Showing papers in "Physiological Reviews in 1971"

Hormonal control of mammalian spermatogenesis

Abstract: Studies of the hormonal control of the spermatogenic process are reviewed. Most of the investigations used the techniques of ablation and replacement therapy and were performed on the rat. Results from the studies indicate that changes in the metabolism of proteins lipids and carbohydrates take place in the testes under the control of hormones. However it may be that the observed biochemical changes which occur are a reflection of the changes in cellular composition of testicular tissue rather than the result of metabolic changes within a specific cell type in response to the effect of a hormone. A hypothesis concerned with the qualitative aspects of hormonal control of spermatogenesis in the rat has been formed. It is proposed that the multiplication and growth of gonocytes prenatally and in the first few days after birth and formation of type A spermatogonia are under the control of testosterone. The formation of type A and B spermatogonia and primary spermatocytes and progression of the meiotic prophase may be influenced by growth hormone. Reduction division is under control of testosterone. The early steps of spermatid formation may be under no hormonal control or may require testosterone while the late stages of spermatid maturation require the presence of FSH.

Interstitial fluid pressure.

Abstract: Interstitial fluid pressures in the lung were estimated in 39 dogs from pressure measurements made in implanted perforated capsules. Special operative procedures were used to minimize operative trauma of the lungs and infection and inflammation in and around the implanted capsules. In 86% of the preparations, the x-ray findings indicated little remaining inflammation and edema around the capsules, though autopsy findings indicated that a few of these did still have some edema not detectable by x-rays. In 29 of 34 animals in which x-ray findings indicated no edema, the intracapsular pressure was negative. The average of the measurements in all 34 animals was −5.8 mm Hg (± 0.8 SEM), and in the 29 animals with negative pressure values the average was −7.3 mm Hg (± 0.6 SEM). In eight capsules the pressures were below −10 mm Hg, ranging to −16 mm Hg. Because the tissues around some of the capsules undoubtedly still had varying degrees of inflammation and edema, despite the failure of roentgenograms to show these, it is suggested that the normal interstitial fluid pressure of pulmonary tissues in dogs is somewhat more negative than the capsule pressure measurements indicate, perhaps as low as −10 mm Hg.

Carotid Body: Structure and Function

Abstract: Through an unfortunate error in make-up of the article “Carotid Body: Structure and Function,” by T. J. Biscoe, in the July issue of this journal, two sections of the review are out of order. To co...

Airway Obstruction and Collateral Ventilation

Abstract: Peter T. Macklem, “Airway Obstruction and Collateral Ventilation,” p. 380, paragraph 5, line 1, should read: Above a critical length-diameter ratio of 2−1/2 catenoid formation is impossible; T. J. ...