Doctrine about endocrine organs endocrine glands

There are specific organs that are similar to secreting glands, however differ from them in a single important specific, viz., they don’t possess any ducts by which their secretion is discharged. These organs are referred to as endocrine glands. They’re able to inner secretion—that’s to say, of forming, from supplies dropped at them within the blood, substances which have a sure affect upon the nutritive and different modifications occurring within the physique. This secretion is carried into the blood stream, both immediately by the veins or not directly by means of the medium of the lymphatics.

  These glands embrace the thyroid, the parathyroids and the thymus; the pituitary physique and the pineal physique; the chromaphil and cortical techniques to which belong the suprarenals, the paraganglia and aortic glands, the glomus caroticum and maybe the glomus coccygeum. The spleen is normally included on this listing and generally the lymph and hemolymph nodes described with the lymphatic system. Different glands because the liver, pancreas and sexual glands give off inner secretions, as do the gastric and intestinal mucous membranes.

ENDOCRINE GLANDS wouldn’t have the ducts, their secret will get instantly into blood. They’ve prettily plentiful blood supplying, and their secret has particular chemical and physiological exercise. Endocrine system for origin subdivides into glands with endodermal, mesodermal or ektodermal origin.

Glands of endodermal origin subdivide into bronchiogenic group (thyroid, parathyroid and thymus glands) and glands developed from epithelium of intestinal tube (endocrine a part of pancreas).

Glands of mesodermal origin (interrenal system) embrace interstitial cells of sexual glands and cortex of adrenal glands.

Glands of ectoderm group embrace hypophysis (neurogenic group) and medulla of suprarenal glands and paraganglia.

The Thyroid gland is located in anterior neck space on stage of the IV-VI cervical vertebrae and consists of proper and left lobes communicated by isthmus, which continues upward by pyramidal portion. Thyroid gland is constructed by parenchyma, which subdivides into lobuli by septa. Follicles are located in lobules, which include hormones of thyroid gland: thyroxine, triiodthyronin, calcitonin. They affect on all sorts of metabolism.

The Parathyroid gland has pair superior parathyroid gland and inferior parathyroid gland that located on again floor of thyroid gland. Accent parathyroid glands may be current. Parathyroid gland excretes parathyroid hormone that regulates metabolism of phosphorus and calcium.

The Thymus is a central organ of immune system, which is located in anterior mediastinum on stage of the 4th ribs behind manubrium sterni. Behind thymus pericardium is located. Thymus gland consists of lobes – proper and left, which have the lobule that constructed by cortex and medulla of thymus gland. In medulla Т-lymphocyte matter purchase that peculiarities which contribute to protecting operate.

Endocrine a part of sexual glands (testicle and ovary)

Interstitial (Leidig) cells are located in parenchyma of testicle. They excrete testosteron, which influences on improvement of secondary sexual indicators. Corpus luteum positioned in ovaric parenchyma produces a progesteron (it prepares a mucous membrane of the uterus membrane to embryo fixation, detains improvement of recent follicles and stimulates improvement of mammary glands throughout being pregnant). Follicular epithelium excretes estrogen, which contributes to improvement of main feminine sexual indicators (ovary and uterus) additionally improvement of secondary feminine sexual indicators, as progress of mammary gland, hair in accordance feminine sort cetera and assists the regulation of menses.

Endocrine a part of pancreas is represented by islets of Langerhans. They produce insulin and glucagon, that regulate metabolism of carbohydrates, regulative a sugar contents in organism. Connected to inadequate manufacturing of those hormonal illness sugar diabetes arises.

The Adrenal gland is a pair endocrine gland, which lies on superior extremity of proper and left kidneys on stage of the Th 11 – Th 12 vertebrae. Every adrenal gland has triangle form and has anterior floor, posterior floor and renal floor and superior margin and medial margin, and in addition has the hilus and consists of cortex and medulla matter. Cortex produces mineralocorticoids (aldosterone), glucocorticoids and androgens. Medulla of adrenal glands produces adrenalin and noradrenalin.

