ENDOCRINE, GLANDS. — In contrast to the glands with external secretion, which elaborate ferments with biochemical activity (secreta) or eliminate materials unusable or harmful to the organism (secreta), there exist glands with internal secretion (e. g.) that discharge their elaborated products directly into the bloodstream by means of the blood or lymphatic vessels passing through them; these products are called “hormones” (ὄρμᾶς = I excite) because of their stimulating action on the most diverse organs and on the autonomic apparatus of vegetative life.
Through the action of these regulators of vital processes, whose activity enzymes (v.), vitamins (v.), and certain metals and metalloids present in the organism, capable, even in minimal quantities, of significant biological actions (oligodynamic activity), that admirable and perfect unity of action becomes possible which, despite the myriad cellular elements and the very large number of organs and functions, appears in the human organism as functional equilibrium. This unity rests, on the one hand, upon the coordinating function of the nervous system, particularly that of vegetative life, and, on the other, upon the humoral equilibrium of the fluids circulating in the body (blood, lymph, cerebrospinal fluid, and the fluid of the cerebral ventricles), whose exceedingly delicate physical, chemical, and biological composition is determined by the elements mentioned above.
Within this framework of actions, the glands with internal secretion should be conceived less as working organs than as highly delicate systems for the regulation and coordination of vital functions. Their activity is manifested: through a morphoregulatory activity, when it stimulates, inhibits, directs, or coordinates the construction of the bodily mass or the morphological differentiation of the individual organism, directing it toward this or that constitutional type (v. COSTITUZIONE); or through a chemioregulatory activity, by activating or moderating the complex chemistry underlying vital phenomena; and through a neuro-psychoregulatory activity upon the great neurovegetative complexes (sympathetic-parasympathetic) or, indeed, upon the nervous functions underlying the higher processes of psychic life and upon the equilibrium of the cortical and subcortical nervous centres of intelligence and emotionality.
At present, the endocrine apparatus as a whole and the various glands constituting it are not yet known in their entirety; of some, much seems to be known, while others are only just appearing on the horizon of knowledge. Among those best known are: the pituitary gland, the thyroid, the parathyroids, the adrenal glands, the endocrine portion of the pancreas (islets of Langerhans), and that of the sexual glands (testis, ovary); the thymus and the pineal gland, certainly endocrine organs, are perfectly known. To these producers of hormones, many others will undoubtedly have to be added in the future; already, some authors include among them certain particular functional aspects of the liver (the antianaemic hormone of the liver, or Asher’s hepatic hormone), the spleen, the tonsils, the intestinal mucosa, the kidney, etc.
A complete study of the e. g. and their hormones would take us beyond the intended scope; a brief functional outline of the most important will therefore suffice, especially in order to highlight the influences that each of them may exert upon higher psychism (emotional and intellectual).
I. THE PITUITARY OR PITUITARY GLAND
It is about the size of a pea or a small bean, weighing barely half a gram, lodged in a small cavity [the sella turcica] excavated in the underlying ethmoid bone, at the base of the brain, with which it establishes particular relations through a stalk (infundibulum) that connects it to the diencephalic region of the brain, the seat of higher nervous centres of vegetative life and indirectly related to the centres of emotional life. Its close relations with the nervous centres, and the possibility of controlling almost all the other endocrine glands through its complex of hormones, place the pituitary on a particularly privileged functional plane, earning it the names of “endocrine brain” or “conductor of the glandular orchestra.” It consists of three portions: an anterior, distinctly glandular portion; a posterior portion of nervous nature, related in its development to the brain and synergistic in action with the diencephalic apparatus; and an intermediate portion of epithelial nature, poorly developed in humans. The anterior lobe (anterior pituitary), rich in so many hormones that few functions of the organism can be said to escape its action, produces a growth hormone, which stimulates the development of body mass, particularly in height, hence gigantism when it is excessive during the growth period, and acromegaly once development is complete; hormones stimulating the thyroid and the adrenal cortex; regulators of the endocrine function of the pancreas; hormones stimulating the liver to release its reserve of hepatic glycogen (diabetogenic hormone); hormones stimulating the mammary glands to secrete