Summary
Parts of the floor of the hypothalamus were microsurgically isolated from 12-day rat embryos and transplanted beneath the kidney capsule (KC) of adult hosts. The grafts became vascularized with extensive areas of neural tissue developing from 17 days through 33 days. Host animals were either hypophysectomized or intact, and no significant morphological differences could be detected in the transplants.
Neural tissue developed with a high degree of organization, with neurons and glial cells, and an abundance of dendritic and axonal processes clustered among glial processes. Glial processes with junctional attachments formed a complete layer at the basal lamina of the neural tissue which prevented nerve endings from making direct contact with the basal lamina. Small clusters of synaptic vesicles were common in nerve endings and in addition some endings contained synaptic vesicles and 600–900Å diameter dense-core granules. Junctional complexes ranged from well-formed synapses of the adult type to areas of membrane contact having minimal specialization. Synapses appeared increased in number, and to assume more mature features, with longer growth periods.
The results indicate that the morphologically undifferentiated floor of the hypothalamus of the 12-day rat embryo can undergo morphological differentiation along lines similar to normal development even in an ectopic site such as the KC.
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Supported in part by Grant No. R01-CA-21426 from the National Cancer Institute, DHEW; California Division ACS Special Grant No. 851; NIH Grant No. RO1-HD-08126; and a Cancer Research Training Fellowship to D.G. under NIH Grant No. Ca 05297 at the University of Southern California
The authors gratefully acknowledge the technical assistance of Sheila Odnert, Vivian Charca, Alicia Thompson and Linda Melsek
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Schechter, J., Gash, D. & Ahmad, N. Neuroembryogenesis of ventral hypothalamus transplanted to kidney capsule. Cell Tissue Res. 190, 247–254 (1978). https://doi.org/10.1007/BF00218173
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DOI: https://doi.org/10.1007/BF00218173