The Paraganglia are small agglomerations of chromaffin cells, positioned intently close to belly aorta (aortic paraganglia) or in thickness of sympathetic trunk (sympathetic paraganglion). Paraganglia has a operate, analogic to operate of medulla suprarenal gland.

a. The Thyroid Gland (Glandula Thyreiodea) is a extremely vascular organ, located on the entrance and sides of the neck; it consists of proper and left lobes related throughout the center line by a slender portion, the isthmus. Its weight is considerably variable, however is normally about 30 grams. It’s barely heavier within the feminine, in whom it turns into enlarged throughout menstruation and being pregnant.

  The lobes (lobuli gl. Thyreoideæ) are conical in form, the apex of every being directed upward and lateralward so far as the junction of the center with the decrease third of the thyroid cartilage; the bottom appears to be like downward, and is on a stage with the fifth or sixth tracheal ring. Every lobe is about 5 cm. lengthy; its biggest width is about 3 cm., and its thickness about 2 cm. The lateral or superficial floor is convex, and coated by the pores and skin, the superficial and deep fasciæ, the Sternocleidomastoideus, the superior stomach of the Omohyoideus, the Sternohyoideus and Sternothyreoideus, and beneath the final muscle by the pretracheal layer of the deep fascia, which kinds a capsule for the gland. The deep or medial floor is moulded over the underlying constructions, viz., the thyroid and cricoid cartilages, the trachea, the Constrictor pharyngis inferior and posterior a part of the Cricothyreoideus, the esophagus (significantly on the left facet of the neck), the superior and inferior thyroid arteries, and the recurrent nerves. The anterior border is skinny, and inclines obliquely from above downward towards the center line of the neck, whereas the posterior border is thick and overlaps the frequent carotid artery, and, as a rule, the parathyroids.

  The isthmus (isthmus gl. thyreoidea) connects collectively the decrease thirds of the lobes; it measures about 1.25 cm. in breadth, and the identical in depth, and normally covers the second and third rings of the trachea. Its state of affairs and measurement current, nonetheless, many variations. Within the center line of the neck it’s coated by the pores and skin and fascia, and near the center line, on both facet, by the Sternothyreoideus. Throughout its higher border runs an anastomotic department uniting the 2 superior thyroid arteries; at its decrease border are the inferior thyroid veins. Typically the isthmus is altogether wanting.

  A 3rd lobe, of conical form, referred to as the pyramidal lobe, incessantly arises from the higher a part of the isthmus, or from the adjoining portion of both lobe, however mostly the left, and ascends so far as the hyoid bone. It’s sometimes fairly indifferent, or could also be divided into two or extra components.

  A fibrous or muscular band is typically discovered connected, above, to the physique of the hyoid bone, and beneath to the isthmus of the gland, or its pyramidal lobe. When muscular, it’s termed the Levator glandulæ thyreoideæ.

  Small indifferent parts of thyroid tissue are generally discovered within the neighborhood of the lateral lobes or above the isthmus; they’re referred to as accent thyroid glands (glandulæ thyreoideæ accessoriæ).

Growth.—The thyroid gland is developed from a median diverticulum, which seems in regards to the fourth week on the summit of the tuberculum impar, however later is discovered within the furrow instantly behind the tuberculum. It grows downward and backward as a tubular duct, which bifurcates and subsequently subdivides right into a sequence of mobile cords, from which the isthmus and lateral lobes of the thyroid gland are developed. The ultimo-branchial our bodies from the fifth pharyngeal pouches are enveloped by the lateral lobes of the thyroid gland; they bear atrophy and don’t type true thyroid tissue. The connection of the diverticulum with the pharynx is termed the thyroglossal duct; its continuity is subsequently interrupted, and it undergoes degeneration, its higher finish being represented by the foramen cecum of the tongue, and its decrease by the pyramidal lobe of the thyroid gland.

Construction.—The thyroid gland is invested by a skinny capsule of connective tissue, which initiatives into its substance and imperfectly divides it into plenty of irregular type and measurement. When the organ is lower into, it’s of a brownish-red shade, and is seen to be made up of a variety of closed vesicles, containing a yellow glairy fluid, and separated from one another by intermediate connective tissue.

