70 NATURE January 8, 1949 Vol. 163

2 3 immature and their relative frequency would natur• stalk to the gland • • If this is so, variable results ally depend on the age of the culture. Treschow1, in might be expected to follow section, 8 his original description of V. psalliotre, recorded that for, as suggested , regeneration of these vessels might the phialides of this species produced only one spore, occur. This possibility has been tested in the following and that this was usually convexo-concave or manner. convexo-plane, although a few were oval. The pituitary stalk has been sectioned in twenty• The use of coverslips in the manner described serves nine female rats. The operative approach was by a also for the observation of spore production in V. temporal route which gives a clear view of the stalk Malthousei Ware, as well as of spore rotation in both and surrounding structures, and allows a deliberate species, which I recorded• in a previous communica• and precise lesion to be made in any desired site. tion. As it might also be of interest to some workers The rnstrous cycles of these animals were followed to know the relative abundance under different by the vaginal smear technique, and they were conditions of spore production from individual tested for a pseudo-pregnancy response to sterile phialides of various disease-producing species of coitus by the deciduoma reaction. Many of the Verticillium and other genera such as Fusarium, the animals showed a normal sexual rhythm and pseudo• use of this technique might perhaps provide interest• pregnancy response after recovery from the operation, ing statistical data. and these results are being reported in detail else• I acknowledge with thanks the permission of the where. After observation (usually for three months) director of research and of the directors of the the animals were killed and the vascular systems Mushroom Research Association to publish this perfused with indian ink solution. The heads were information. decalcified and a block of tissue containing the hypo• C. J. LA TouCHE and serially sectioned in Mushroom Research Association, celloidin at 100-200 f.l· On histological examination Yaxley, Hunts. it was seen that the neural lobe was atrophic, the 1 Treschow, C., Dansk. Botanisk Archiv., 11 (1941). enlarged relative to the rest of the • J..a Touche, C. J., Nature, 160, 679 (1947). gland, and, in many ca,ses, the pars distalis appeared slightly diminished in size. The point that has been clearly established is that in many cases the hypo• Regeneration of the Hypophysial Portal physial portal vessels showed regeneration across the cut region of the stalk (Figs. 1 and 2). Vessels The hypothesis of neurovascular transmission of THERE would seem little doubt that the nervous stimuli from the median eminence of the tuber system controls the activity of the anterior pituit.ary cinereum to the finds indirect sup• gland, but the mechanism by which this control is port from two sources. First, the anatomical evidence exerted is debatable. Many workers have cut possible that the hypophysial portal vessels are present in a wide variety of vertebrates though X N .L. nerve fibres in the anterior pituitary gland are scarce•,•,a, and micro• scopic observation of these vessels in the living rat has shown the blood flow to be from the to the anterior pituitary•. Secondly, the experimental evi• dence that (a) electrical stimulation of the tuber cinereum in rabbits (for three minutes) may produce ovula• tion, whereas similar stimuli ap• Fig. I Fig. 2 plied to the anterior pituitary Fig. 1. Photomicrograph of a mid-sagittal section through the pituitary stalk of a control directly (for seven and' a half rat. Vascular system perfused with indian ink. Note the portal vessels (V) passing from the ventral surface of the pituitary stalk (S) Into the pars dfstalis (P.D.). Magnification x c. 50 hours) does not produce this re• Fig. 2. Photomicrograph of a mid-sagittal section through the pituitary stalk of a rat in sult, indicating a lack of secreto• which the stalk had been sectioned ten weeks previously. Vascular system perfused with motor nerve fibres in this gland Indian ink. The neural lobe (N.L.) of this gland showed marked atrophy. Note the large regenerated portal trunk passing across the ventral surface of the line of section (XX) from and probably a humoral trans• the tuber cinereum (on the left) to the pars distalis (on the right). Magnification x c. 50 mission of stimuli', and similar evi• dence•; and (b) section of the nerve pathways to the gland. Interruption or removal pituitary stalk results in variable degrees of dys• of the cervical sympathetic system, or the facial and function of the anterior pituitary, which it would petrosal nerves, has little or no effect on the normal seem likely may be correlated with varying degrees functioning of the gland. Section of the pituitary of regeneration of the portal vessels. stalk has given discordant results in the hands of G. w. HARRIS different workersl, but it would seem established that Physiological Laboratory, some animals retain normal anterior pituitary function Cambridge. after this operation. This fact indicates that the nerve July 10. fibres of the pituitary stalk are not involved in the 1 link between the nervous system and the anterior Harris, G. W., Physiol. Rev., 28, 139 (1948). • Green, J . D., and Harris, G. W., J. Endomnol.,li, 136 (1947). pituitary, for once cut these fibres do not regenerate. 'Harris, G. W., thesis for M.D. degree, Unlv. of Cambridge (1944>. However, little attention has been paid to the • Green, J . D., Alnantkr Blain Hosp, Bull., 6, 128 (1947). possibility that the may control the 'Harris, G. W., 159, 874 (1947), anterior pituitary gland by liberating a humoral • Green, J. D. , and Harris, G. W., J . Physiol. (in the press). excitant into the hypophysial portal vessels, which ' Harris, G. W., J. PhyBiol., 107, 418 (1948). • Markee, J. E., Sawyer, C. H., and Hollinshead, w. H. then transmit the substance along the pituitary 38, 346 (19t6). , -·

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