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SUMMARY Two endocrine glands of branchial origin are involved in regulation of calcium metabolism—the parathyroids which secrete parathormone (parathyroid hormone) in response to hypocalcaemia, and the ultimobranchial glands which release calcitonin (thyrocalcitonin) during hypercalcaemia. The ultimobranchial glands are distinct organs in most vertebrates but in mammals the cells become embedded in the internal parathyroid and thyroid where they constitute the parafollicular 'C' cells. Calcitonin can be extracted from mammalian thyroid (hence the alternative name, thyrocalcitonin) but it is present in much higher concentrations in the ultimobranchial glands of lower vertebrates. In mammals, both hormones appear to act primarily on bone resorption and calcium mobilization from the skeleton, which is stimulated by parathormone and inhibited by calcitonin. Secretion or release of both hormones is determined by the level of calcium in the blood, and the two constitute a dual endocrine control comparable to that of insulin and glucagon in regulation of blood glucose. The ultimobranchials are the older glands phylogenetically for they are found in sharks and bony fishes, while the parathyroids appear first in amphibians.

Previous investigations into arthropod metabolism have been restricted to the study of a few representatives of the two classes, Insecta and Crustacea. Thus, progress in the study of the physiology and biochemistry of arthropods is just beginning. In fact, previous to 1950, little information regarding the influence of neuroendocrine systems on their metabolism was recorded, and except where references to earlier classical discoveries are made, the work described in this review is of the past decade.

Experimental evidence suggests that the adult life of G. tanaceti can be divided into the physiological phases of pre-diapause, diapause, ovarian maturation, and oviposition. These phases are controlled by different levels of hormonal activity. Diapause is sustained by a low level of activity of the neurosecretory cells of the brain. Concurrently, the corpus cardiacum/allatum complex functions at a low level of activity. Measurements of nuclear volumes of the neurosecretory cells have been taken as an index in assessing their level of activity; the larger the nucleus, the more active the cell. Three criteria were used to determine the corpus cardiacum/allatum activity: (1) the volumes of the glands, (2) the nuclear-cytoplasmic ratio, and (3) the nuclear volumes of the secretory cells. When diapause is terminated, there is increased activity of the neurosecretory system. During the phase of oviposition the neurosecretory system functions at its highest level, sufficient to ensure the continued differentiation and maturation of oocytes and is probably involved in the process of oviposition.

THE conception that progesterone is the hormone responsible for the maintenance and therefore secondarily also for the onset of labour is based on several important findings: the indispensability of the corpus luteum for pregnancy in the rabbit1; the extraction of the effective substance from corpora lutea2; the role of progesterone in the implantation and early development of the fertilized ovum3; the excretion of progesterone as urinary pregnanediol and the relation between pregnanediol output and the prognosis of pregnancy4; finally, the elucidation of the mechanism of the endocrine control of the pregnant rabbit uterus5–7.

Pancreatectomy in the eel causes a slight tendency toward hyperglycemia; total and partial pancreatectomies cause a drop of total serum cholesterol. Thus, complete removal of the islet tissue in this teleost is not followed by diabetes mellitus, and also the endocrine control of the cholesterol-containing serum components seems to differ from that in mammals.

REVERSAL of the albumin/globulin ratio is commonly encountered in Africans in different parts of the continent of Africa. This reversal is ascribed in large measure to malnutrition and/or infection. Whatever the cause, the mechanism for this reversal still remains obscure.

The duration, dose and temporal interrelationship of three hormonal parameters: estrous (priming) estrogen, progesterone and nidatory estrogen, are concerned in the timing and degree of endometrial sensitivity to an artificial intrauterine decidual stimulus. Following priming by estrous estrogen the uterus is maximally responsive to subsequent treatment with progesterone and nidatory estrogen for a period of about three days starting on the fourth day after the last priming injection. During this time the fine timing is determined by the duration of progesterone and nidatory estrogen. Neither hormone alone is able to induce sensitivity but in combination sensitivity is maximal in three days. This is followed by a period of insensitivity. Progesterone alone induces a partially prepared state which can be held for several days until sensitivity is completed by estrogen.

Surgical removal of the pituitary gland had little apparent effect on the distribution or morphology of skin and feather polysomes in chicken embryos incubated for 12 days. However, polysome patterns obtained from 15-day-old hypophysectomized embryos differed markedly from those of their controls. In addition, a tetrad-shaped polysome, characteristic of the 158S peak of the 12-day-old embryo but not of the 15-day-old control, is still retained in the operated embryo at 15 days. Therefore, it appears that after day 12 of embryogenesis the structure of the four-ribosome polysome from skin and feathers is contingent on a functional hypophysis.