  The vesicles of the thyroid of the grownup animal are usually closed spherical sacs; however in some younger animals, e. g., younger canines, the vesicles are roughly tubular and branched. This look is meant to be because of the mode of progress of the gland, and merely signifies that a rise within the variety of vesicles is going down. Every vesicle is lined by a single layer of cubical epithelium. There doesn’t seem like a basement membrane, in order that the epithelial cells are in direct contact with the connective-tissue reticulum which helps the acini. The vesicles are of varied styles and sizes, and include as a traditional product a viscid, homogeneous, semifluid, barely yellowish, colloid materials; purple corpuscles are present in it in numerous levels of disintegration and decolorization, the yellow tinge being in all probability because of the hemoglobin, which is thus let loose from the coloured corpuscles. The colloid materials comprises an iodine compound, iodothyrin, and is quickly stained by eosin. Based on Bensley the thyroid gland prepares and secretes into the vascular channels a substance, fashioned beneath regular circumstances within the outer pole of the cell and excreted from it immediately with out passing by the oblique route by means of the follicular cavity. Along with this direct mode of secretion there’s an oblique mode which consists within the condensation of the secretion into the type of droplets, having excessive content material of solids, and the extension of those droplets into the follicular cavity. These droplets are fashioned in the identical zone of the cell as that through which the first or direct secretion is fashioned.

  This inner secretion of the thyroid is meant to include a particular hormone which acts as a chemical stimulus to different tissues, growing their metabolism.

Vessels and Nerves.—The arteries supplying the thyroid gland are the superior and inferior thyroids and generally an extra department (thyroidea ima) from the innominate artery or the arch of the aorta, which ascends upon the entrance of the trachea. The arteries are exceptional for his or her massive measurement and frequent anastomoses. The veins type a plexus on the floor of the gland and on the entrance of the trachea; from this plexus the superior, center, and inferior thyroid veins come up; the superior and center finish within the inner jugular, the inferior within the innominate vein. The capillary bloodvessels type a dense plexus within the connective tissue across the vesicles, between the epithelium of the vesicles and the endothelium of the lymphatics, which encompass a higher or smaller a part of the circumference of the vesicle. The lymphatic vessels run within the interlobular connective tissue, not uncommonly surrounding the arteries which they accompany, and talk with a net-work within the capsule of the gland; they might include colloid materials. They finish within the thoracic and proper lymphatic trunks. The nerves are derived from the center and inferior cervical ganglia of the sympathetic.

The parathyroid glands are small brownish-red our bodies, located as a rule between the posterior borders of the lateral lobes of the thyroid gland and its capsule. They differ from it in construction, being composed of plenty of cells organized in a roughly columnar vogue with quite a few intervening capillaries. They measure on a median about 6 mm. in size, and from 3 to 4 mm. in breadth, and normally current the looks of flattened oval disks. They’re divided, in response to their state of affairs, into superior and inferior. The superior, normally two in quantity, are the extra fixed in place, and are located, one on both facet, on the stage of the decrease border of the cricoid cartilage, behind the junction of the pharynx and esophagus. The inferior, additionally normally two in quantity, could also be utilized to the decrease fringe of the lateral lobes, or positioned at some little distance beneath the thyroid gland, or present in relation to one of many inferior thyroid veins.

Growth.—The parathyroid our bodies are developed as outgrowths from the third and fourth branchial pouches. A pair of diverticula come up from the fifth branchial pouch and type what are termed the ultimo-branchial our bodies these fuse with the thyroid gland, however in all probability contribute no true thyroid tissue.

Construction.—Microscopically the parathyroids encompass intercommunicating columns of cells supported by connective tissue containing a wealthy provide of blood capillaries. A lot of the cells are clear, however some, bigger in measurement, include oxyphil granules. Vesicles containing colloid have been described as occurring within the parathyroid, however the statement has not been confirmed.