milk during the puerperium (prolactin); and gonadotropic hormones (gonadin A and B), which promote or inhibit the specific activity of the germinal tissues and of the endocrine tissues of the sexual glands.The posterior portion of the pituitary gives rise to a hormone that restrains urinary secretion (its deficiency produces “insipid diabetes,” polyuria without glucose); a hormone (vasopressin) capable of raising arterial pressure through the contraction of the small capillary arteries; and oxytocin, which, having reached a particular concentration in the blood towards the end of pregnancy, causes the expulsive contractions of the uterus. The intermediate lobe, of lesser importance in humans, produces intermedin, which, particularly in certain animals, acts by modifying the size of the pigment cells of the skin, thereby producing patches on the skin of varying size, configuration, and colour (the “nuptial livery” of the male wrasse during the mating season); in the human species too, this hormone appears to be related to the generative function, producing the increased pigmentation characteristic of particular areas of the skin during pregnancy. This is sufficient to make us realise how heavily the pituitary weighs in the economy of the entire organism and how necessary a perfect quantity and mixture of its many hormones are: so that the organism, in a proper balance of development, may avoid the two opposite anomalies of gigantism and dwarfism; so that equilibrium may be maintained in the complex interplay of the germinal and endocrine activity of the sexual glands, during pregnancy, childbirth, and lactation; so that adipose tissue may be deposited in normal quantities and with the proper topographical distribution; for the normal exchange of water in the organism, a condition for the regular intake and elimination of saline substances, particularly sodium chloride; for the metabolism of sugars; for the balance between wakefulness and sleep, avoiding either the most obstinate insomnia or a state of lethargic hypersomnia; and for an optimal arterial pressure, etc.
No less important, however, are the pituitary hormones with regard to the individual’s neuropsychic and intellectual manifestations. The balance of affective life and the normal development of intelligence, especially its particular characteristics, are connected with the functioning of the pituitary; the neuropsychic temperament and the disposition, varying according to the “individual type,” receive their imprint from an excess or deficiency of pituitary function. All this must be borne in mind in educating the individual and in formulating a moral judgment of him.
II. THE THYROID
It is situated anterior and lateral to the larynx and the first rings of the trachea and, in importance, immediately follows the pituitary; before all the others, it earned the name of “queen of the endocrine glands.” Its hormone has numerous functions, with points of impact both on vegetative life and on relational life. Through its morphoregulatory activity, the thyroid hormone influences the development of many tissues: connective, cutaneous and its appendages (hair and nails), skeletal, blood elements, the nervous system, and other endocrine glands. Among other things, the thyroid is responsible for regulating the biochemical activities that constitute the substrate of the phenomena of vegetative and relational life; it directly stimulates oxidative processes and indirectly, through the sympathetic system, the exchange of matter and energy that takes place between the organism and the environment surrounding it (metabolism), particularly with regard to fats, nitrogenous substances, water, salts, and carbohydrates (glycogen), while also influencing the production and regulation of body heat. Of very special importance is the stimulating action which, likewise through the sympathetic system, is exerted on the nervous activities of the organism, both neurovegetative and those of relational life; hence the particular importance of the thyroid for the development and characteristics of the individual’s psychic functions (hyperemotionality, readiness and rapidity of action and ideation).The thyroid maintains collaborative relations (synergy) with the germinative portion of the genital glands, the medullary portion of the adrenals, and the anterior pituitary; and relations of opposition (antagonism) with the thymus, the pancreatic islets, the parathyroid, the cortical portion of the adrenals, and the posterior pituitary. The aforementioned bioregulatory elements (vitamins, oligodynamic minerals) establish links with it: vitamins A and B hinder its function; in the blood, the increased iodine content—which is particularly abundant (95.5%) in the thyroid’s principal hormone, thyroxine—intensely stimulates its action; violent emotional states, capable even of doubling the iodine content of the blood, enhance the gland’s action, producing in the individual an accentuation of the catabolic phase of metabolism, thinness, and nervousness; nicotine has a particularly excitatory action (thinness and nervousness in smokers).
