Samuel L. Leonard

Induction of Singing in Female Canaries by Injections of Male Hormone.

It is generally recognized that singing in canaries is limited to the male and as such this may be considered as a secondary sexual characteristic. In order to determine if this behavior is conditioned by secretions of the testis, male hormone was injected into female birds. The canaries used were raised by a local breeder, Mr. J. Frederichs, who has developed a hardy strain of birds by acclimating them to life out of doors throughout the year. They were brought into the laboratory in January, a few weeks before the normal breeding season. Females can be distinguished from males during the breeding season by observing differences in the cloacal eminence. The male cloacal eminence is long, pointed and projects ventrally while that of the female is broad and is directed posteriorly. At no time did the females sing previous to injections; they gave only the characteristic “chirp” of the female and were busy carrying bits of straw and paper, to build nests. Testosterone propionate (Oreton)† in 0.2 cc doses equal to 5 mg of hormone, was injected into the breast muscles every 3 or 4 days until singing occurred. Five birds were used in this study. In 4 out of 5 birds, the typical male song was sung by the injected females. One of them began singing after 2 injections, the others after 4 injections. The singing was continued for periods of 5 to 13 days after the last injection, depending on how much hormone was given. The remaining bird, though it sang no sustained song, behaved like the normal males or the stimulated females in her attempts to sing. She strutted on her perch, swelled out her throat and moved it as if singing but the sounds emitted were interrupted and resembled only portions of the male song in variation and duration.

Relation between time of fertilization and follicle cell dispersal in rat ova.

Conclusions Fertilization of the rat ovum occurs before mass displacement of the surrounding follicle cells; denudation of the ova occurs subsequently. Since hyaluronidase, introduced into the uterus, does not pass into the tubes to denude the ova, it seems that only the enzyme associated with the sperm which reach the oviduct disperses the follicle cells.

Increased Stimulation of Immature Rat Ovaries by Combined Injections of Prolan and Hypophyseal Sex Hormone.

Experiments on the effect of combined injections of various anterior pituitary or pituitary-like hormones on the weight and changes in immature rat ovaries have given suggestive results. Fevold, Hisaw, and Leonard 1 have shown that combinations of fractions of the anterior lobe of sheep produced effects which suggested the possibility of 2 sex hormones, a follicular stimulator and a luteinizer. Leonard 2 showed that a growth hormone (phyone, van Dyke) when injected simultaneously with a sex stimulating extract of the sheep anterior pituitary, inhibited the action of the latter. More recently, Evans, Meyer and Simpson 3 have combined injections of prolan with sex-free growth hormone and also with growths-free sex hormone and have obtained activation only of their growth hormone with the production of ovaries greater than can be predicted by the additive effects of either hormone injected separately. Prolan did not react on their growth-free sex hormone which led them to conclude they were dealing with a prohormone (growth hormone) and an activator (prolan). We here present data concerning the effect of single and combined injections of prolan with the sex hypophyseal hormone of sheep glands prepared by the pyridine method. 1 Only the water soluble fraction of the pyridine extract was used. The prolan was prepared by the alcoholic precipitation method as described by Zondek. In a litter of at least 3 immature rats between the ages of 21-24 days, one received prolan in doses sufficient to produce at least several corpora lutea in the ovaries in 5 days, one received a known amount of the hypophyseal extract, and the other a combination of the two.

Phosphorylase and Glycogen Levels in Skeletal Muscle of Mice with Hereditary Myopathy

Conclusions In skeletal muscles of mice with hereditary dystrophia muscularis, (1) the “active” and “total” phosphorylase activities were significantly less than normal, (2) the phosphorylase activity ratios were normal, (3) the glycogen concentration was higher than normal. The body weights and the width of the tibial epiphyseal cartilages in the dystrophic mice were less than normal.

Effect of Anesthesia on Artificial Production of Pseudopregnancy in the Rat.

The condition of pseudopregnancy in the rat was first described by Long and Evans. 1 These authors demonstrated that pseudopregnancy could be produced artificially by the introduction of a small glass rod into the cervical canals at the time when the animal was in stages 1, 2 or 3 of the oestrous cycle, as specified by them. Wang 2 corroborated the findings of Long and Evans and recently Slonaker 3 has made additional contributions to the subject. Long and Evans showed that there was no direct nervous connection between cervix and ovary. Slonaker suggests that a substance, most likely to be found in the vaginal or uterine mucosa, is responsible for the continued action of the corpora lutea in pseudopregnancy and possibly in pregnancy. He further suggests that this substance could act either directly on the corpora lutea or through some intermediary agency, possibly the anterior part of the pituitary gland. It has been shown by Smith, 4 Smith and Engle, 5 Evans and Simpson 6 and others that there are one or more substances secreted by the anterior portion of the pituitary body which influence the growth of follicles and the formation of corpora lutea of the ovary. We wish to report results obtained when rats in the first 2 stages of the oestrous cycle are anesthetized for a short time with ether, nitrous oxide, or ethylene, and the cervical canals then stimulated by a small glass rod, as compared with controls which were not anesthetized. The rats used in this study were all healthy and sexually mature. A number of the animals were selected from the stock cages at the time when they were in oestrum, without first determining the regularity of their cycles.

Ovarian Response of Hypophysectomized Rats to Urinary Follicle-Stimulating Principle.

Zondek 1 and Kurzrok, 2 by injections in normal immature female rodents, have demonstrated that certain urines (after ovariectomy and the menopause) may induce predominantly a follicular growth. Leonard 3 has shown that the principle in this urine can be differentiated from that in P.U. by the rabbit ovulation test.

Limited Effects of Certain Steroid Hormones on Mammary Glands of Hypophysectomized Rats.

Summary Hypophysectomized rats were treated immediately or several days after the operation with progesterone alone or in combination with estrogen and with desoxycortico-sterone acetate. The mammary glands of these animals were stimulated with progesterone and estrogen alone or in combination only when treatment was begun immediately. The effects of the combined hormones revealed a summation of the individual responses. Desoxycorticosterone was ineffective.

Phosphorylase Activity in Denervated Skeletal Muscle.

Summary Following denervation of the rat rectus femoris muscle, phosphorylase a and t activity and the a/t ratio were maintained for 5 days, decreased by 10 days and remained low for 60 days. In muscles denervated for 15 days epinephrine increased the activity of phosphorylase a and t and the a/t ratio, and markedly inhibited the expected decrease in enzyme activity which follows tetanic contraction. Following electrical stimulation, the recovery of activity ratios in both intact and denervated muscles occurred at the same time. In denervated muscle the return of phosphorylase a and t was delayed as compared to that in normal muscle. Epinephrine showed no effect on the recovery of enzyme activity in the denervated muscle. Changes in muscle phosphorylase activity after denervation atrophy differ from those incurred from other causes.

Comparison of Atrophy and Glycogen Storage in Some Muscles After Castration and Denervation.

Summary Comparison of the weight and glycogen losses in the levator ani and cremaster muscles of the rat after castration and denervation show that (1) denervation atrophy is greater in the levator ani than in the cremaster, (2) denervation atrophy is greater than castration atrophy in the levator ani, (3) the loss of glycogen in both muscles after denervation is greater than after castration. Growth of the denervated cremaster continues in the young animal. Testosterone and cortisone can induce glycogen deposition in some denervated skeletal muscles; the effect of the nerves on this response is quantitative rather than conditioning.

Partial Maintenance of Adrenal Weight in Hypophysectomized Immature Male Rats by Testosterone Injections.

Summary Tnjections of large doses of male hormone partially prevent the atrophy of the adrenal cortex which normally follows hypophysectomy in the immature male rat.