  Little doubt the parathyroid glands produce an inner secretion important to the well-being of the human economic system; however it’s nonetheless a matter of dispute what signs of illness are produced by their elimination and suppression of their secretion. Pepere believes that they present indicators of remarkable exercise throughout being pregnant, and that parathyroid insufficiency is a principal issue within the manufacturing of tetany in infants and adults, of eclampsia, and of sure types of matches. It’s possible that the tetany following parathyroidectomy is because of the accumulation of ammonium carbonate and Kendall has recommended that the operate of the parathyroid is to transform ammonium carbonate into urea.

The Thymus is a short lived organ, attaining its largest measurement on the time of puberty (Hammar), when it ceases to develop, step by step dwindles, and nearly disappears. If examined when its progress is most lively, it is going to be discovered to encompass two lateral lobes positioned in shut contact alongside the center line, located partly within the thorax, partly within the neck, and increasing from the fourth costal cartilage upward, as excessive because the decrease border of the thyroid gland. It’s coated by the sternum, and by the origins of the Sternohyoidei and Sternothyreoidei. Beneath, it rests upon the pericardium, being separated from the aortic arch and nice vessels by a layer of fascia. Within the neck it lies on the entrance and sides of the trachea, behind the Sternohyoidei and Sternothyreoidei. The 2 lobes usually differ in measurement; they’re sometimes united, in order to type a single mass; and generally separated by an intermediate lobe. The thymus is of a pinkish-gray shade, mushy, and lobulated on its surfaces. It’s about 5 cm. in size, 4 cm. in breadth beneath, and about 6 mm. in thickness. At delivery it weighs about 15 grams, at puberty it weighs about 35 grams; after this it step by step decreases to 25 grams at twentyfive years, lower than 15 grams at sixty, and about 6 grams at seventy years.

Growth.—The thymus seems within the type of two flask-shaped entodermal diverticula, which come up, one on both facet, from the third branchial pouch and prolong lateralward and backward into the encircling mesoderm in entrance of the ventral aortæ. Right here they meet and turn out to be joined to at least one one other by connective tissue, however there’s by no means any fusion of the thymus tissue correct. The pharyngeal opening of every diverticulum is quickly obliterated, however the neck of the flask persists for a while as a mobile twine. By additional proliferation of the cells lining the flask, buds of cells are fashioned, which turn out to be surrounded and remoted by the invading mesoderm. Within the latter, quite a few lymphoid cells make their look, and are agregated to type lymphoid follicles. These lymphoid cells are in all probability derivatives of the entodermal cells which lined the unique diverticula and their subdivisions. Extra parts of thymus tissue are generally developed from the fourth branchial pouches. Thymus continues to develop till the time of puberty after which begins to atrophy.

Construction.—Every lateral lobe consists of quite a few lobules held collectively by delicate areolar tissue; the complete gland being enclosed in an investing capsule of an analogous however denser construction. The first lobules fluctuate in measurement from that of a pin’s head to that of a small pea, and are made up of a variety of small nodules or follicles, that are irregular in form and are roughly fused collectively, particularly towards the inside of the gland. Every follicle is from 1 to 2 mm. in diameter and consists of a medullary and a cortical portion, and these differ in lots of important particulars from one another. The cortical portion is principally composed of lymphoid cells, supported by a community of finely branched cells, which is steady with an analogous community within the medullary portion. This community kinds an adventitia to the bloodvessels. Within the medullary portion the reticulum is coarser than within the cortex, the lymphoid cells are comparatively fewer in quantity, and there are discovered peculiar nest-like our bodies, the concentric corpuscles of Hassall. These concentric corpuscles are composed of a central mass, consisting of a number of granular cells, and of a capsule which is fashioned of epithelioid cells. They’re the stays of the epithelial tubes which develop out from the third branchial pouches of the embryo to type the thymus.

  Every follicle is surrounded by a vascular plexus, from which vessels go into the inside, and radiate from the periphery towards the middle, forming a second zone simply throughout the margin of the medullary portion. Within the heart of the medullary portion there are only a few vessels, and they’re of minute measurement.

