The pituitary of the human fetus in the second trimester of pregnancy contains a considerable amount of LH and HGH. The average LH and HGH contents of the pituitaries were found to be 3.4IU/gland and 2.3μg/gland, respectively. The pituitary content and concentration of HGH increased significantly as the fetal age advanced, although there were no remarkable changes in the pituitary content of LH. The pituitary incubated in vitro secreted LH, FSH and HGH into the medium. The addition of rat hypothalamic extract into the medium increased the release of LH and HGH by the pituitary. Synthetic LH-RH also enhanced the pituitary release of LH and FSH in vitro. However, in the pituitaries of the fetuses younger than the 16th weeks of gestation the secretion of LH and FSH in vitro was not stimulated by the addition of synthetic LH-RH. The results demonstrate that the anterior pituitary of the human fetus is responsive to hypothalamic releasing factors in vitro at least by the 19th weeks of fetal age.

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Previously the authors reported that thyroid peroxidase is bound mainly on the membranes of rough-surfaced endoplasmic reticulum. In the present paper, the question whether the enzyme is also contained in other subcellular organelles in the cells or not was investigated. Attempts to isolate plasma membranes and Golgi membranes were made, being monitored by following Na⁺, K⁺-ATPase and galactosyltransferase activities, respectively, through differential centrifugation and twice-repeated sucrose gradient centrifugation. The final preparations showed properties characteristic of these membranes and specific activities comparable to those of reported preparations of liver, but revealed practically no peroxidase activity. The buoyant densities of the Na⁺, K⁺-ATPaseand galactosyltransferase-associated particulates were around 1.136 and 1.154, respectively, while that of peroxidase-associated particulates (rough-surfaced endoplasmic reticulum) was about 1.192. Isolated nuclei did not show any peroxidase activity and the behaviour of both mitochondria and lysosomes was different from that of the peroxidaseassociated particulates. Thus, all the results obtained in the present experiments are not favorable to the view that peroxidase is located in nuclei, mitochondria, lysosomes, Golgi apparatus and plasma membranes (microvilli) of thyroid cells.

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Development and differentiation of lateral thyroid were investigated histologically upon the serial sections of the rat embryos. On the 11th day of gestation, the “third pharyngobranchial duct” (3. PBD) develops from the third pouch and elongates rapidly downward. The “fourth pharyngobranchial duct” (4. PBD) develops transversally from the 4th pouch on the same day. Median thyroid forms the diverticulum. On the 13th day, median thyroid elongated perpendicularly. On the 14th day, the short 4. PBD is separated from the pharyngeal pouch and approximates the dorso-medial surfaces of the median thyroid. The primordial parathyroid III is set free from the 3. PBD. On the 15th day, the peripheral parts of. PBD develop into the numerous cords provided with the characteristic features of primordial thyroid follicles. In this manner, the 4. PBD constitutes the lateral thyroid. On the 15th day, in the central region of the primordial median thyroid, mitotic division of nuclei is frequently observed. This area designated as “proliferating area” comes in contact, on the 16th day, with the thickened wall of 4. PBD. On the 17th day, however, the proliferating area becomes obscure with the promoted peripheral outgrowth of numerous cords. Thus, it has been clearly demonstrated that a large number of thyroid follicles are derived from the lateral thyroid of 4. PBD origin. The primordium of parathyroid IV can be seen transiently from 4. PBD on the 17th day, but becomes soon undetectable.

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A single injection of PMS induces ovulation in immature rats on the third day morning after the treatment. The second estrus occurred 9 days after the first ovulation. Follicles of the succeeding cycle developed the capacity to ovulate 3 days after the first ovulation in 3 out of 5 rats, but could not be maintained in an ovulable state during the next 24 hr.
When supplementary PMS was given just after the first LH surge, follicles developed the capacity to ovulate within 1.5 days after the first ovulation and the second ovulation occurred in 7 out of 10 on the fourth day morning after the first ovulation. Vaginal smears showed a 4-day-cyclic pattern in these animals after supplementary PMS administration.
From these experiments, it is concluded that immature rats pretreated with PMS were in an anestrous state during 8 days after the first ovulation, not due to the activation of corpora lutea, but due to the failure of follicular development. Plasma levels of gonadotropin responsible for follicular growth and maintenance after the first ovulation were discussed.

