Cyclic Changes in the Thyroid and Adrenal Cortex of the Male Starling, Sturnus Vulgaris, and Their Relation to the Sexual Cycle

1938 ◽  
Vol 72 (743) ◽  
pp. 562-570 ◽  
Author(s):  
J. Wendell Burger
Keyword(s):  
Adrenal Cortex ◽  
Sturnus Vulgaris ◽  
Sexual Cycle ◽  
Cyclic Changes

Central effects of photoperiod on reproduction in the ram revealed by the use of a testosterone clamp

1984 ◽  
Vol 103 (2) ◽  
pp. 233-241 ◽  
Author(s):  
G. A. Lincoln
Keyword(s):  
Sexual Cycle ◽  
Blood Levels ◽  
Light Cycle ◽  
Artificial Lighting ◽  
Wool Growth ◽  
Sexual Skin ◽  
Cyclic Changes ◽  
The Brain ◽  
Lighting Regimen ◽  
Short Days

ABSTRACT Over a 3-year period eight adult Soay rams were exposed to an artificial lighting regimen of alternating 16-week periods of long days (16 h light:8 h darkness; 16L:8D) and short days (8L:16D) to induce a seasonal cycle in reproduction and wool growth every 32 weeks. Early in the study the rams were castrated (four during long days and four during short days) and 48 weeks later the castrated animals were each given an s.c. implant of testosterone to increase the blood plasma concentration of testosterone to 14–20 nmol/l. The changes in the concentrations of LH, FSH and testosterone were measured in blood samples collected once or twice weekly while records were made of the changes in the size of the testes (before castration), the intensity of the sexual skin flush, the expression of aggressive and sexual behaviour and the rate of wool growth. The results showed that in the castrated rams there were only minor changes in the blood levels of LH, FSH and the expression of aggressive behaviour related to the 32-week light cycle, while the sexual skin flush was permanently absent. However, after the commencement of the constant testosterone therapy, there were major changes in all the reproductive parameters related to the lighting regimen with a similar temporal relationship as observed in the rams before castration. Cyclic variation in wool growth occurred throughout the study related to the changes in photoperiod but this was not markedly affected by castration and testosterone replacement. The conclusion is that photoperiod acts centrally within the brain to dictate the cyclic changes in reproduction and wool growth in the ram, but testosterone is required for the full expression of the effects on reproduction. In the normal seasonal sexual cycle, photoperiod affects both the secretion of testosterone and the responsiveness to testosterone, resulting in a peak of sexuality in autumn. J. Endocr. (1984) 103, 233–241

scholarly journals THE EFFECT OF THE INTRAVENOUS INJECTION OF SUBSTANCES AFFECTING TUMOR GROWTH ON THE CYCLIC CHANGES IN THE OVARIES AND ON PLACENTOMATA

1914 ◽  
Vol 20 (2) ◽  
pp. 180-190 ◽  
Author(s):  
Moyer S. Fleisher ◽  
Leo Loeb
Keyword(s):  
Marked Effect ◽  
The Body ◽  
Sexual Cycle ◽  
Corpora Lutea ◽  
Ether Anesthesia ◽  
Normal Cycle ◽  
Intravenous Injections ◽  
Blood Coagulability ◽  
Cyclic Changes ◽  
Active Proliferation

If six to seven days after copulation incisions are made under ether anesthesia into the uterus, and on the day following this operation one or several injections of hirudin are given, changes set in in the ovaries which correspond to those found at the time of ovulation; namely, a degeneration of all the follicles with the exception of the small ones. These degenerative changes are followed by the same developmental changes as in the normal cycle. This represents a second method of altering experimentally the periodicity of the sexual cycle, the first consisting in the early extirpation of the corpora lutea described previously by one of us. Under the same conditions intravenous injections of hirudin destroy in the large majority of cases the greater part of experimental placentomata through hemorrhages, and they prevent the remaining placentomatous areas from active proliferation, probably as a result of interference with the circulation. These injections may also cause abortion in pregnant animals. Intravenous injections of hirudin produce a tendency to hemorrhage at various places in the body, and these hemorrhages are prone to occur, especially in rapidly growing tissues, where the blood vessels are less resistant, as in tumors and in placentomata, also in the neighborhood of necrotic areas. In the stomach the hemorrhages may be followed by digestion of the tissues through the gastric juice. It is probable that there is a connection between the action of hirudin on the blood (coagulability and viscosity) and the tendency to hemorrhage. Withdrawal of blood, intravenous injections of distilled water, colloidal copper, nucleoproteid, or casein have no marked effect on the cyclic changes in the ovaries or on placentomata.