Hyperfunction of the thyroid, when it exceeds the limits of normal individual variability, gives rise to the condition known as “Flajani–Basedow disease” or “exophthalmic goiter,” more frequent in females (6:1) and in youth (20–40 years). In this disease, enlargement of the hyperfunctioning thyroid is accompanied by an excessive increase in the pulse rate, reaching as many as 100 beats (tachycardia), protrusion of the eyeballs, excessively prominent within the widened palpebral fissure (exophthalmos), an exaggeration of internal oxidation processes with increased oxygen consumption, predominance of the catabolic phase of metabolism, and at times pronounced, extreme weight loss. Various other ocular symptoms, trembling of the outstretched hands, excessive sweating, alterations of the skin and its appendages, and disturbances of intestinal function (diarrhea, etc.) complete the picture of pathological hyperfunction of the thyroid. A decrease in thyroid activity, falling below normal individual variability, gives rise, conversely, to the condition known as myxedema, a particular form of elastic swelling of the skin, accompanied by a slowing and more or less severe deterioration of all the functions of vegetative and relational life, with impaired bodily development; thus, if the defect has been present since birth, the individual remains a dwarf. The nervous system and the subject’s psychic activity are particularly affected, with slowness of action and mental apathy appearing, extending to the most absolute lack of intelligence (cretinism). Often
the picture is completed by enlargement of the thyroid in its supporting connective portion, which, through its excessive development, compresses the secreting portion of the gland; hence the characteristic prominence at the front of the neck, namely, the goiter. This, together with thyroid hypofunction and a more or less severe degree of cretinism, constitutes an endemic disease and characteristic in certain mountainous regions of Switzerland, the Pyrenees, Germany, Savoy, and in Italy in Piedmont (Aosta Valley), Lombardy (Valtellina), and certain areas of Liguria, Sicily, and Sardinia. The cause of endemic goiter is still debated; according to some authors, the phenomenon would be due to the presence of particular goitrogenic substances, in a colloidal state, contained in the water consumed locally (gypsum, fluorine); N. Pende speaks of an “endemic disease of the mountains” and admits multiple causes (scarcity of iodine, solar radiation, certain foods, hygiene, consanguinity in marriages, etc.). Because of the aforementioned relations between the thyroid and the sexual glands, thyroid hyperfunction is accompanied by absent or delayed pubertal development, with a more or less marked deficiency of the primary and secondary sexual characteristics. In hyperthyroidism, conversely, there is early sexual transformation. The functional equilibrium of the thyroid, or its shift toward excess or deficiency within the limits of normal individual variability, impresses particular constitutional characteristics upon the organism, type (v.) type (v.), and likewise orienting it differently with regard to temperament and character.
III. THE PARATHYROID GLANDS
They are situated posteriorly, close to the thyroid, normally four in number, approximately the size of a grain of rice; and, despite their smallness, they weigh so heavily in the individual’s endocrine balance that their removal leads to the gravest consequences. Their function has been sufficiently clarified to reveal their enormous importance as regulators of the mineral metabolism of calcium and phosphorus, fundamental elements for the mechanical balance of bone tissue and the biochemical balance of the nervous system. Bones owe their rigidity, which gives the organism the necessary firmness and resistance in its form, to calcium carbonate (10%) and tricalcium phosphate (90%). The nervous system undergoes variations in its excitability corresponding to changes in the molecular balance of the mineral salts dissolved in the blood plasma: calcium, together with magnesium, exerts a sedative action on neuromuscular and psychic excitability, whereas sodium and potassium increase its irritability. All life, therefore, seems to gravitate between these two “chemical poles” (Rondoni): on the one hand asthenicity, that is, diminished neuromuscular excitability, owing to the predominance of the calcium-magnesium pair in the osmotic balance of the circulating fluids; on the other, the predominance of sthenicity, an increase in neuromuscular excitability, owing to the predominance of the sodium-potassium pair. In all this, the delicate regulation of calcium exchanges and balance reveals the marvelous importance of the parathyroid glands in the economy of the organism.In parathyroid deficiency, because of the diminished quantity of calcium circulating in the blood (hypocalcemia), compensated by an increase in phosphorus (hyperphosphatemia), the bones neither acquire nor retain calcium, while neuromuscular irritability increases, reaching the forms of spastic and convulsive contractions seen in tetany, eclampsia, and spasmophilia. Indications revealing deficient parathyroid function may include fragile, furrowed nails; defects in the enamel of the incisor teeth; the so-called bags under the eyes; a tendency toward grimacing and facial “tics”; staring or rolling of the eyes; certain forms of migraine, asthma, and neuralgia; and a tendency toward swelling. Particular morbid forms are produced by a state of hyperfunction of the parathyroid glands (fibrocystic osteitis, or von Recklinghausen’s disease).