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A method for the ultramicro-measurement of human growth hormone (HGH) in plasma based on the solid-phase radioimmunoassay (RIA) using antibody-coated disposable microtiter trays was described. This method is simple, rapid and inexpensive, and particularly useful for ultramicro-measurement of plasma HGH levels in large numbers of plasma samples.
The lower limit of sensitivity for purified HGH was 25pg/ml (P<0.05). The precision of the measurement of HGH in plasma has been calculated, and the quantitative sensitivity of the method derived from the results given by its routine use was 56.8pg/ml (P<0.05). The HGH level of normal pooled plasma in 10 replicates was 1, 515pg/ml (±126;1SD), and the coefficient of variation was 8.3%.The mean basal plasma HGH level after an overnight fasting in 23 normal males was 2, 100pg/ml (±1, 491; 1 SD) by this method and 2, 036pg/ml (1, 643; 1 SD) by double-antibody RIA, and in 23 normal females, 2, 589pg/ml (±1, 189; 1 SD) and 3, 300 pg/ml (±1, 690; 1 SD) respectively; there was no statistically significant difference between the basal HGH level obtained from this method and that from double-antibody RIA in normal subjects. On the other hand, the mean basal plasma HGH level after an overnight fasting in 21 hypopituitary patients was 484pg/ml (±282; 1 SD) by this method, and this value was significantly lower (P<0.001) than 1, 376pg/ml (±498; 1 SD) by double-antibody RIA. These data show that determination of basal plasma HGH levels by this method is of much value in the diagnosis of hypopituitarism.

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Sexual differentiation of the brain was investigated in normal females, neonatally androgenized females and males from the viewpoints of the effects of steroid feedback and the responsiveness to electrical stimulation. Pituitary and serum gonadotropins and prolactin were measured by radioimmunoassay. 1) Pituitary LH in the male was as high as or slightly higher than that in the normal female, but pituitary FSH was much higher in the male than that in the female and pituitary prolactin was much lower in the male than the female. In androgenized females pituitary LH was as low as or slightly lower than that in the normal female, but pituitary prolactin was higher than those in normal cycling females and males. No sex differences were observed in the serum LH and prolactin levels, and serum LH in androgenized females was the same levels in male and female rats. Serum prolactin in androgenized females was higher than that in both normal females and males. Serum FSH in males was higher than that in normal females or in androgenized females. 2) Gonadectomy increased in pituitary and serum LH and FSH in all of normal females, androgenized females and males. Gonadectomy, however, decreased both pituitary and serum prolactin in normal females, but did not change their concentrations in males. In androgenized females pituitary prolactin was reduced by ovariectomy, but not serum prolactin. Estrogen injection into all of gonadectomized animals reduced serum LH and FSH and increased serum prolactin. 3) Electrical stimulation of the medial preoptic area consistently increased serum LH in orchidectomized males and ovariectomized-androgenized females under the estrogen influences. However, stimulation of the medial amygdala did not increase serum LH in orchidectomized males and ovariectomized-androgenized females under the estrogen influences, by contrast, it increased serum LH in the ovariectomized normal females under the same conditions. Hippocampal stimulation increased serum LH slightly in gonadectomized males and androgenized females; by contrast, it decreased serum LH in ovariectomized normal females. 4) In the light-induced constant estrous rats electrical stimulation of both medial preoptic area and medial amygdala increased serum LH, while stimulation of the hippocampus neither increased nor decreased it.
Thus, there exists the sexual differentiation of the brain in control of gonadotropin secretion including regulation by the negative and positive feedback influence with gonadal steroids. However, the sexual differentiation of the brain capacity to be involved in the ovulatory release of gonadotropins responding to electrical stimulation appears to be induced by neonatal androgenization in both sexes.