  Watney has made the essential statement that hemoglobin is discovered within the thymus, both in cysts or in cells located close to to, or forming a part of, the concentric corpuscles. This hemo globin happens as granules or as round plenty precisely resembling coloured blood corpuscles. He has additionally found, within the lymph issuing from the thymus, related cells to these discovered within the gland, and, like them, containing hemoglobin within the type of both granules or plenty. From these info he arrives on the conclusion that the gland is one supply of the coloured blood corpuscles. Extra just lately Schaffer has noticed precise nucleated red-blood corpuscles within the thymus. The operate of the thymus is obscure. It appears to furnish throughout the interval of progress an inner secretion involved with some phases of physique metabolism, particularly that of the sexual glands.

Vessels and Nerves.—The arteries supplying the thymus are derived from the interior mammary, and from the superior and inferior thyroids. The veins finish within the left innominate vein, and within the thyroid veins. The lymphatics are described on web page 698. The nerves are exceedingly minute; they’re derived from the vagi and sympathetic. Branches from the descendens hypoglossi and phrenic attain the investing capsule, however don’t penetrate into the substance of the gland.

The hypophysis (pituitary physique) is a small reddish-gray physique, about 1 cm. in diameter, connected to the tip of the infundibulum of the mind and resting within the hypophyseal fossa.

  The hypophysis consists of an anterior and a posterior lobe, which differ from each other of their mode of improvement and of their construction. The anterior lobe is the bigger and is considerably kidney-shaped, the concavity being directed backward and embracing the posterior lobe. It consists of a pars anterior and a pars intermedia, separated from one another by a slender cleft, the remnant of the pouch or diverticulum. The pars anterior is extraordinarily vascular and consists of epithelial cells of various measurement and form, organized in cord-like trabeculæ or alveoli and separated by massive, thin-walled bloodvessels. The pars intermedia is a skinny lamina intently utilized to the physique and neck of the posterior lobe and increasing onto the neighboring components of the mind; it comprises few bloodvessels and consists of finely granular cells between that are small plenty of colloid materials. The pars intermedia despite the truth that it arises in frequent with the pars anterior from the ectoderm of the primitive buccal cavity is usually thought of as part of the posterior lobe which arises from the ground of the third ventricle of the mind. Though of nervous origin the posterior lobe comprises no nerve cells or fibers. It consists of neuroglia cells and fibers and is invaded by columns which develop into it from the pars intermedia; imbedded in it are massive portions of a colloid substance histologically just like that discovered within the thyroid gland. In sure of the decrease vertebrates, e.g., fishes, nervous constructions are current, and the lobe is of enormous measurement.

  From the pars intermedia a substance, little doubt an inner secretion, causes constriction of the bloodvessels with rise of arterial blood-pressure. This substance appears to have a stimulating impact on a lot of the clean muscle groups, performing immediately upon the muscle inflicting contraction. It additionally will increase the secretion of the urine; of the mammary glands when in practical exercise; and of the cerebrospinal fluid. Extracts of this lobe additionally affect the overall metabolism of the carbohydrates by accelerating the method of glycogenolysis within the liver.

  The pars anterior workouts a stimulating impact on the expansion of the skeleton and doubtless on connective tissues typically.

  Enlargement of the hypophysis and of the cavity of the sella turcica are discovered within the uncommon illness acromegaly, which is characterised by gradual enlargement of the face, arms, and ft, with headache and infrequently a peculiar sort of blindness. This blindness is because of the stress of the enlarging hypophysis on the optic chiasma.