Parathyroid hormone is linked in cooperative relationships with vitamin D₃ (calcium-fixing vitamin) and with other hormones, such as those of the thyroid and thymus.
IV. THE ADRENAL GLANDS
They are two in number, situated like caps, one on each side over the upper pole of the kidneys, and measuring a few centimetres (maximum: 6 × 3 × 1 cm); because of their specific activity they have deserved the name “glands of energy.” Each adrenal does not constitute a single organ, but comprises a cortical portion (cortex) and a medullary portion (medulla), each producing different hormones.The cortex, previously regarded as anatomically and functionally unitary, has been shown by modern studies to consist of three different zones: the “glomerular” zone, whose hormones (the most important being deoxycorticosterone, the only one at present obtained by synthesis) regulate hydroxylin metabolism, causing the retention of sodium (sodium chloride and table salt) and water in the tissues and the elimination of potassium in the urine; they also raise arterial pressure. The “fasciculata” zone produces another group of hormones, among which corticosterone is noteworthy; it regulates the metabolism of sugars and their formation at the expense of proteins, and, when present in excess, displays a diabetogenic action, with an increase of sugar in the blood and its elimination in the urine. The “reticular” zone likewise elaborates a number of substances not yet well defined, for example adrenocosterone, whose action is similar to that of the sex hormones, predominantly male and much less frequently female; their effects appear in cases of hyperfunction of the adrenal cortex. The first two groups of adrenocortical hormones are truly indispensable for life: their complete deficiency produces “Addison’s disease,” or “bronze disease,” which, within a few years, leads the individual to cachexia and death. It is extremely rare in childhood; in a high percentage of cases it is due to tuberculosis of the adrenals. Clinically, it is manifested by progressive and intense loss of weight, neuromuscular weakness, lowered arterial pressure, diminution of sodium chloride and sugar in the blood, inconstant disturbances of the sexual sphere (impotence, amenorrhoea), diminished resistance of the organism to harmful toxic and infectious causes, a particular brown coloration of the skin and mucous membranes (whence the name), and loss of hair, especially in the axillary and pubic regions. Hypercorticalism, which, from total cases (Cushing’s disease) to cases of partial hyperfunction, presents the greatest variety in the intensity and combinations of symptoms, is based on the already described characteristic activities of the glomerular, fasciculata and reticular zones. A characteristic symptom always appears in it, namely “hypertrichosis” (excessive development of hair), not only on the trunk and limbs but also, in women, on the face. In relation to the hyperfunction of the reticular zone and the excessive quantity of substances with sexual activity (particularly of the androgenic and masculinizing fraction, and less often of the feminizing or oestrogenic fraction), the various patterns of alteration of the individual’s sexual constitution may be observed in partial hypercorticalisms, both with regard to primary and secondary characteristics: “adrenal virilism,” “adrenal feminilism,” and “precocious puberty” associated with Addison’s disease. In the first case, if hyperfunction of the reticular zone is established in an individual of the female sex during foetal life, a picture of “pseudohermaphroditism” is seen, whereby the individual (gynandrous) possesses both female sexual glands (ovaries) and external sexual organs of the opposite sex (v. ERMAFRODITISMO); if it is established before puberty, the picture is that of “heterosexual precocious puberty” or “prepubertal virilism”; in women who are already adults, it causes the addition of masculinizing features to the preceding feminine characteristics; in the male, androgenic hypercorticalism beginning before puberty is manifested by its premature appearance. In certain cases, in the adult male, a particular excess of oestrogenic hormones may produce “adrenal feminilism,” with loss of masculine characteristics and deviation towards the female type. On the other hand, cases are known in which atrophy of the fasciculata and glomerular zones, together with hyperfunction of the reticular zone, leads to a form of pseudohermaphroditism or precocious puberty developing within the clinical picture of Addison’s disease.
If these are the principal aspects of pathological hypo- and hypercorticalism, one may admit, within the physiological functional balance of the adrenal cortex, an entire nuanced series of ectopies ranged between the limits of fluctuating individual variability which, while explaining many constitutional, functional and neuropsychic anomalies, reveal the immense importance of these studies for the educational and moral guidance of the individual and for the moral judgment of his actions.
