PFLUGER. Pfliiger's Archiv. Bd. II. 1869. u. IV. 1871.
HENLE. Eingeweidelehre. 1873.
LEGROS. Jour, de 1'anat. et de la phys. 1874.
COHNHEIM u. LITTEN. Virchow's Archiv. Bd. LXVI. 1876.
EWALD u. KUEHNE. Verhand. Naturhist. med. Vereins zu Heidelberg. 1 Bd. 5
KOLATSCHEWSKY. Schultze's Archiv. Bd. XIII. 1876.
TURNER. Journ. of Anat. and Phys. Vol. XI. 1877.
WENDT. Med. Centralblatt No. 15. 1878.
DAVIS. Amer. Jour. Med. So. Vol. LXXVIII. 1879.
FRITSCH. Archiv. fur Anat. und Phys. Phys. Abtheil. 1879.
KLEIN and SMITH. Atlas of Histology. Part X. 18791881.
Br ABRAHAM MAYER, M.D.,
Curator of the Manhattan Eye and Ear Hospital, New York City.
General plan of structure. The glandular substance of the
kidney is divided into two parts, an external or convex por-
tion, called the cortical substance, or cortex, and an internal
or concave portion, the 'medullary substance, or medulla.
This division can be readily seen by cutting a kidney into two
equal parts in the line of its long diameter. An intermediate
zone, which separates the cortical from the medullary sub-
stance, is called the boundary layer of the kidney. The whole
organ is enveloped in a fibrous membrane, the capsule.
The medullary substance contains the pyramids of the kid-
ney, and is therefore also called the pyramidal portion. The
apex of each pyramid, the papilla, projects into a special arm
of the renal pelvis, viz., a calyx; the base or expanded por-
tion is directed toward the cortical substance, and sends pro-
longations into the latter.
An examination of the cortical substance shows it to be
composed of two distinct varieties of tissue, running parallel
to one another toward tlie free surface. One has a fibrous ap-
pearance, and is composed of cylindrical cords. It is a con-
tinuation of the pyramids. These pyramidal prolongations *
(Henle) are also called medullary rays (Fig. 89). The other
portion, situated between the prolongations, is a granular-look-
ing material, called the cortical substance proper, or labyrinth
of Ludwig* The latter contains numerous small bodies,
which are of a distinctly red color when there is a large
1 Ludwig und Zawarykin : Zeitschrft. f iir rat. Med., 1863. They are also called
the prolongations of Ferrein.
2 Ludwig : Strieker's Manual, p. 461.
MANUAL OF HISTOLOGY.
amount of blood in the kidney ; they are the MalpigJiian
bodies, or glomeruli (Fig. 89, E).
The boundary layer ' is characterized by numerous blood-
vessels, some of which, unite to form an arcade (Fig. 89, C),
which is parallel to the convex surface of the kidney, and from
which branches are given off to the cortical substance proper.
The renal artery, before it enters the
hilum of the kidney, divides into
branches, which pierce the medulla
between the pyramids and ascend
toward the cortical substance until
they reach the boundary layer. Here
they divide obliquely or at right
angles to give off smaller branches,
which have the direction and arched
ppearance above referred to (Fig.
89, C). These arched vessels then
send off the branches already men-
tioned, which traversing the centres
of the cortical substance proper, at
right angles to the parent stem (Fig.
89, D), extend almost to the capsule
of the kidney. On their way they in
turn give off smaller twigs, each of
which bears a glomerulus upon its
extremity (Fig. 89, E). In this way
there is an alternate arrangement of
pyramidal prolongation and cortical
substance proper (Fig. 90). Though
he pyramidal prolongations almost
reach the capsule of the kidney,
they never quite touch it, being sep-
arated by the interposition of some cortical substance proper
Specimens for study should be made from a fresh kidney,
in which the renal artery has been injected with carmine-gela-
tine, the whole organ having been subsequently immersed in
alcohol of 50 per cent, strength. When in that fluid it is to be
divided into four or more parts, allowed to remain therein for
FIG. 89. Human kidney. Vertical
section through cortical and medullary
substances : A, branch of renal artery ;
B, vein, immediately beneath former, but
hardly visible in the figure; C, arched
arterial branches in the boundary layer ;
D, artery of the cortical substance proper ;
E, Malpighian bodies or glomeruli : F,
medullary rays or pyramidal prolonga-
tions ; G, vessels of the medulla, the vasa
recta, x 10.
