Wayne J. Atwell

Differentiation and Function of Heterotopic Autoplastic Transplants of the Amphibian Hypophysis

Conflicting evidence has been obtained regarding the ability of the epithelial hypophysis to differentiate and function in heterotopic transplants in amphibia. Blount, 1 using Amblystoma punctatum, failed to obtain differentiation of the epithelial hypophysis independent of the infundibulum. Etkin 2 made successful single and multiple transplants in Rana sylvatica with a minimum of brain tissue, but he made no attempt to remove all possible adherent brain. The writer, in 1931, removed the hypophysis from 18 specimens of R. sylvatica at the tail-bud stage and transplanted it in the same individual to a location between the right otic vesicle and the hind brain. Care was taken not to include any brain tissue or any entoderm. Eight of these animals gave evidence of function of the hypophysis according to one or more of the criteria enumerated below, although 5 were sacrificed at a stage before evidence of anterior lobe function can be obtained. In the present year similar operations were attempted on 75 R. sylvatica, 30 R. pipiens and 50 A. punctatum. From the experiments of these 2 years serial sections of head, thyroid and gonad-adrenal regions have been studied from 64, 8 and 5 animals of the above species, respectively. In addition, the condition of the hypophysis and the thyroid has been determined at autopsy in 10 A. punctatum, while 30 animals of this species are still alive. For control study records and sections from more than 200 normal, or completely or partially hypophysectomized amphibia, mostly R. sylvatica, were available.

Functional transplants of epithelial hypophysis in three species of Amblystoma

Summary Autoplastic, heterotopic transplants of the pnmordium of the epithelial hypophysis have been made in three species of Amblystoma. These transplants differentiated without contact with the brain, and gave evidence of chromatophorotropic and thyreo-tropic activity.

Effects of Thyreotropic and Adrenotropic Hormones on Hypophysectomized Frog Tadpoles

Twenty-four specimens of Rana sylvatica and Rana pipiens hypophysectomized at the tail-bud stage, and kept in the laboratory for 525 days, whose normal mates had metamorphosed at 65–70 days, were divided into 3 groups. Seven animals were kept as controls, 7 were treated with Collips adrenotropic 1 hormone, batch AI, and the remaining 10 with his thyreotropic 2 hormone, batch TG. As a result of his own bio-assays (on rats) Collip stated that the thyreotropic hormone was not free from adrenotropic material but that the adrenotropic hormone was ‘fairly pure’. The hormones were administered by intraperitoneal injection, using special fine needles, in 0.05 cc. doses, given once daily, 6 days a week. For the injection an animal was removed from its aquarium and placed on a pad of absorbent cotton wet with ice water. It was then immobilized, ventral side uppermost, by a smaller sheet of wet cotton having a slit cut in it through which the injection could be made. Following the injection the animal was quickly returned to its aquarium. In 4 days both of the treated groups were dark in color. The adrenotropic group was decidedly darker than the thyreotropic. The only other change noted in the first 5 days was a slight reduction of the tail fin in a few cases. On the 6th day the hind legs of one animal in the thyreotropic group appeared to be lengthening and by the 10th day all but 2 of this group showed definite growth of the hind legs. From then on the changes normally seen at metamorphosis appeared rapidly. Forelegs emerged from the 11th day on, the tail shortened, the mouth became a transverse slit, characteristic frog spots (R. pipiens) appeared and from the 14th day animals were living out of the water.