The adrenal cortex has close synergistic relations with vitamins C, A and B₆; with regard to the regulatory apparatus of vegetative life, its hormones have a vagotonic function (v. NEUROVEGOTATIVO, SISTEMA).
The medullary substance of the adrenals expresses its hormonal function through the production of adrenaline, or suprarenin, with a hypertensive action, which effectively stimulates the sympathetic portion of the autonomic apparatus of vegetative life; it is extraordinarily active, capable of exerting its specific action on the sympathetic system even when present in the blood at a dilution of one to a billion; on the frog’s heart it remains active even when diluted in the ratio of 1:1,000! It is used, in the form of an intracardiac injection, to stimulate the revival of the heart in cases of sudden cardiac paralysis.
V. SEX GLANDS
Alongside the germinal epithelia producing the sexual elements (spermatozoa, ova), destined for the procreation of the new individual, these glands also possess a portion with the function of endocrine organs.The endocrine testis consists of “interstitial cells” nestled among the tangle of seminiferous tubules in which the sexual elements originate; they unquestionably have an endocrine function, producing a hormone (interstitial hormone or testosterone) whose action benefits the procreative function and the general organic equilibrium. Indeed, testosterone, entering the circulation, puberty (v.), which in man is reached between the ages of 15 and 18, the perfection of the primary sexual characteristics, already present at birth, and the development of the secondary sexual characteristics proper to the respective sex; at the same time it nourishes the “libido” and the “potentia coeundi.” With regard to its general action, testosterone stimulates catabolic metabolism, particularly of fats; it exerts a neuromuscular tonic and strength-giving action (a restorative action in neurasthenia), as well as a psychotonic and psychosthenic action, promoting the characteristic qualities of manhood—activity, boldness, vivacity, and acuity of psychic processes—and, according to N. Pende, jointly with other glands (the anterior pituitary, thyroid, and thymus), opposing the onset of physical and psychic ageing (slowing of the major organic functions, arteriosclerosis, myocardial weakness, diminished resistance to physical and psychic exertion and trauma, psychic depression, despondency, and diminished combativeness).
A negative demonstration of the hormonal action of testosterone is provided by castration. In individuals thus mutilated (eunuchs), if the deprivation occurs before puberty, development of the primary sexual characteristics comes to a halt and the secondary characteristics fail to appear, with evident and persistent signs of physical and psychic infantilism, often accompanied by excessive elongation of the body (gigantism); in addition, the masculine psychic characteristics are absent: the “libido,” the “potentia coeundi,” and the “potentia generandi.” In the adult, following castration, the primary sexual characteristics tend to regress; for some time, sometimes even for a long period, the “libido” and the “potentia coeundi” may persist, sustained by a residual hormonal charge from the testes, by the adrenocortical hormones, and by the neuropsychic mechanism of acquired habit; the secondary sexual characteristics are also impaired: the beard becomes sparse and disappears completely, adiposity develops with a female distribution (breasts, pubis, hips), the voice acquires a high, feminine timbre, the disposition tends to lose its virile characteristics, becoming soft and effeminate, while intelligence does not suffer and may even become more acute; often the individual lapses into psychasthenia and melancholy. The efficacy of the surgical transplantation into man of the testes of an anthropoid ape (Woronoff operation [v.]) is based on the general action of testosterone.
The ovary likewise possesses, like the testis, well-defined and extremely important endocrine functions connected with the cells of the walls of the ovarian follicle (Graafian follicle) and with the corpus luteum. The former, by virtue of their internal secretion (folliculin), promote the perfection of the primary sexual characteristics already formed at birth; the appearance and development of the secondary sexual characteristics during puberty, in women between 13 and 15 years of age; and they nourish the “libido,” albeit in that more moderate form ordinarily observed in women. The onset of folliculin activity at the beginning of puberty is marked by the appearance of the first menstruation, which then recurs periodically at every maturation of an ovum (on average every 28 days in 70 percent of cases), throughout the entire period of female sexual life, until the time of menopause (v. ETÀ), at about 45–56 years, and sometimes 55–60; the extreme limit of 65 is highly doubtful.