Blood glucose system is one of the most important systems of the human body, since energy transport is fulfilled through this complex endocrine control process. Because of great importance (in case of failure, its primary consequence is diabetes mellitus), many models were published, most of them with phenomenological approach. The aim of the current paper is to analyze a new molecular model published recently [1]. Global control theoretical characteristics are determined with nonlinear analysis. Physiological working points are defined for further polytopic modeling with linearization and model reduction is discussed and presented based on medical principles.

these conditions the massive increase in excretion of sodium and water did not occur until the arterial pressure rose to 35 mmHg above the control value, a pressure rise six times that in normal animals. Therefore it seems clear that minute amounts of angiotensin can cause sodium and water retention, which can be overcome only by elevated arterial pressure. These studies also suggest that an intrarenal mechanism might exist whereby decreased angiotensin formation is one of the important mechanisms for natriuresis when an animal is sodium loaded or when the arterial pressure increases. Effect of chronic angiotensin 11 infusion on aldosterone secretion

It is argued that the close endocrine control of human sebaceous glands and the likely effects of acne on selection indicate that both gland and disease have persisted because they are biologically useful. Two possibilities are proposed: sebum may provide precursor substrates for metabolism and synthesis by the epidermis of compounds of both local and systemic importance; and the adjuvent properties of corynebacteria which colonise the active sebaceous glands of acne may facilitate certain general immunological membrane.

Within hours of birth, some physical properties of liver lysosomes are modified. These alterations, which may be related to the autophagic vacuoles formation known to occur during this period, were inhibited by insulin administration. Glucagon, a potent inducer of autophagy in adult rat liver, did not anticipate this process in fetal liver. Our results suggest that the decrease of plasma insulin immediately after birth is an important factor in the development of hepatic autophagy.

Juvenile hormone (JH) administration increases the sensitivity of labellar chemosensilla inPhormia. It is suggested that this hormone plays a role in controlling both chemosensillar sensitivity and ovarian cycles.

Electron miticroscopy of the abdominal nerves of Rhodnius reveals neurosecretory axons which supply the abdomizinal epidermis. This suggests that thle epidermnal cells of insects are under more localized endocrine control than has previously been supposed.

THE breeding of the barnacle Balanus balanoides (L.) is controlled by light and temperature; a temperature below a critical value of 10° C and a light periodicity of less than 12 h/day are necessary before the barnacle will breed 4–8 weeks later1. As part of the cyclic activity of the oviducal glands during the natural breeding phase of B. balanoides 2–3 weeks before fertilization an elastic sac is formed within each gland2 which envelops the eggs as they pass down the oviduct, forming a membrane binding the egg mass together.

SummaryDevelopment and maintenance of the scrotum and differentiation of a male, “sexual skin” at the tip of the scrotum of rats is dependent upon the male hormone.

In the ovariectomized rat, the adrenal gland secretes progesterone. Adrenocorticotropin treatment elevates concentrations of this steroid in plasma, and inhibitors of adrenocorticotropin or progesterone biosynthesis lower the concentration. Adrenocorticotropin controls progesterone secretion by the adrenal but not by the ovary. Adrenal progesterone and its mode of control may have important influences on reproductive processes.

Recent research on the endocrine control of the initiation of lactation, on the hypothalamic control of prolactin secretion, and on the utilization of nutrients by the mammary gland for the synthesis of milk is reviewed. Particular emphasis is placed on the mechanism of action of prolactin, and the role played by prolactin receptors.

productive guilds of percids: results of the paleogeographical history and ecological succession. Ibid. 34:1910-1921. COOK, F. A. 1959. Freshwater fishes in Mississippi. Mississippi Game and Fish Comm., Jackson, MS. DEVLAMING, V. L. 1972. Environmental control of teleost reproductive cycles: a brief review. J. Fish. Biol. 4:131-140. 1974. Environmental and endocrine control of teleost reproduction, p. 13-83. In: Control of sex in fishes. C. B. Schreck (ed.). Extension Division, Virginia Polytechnic Inst. and State Univ. HEINS, D. C. 1981. Life history pattern of Notropis sabinae (Pisces: Cyprinidae) in the lower Sabine River drainage of Louisiana and Texas. Tulane Stud. Zool. and Bot. 22:67-84.

It is but natural that Dorothy Villee would have written a developmental approach to human endocrinology. Her long interest and expertise in the field of perinatal steroidology admirably prepared her for this accomplishment. The explosive nature of recent knowledge regarding the biochemistry of the fetoplacental unit has made putting together the pieces of the puzzle difficult at times, and Dr Villee has integrated this into a clear discussion in the early chapters of her book. The presentation begins with fertilization and the subsequent early events of embryogenesis, leading directly into a consideration of the placenta and its hormonology. This is followed by a description of the development of the endocrine glands of the fetus and the endocrine control of fetal metabolism and differentiation. Such an organized essay on this fascinating area of human development has been long overdue. The chapter on endocrine and metabolic changes in the perinatal period reflects

IT is well known that opalinids parasitizing the recta of Amphibia multiply asexually by binary fission during most of the year. During the breeding season, however, the reproductive pattern changes to a sexual one, the preliminary stages of which are marked by an increase in the multiplication-rate and the production of small forms and minute individuals. The latter eventually encyst and are passed out with the faeces of the frog. If ingested by tadpoles, they excyst, form micro- and macro-gametes, and the resulting zygotes give rise to the multinucleated opalinids in the newly metamorphosed frogs.

