When the socially joined epidermic cells at the surface of the tissue-body thrust forth in common a protective covering, we get the cuticles, which are often thick and solid armor-plates.
Ontogeny teaches unmistakably that its elementary organs, the epidermic cells, develop entirely from the ectoderm.
A single layer of epidermic cells, some of which are glandular, forms the outer layer.
The setae are invariably formed each within an epidermic cell, and they are sheathed in involutions of the epidermis.
With few exceptions, the terminal extremities of the digits of both limbs of mammals are more or less protected or armed by epidermic plates or sheaths, constituting the various forms of nails, claws or hoofs.
A, Early condition before the lens is deposited, showing the folding of the epidermic cell-layer into three.
It is found that in embryological growth the retinal layer of the central eyes forms as a separate pouch, which is pushed in laterally beneath the corneagen layer from the epidermic cell layer.
As has already been mentioned, the central epithelium of the nervous system probably corresponds with the so-called epidermic layer of the epiblast.
They are however developed like true teeth, as a deposit between a papilla of subepidermic tissue and an epidermic cap.
Calberla and Scott hold that the epidermic layer of the skin is involuted into this keel in Petromyzon, and Calberla maintains the same view for Teleostei (fig.
Both of these strata eventually become the epiblast, of which they form the epidermic and nervous layers.
The hair itself arises from a cornification of the cells of the axis of one of the above processes; and is invested by a sheath similarly formed from the more superficial epidermic cells.
The upper of these, formed of a single row of cells, is known as the epidermic stratum, and the lower, formed of several rows, as the nervous stratum.
A small papilla of the dermis grows into the inner end of the epidermic process when the hair is first formed.
According to Goette this is the whole explanation, but Calberla states for Syngnathus and Salmo that the epidermic layer of the epiblast is carried down into the keel as a double layer just as if it had been really folded in.
Both layers of epiblast would thus have a share in the formation of the central nervous system; the epidermic layer giving rise to the lining epithelial cells of the central canal, and the nervous layer to the true nervous tissue.
Then, by a further process of growth, an irregular mass of epidermic cells becomes developed, which pushes the glandular cells to one side, and constitutes the rudiment of the eye.
We have still to describe, in connection with the horse, some epidermic tissues, which are known as chestnuts.
In the latter something like an otosome has been found which is certainly lacking in the Eudrilidae, whatever may be the function of the cellular epidermic bodies here briefly referred to.
What is life, what is organic substance in the monstrous universe but an indifferent mass, a passing accident, the corruption of a few epidermic particles?
Such a stimulation must affect the living epidermic cells of the feather papilla.
The plumage is an epidermic structure, and therefore distinct from the connective tissue, but it is difficult to understand why a pigment factor though present in every cell has no effect on epidermic cells.
It is often stated that the feathers of birds are a modification of the epidermic scales of reptiles, but investigation does not fully confirm this statement.
In August and September the epidermic papillae begin to be obvious, and from this time till February a continuous increase in the papillae and their pigmentation occur.
The epidermic horny tube splits posteriorly towards the apex of the feather, and is divided into rachis and barbs, and thus the dermal tissue within, by this time dead and dry, is exposed and is shed.
The two horns in the section are two of the eighteen projections, formed entirely of the dark epidermic layer, which fill up the eighteen flattened cavities produced by the folding of the walls.
The division of the epiblast into a nervous and epidermic stratum.
The epidermic stratum passes over this plate without undergoing any change of character, and the plate is entirely constituted of the nervous stratum of the epidermis.
The cells of both strata are somewhat flattened, but those of the epidermic stratum are decidedly the more flattened of the two.
The vesicular portion is lined by columnar cells, with very large oval nuclei, while the duct is lined by cells similar to the epidermic cells, with which they are continuous at the opening.
The patches very soon become partially invaginated; and a small cavity is developed between them and the epidermic layer of the epiblast (Plate 37, figs.
Each pit is covered over by the epidermic layer above, which has no share in its formation.
It appears that outside this bony system of scutes were horny epidermic scales, corresponding exactly with the tesserae which they cover.
The hairs and the nails, which are epidermic outgrowths, continue to grow throughout life, their growth being due to the proliferation of their constituent cells.
According to him, it is theoretically obvious that a time must come when the replacement of the epidermic cells completely ceases.
Hence handkerchiefs or linen containing the saliva or mucus of a patient, the epidermic scales shed abundantly in the desquamative period, and probably also the urinary and fecal evacuations, contain the poison, so as to be highly infectious.
This extensive epidermic sense-organ probably serves for the perception of changes in the pressure, or in other properties, of the water.
Anatomically the essential feature is epidermic hypertrophy, with usually a varying degree of papillary hypertrophy also.
Horns consist of closely agglutinated epidermic cells, forming small columns or rods; in the columns themselves the cells are arranged concentrically.
After several days or a week, during which time there is usually continued mild or severe febrile action, the process begins to subside, and is followed by epidermic desquamation.
As found in epidermic scrapings of ringworm, showing mycelium and spores.
Erythrasma is an extremely rare disease, due to the presence and growth in the epidermic structures of the vegetable parasite--the microsporon minutissimum.
Circumscribed epidermicelevations containing pus; as, for example, the pustules of acne, of impetigo, and of sycosis.
Keratosis pilaris may be defined as a hypertrophic affection characterized by the formation of pin-head-sized, conical, epidermic elevations seated about the apertures of the hair follicles.
In the epidermic scrapings it is never to be found in abundance, and the mycelium predominates, while in affected hairs the spores and chains of spores are almost exclusively seen, and are usually present in great profusion.
Callosities are most common about the hands and feet, and consist of small or large patches of dry, grayish-yellow looking, hard, slight or excessive epidermic accumulations.
A wart consists of both epidermic and papillary hypertrophy, the interior of the growth containing a vascular loop.
Such epidermicanomalies as ichthyosis, scleroderma, and molluscum simplex, sometimes appearing shortly after birth, but generally seen later in life, will be spoken of in the chapter on Anomalous Skin Diseases.
The superficial epidermic layer e is elevated by a fluid exuded between it and the rete mucosum.
The raising of the epidermic layers is due chiefly to their delicacy, their slight resistance, and their previous immersion in the amniotic fluid--i.
Groups of sensitive nerve cells separate from the ordinary epidermic cells; they retire into the more protected tissue of the mesodermic under-skin, and form special neural ganglia there.
The hair is an epidermic formation, consisting of epidermic cells more or less flattened and altered in shape by mutual pressure.
Feathers areepidermic formations, or consist of aggregations of epidermic cells, yet so altered by compression and fusion together that the cell-structure is in most parts difficult to detect.
They arise from little projecting ridges, formed of rectangular epidermic cells.
Longitudinal sections show that the forms of the epidermic cells may be taken as a fair representation of those constituting the pulvinus.
The epidermic cells in the lower part of the petiole project conically, and thus differ in shape from those over the pulvinus.