1 Henle: Grenzschicht, Eingeweidelehre.
twenty-four hours, afterward transferred to stronger alcohol,
then to absolute alcohol, and finally mounted in dammar or
balsam. Vertical sections show the arrangement represented
in Figs. 89 and 90 ; transverse sections, the appearance of
The substance of the kidney is composed of secreting and
collecting tubules, vessels, and a stroma, which fills the inter-
Fro. 90. Human kidney. Vertical section through cortical portion : A, pyramidal prolongation ; B,
cortical substance proper ; C, artery ; D, glomerulus. x 64.
spaces between the tubules, and is more abundant in the med-
ullary than in the cortical substance. In human adults this
connective material is found in small quantity and is a sort of
colloid substance. In the lower animals it is more abundant,
and assumes the character of real connective tissue. In young
infants there is said to be a greater proportionate amount of
this tissue than in subsequent life.
The renal tubules. The tubules are found both in the corti-
MANUAL OF HISTOLOGY.
cal and medullary substances ; they are of different diameters
and pursue either a straight or tortuous course. Some have a
basement membrane (membrana or tunica propria), on which
the epithelium rests ; others appear to have none. The tu-
bules are clothed with epithelium of different varieties. Speci-
mens' should be made from a kidney that has lain for twenty-
four hours in a 5 per cent, solution of chromic acid. A small
FIG. 91. Schematic representation of the kidney : A, medulla ; B, boundary layer ; C, cortical por-
tion ; a, renal artery ; b, renal vein ; c, artery penetrating cortex ; D, capsule enclosing glomerulus ; E,
capillaries ; F, convoluted tubules of first order ; G, looped tubule, descending branch ; H, looped tubule,
ascending branch ; I, convoluted tubule of second order ; J, collecting tubule ; K, vasa recta.
piece of the gland is to be placed on a slide, and a drop of glycer-
ine added ; the tubules may be isolated by teasing with needles.
In Fig. 91 there is a schematic representation of the vascular
distribution and course of the tubules in one of the pyramids.
Each tubule takes its origin in an expansion that surrounds
the glomerulus, and is called Bowman ' s or Mullens capsule. 1
1 Miiller, in 1830, described the capsules, but regarded them as vesicles which had
no connection whateyer with the uriniferous tubules. Bowman, in Philosoph. Trans;
THE KIDNEY. 205
It is round or elliptical in shape, and has a diameter of about
0.2 mm. Where the capsule empties its contents into the
tubule, there is a slight constriction known as the neck ; it is
very distinct in some of the lower animals. The canal then en-
larges and begins to pursue a tortuous course in the cortical
substance ; it is now called a convoluted tube 1 (Fig. 91, F). It
next undergoes sudden diminution in size and passes straight
through the medulla until, at a variable point, it bends upon
itself, forming a loop ; then, ascending, it increases in calibre, and
in the cortical substance becomes convoluted for the second time.
Those canals that are nearest the glomeruli are called convo-
luted tubules of the first order, the others convoluted tubules
of the second order. Between these two are the looped tubules
of ffenle, just described, each being divided into a descending
and ascending branch (Fig. 91, G and H). The convoluted
tubules of the second order terminate by emptying into tubules
of greater diameter, called collecting tubules,* which descend
through the cortical and medullary substances, and, receiving
other collecting tubules on the way, finally empty into the
pelvis of the kidney (Fig. 91, J). *
At the base of each pyramid there are a vast number of col-
lecting tubules, but as they successively empty into larger
collecting tubes, the area they occupy is thereby diminished ;
at the apex of the papillae, where they ultimately discharge
the urine into the pelvis of the kidneys, there are only about
twenty in number. This gradual coalescence of the tubes gives
to the pyramids a conical shape, but the breadth of the base is
also partly due to the presence of the looped tubules which
pass down into the pyramids for a varying depth.
The larger collecting tubules may be readily injected with
Beale's blue fluid 3 or carmine-gelatine, either directly or from
the ureters ; it will be found, however, that the injection will
seldom extend beyond the looped tubules, owing to the small
diameter of the descending branches.
1 Tubulus contortus. 2 Straight tubules of Bellini.
3 Glycerine, pure, 2 oz. ; tr. perchloride iron, 10 drops ; ferrocyan. potassium, 3
grains ; strong hydrochl. acid, 3 drops ; water, 1 oz. Mix the tincture of iron with
one ounce of the glycerine ; and the f errocyanide of potassium, first dissolved in a little
water, with the other ounce ; mix gradually, and shake during admixture ; add the
iron to the ferrocyanide ; lastly, add the water and hydrochloric acid. Beale :
Microscope, p. 87.