Despite the large volume of research that has been published in the field of endocrinology during the past 50 years, the precise biochemical function of a hormone has yet to be established. It is clear, however, that several hormones influence protein metabolism in such a way as to produce effects of considerable interest to the clinician as well as to the biochemist. The purpose of this presentation will be to consider both the clinical and biochemical implications of the hormonal adjustments in a number of common medical situations. The object of endocrine control might be stated to be an adjustment of metabolism through the intervention of numerous hormones acting in specific biochemical or biophysical areas to produce optimum substrate concentrations, adequate enzyme activity, and appropriate work performance in all organs and tissues in a variety of physiological and pathological states. In some instances, two hormones may stimulate a single process

Thou knowest not... how the bones do grow in the womb of her who is with child.—Eccles. xi:5. Introduction Details of the biochemistry of purified mammalian pituitary growth hormone and many of its physiologic and therapeutic actions in experimental animals are a matter of record. However, as Gaunt 1 put it in 1954, "We are sadly lacking in information concerning the different rates of secretion of this and related hormones at different times of the life span." The same problem was stated by C. N. H. Long 2 in 1955, when he said: "The central problem of anterior lobe physiology [is] what regulates the secretion of growth hormone. Is the growth of a rat or man, from birth to... adulthood, accompanied first by an increased proportion of growth hormone in the secretion of the anterior lobe, followed by a decline in later years; or is... endocrine control of growth merely

Tanning of the newly formed exoskeleton of the dwarf crayfish, Cambarellus shufeldti, depends in part upon the presence of a substance from the eyestalk. Injection of eyestalk extract enhances tanning in a specimen with its eyestalks removed, whereas the exoskeleton of an untreated crayfish without eyestalks will not become as dark as that of an intact individual.

Various lines of evidence have been assembled that are consistent with a new hypothesis concerning the pipping mechanism in chicken eggs. It is suggested that the Musculus complexus in the upper cervical region functions in pipping not primarily as a contractile mechanism but as a hydraulic pressure mechanism to force the egg tooth against the shell with sufficient force to break the latter or, alternatively, as a turgid cushion against which contractions of other muscles (such as the M. biventer and M. spinalis) or even of its own muscle fibers would effect the same result. Size of the muscle and its turgidity are maximal at the time of pipping. The turgidity is due to selective infiltration by lymph. Size and lymph content diminish rapidly after pipping. The paired Musculus complexus of the chick embryo is located superficially in the antero-dorsal cervical region (Figs. 1, 2). It has been described grossly in chickens (Pohlman, 1919; Fisher, 1958; Brandstetter, 1960), grebes (Fisher, 1961), Franklin's Gull (Fisher, 1962), and coots (J. Fisher, 1962). Contraction of this muscle would seemingly elevate the head and therewith the beak and egg tooth whenever the head is free to move, since the M. complexus originates on several cervical vertebrae and inserts on the posterior end of the parietal bones. Histological changes during its development have been observed by Pohlman (1919) and have been described briefly by Fisher (1958) and in detail by Brandstetter (1960). The muscle is bounded laterally by very large lymph glands (arrows, Figs. 1, 2). Prominent lymph glands are likewise present in the same relative positions in Franklin's Gull, and in coots, but they are absent in grebes. Preliminary attempts have been made to understand the endocrine control of development of the M. complexus (Brandstetter, 1960; Brandstetter, Watterson and Veneziano, 1962). Keibel (1912) first noted that the muscle becomes greatly enlarged and infiltrated with serous fluid during the period when the shell is broken (pipped) prior to hatching. He stated emphatically that the M. complexus supplies the power used to break through the shell. Although he did not so state, he implied that the power was provided by contraction of the hypertrophied muscle. He also, noted that the M. complexus is normal in appearance by the tenth day after hatching. Pohlman (1919) agreed that the muscle attains its greatest weight on the "picker day" and that infiltration of the muscle by lymph is 1 Present address: Department of Biology, Macalester College, St. Paul, Minnesota. The author acknowledges the suggestions, criticism and help with the manuscript generously given by Dr. Ray L. Watterson.

Endocrine Control in Crustaceans By David B. Carlisle and Sir Francis Knowles, Bart. (Cambridge Monographs on Experimental Biology, No. 10.) Pp. vii + 120 + 5 plates. (Cambridge: At the University Press, 1959.) 21s. net.