Menopause marks the cessation of the folliculinic function of the ovary; once this has occurred, the characteristics of femininity gradually regress: changes in the external forms, the growth of hair on the face, the roughening and lowering of the pitch of the voice, and modifications of disposition confer on the woman increasingly pronounced signs of masculinization, which progressively tend to shorten the distances that had separated the two sexes.
Alongside the action of folliculin, that of the corpus luteum must be recalled, an endocrine formation that periodically comes to life again, whenever a Graafian follicle ruptures, in the empty follicular cavity. The hormone secreted by it (progestin or progesterone or luteostorone), chemically related to testosterone, pregnancy (v.), since, during the approximately 12–16 days between the rupture of the follicle and the possible subsequent menstruation (if the ovum has not been fertilized), progestin promotes such changes in the uterine mucosa as to make it suitable ground for the implantation and development of the ovum; these favorable modifications are maintained by the corpus luteum during the first four months of pregnancy, if the ovum has been fertilized. For the remainder of gestation, the protective activity of the corpus luteum is taken over by the endocrine function of the placenta. Up to the fourth month, the action of the corpus luteum is supplemented by that of “vitamin E” or “antisterility vitamin.” It should be remembered that the endocrine activity of the follicle and of the corpus luteum is under the control and stimulation of the gonadotropic hormones A and B of the anterior pituitary and of a sexual nervous center.
VI. THE PANCREAS
Located in the abdomen within the loop formed by the first portion of the intestine (duodenum), it is not only a gland secreting digestive juices but, through its “islets of Langerhans,” also an endocrine organ that produces insulin, a hormone regulating the metabolism of carbohydrates (sugars and starches) in glycogenesis—that is, their transformation and storage in the form of “glycogen” in the liver cells and muscles—and enabling the cells to make fuller use of the portion of sugar dissolved in the blood. The antagonist of insulin is the previously mentioned adrenaline, the hormone of the adrenal medulla, which stimulates the mobilization and breakdown of hepatic glycogen (glycogenolytic function), thereby leading to an increase in the percentage of glucose (in a normal individual, approximately 1 per thousand) present in the circulating blood.If one considers that carbohydrates are par excellence our dynamogenic foods, fuel which, through its oxidation within the tissues, particularly the muscular tissues, is the source of the energies we expend, one can appreciate the importance of the insulin–adrenaline endocrine balance as regulator of the mechanism governing the accumulation and utilization of carbohydrate substances. Vitamins B₁, B₂, and C, and zinc in an oligodynamic capacity, act in cooperation with insulin.
VII. THE EPIPHYSIS OR PINEAL GLAND
It is approximately the size of a large pea, weighing scarcely a quarter of a gram, situated above the isthmus of the brain, between the corpus callosum and the cerebellum, symmetrically with respect to the hypophysis, situated inferiorly; it likewise establishes highly particular relations with the third ventricle, which, as has already been said, is the seat of important nervous centres regulating vegetative life. Its hormone may still be regarded as unknown in its constitution, but not in its action, which is particularly important during the first period of the individual’s life. The epiphysis acts upon the sex glands, with an action opposed to that of the hypophysis; indeed, whereas the latter, as is already known, promotes the activity of the gonads by means of gonadotropins, the epiphysis, deserving the name of “guardian of childhood,” prevents pubertal development and sexual differentiation by means of an anti-gonadotropic hormone; hence, from the tenth year of age, in relation to the preparation for and subsequent course of the individual’s sexual development, the gland undergoes a natural process of atrophy and functional regression. Confirmation of this is provided by the fact that experimental removal of the epiphysis in animals, and its destruction before the tenth year of life in human beings through pathological lesions affecting it, particularly tumours, leads to excessive bodily development and precocious puberty (pineal macrogenitosomia, hypergenitalism), with the gradually increasing and complete appearance of the primary and secondary sexual characteristics, including the appearance of menstruation in girls even during the very earliest years of life. It appears that epiphyseal preparations may be useful in schizophrenia and may be capable of making hair growth more active.The epiphysis protects the existence of the thymus, which is thereby destined to undergo gradual atrophy as the activity of the sex glands awakens; it is functionally opposed to the anterior portion of the hypophysis, the sex glands, the thyroid, and the adrenal cortex.