206 MANUAL OF HISTOLOGY.
Bowman's capsule is composed of a structureless basement-
membrane surrounding each glomerulus. Upon the inner sur-
face of these capsules is a continuous layer of flat, epithelioid
cells, 1 which are continued over the glomerulus itself. 2 Occa-
sionally an epithelioid cell may be seen between the vessels of
the coil composing the glomerulus.
Each capsule is pierced by two vessels, called, respectively,
afferent and efferent. The former enters the capsule and forms
FIG. 92. Human kidney. Transverse section of cortical portion, showing the alternating arrangement
of pyramidal ray and cortical substance proper : A, A, pyramidal rays : B, convoluted tubule : C, elom-
erulus ; D, D, arterial vessels, x 55.
the glomerulus, while the latter makes its exit close to the en-
trance of the former. The layer of epithelium above described
passes over from the inner surface of the capsule on to the
glomerulus about the points of entrance and exit just men-
tioned. On the opposite side, the capsule becomes continuous
with a convoluted tubule. To obtain specimens, the renal artery
of a fresh kidney should be injected with blue gelatine and then
placed in alcohol. Vertical and transverse sections of the cor-
tical substance may then be made. They should be stained in
carmine and examined in glycerine, or the artery may be in-
jected with absolute alcohol and the sections stained as above.
The epithelium of the tubules. The basement-membranes
of the convoluted tubules of the first order are in direct con-
tinuation with the basement-membranes of the capsules. Their
diameter averages 0.04 mm. The epithelium of these canals is
1 Schweigger-Seidel : Die Nieren. Halle, 1865. Henle : Eingeweidelehre, p. 329.
Heidenhain : Zur anat. d. Nieren, in Schultze's Archiv, Bd. X., Hft. I. Mayer : His-
tology of the Kidney, Dis. Inaug., 1876. Also Bowman, Johnson, Frerichs, etc.
2 Gerlach, Heidenhain.
peculiar, and was first correctly described by Heidenhain.
According to this writer, the greater part of the cell-protoplasm
assumes the form of small, cylindrical bodies, the so-called
rods of HeidenJiaiU) giving the epithelium a stri-
ated appearance (Fig. 93).
To exhibit these appearances, the cortical sub-
stance of a dog's or rabbit's kidney should be
cut into small pieces and immersed for twenty-
four hours or more in a 5 per cent, solution of
the neutral chromate of ammonia. After this
time has elapsed, a small piece of the gland is to
be placed on a slide and a drop of glycerine
added ; the specimen may then be teased and ex-
amined. Portions of the convoluted tubules will
be found floating about in the glycerine, and
should be closely scrutinized. By this mode of
preparation, individual epithelioid corpuscles can-
not be recognized ; on the contrary, they seem
to merge with one another. The tubule may be
regarded as made up of rods transversely dis-
posed, with nuclei embedded in a pulpy mass
that appears to fill its lumen, the whole envel-
oped by the membrana propria. The rods sur-
round the nuclei, and are not all of the same length. They
appear to be hollow, as shown by their sometimes containing
fatty granules. Here and there in the specimen a separate
corpuscle will present itself to the eye; in
such instances the rods can readily be made
out (Fig. 94, A). In the kidney of the rat
these bodies may be isolated with little diffi-
culty (Fig. 94, B). At one end the rods rest
against the membrana propria, to which they
are attached by a colloid material ; their other
extremity is lost in the protoplasm of the cap-
sale, which latter lies internal to them and
appears to have the character of a pulpy mass
containing nuclei. In the dog, the nucleus of
each cell is about midway between the lumen
and the membrana propria. It is surrounded by rods (Fig.
94, A). In the rat this is not the case (Fig. 94, B). Assuming
that the rods begin at the membrana propria, they are directed
xlio B ' kidn ' y f rat *
208 MANUAL OF HISTOLOGY.
toward the centre of the lumen of the tubule, and the distance
between any two adjoining rods at the periphery is necessarily
greater than at the centre. For the same reason, also, the rods
are more distinctly defined in the former situation ; the micro-
meter screw will have to be used in tracing them inward.
Transverse sections of the cortical substance may be made
by freezing small pieces which have been immersed in a solu-
tion of the neutral chromate of ammonia. Such sections should
be examined in glycerine, or, better, in a saturated solution of
the chloride of potassium in glycerine. 1 The radial direction
of the rods is beautifully seen in such specimens (Fig. 95, C),
FIG. 95. Kidney of dog. Transverse section through the medullary portion, about midway between
the apex and boundary layer. Neutral chromate of ammonia preparation : A, blood-vessel ; B, looped
tubule, descending portion ; C, looped tubule, ascending portion ; D, collecting tubule ; E, connective
tissue, x 300.
and the individual cells are more clearly defined. Another
method of exhibiting these rod epithelia is to inject the artery
or vein of a fresh, bloodless kidney with a cold saturated solu-
tion of the chloride of potassium, then, after placing the whole
organ in alcohol, divide it in small pieces under that fluid.