Growth of the Hypophysis Cerebri.—This within the grownup consists of a big anterior, consisting of the pars anterior and the pars intermedia, and a small posterior lobe: the previous is derived from the ectoderm of the stomodeum, the latter from the ground of the fore-brain. Concerning the fourth week there seems a pouchlike diverticulum of the ectodermal lining of the roof of the stomodeum. This diverticulum, pouch of Rathke, is the rudiment of the anterior lobe of the hypophysis; it extends upward in entrance of the cephalic finish of the notochord and the remnant of the buccopharyngeal membrane, and comes into contact with the beneath floor of the fore-brain. It’s then constricted off to type a closed vesicle, however stays for a time related to the ectoderm of the stomodeum by a stable twine of cells. Plenty of epithelial cells type on both facet and within the entrance wall of the vesicle, and by the expansion between these of a stroma from the mesoderm the event of the anterior lobe is accomplished. The upwardly directed hypophyseal involution turns into utilized to the antero-lateral side of a downwardly directed diverticulum from the bottom of the fore-brain. This diverticulum constitutes the longer term infundibulum within the flooring of the third ventricle whereas its inferior extremity turns into modified to type the posterior lobe of the hypophysis. In a number of the decrease animals the posterior lobe comprises nerve cells and nerve fibers, however in man and the upper vertebrates these are changed by connective tissue. A canal, craniopharyngeal canal, is typically discovered extending from the anterior a part of the fossa hypophyseos of the sphenoid bone to the beneath floor of the cranium, and marks the unique place of Rathke’s pouch; whereas on the junction of the septum of the nostril with the palate traces of the stomodeal finish are sometimes current (Frazer).

The pineal physique (epiphysis) is a small reddish-gray physique, about 8 mm. in size which lies within the melancholy between the superior colliculi. It’s connected to the roof of the third ventricle close to its junction with the mid-brain. It develops as an outgrowth from the third ventricle of the mind.

  In formative years it has a glandular construction which reaches its biggest improvement at in regards to the seventh yr. Later, particularly after puberty, the glandular tissue step by step disappears and is changed by connective tissue.

Construction.—The pineal physique is destitute of nervous substance, and consists of follicles lined by epithelium and enveloped by connective tissue. These follicles include a variable amount of gritty materials, composed of phosphate and carbonate of calcium, phosphate of magnesium and ammonia, and just a little animal matter.

  It comprises a substance which if injected intravenously causes fall of blood-pressure. It appears possible that the gland furnishes an inner secretion in kids that inhibits the event of the reproductive glands for the reason that invasion of the gland in kids, by pathological growths which virtually destroy the glandular tissue, ends in accelerated improvement of the sexual organs, elevated progress of the skeleton and precocious mentality.

Chromaphil or chromaffin cells, so-called as a result of they stain yellow or brownish with chromium salts, are related to the ganglia of the sympathetic nervous system.

Growth.—They come up in frequent with the sympathetic cells from the neural crest, and are due to this fact ectodermal in origin. The chromaphil and sympathetic cells are indistinguishable from each other on the time of their migration from the spinal ganglia to the areas occupied within the grownup. Differentiation of chromaphil cells begins in embryos about 18 mm. in size however shouldn’t be full till about delivery. The chromaphiloblasts enhance in measurement greater than the sympathoblasts and stain much less intensely with peculiar dyes. Later the chrome response develops. The aortic our bodies differentiate first and are outstanding in 20 mm. embryos. The paraganglia of the sympathetic plexuses differentiate subsequent and final of all of the paraganglia of the sympathetic trunk. The carotid physique is totally differentiated in 30 mm. embryos. After delivery the chromaphil organs degenerate however the paraganglia may be acknowledged with the microscope in websites initially occupied by them.

  The paraganglia are small teams of chromaphil cells related with the ganglia of the sympathetic trunk and the ganglia of the celiac, renal, suprarenal, aortic and hypogastric plexuses. They’re generally present in reference to the ganglia of different sympathetic plexuses. None have been discovered with the sympathetic ganglia related to the branches of the trigeminal nerve.

  The aortic glands or our bodies are the biggest of those teams of chromaphil cells and measure within the new child about 1 cm. in size. They lie one on both facet of the aorta within the area of the inferior mesenteric artery. They lower in measurement with age and after puberty are solely seen with the microscope. About forty they disappear solely. Different teams of chromaphil cells have been discovered related to the sympathetic plexuses of the stomach independently of the ganglia.