VIII. THE THYMUS
This too is a gland characteristic of youth, as is demonstrated by the progressive decrease in its relative weight as one approaches puberty, at which time it rapidly undergoes atrophy; it is situated in the anterior mediastinum, within the thorax between the sternum, the heart, and the two inner surfaces of the lungs; in common speech it is called “animalia”; Gifeno regarded it as the seat of courage and emotions.While the inner portion of the thymus is formed of lymphoid tissue, akin to the lymphatic glands, the medullary portion (Hassall’s corpuscles) is the truly endocrine part, producing the thymic hormone, which, although it has not yet been definitively isolated or chemically identified, is empirically known through its actions: stimulation of the anabolic phase of metabolism, principally with regard to glucose (in collaboration with insulin), with an increase in body mass, particularly during the periods of “turgor” of intrauterine and prepubertal life (v. ETÀ DELLA VITA). In collaboration with vitamin D₃, the thymic hormone facilitates the uptake of calcium and phosphorus by the skeleton; by supporting and protecting the action of the pineal gland, it restrains the pubertal development of the gonads, and is therefore in functional opposition to the anterior portion of the pituitary gland, the sex glands, and the adrenal cortex. Excessive thymic function (Pende’s constitutional hyperthymic syndrome) leads, in a substantial percentage (45%), cryptorchidism (v.); it causes excessive development of the body (macrosomia) and of adipose tissue, with puerile somatic, sexual, and psychic characteristics; and exaggeration of the infantile lymphatic state (adenoid vegetations, hypertrophy of the tonsils and spleen, susceptibility to cutaneous exudative conditions, etc.). Conversely, extirpation of the gland in young animals, or its deficient development in the child, produces arrested bodily development, particularly in height, and defective calcification of the bones, which remain soft and pliable.
With regard to the neurovegetative system, the thymic hormone has an excitovagal action, in opposition to the sympathicotropic action of adrenaline; in hyperthyroidism (Flajani-Basedow’s disease), there is marked thymic hypertrophy and hyperfunction, in an attempt to counterbalance the hypersympathicotonic state and the accentuation of the catabolic basis of metabolism. These are the most important and best-known g. e.; of others, one can only glimpse their existence or conjecture their function.
IX. CONCLUSION
In view of what has been said, it is necessary to insist on the great importance of the function of the endocrine apparatus for all phases of the development of the organism, from the earliest moments of intrauterine life, when it is affected by the action of the maternal hormones, subsequently, through the action of its own hormones, along the ascending course of childhood, adolescence, and youth, in the state of equilibrium of maturity and the regression of old age; this applies both to the lower manifestations of vegetative life and to the higher ones of relational life, including those that accompany and serve as instruments of the psychic functions of feeling, intelligence, and will.Through the collaborative relationships established by enzymes and elements originating in the plant environment (vitamins) and the mineral environment (metallic ions, oligodynamic minerals) with the hormones, the organism finds itself immersed in, sustained by, and to some extent determined by a complex atmosphere of physical and biological causes that interweave and subordinate to one another the life of the macrocosm and the microcosmic life of our organism. Although some of these causes, particularly the vitamins and minerals (and here one must not even forget the meteorological ones), act, up to a certain point, in an equal manner upon that group of organisms living in a given environment, it can be seen that, in fact, each responds differently, giving rise to the almost infinite variability of the various individual morphological-functional types characteristic of living beings. This is due to the action and mutual equilibrium of the g. n., which, in the manner of a “constellation” (N. Pende), establish themselves in a specific equilibrium for each organism; it is due to the hereditary ground upon which the entire complex of these causes acts, particularly upon the tissue at the summit of the organic hierarchy, that is, that of the encephalic nerve centres. «Se il terreno organico, se i vari tessuti, su cui la detta costellazione neurochimica regolatrice delle vita deve agire presentano alterazioni strutturali creditarie ed acquarie, allora le azioni ormoniche, come quelle vitamineche, non potranno avere una risposta normale da parte dei tessuti già abornermente costituiti. Questo è il principio fondamentale da tenere presente soprattutto per la comprensione dei rapporti tra neuropsicopatologia ed endocrinologia o vitaminologia, e per le applicazioni delle cure ormoniche e vitamineche alle malattie dello sviluppo, del ricambio, del sistema nervoso, della sfera psichica» (N. Pende, La scienza moderna della persona umana, Milano 1947, p. 93).
Giuseppe de Nino