After a day or two sections may be made ; they then should be
immersed for a short time in absolute alcohol and clarified by
oil of turpentine. Such specimens show the epithelium to
perfection and may be preserved for a considerable time. Per-
manent specimens can be made by substituting resinous turpen-
1 The glycerine should be heated in a porcelain evaporating-dish, the chloride of
potassium added, and the whole mixture stirred for several minutes with a glass rod.
The glycerine is ready for use after cooling.
THE KIDNEY. 209
tine l for the common oil. The renal artery or vein may also
be injected with absolute alcohol, and sections prepared as
above. But the epithelium suffers in this way, for the alcohol
causes the rods to shrink, and the colloid substance between
the rods coagulates. Still, the striated appearance is seen near
the membrana propria. Another fact which seems to have es-
caped Heidenhain is that alcohol so injected causes the nuclei
of the cells to recede toward the membrana propria by its
action on the rods.
The action of water on the rods is peculiar. A fresh kidney
must be used and a portion of the cortical substance placed on
a slide, together with a drop of water ; it is then to be teased
with needles and immediately examined. At- first the rods are
not distinctly brought into view, but they soon appear with
their contours sharply delineated. This appearance, however,
does not last very long, for the epithelium soon imbibes water,
swells, and then forms an indistinct mass.
In the neck of the convoluted tubules of the frog, coluber,
etc., the epithelium is ciliated. In the frog the cilia have great
length, but the convoluted tubules do not have the rod epithe-
lium. In the dog, cat, rabbit, etc., the rod epithelium begins
at the neck of the tubule and is continued as far as the loops.
The convoluted tubules of the first order, after ramifying
in the cortical substance, become continuous with the looped
tubules of Henle, as already described. 2 The change takes
place in the vicinity of the boundary layer.
The looped tubules. The looped tubules traverse the
medulla for a greater or lesser distance. A few almost reach
the apices of the pyramids ; others extend but a short distance
below the boundary layer, while a third class occupies an inter-
mediate position. Good specimens are obtained by macerating
vertical sections of the medulla in a solution of caustic potassa
(i to 1 per cent.). The potassa destroys the epithelium, the
stroma, and the blood-corpuscles, but leaves the basement-
1 Resinous turpentine is prepared as follows : some common oil of turpentine is
poured upon a deep plate, so as to form a thin layer, and a piece of fine muslin is
snugly fastened over it to keep out the dust. The liquid is now exposed to the ac-
tion of the air. In a few days, if the weather be warm, or a week or more, if the
weather be cold, the turpentine will have become thick, yellow, and resinous, and is
now no longer transparent. Resinous turpentine, prepared in this way, forms one of
the best preserving agents. Its use will be spoken of further on.
- Henle: Eingeweidel., 2te Aufl., p. 316.
210 MANUAL OF HISTOLOGY.
membrane perfectly intact. A fresli kidney is necessary, and
one slightly infiltrated with fat makes the best specimens.
Another method is to embed the kidney of a dog or rabbit
in powdered chlorate of potassa, adding enough dilute nitric
or hydrochloric acid to cover the crystals. After some hours
the connective tissue in the gland will have been destroyed.
Portions of the medulla should then be placed upon a slide
with a drop of glycerine and teased slightly. A great many
of the loops are broken in this way, to be sure, but still some
will be seen, By this method the epithelium of the narrow
branch is not destroyed.
TJie epithelium of the looped tubules. The descending
branch of the loop is small in diameter (0.02 mm.) and pos-
sesses a peculiar distinctive epithelium. The corpuscles are
flat, have prominent nuclei, and rest against the membrana
propria. The disproportionate size of the nuclei causes the
corpuscle to project into the lumen. But these prominences
do not obstruct the passage,
for each one corresponds to
the space between two on
FIG. 96. Kidney of dog. Descending portion of the Opposite side of tll6 tU-
Henle's looped tubule. , -, i - -,
bule, so that there is no bar
to the urine, but the passage is made more or less spiral (Fig.
96). The corpuscles are of a light color. Specimens should
be made from a gland that has been macerated in a 5 per cent,
solution of the neutral chromate of ammonia; they should
be examined in glycerine. The length of the narrow portion
of the loop is variable in man, the pig, and horse.