  The medullary parts of the suprarenal glands and the glomus caroticum belong to the chromaphil system.

the Suprarenal Glands (Glandulæ Suprarenalis; Adrenal Capsule) are two small flattened our bodies of a yellowish shade, located on the again a part of the stomach, behind the peritoneum, and instantly above and in entrance of the higher finish of every kidney; therefore their title. The suitable one is considerably triangular in form, bearing a resemblance to a cocked hat; the left is extra semilunar, normally bigger, and positioned at the next stage than the correct. They fluctuate in measurement in numerous people, being generally so small as to be scarcely detected: their regular measurement is from 3 to five cm. in size, reasonably much less in width, and from 4 to six mm. in thickness. Their common weight is from 1.5 to 2.5 gm. every.

Growth.—Every suprarenal gland consists of a cortical portion derived from the celomic epithelium and a medullary portion initially composed of sympatho-chromaffin tissue. The cortical portion is first recognizable in regards to the starting of the fourth week as a sequence of buds from the celomic cells on the root of the mesentery. Later it turns into utterly separated from the celomic epithelium and kinds a suprarenal ridge projecting into the celom between the mesonephros and the basis of the mesentery. Into this cortical portion cells from the neighboring plenty of sympatho-chromaffin tissue migrate alongside the road of its central vein to achieve and type the medullary portion of the gland.

Relations.—The relations of the suprarenal glands differ on the 2 sides of the physique.

  The proper suprarenal is located behind the inferior vena cava and proper lobe of the liver, and in entrance of the diaphragm and higher finish of the correct kidney. It’s roughly triangular in form; its base, directed downward, is involved with the medial and anterior facets of the higher finish of the correct kidney. It presents two surfaces for examination, an anterior and a posterior. The anterior floor appears to be like ahead and lateralward, and has two areas: a medial, slender, and non-peritoneal, which lies behind the inferior vena cava; and a lateral, considerably triangular, involved with the liver. The higher a part of the latter floor is devoid of peritoneum, and is in relation with the naked space of the liver close to its decrease and medial angle, whereas its inferior portion is roofed by peritoneum, mirrored onto it from the inferior layer of the coronary ligament; sometimes the duodenum overlaps the inferior portion. Slightly beneath the apex, and close to the anterior border of the gland, is a brief furrow termed the hilum, from which the suprarenal vein emerges to affix the inferior vena cava. The posterior floor is split into higher and decrease components by a curved ridge: the higher, barely convex, rests upon the diaphragm; the decrease, concave, is involved with the higher finish and the adjoining a part of the anterior floor of the kidney.

  The left suprarenal, barely bigger than the correct, is crescentic in form, its concavity being tailored to the medial border of the higher a part of the left kidney. It presents a medial border, which is convex, and a lateral, which is concave; its higher finish is slender, and its decrease rounded. Its anterior floor has two areas: an higher one, coated by the peritoneum of the omental bursa, which separates it from the cardiac finish of the abdomen, and generally from the superior extremity of the spleen; and a decrease one, which is involved with the pancreas and lienal artery, and is due to this fact not coated by the peritoneum. On the anterior floor, close to its decrease finish, is a furrow or hilum, directed downward and ahead, from which the suprarenal vein emerges. Its posterior floor presents a vertical ridge, which divides it into two areas; the lateral space rests on the kidney, the medial and smaller on the left crus of the diaphragm.

  The floor of the suprarenal gland is surrounded by areolar tissue containing a lot fats, and intently invested by a skinny fibrous capsule, which is troublesome to take away on account of the quite a few fibrous processes and vessels coming into the organ by means of the furrows on its anterior floor and base.

  Small accent suprarenals (glandulæ suprarenales accessoriæ) are sometimes to be discovered within the connective tissue across the suprarenals. The smaller of those, on part, present a uniform floor, however in a number of the bigger a definite medulla may be made out.

Construction.—On part, the suprarenal gland is seen to encompass two parts: an exterior or cortical and an inner or medullary. The previous constitutes the chief a part of the organ, and is of a deep yellow shade; the medullary substance is mushy, pulpy, and of a darkish purple or brown shade.

