the posterior mesencephalic and anterior rhombencephalic parts of the neural crest, in a total of 52 six-somite stage chick embryos (about 26 hours of incubation) these parts of the neural crest were partially eliminated by tangential micro-laser irradiation. Among the 17 irradiated embryos sacrificed after 24 hours, several ones showed an underdevelopment of the mesenchyme in the ventral part of the first branchial arch; in 2 of these cases, additionally the second branchial arch was underdeveloped. At the age of 7-8 days, 4 out of 15 surviving embryos showed an underdevelopment of the lower beak and a reduction in size of Meckel's cartilage; in 3 of these cases, in addition, a median cleft in the lower beak and/or reduction or absence of the hyoid cartilage were observed. From these observations the conclusion is drawn that for a normal development and growth of the mandibular part of the face and the hyoid cartilage sufficient numbers of posterior mesencephalic and anterior rhombencephalic neural crest cells are indispensable, indeed.
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The mesencephalic crest was partially eliminated in chick embryos by means of tangential microlaser. The heads of the surviving embryos were serially sectioned and microscopically studied. A deficiency of mesenshyme in the anlage of the maxillary process was observed in 4 of the 42 embryos sacrificed after 24 hours, on the side of irradiation. Among the 99 surviving embryos sacrificed at the ages of 7 or 12 days, 26 showed a unilateral cleft lip, a wide palatal cleft or a combination of these anomalies. It is concluded that cleft lip and palate can result from insufficient growth of the mesenchyme in the maxillary process caused by partial deficiency of mesencephalic neural crest cells.
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In an effort to answer the question whether prosencephalic neural crest cells play an essential part in the differentiation of the facial skeleton, in twenty 2- to 6-somite stage chick embryos the anteriormost part of the neural crest was eliminated. Observations on 10 of these embryos, sacrificed 2 hours after the microlaser irradiation, showed that often also some damage is done to the prosencephalic neural tissue. Among the remaining 10 embryos, 6 survived until the age of 12 days. One of these embryos showed unilateral microphthalmia, two bilateral microphthalmia, two synophthalmia and one cyclopia. In the microphthalmic embryos, the facial skeleton proved to have differentiated normally; in the other embryos, several facial bones were entirely lacking, while others only had developed rudimentarily. All affected eyes lacked a cartilaginous sclera. On the basis of these results, the question posed could not be answered. On the other hand, however, the experiments revealed that (1) prosencephalic neural crest cells are indispensable for a normal differentiation of the scleral cartilage, (2) elimination of the prosencephalic neural crest and a part of the prosencephalon does not affect the development of the mandible and the hyoid, and (3) the mesodermal mesenchyme bordering the prosencephalon, has no developmental capacities of its own. Finally, the craniofacial anomalies observed in the synophthalmic and cyclopic chick embryos, proved to be highly similar to the corresponding anomalies in man.
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A study of microscopical serial sections of 40 well-preserved human embryos, ranging in age from about 40 to 65 days (8-33 mm C.-R. length), revealed that the prevertebral main lymphatics develop from a number of separate primordia, all derived from venous walls. These primordia are: paired jugular and axillary lymph sacs and paratracheal, internal throacic, lumbar and iliac lymph plexuses, and single subtracheal and mesenteric lymph plexuses. Probably, the thoracic ducts develop from a series of small additional primordia. All these primordia, except the jugulo-axillary lymph sacs, lose their connections with the veins. They rapidly enlarge, fuse with one another and send out sprouts into peripheral regions, so that soon the definitive pattern of the major lymphatics can be recognized. During development some variations may occur, in particular in the area where the lower extensions of the two throacic ducts meet the lumbar lymph plexuses. Usually, the right thoracic duct primarily comes into contact with the jugulo-axillary lymph sac. The conclusion is drawn that on an embryological basis in the prevertebral region additional lymphatico-venous communications might be expected, but that possible lymphatico-venous communications elsewhere in the body always point to developmental aberrations or to pathology.
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In duck embryos, a study was made of the role the suprarenal glands might play in the process of sex determination. The experiments included the transplantation of suprarenal gland taken from embryos aged from 9 to 25 days, into the coelomic cavity of embryos ranging from 71 to 139 hours of age. Out of a total of 388 transplantations, 222 succeeded in the sense that the hosts reached the age, at which the gonads have sexually differentiated. The results show that the implantation of a suprarenal gland does not influence the sex-ratio. Moreover, no disturbances in the development of the gonads were observed. Hence, the conclusion may be drawn that it is highly improbable that the suprarenal gland plays an essential role in the production of substances guiding the differentiation of the gonadal primordia into ovaries or testes.
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