The second portion of the looped tubule is wider and its
epithelium peculiar. In man both the loop and ascending
branch are wide, usually ; especially is this the case with loops
high up in the medulla ; in the rabbit it is the ascending
branch only that has this property. Generally speaking, the
length of the broader branch of the loop exceeds that of the
narrow portion. The diameter of the broad portion averages
0.04 mm. The epithelium has the same character as that in
the convoluted tubules ; it is striated and possesses rods. 1 It
is not precisely similar, however. The width of the individual
cells is not so great as in the former, and hence the lumen in
1 Heidenhain : loc. cit. Henle : loc. cit. , p. 317.
THE KIDNEY. 211
this portion of the loop is greater than in the convoluted tu-
bules. Specimens prepared with the neutral chromate of am-
monia, as before detailed, give good results. Vertical sections
may be made from a kidney macerated in the ammonia solu-
tion and afterward treated with alcohol ; or, better, from frozen
The broader extremity of the looped tubule ascends through
the medulla into the cortical substance and becomes continu-
ous with a convoluted tubule of the second order (Fig. 91, i).
These tubules, the intercalated portions, 1 greatly resemble con-
voluted tubules of the first order, as already mentioned. Spe-
cimens should be prepared in the same way as those of the
latter. The convoluted tubules of the second order, after rami-
fying in the cortical substance, terminate by emptying into the
collecting tubules (Fig. 91, J).
The collecting tubules and their epithelium. The collecting
tubules a possess cylindrical epithelia, the bases of which are
irregular and present point-like prolongations 3 (Fig. 97), which
interdigitate with one another. The nuclei in
the smaller collecting tubules are large and
very prominent, but the protoplasm which sur-
rounds them is not very abundant. The base-
ment membrane is comparatively thick and
exhibits a double contour. The smaller col-
lecting tubules are situated in the cortical sub-
stance, a little distance below the capsule.
_,. _ FIG. 97. Kidney of
Their diameter ranges between 0.04 and 0.06 d s- isolated ceiis of
two collecting tubnles,
mm. The small tubules unite to form larger Bowing irregular base
and point-like prolonga-
ones, and these again to form tubules of still jJJSiiS
larger diameter. The irregular appearance at from one^near boundary
the bases of the epithelia is the same in the
larger trunks as in the smaller branches ; in the former, how-
ever, the cells are larger, and the protoplasm more voluminous
than in the latter. The nuclei have about the same size in
each (Fig. 98). The basement-membrane diminishes in impor-
tance in an inverse ratio with the size of the collecting tubules.
In the smaller ones it is prominent and possesses a double con-
1 Schweigger-Seidel : Schaltstiicke ; Roth : Verbindungscanale (connecting tu-
2 Open tubules of Henle. Zur Anat. der Niere. Gottingen, 1862.
3 Heidenhain : loc. cit.
MANUAL OF HISTOLOGY.
tour ; in those of intermediate size it is thin, and has but a
single contour ; the largest tubes possess no basement-mem-
brane whatever. In the latter the great cylindrical cells are
held together by the prolongations above mentioned and a
colloid substance. The diameter of -the largest tubules at the
apices of the pyramids is 0.2 to 0.3 mm., after the first division
0.1 to 0.2 mm., the smallest being about 0.06
mm. The height of the epithelium in the
largest tubules is between 0.02 and 0.04 mm. ;
in those at the boundary layer about 0.015
mm. Good specimens are obtained by im-
mersing a fresh gland in dilute muriatic or
nitric acid for a variable period (six to twenty-
four hours), and examining in dilute gly-
cerine. The collecting tubules 1 should be
injected from the ureter with blue or red gel-
atine, and the whole organ immersed in alco-
hol, until ready for cutting. Sections made
parallel to the collecting tubules produce t
splendid specimens. The connection between
the collecting and convoluted tubules of the
human kidney cannot be shown by injection,
for the colored fluid thrown in from the ure-
ter rarely reaches the convoluted tubules of the first order. In
the lower animals fishes, frogs, etc. however, if the ureter be
injected under constant pressure the entire length of the urin-
iferous tubules may be filled with the carmine, or, better, Berlin
blue 2 fluid.
FIG. 98. Kidney of
dog. Small collecting tu-
bule above the boundary
layer, x 450.
1 In the pig Henle finds that two large collecting tubules begin at the apex of
each pyramid, then run along the outer borders of the cortical substance proper,
high up into the cortex, and there unite by forming a loop. Henle states that
the convoluted tubules empty into these, or their divisions by intercalated portions,