  The cortical portion (substantia corticalis) consists of a superb connective-tissue net-work, through which is imbedded the glandular epithelium. The epithelial cells are polyhedral in form and possess rounded nuclei; lots of the cells include coarse granules, others lipoid globules. Owing to variations within the association of the cells, three distinct zones may be made out: (1) the zona glomerulosa, located beneath the capsule, consists of cells organized in rounded teams, with right here and there indications of an alveolar construction; the cells of this zone are very granular, and stain deeply. (2) The zona fasciculata, steady with the zona glomerulosa, consists of columns of cells organized in a radial method; these cells include finer granules and in lots of cases globules of lipoid materials. (3) The zona reticularis, involved with the medulla, consists of cylindrical plenty of cells irregularly organized; these cells usually include pigment granules which give this zone a darker look than the remainder of the cortex.

  The medullary portion (substantia medullaris) is extraordinarily vascular, and consists of enormous chromaphil cells organized in a community. The irregular polyhedral cells have a finely granular cystoplasm which are in all probability involved with the secretion of adrenalin. Within the meshes of the mobile community are massive anastomosing venous sinuses (sinusoids) that are in shut relationship with the chromaphil or medullary cells. In lots of locations the endothelial lining of the blood sinuses is in direct contact with the medullary cells. Some authors take into account the endothelium absent in locations and right here the medullary cells are immediately bathed by the blood. This intimate relationship between the chromaphil cells and the blood stream undoubtedly facilitates the discharge of the interior secretion into the blood. There’s a free meshwork of supporting connective tissue containing non-striped muscle fibers. This portion of the gland is richly equipped with non-medullated nerve fibers, and right here and there sympathetic ganglia are discovered.

Vessels and Nerves.—The arteries supplying the suprarenal glands are quite a few and of comparatively massive measurement; they’re derived from the aorta, the inferior phrenic, and the renal. They subdivide into minute branches earlier to coming into the cortical a part of the gland, the place they break up into capillaries which finish within the venous plexus of the medullary portion.

  The suprarenal vein returns the blood from the medullary venous plexus and receives a number of branches from the cortical substance; it emerges from the hilum of the gland and on the correct facet opens into the inferior vena cava, on the left into the renal vein.

  The lymphatics finish within the lumbar glands.

  The nerves are exceedingly quite a few, and are derived from the celiac and renal plexuses, and, in response to Bergmann, from the phrenic and vagus nerves. They enter the decrease and medial a part of the capsule, traverse the cortex, and finish across the cells of the medulla. They’ve quite a few small ganglia developed upon them within the medullary portion of the gland.

  In reference to the event of the medulla from the sympathochromaffin tissue, it’s to be famous that this portion of the gland secretes a substance, adrenalin, which has a robust affect on these muscular tissues that are equipped by sympathetic fibers.

Glomus Caroticum (Carotid Glands; Carotid Our bodies)—The carotid our bodies, two in quantity, are located one on both facet of the neck, behind the frequent carotid artery at its level of bifurcation into the exterior and inner carotid trunks. They’re reddish brown in shade and oval in form, the lengthy diameter measuring about 5 mm.

  Every is invested by a fibrous capsule and consists largely of spherical or irregular plenty of cells, the plenty being roughly remoted from each other by septa which prolong inward from the deep floor of the capsule. The cells are polyhedral in form, and every comprises a big nucleus imbedded in finely granular protoplasm, which is stained yellow by chromic salts. Quite a few nerve fibers, derived from the sympathetic plexus on the carotid artery, are distributed all through the organ, and a net-work of enormous sinusoidal capillaries ramifies among the many cells.

Glomus Coccygeum (Coccygeal Gland or Physique; Luschka’s Gland)—The glomus coccygeum is positioned in entrance of, or instantly beneath, the tip of the coccyx. It’s about 2.5 mm. in diameter and is irregularly oval in form; a number of smaller nodules are discovered round or close to the primary mass.

  It consists of irregular plenty of spherical or polyhedral cells, the cells of every mass being grouped round a dilated sinusoidal capillary vessel. Every cell comprises a big spherical or oval nucleus, the protoplasm surrounding which is obvious, and isn’t stained by chromic salts.