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In order to study the role of the splanchnic nerves in the control of glucagon and insulin secretion, the distal stump of the splanchnic nerve was electrically stimulated at the diaphragmatic level first on the left side and then on the right with an interval of 100 min in an anesthetized dog. During the stimulation, systemic plasma glucose level rapidly rose and glucagon and insulin in the pancreatic vein blood showed a delayed rise in response to the stimulation, followed by a rebound rise in pancreatic vein blood insulin on cessation of the stimulation. An immediate augmentation of the pancreatic venous blood flow and a slower increase in hematocrit were also found. A significant increase of glucagon and insulin secretion was found upon taking into consideration of these hemodynamic changes. Pretreatment with phentolamine resulted in a rise of the basal level of insulin in the pancreatic vein blood and disappearance of the rebound after stimulation. In propranolol-pretreated animals, the basal secretion of glucagon was significantly suppressed and the rise during the first stimulation was smaller, along with a significant decrease of insulin secretion during the stimulation and exaggerated poststimulatory rebound phenomenon. These effects of the blocking agents suggest a possibility of adrenergic receptor mechanisms operating in glucagon secretion as well as insulin release.

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Effective doses of synthetic LH-RF for induction of ovulation at various stages, except the stage of estrus, of 4-day cyclic rats and mice were investigated. In rats injected subcutaneously at 4p.m., the maximal effective doses were 6.4μg on mtestrus, 0.8μg on diestrus, and 0.2μg on proestrus (proestrus rats were pretreated with pentobarbital). In mice the corresponding doses were 0.05μg on diestrus, and 0.02μg on proestrus. On metestrus, however, most of the mice ovulated by 0.4μg, while even larger doses up to 1.6μg failed to elicit ovulation in the others.

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Intravenous injection of 40 or 4 MRC U of porcine calcitonin in 9 old patients with chronic non-endocrine disorder caused a marked fall in serum immunoreactive gastrin in a dose related manner. This finding is consistent with the observation of Sizemore et al.(1973) who have found a decreased serum gastrin in the patients with medullary carcinoma of the thyroid and suggests the inhibitory effect of calcitonin on the secretion of gastrin in man.

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Activity of luteinizing hormone (LH) was separated into two major components and an additional minor component by isoelectrofocusing of a partially purified bovine adenohypophysial preparation obtained by the gel filtration with Sephadex G-100. The components posessed the isoelectric point at pH 8.8, 8.3, and about 4.0, respectively. This result shows that bovine LH consists of two or three kinds of molecules with different isoelectric points.

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Cellular RNA content in the rat ventral prostate is decreased by castration, and therefore the influence of castration on prostatic alkaline and acid RNase activities was investigated. Castration resulted in the increase of both prostatic RNase activities pertissue protein with the resultant decrease of prostatic RNA content. RNase activities in lung or liver homogenates were not altered by the castration. Prostatic alkaline RNase activity (pH 7.9) was more sensitive to the androgen level than acid RNase activity (pH 5.5), although the latter was higher. The specific activity of alkaline RNase increased remarkably, and in a reverse relation to this, the protein content decreased in the ventral prostate after castration. Therefore, the total activity of the RNase in the prostate was hardly altered by the castration. This selective retention of the RNases would contribute to the maintenance of the RNA degradative ability during the prostate involution. Therefore, the marked decrease of RNA content in the prostate of a castrated rat would be attributed to the decline of RNA synthesizing ability and furthermore the maintenance of RNA degradative ability.

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A 5α-dihydrotestosterone binding component, sedimenting in the 8 S region, was detected by sucrose gradient analysis in rat hypophyseal cytosol labelled in vitro with 5α-dihydrotestosterone-³H. The dissociation constant of the androgen-protein complex and the number of binding sites of the component were approximately 2.4×10^-9 M and 5.3×10^-14 moles/mg cytosol protein, respectively. The binding component seemed to have a specificity for 5α-dihydrotestosterone relative to other hormones. These results suggest that the cytosol from male rat hypophysis contains a “receptor” for 5α-dihydrotestosterone.

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LH synthesizing activity of synthetic LHRH was proved by using the rat pituitary implanting system of the rat intratesticular test which the authors had previously proposed for the evaluation of LH releasing factor. In this test system, administration of a very low dose of LHRH (0.1 ng) gave a definite positive response within 1 hr.

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