CATECHOLAMINES: THYROID FUNCTION AND THE SEXUAL CYCLE IN RATS

1973 ◽  
Vol 73 (2) ◽  
pp. 273-281 ◽  
Author(s):  
B. E. Fernández ◽  
A. E. Domínguez ◽  
N. A. Vidal
Keyword(s):  
Thyroid Function ◽  
Wistar Rats ◽  
Sexual Cycle ◽  
Vanillylmandelic Acid ◽  
Acid Excretion ◽  
Reverse Effect ◽  
Sexual Hormones ◽  
The Central Nervous System ◽  
Cyclic Variations ◽  
Cyclic Changes

ABSTRACT Investigations were performed on the daily urinary excretion of noradrenaline (NA), adrenaline (A) and 4-hydroxy-3-methoxymandelic acid (vanillylmandelic acid) and on the concentration of both amines in different areas of the central nervous system, in control, triiodothyronine (T3), and 131I-treated Wistar rats in order to gain some knowledge about the interrelation between thyroid function, sexual hormones and catecholamines. Cyclic variations were observed in NA excretion and in the excreted NA/A relationship in the three groups of animals. T3 increased NA excretion and decreased vanillylmandelic acid excretion in both sexes. A excretion did not show cyclic changes, nor was it influenced by the thyroid function. In the hypothalamus, there was an increase of NA in experimental hyperthyroidism. No changes were observed in 131I-treated animals. Progesterone stimulated the synthesis and/or depletion of NA storage while oestrogens had the reverse effect, making it also possible for the latter to potentiate the activity of phenylethanolamine-N-methyltransferase. The thyroid hormones inhibited monoamine-oxidase and extended the half life of catecholamines, a fact which was corroborated by the increase in NA excretion and the decrease in vanillylmandelic acid.

scholarly journals THE CYCLIC CHANGES IN THE MAMMARY GLAND UNDER NORMAL AND PATHOLOGICAL CONDITIONS

1917 ◽  
Vol 25 (2) ◽  
pp. 305-321 ◽  
Author(s):  
Leo Loeb ◽  
Cora Hesselberg
Keyword(s):  
Mammary Gland ◽  
Guinea Pig ◽  
Proliferative Activity ◽  
Early Period ◽  
Sexual Cycle ◽  
Corpora Lutea ◽  
Pathological Conditions ◽  
Mitotic Proliferation ◽  
Cyclic Changes ◽  
In The Beginning

1. In the pregnant guinea pig proliferation of the mammary gland becomes regular only at a later stage of pregnancy; namely, during the period following the 24th day of pregnancy. Previous to this period proliferation was absent in the majority of cases. Proliferation of the mammary gland during pregnancy becomes regular only at a period of time which exceeds the duration of the normal sexual cycle unaccompanied by pregnancy. It is probable that pregnancy as well as the presence of living deciduornata and corpora lutea increases the proliferative activity of the mammary gland as compared with the ordinary cycle in non-pregnant animals or in animals lacking corpora lutea and deciduornata. 2. After the completion of pregnancy and in the beginning of secretion some mitotic proliferation may still be present, but it soon ceases, probably as the result of those processes that lead to secretion. While during the period of secretion, notwithstanding the presence of a new pregnancy, mitotic proliferation soon ceases, some proliferative stimulus seems still to be active, which, however, under existing conditions apparently leads only to a mitotic multiplication of nuclei. The latter conclusion is only suggested at the present time and needs confirmation through further studies. 3. In cases in which abortion took place in the first half of pregnancy secretion in the gland was not established; secretion occurred in two animals aborting toward the latter part of pregnancy. In one of these cases, mitotic proliferation of some gland cells was associated with the microscopic appearances of secretion. 4. In guinea pigs castrated during an early period of pregnancy in which pregnancy continued for some time, proliferative changes were absent in the mammary gland. In conjunction with a partial similar effect observed after extirpation of the corpora lutea during pregnancy, we may perhaps attribute the lack of proliferation in some of these cases to the absence of the ovaries. 5. Extirpation of the corpora lutea during pregnancy induces a new ovulation and with it the primary proliferation in the mammary gland; abortion does not necessarily prevent these proliferative changes. Extirpation of the corpora lutea during pregnancy perhaps prevents the secondary proliferative changes in the mammary gland. 6. Five injections of cow's lutein given in relatively large quantities intraperitoneally do not produce proliferation of the mammary gland in the guinea pig.

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