Experimental Hypertrophy of the Adrenal Glands

The relationship between the hypophysis and the adrenal glands which has long been known to exist in clinical cases, 1 has not been well understood. Experiments in animals have thrown considerable light on this subject especially in regard to a pituitary substance necessary for normal adrenal function. 2 Many studies on pituitary implants and extracts in relation to the reproductive system have been made in recent years but the effects on the adrenal glands, when reported, were not significant. In immature rats implanted with pituitary glands of castrated rats some hypertrophy of the adrenals was noted at autopsy but the results were not outstanding. 3 Recently we have continued these studies and have arranged the experiments to show the effects of the cortico-adreno-tropic substance of the pituitary. The results have been very striking and consistent. Albino rats weighing about 150 gm. were divided into 2 groups of equal weight; one group consisted of 35 controls which were not injected; the other group consisted of 35 rats which were injected daily for 10 days with an extract of the pituitary gland. On the eleventh day the rats were killed and the adrenals weighed. The hypertrophy of the adrenal glands produced in the injected group amounted to as much as 150% and as little as 20% in the individual rats. Accurate determinations show that this hypertrophy is largely confined to the cortex which consists of cells larger than normal and more filled with lipoid material. Experiments with the growth hormone of the pituitary showed some enlargement of the adrenals but the effects were slight in comparison with whole pituitary extract. The thyroid gland was not increased in size.

Effect of Extracts of Pars Tuberalis of Hypophysis on Urine Secretion.

Saline suspensions or boiled acidulated extracts of the bovine pars tuberalis when injected intravenously into rabbits under paraldehyde anesthesia produce a diuresis differing from that produced by injection of posterior lobe extracts. The resulting diuresis comes on without a marked rise of blood pressure and without the latent period of 3 to 5 minutes (during which the flow of urine is entirely suppressed) which are characteristic accompaniments of posterior lobe diuresis. Diabetes insipidus is held 1 , 2 to be due to injury of the base of the brain in the region of the tuber cinereum. Critical examination of the figures of Bailey and Bremer, 2 and of Curtis, 3 shows that in practically every instance the injury has involved the pars tuberalis of the hypophysis. Bourquin 4 has shown that experimental diabetes insipidus in dogs is an irritation rather than a deficiency phenomenon. Slight cauterization of the floor of the third ventricle produces the diabetes but deeper cautery destroys it. She further concludes that “the diuresis must be due to a substance produced at the site of the causative disturbance” for the diabetes insipidus “runs its typical course after trans-section of the spinal cord at the level of the eighth cervical vertebra, double vagotomy below the diaphragm, and paralysis of the parasympathetic nervous system with atropin.” If the cause of experimental diabetes insipidus is to be ascribed to the irritative production of a hormone in the floor of the third ventricle, it is no less reasonable to suppose that the hormone is derived from the pars tuberah, which is distinctly a glandular structure, than that it is produced by brain tissue.

Quantitative studies on the pars tuberalis of the hypophysis cerebri

The pars tuberalis has been shown to be a distinct portion of the epithelial hypophysis both embryologically and histologically. 1 , 2 Whether it serves a distinct function, if any, has not been determined. 3 The method employed has been that utilized by Hammar, Rasmussen 4 and others. The three parts of the epithelial hypophysis were carefully outlined on paper of uniform thickness using serial sections and the projection microscope. The several parts were then cut out with scissors, and weighed. The volume of each part was determined in per cent of the total volume of the entire epithelial hypophysis. Then the value of the pars tuberalis in per cent of the pars intermedia was calculated. In seventeen amphibia examined, there is great variation in the relative size of the pars tuberalis and the pars intermedia. In the tailed amphibia the pars tuberalis is relatively much larger than it is in the Anura. In Plethodon gutinosus and P. cinereus it is from one and a half to nearly five times as large as the pars intermedia. In Ram pipiens, on the other hand, the pars tuberalis is much the smaller. In four frogs examined, the volume of the pars tuberalis was only 4 1/4 per cent of the volume of the pars intermedia. The cat was selected as the mammalian type for this study. In this species the pars tuberalis may be distinguished with ease. The relative values for the three lobes is shown in the appended table. Two important deductions may be drawn from our data: (1) In a number of vertebrate forms the volume of the pars tuberalis is equal or nearly equal to that of the pars intermedia; (2) As far as volume is concerned the pars tuberah may be capable of producing an important secretion in forms as high as the mammals.