caa a22 4500 469082682 CHVBK 20180323132955.0 cr unu---uuuuu 170328e19920301xx s 000 0 eng 10.1007/BF00319366 doi (NATIONALLICENCE)springer-10.1007/BF00319366 Morphology and function of capillary networks in subregions of the rat tuber cinereum [Elektronische Daten] [Steven Shaver, Judy Pang, Dan Wainman, Katharine Wall, Paul Gross] Summary: The differentiated cytology, cytochemistry, and functions within subdivisions of the tuber cinereum prompted this morphometric and physiological investigation of capillaries in the median eminence and arcuate nucleus of albino rats. Morphometric studies established that the external zone of the median eminence had 3-5 times the number and surface area of true and sinusoidal capillaries than the internal or subependymal median eminence zones, or either of two subdivisions examined in the arcuate nucleus. Type-I true capillaries, around which Virchow-Robin spaces comprise 1% of arcuate tissue area, were situated proximally to the median eminence border. This finding is consistent with a premise that confluent pericapillary spaces enable infiltration of arcuate neurons by factors from capillary blood from the median eminence or Virchow-Robin spaces. Physiologically, the rate of penetration across the median eminence capillaries by blood-borne [14C]α-aminoisobutyric acid (a neutral amino acid used as a capillary permeability tracer) was 142 times greater than for capillaries in the distal arcuate nucleus within 12 s of tracer administration. A new finding was that the proximal arcuate nucleus had a permeability x surface area product of 69 μl g−1 min−1, 34 times greater than that in more distal aspects of the tuber where blood-brain barrier properties exist. We also found that the microcirculatory transit time of a plasma space marker, [14C]sucrose, was considerably longer (1.2 s) in the median eminence and proximal arcuate nucleus than in the distal arcuate or ventromedial nucleus (0.4 s). By virtue of its high capillary permeability and extensive blood-tissue surface area, including the wide Virchow-Robin spaces, the median eminence external zone could be a gateway for flooding other tuberal compartments with blood-borne factors. This effect may be compounded by capillary bed specializations in the proximal arcuate nucleus where Type-I true capillaries, Type-III sinusoids, and pericapillary spaces are confluent with those in the median eminence. The results indicate that the proximal arcuate parenchyma could be exposed to circulating neuroactive substances on a moment-to-moment basis. Springer-Verlag, 1992 Median eminence nationallicence Arcuate nucleus nationallicence Endothelial cells nationallicence Capillary permeability nationallicence Blood flow nationallicence Quantitative autoradiography nationallicence Rat (Sprague-Dawley) nationallicence Shaver Steven Neurosurgical Research Unit, Department of Surgery, Queen's University, K7L 3N6, Kingston, Ontario, Canada aut Pang Judy Neurosurgical Research Unit, Department of Surgery, Queen's University, K7L 3N6, Kingston, Ontario, Canada aut Wainman Dan Neurosurgical Research Unit, Department of Surgery, Queen's University, K7L 3N6, Kingston, Ontario, Canada aut Wall Katharine Neurosurgical Research Unit, Department of Surgery, Queen's University, K7L 3N6, Kingston, Ontario, Canada aut Gross Paul Neurosurgical Research Unit, Department of Surgery, Queen's University, K7L 3N6, Kingston, Ontario, Canada aut Cell and Tissue Research Springer-Verlag 267/3(1992-03-01), 437-448 0302-766X 267:3<437 1992 267 441 https://doi.org/10.1007/BF00319366 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/BF00319366 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Shaver Steven Neurosurgical Research Unit, Department of Surgery, Queen's University, K7L 3N6, Kingston, Ontario, Canada aut NATIONALLICENCE 700 1- Pang Judy Neurosurgical Research Unit, Department of Surgery, Queen's University, K7L 3N6, Kingston, Ontario, Canada aut NATIONALLICENCE 700 1- Wainman Dan Neurosurgical Research Unit, Department of Surgery, Queen's University, K7L 3N6, Kingston, Ontario, Canada aut NATIONALLICENCE 700 1- Wall Katharine Neurosurgical Research Unit, Department of Surgery, Queen's University, K7L 3N6, Kingston, Ontario, Canada aut NATIONALLICENCE 700 1- Gross Paul Neurosurgical Research Unit, Department of Surgery, Queen's University, K7L 3N6, Kingston, Ontario, Canada aut NATIONALLICENCE 773 0- Cell and Tissue Research Springer-Verlag 267/3(1992-03-01), 437-448 0302-766X 267:3<437 1992 267 441 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer