Part 29

Tracing the evolution of the pelvis, it is to be found first in fishes where it is a loose disjointed, variable structure not attached to the spine; in some it consists merely of ischia. In reptiles the box assumes a form suggesting higher types. Passing from the toads to turtles and to the crocodiles, the elements which go to make up the pelvis assume a more and more osseous character and become more and more definitely articulated with the spine or with the differentiated sacrum. Its purpose in these low forms is mostly as a support for the muscles of the legs and back. Birds present an advance in pelvic construction but with a great preponderance of the vertebral column since thirteen to seventeen bones may fuse to form a sacral “roof.” The ilia, ischia and pubis are firmly combined. The box is long and narrow with a heavy part for the acetabulum and broad surfaces for muscular insertions. The pelvis of birds differs from that of cold-blooded vertebrates in the greater number of vertebral segments entering into its composition, and in their bony confluence. It differs from that of mammals by being unclosed by an anterior symphysis and by a widely perforate acetabulum. The ossification of the pelvic bones is to afford a support for the legs, and the open pelvis allows passage of the large brittle egg. The shape of the pelvis is of little importance in parturition in the foregoing animals, except for birds which bear large eggs when the pubis anteriorly is open for that purpose.

In monotremes one finds the reptilian type of pelvis with the three divisions of the innominate bone remaining separate. The pelvis is short, heavy and flat and is fitted with marsupial bones. The marsupial pelvis, possessing parallel walls made by the ilia and ischia and a long symphysis, resembles roughly a triangular prism. The sacrum is wedge- shaped, without a promontory and has a considerable movability. The marsupial bones are quite long. The triangular outlet is many times the size necessary for the passage of the fetus.

The rodent pelvis is difficult to summarize morphologically by reason of the great diversity of form occurring in the many genera of the order, but it may be said that here the pelvis is usually of a type rather higher in the scale than the other structural characteristics of the order would indicate. The outlet is more commonly ovate than rectangular, the ischia and ilia lie at a more marked angle to each other, and the true conjugate forms a lesser angle than is common in quadrupeds. The sacroiliac joint is, in general, freely movable.

The female insectivorous pelvis is relatively large, the sacroiliac junction usually being long and well knit while the pubes are slender, wide of angle as to their descending rami and there may be no symphysis, as in bats. Edentates have distinct bony unions of the elements of the innominate bone and of this to the sacrum which increases in width downward permitting a long synostosis with ischia and pubes; these joints are not movable. The pubes are slender and the symphysis short. The sacrosymphyseal angle is 80 degrees in the armadillo. The inlet is roughly triangular to almost round. Cetacea have no clearly developed pelvis, its place being represented by two long bones, larger in males, which seem to be the insertion of the genital erector muscles. There is no junction to form a pelvis nor is there an acetabulum. A pelvic box is absent in the Sirenia, but lateral processes from the lumbar vertebræ form a sort of ileum between which an ischium is located.

Proboscidea have a massive pelvis lying vertical to the spine. The iliac alæ are wide and deeply concave; the ischia are short, heavy and parallel to the ilia; the pubes are short and combined in a heavy symphysis; the sacroiliac joint is short, heavy and slightly movable; the outlet is ovate. In one specimen examined the length was 4 feet, symphysis 18 inches, true conjugate 19 inches, transverse diameter 17.5 inches; crests of iliac were 28 inches long.

Perissodactylic animals throughout this suborder have similar pelves except in so far as the obliquity is concerned. In the rhinoceros it is 90° with the spinal column, in the horse 135°; the angle of the true conjugate is 10° in the former, 50° in the latter. The lateral halves of the box are heavy and parallel; the symphysis is short in the rhinoceros, large in the horse; the outlet is ovoid. Artiodactyla, including pachyderms and ruminants, show a variety of shapes and constructions. Hippopotami have a short massive box tilted at about 150° from the spine, with widely flaring ilia and ischia; the pubes are slender but not combined in a strong symphysis. In ruminants the sacrum consists of four fused units; the sacroiliac joint is fairly movable; the obliquity is about 145°; ilia are long and slender and flaring; the ischia are broad and parallel with the ilia; pubes are slender but form a symphysis about two-fifths the total pelvic length; the infrapelvic angle is wide; the outlet of the pelvis is almost rectangular.

The general characteristics of the carnivorous pelvis may be summarized as consisting of a long strong symphysis, parallel lateral pelvic walls, a great sacrosymphyseal angle, and a marked separation of the bodies of the ischia. The sacroiliac joint is in general moderately movable.

The pelvis of lemurs is narrow, attached lightly to the slender sacrum, tilted at an angle of 140° and is possessed of a short weak symphysis; it resembles the structure in bats. In macaques the box is long, the sacrum wide, with a short iliac synostosis, the ilia long, narrow and curved out sharply, the ischia are continuous with the ilia and widely separated; the symphysis is short, about one-sixth the pelvic length; the angle of the superior strait is about 60°; the outlet is oval, the transverse diameter being short. The chimpanzee pelvis is made up of a wedge-shaped sacrum composed of three vertebræ, wide, flaring, concave ilia, stout well separated ischia with flattened tuberosities and a short symphysis parallel to the sacrum; the outlet is ovoid; true conjugate angle is 65°; the sacroiliac junction has little motility. In the gorillas the following points differ from the last described structure. Five vertebræ comprise the sacrum and the anterior surface is distinctly concave; the pelvic contour while still ovoid, has the two diameters more nearly equal; the pelvic angle is obtuse; the true conjugate is at an angle of 70°.

In man the salient features of the pelvis are—a broad, wedge-shaped sacrum, concave anteriorly, with wide articular surfaces and a limited motility; widely flaring ilia including the concave curvature of the body of the bone whereby the lateral diameter of the pelvic inlet becomes wider than in lower orders; short stout pubes with a narrowed angle beneath them; heavy blunt ischia with large tuberosities; true conjugate is at an angle of 55°. The human fetal pelvis resembles that of quadrupeds.

Study of these data indicates that the quadruped pelvis retains many things in common through all the orders especially in being a roughly rectangular structure lying chiefly horizontally, with a poorly developed false pelvis, straight ischia and a long symphysis pubis; the angle of the true conjugate is greater than in man and may be up to 80°. The long pubic synostosis changes the relation of the true and diagonal conjugate, but the former is no indicator of pelvic capacity, since in lower mammals the promontory of the sacrum lies anterior to the symphysis; the vertical diameter is a better measure of pelvic size and form. Sacral movement seems greater in lower animals especially in youth. The shape of the pelvic inlet is triangular in the lowest forms, the posterior base of this becoming wide as one ascends in a zoological line; the concavity of the ilia also increases so that the higher the animal the more curved are the lateral borders. In quadrupeds the anteroposterior diameter is greater than the lateral; the reverse is true in man. The long straight-sided quadruped pelvis is retained because of the direction of the forces from the legs, which is as much or more upon the anterior or pubic arch as upon the sacroiliac junction. In the semiupright position of the monkey the force is directed backward and downward upon the sacrum, this aiming to widen the pelvis by forcing the ilia apart. The effect of the upward force from the femora is to throw the pelvis upward and anteriorly by directing the line of action through the acetabula more toward the ventral surface. The sacroiliac ligaments hold the ilia firmly, their alæ being spread outward by the force from above. Elevation of the pubes shortens their symphysis and the true conjugate. By these changes the birth canal is shorter, entirely bony, with the upper inlet on the same plane, and promontory and symphysis are near enough the same level to be met at the same time by the engaging head. In these pelves the anteroposterior diameter is still long and superior rotation is not necessary.

In Man the force exerted on the pelvis from above is greatest among all animals and is greater when he is in active motion. The force is directed from above to the sacroiliac joint, the iliac bodies and the acetabular region while from below the pressure is directly exerted upon the last named. The force from above rotates the sacrum downward at its upper end, the attached sacroiliac ligaments at the same time pulling the alæ inward and throwing outward the lower end, the acetabular part. This tends to widen the pelvic box and to reduce its anteroposterior diameter. But the force acting from the legs and the adductors of the thigh push the lower parts of the ilia and the ischia and pubes apart, thus counterbalancing the effort of the force from above. The combined forces tend to bend the iliac bodies, thereby producing the curved lateral margins of the superior strait and making the lateral axis long. As between these two forces that from above is certainly the greater.

The effect of these forces can be followed by comparing a quadruped pelvis, a human fetal pelvis and an adult human one. The first two are similar chiefly in the shape of the inlet and the flat character of the ilia. This is strongly corroborative of the evolutionary development of the pelvis to meet the demand of the upright position. The effects of this evolution are as follows: First, to develop a forward inclination of the sacrum and a concavity in its surface anteriorly, second to increase greatly the iliopubic and ilioischiatic angles, third to cause the acetabula to move forward of the lumbosacral axis, fourth to shorten the bodies of the ilia and to develop in them a regularly curved surface, the concavity of which faces forward and inward, fifth to decrease the interpubic angle and accordingly to remove the triangular quality of the pelvic contour, sixth to increase the transverse diameter at the expense of the anteroposterior, and seventh to decrease greatly the sacrosymphyseal angle with the result that the entire pelvic cavity lies in one plane.

The effect of forces in alterations of the pelvic architecture may be seen in their several stages by the observation of the mammalian pelvis in the course of its evolution and development. The transitions in form are very gradual, but their gradations are well shown in the characteristic forms which have been described; the quadruped, monkey, anthropoid ape, human fetal and adult human type.

By an examination of the adult pelvis and fetal skulls it will be seen that the shape of the quadruped birth canal accommodates the fetal head nicely when in extension since there is no large posterior cranial development, the head and neck being of nearly the same thickness. In the monkey, where the facial angle increases, the head does not advance as a pointed presentation but as an irregular surface—the chin, forehead or occiput. It is only when the head has assumed a high facial angle and a well developed occipital lobe and the pelvic inlet has become transversely wide, that internal rotation is necessary.

Resuming a discussion of our records I shall at this place introduce additional cases of pathology in the parturient genital organ and then discuss the general system. Beside the cases of dystocia discussed in preceding pages there occurred in a deer a complete eversion of the uterus, which was incompletely involuted, accompanying prolapse of the rectum and bladder due to straining after severe injuries, probably inflicted by a male. The animal lived long enough to develop a purulent cystitis which spread to the vagina, uterus and pelvic soft parts. The left uterine cornu of an American bison was found to contain a decomposing fetus at about half term; general sepsis had supervened which led to the animal’s death in about a week, according to the keeper’s observations. The history of a monkey, followed through two pregnancies and finally dying of tuberculosis and sepsis is interesting.

Pigtailed Macaque (_Macacus nemestrinus_). Received March 5, 1903, died October 29, 1904. This animal gave birth on December 28, 1903 to a young one which appeared feet first; the arms appeared to have penetrated the septum between the vagina and rectum and protruded through the anus. Had to be cut off before delivery. She had a second young one October 21, 1904, which was properly delivered but was weak and lived two days, having received little attention from the mother. The mother since has been weak in the hind legs, eaten almost nothing and several times has passed a little blood in the stool. Lungs are partially collapsed; contain scattered small pinhead tubercles; right lower lobe contains a caseous nodule about the size of a cherry. Both pleuræ contain clear fluid. Abdomen contains a half pint of cloudy fluid. Omentum adherent along lower border and region of spleen and contains pinhead tubercles. Surface of the liver is studded with numerous pinpoint, pinhead and (old) pea sized tubercles. Some places in the liver seem to be the result of two invasions. Spleen presents small cherry sized tubercles thickly grouped together leaving small amount of splenic tissue to be seen. Kidneys contain pinhead to barley grain tubercles. Uterus is somewhat enlarged. External surface smooth. Section shows wall to be about one-quarter inch thick. Uterine cavity enlarged. Considerable bloody pus in uterine cavity. No communication can be found between the bladder and the vaginal wall or between the vaginal wall and the rectum. The intestines are negative. Mesenteric glands enlarged and caseous.

Abortion and miscarriage are occasionally seen in the monkeys, rodents and ungulates. The underlying reason for this can seldom be determined. A few cases seem to depend upon annoyance or abuse by cage-mates, a few to immaturity of the mother and some others seem the result of bone diseases such as osteomalacia. It does not occur regularly in any group or enclosure and appears to have no comparative pathological value.

Injuries of the external genitalia of the nature of lacerated wounds are occasionally seen in ungulates and carnivores, but never in monkeys. Acute vaginitis, sometimes localized into an abscess of the wall has been known to follow these traumata. Chronic changes have been met but once, which example will be detailed under another heading.

INFLAMMATIONS.

Endometritis has been observed sixteen times, as follows: Carnivora 10, Rodentia 3, Ungulata 2, Edentata 1. In searching for causes it was found that the association with a recent delivery of young, an abortion or the retention of a fetus, was responsible five times. Association with tumors of the uterus was noted four times. Injury preceded the condition on two occasions, while one instance seemed to be hematogenic, being secondary to a septic pneumonia. On four occasions the actual cause could not be established with satisfaction. Pathologically the traumatic and parturient cases were purulent while tumors seemed to produce a more exfoliative or hypertrophic inflammation.

Inflammation of the Fallopian tube has been observed but five times, and only in one of these did the uterine wall fail to participate in the disease. The animals affected were three carnivores, one rodent and one marsupial.

No particularly important association of this salpingitis and other pathology was noted, and indeed the only noteworthy lesion of the organ under discussion is now to be cited.

Nylghaie (_Boselaphus tragocamelus_). Chronic vaginitis, fibroma uteri, chronic tuberculous salpingitis. The vulva and lower half of the vagina are covered by a thin coating of yellowish mucus. Mucosa is mottled purple, irregular, in some places smooth and flat, and in others showing clear cysts with yellowish fluid contents. The upper part of the vagina shows a pedunculated fibroid extending from the cervix. This tumor measures 32 × 20 mm., and is attached to the posterior cervical wall by a broad pedicle and is of smooth surface. The right uterine wall shows a large fibroid which twists the uterine lumen to the left. The tumor in the right uterine cornu is nodular, measures 11 × 9 × 7 cm., shows many dilated veins coursing over the surface and one section shows a soft central necrotic area. The left uterine cornu shows a small fibroid at the lower end. There is a chronic endometritis present. The outer half of the right tube is the seat of firm nodular swellings, one of which proves to be a purulent salpingitis (tuberculous), the others calcareocaseous salpingitis. Both ovaries are fibroid and cystic. Microscopic section shows some exfoliation of the epithelium of the vagina. The uterine cornu is thickened and the fibrous tissue is greatly increased. The tube is the seat of a purulent salpingitis with an occasional broken down tubercle present. The ovaries show a mild degree of oöphoritis (Fig. 23).

OBSTRUCTIONS TO CONTINUITY OF BIRTH CANAL.

Obstruction to the lumen of the genital canal was observed in three mammals.

An American Bison (_Bison bison_), five years old and known to have been in captivity three years died of a chronic gastroenteritis and pulmonary parasites after many weeks of failing health. At autopsy a double hydrosalpinx, and probably unilateral hydrometra, with low grade cystic oöphoritis were found. A picture is reproduced. The notes are not perfectly clear as to the anatomy but from the gross specimen in preservative it would seem that the left uterine cornu was involved in the dilatation (Fig. 24).

Lion cub (_Felis leo_) had congenital cystic uterus. The only abnormality found is in connection with the internal genitalia. The vagina is 50 mm. long, uterus 23 mm. long, horns of uterus each 90 mm. long. The diameter of the uterus measures 10 mm. in both body and cornua, the latter being distended by clear watery fluid. They are symmetrically curved downward. They show no adhesions or obliteration of the os uteri to account for fluid retention. The probe is readily passed from the vagina to the end of the uterine horns. Vagina is patulous through its whole course. Ovary and tube normal.

An Axis Deer (_Cervus axis_) showed congenital hydrometra. This specimen is from a day old animal, consists of the genitalia in which the entire body of the uterus and both uterine cornua have been transformed into a thin-walled translucent cystic cavity containing clear fluid. The body of the uterus measures 15 mm. diameter, each cornu reaching the diameter of 5 mm. The cornua are curled not unlike ram’s horns, and are united by a line of adhesions above the body in the midline. From the ends of the convoluted and cystic uterus and cornua spring the normal tubes each with its ovary.

CYSTS.

Cysts have not been noticed in the lower genital canal, but it is true that this region is not exhaustively studied in routine autopsies; however, no large cysts have occurred there. Cysts of the ovary have been limited to the so-called cystic disease of this organ; one parovarian cyst has been found. These animals, two ungulates, two carnivores and a rodent, are noted as being young adults, only one of which was known to have borne young. In only one, the rodent, was there evidence of chronic peritoneal disease. The notes of the parovarian cyst case are as follows:

An Aoudad (_Ovis tragelaphus_) showed a ruptured parovarian cyst with normal right side pregnancy. The fetus, its placenta and membranes show no change. The right broad ligament and ovary are negative, the latter containing a red and gray corpus luteum. The left ovary is fibrotic and the left ligament is the seat of a large hematoma, which on section is found to contain thin sheets of gray translucent membrane, like walls of a cyst. The vessels are all distended. Arteries have stiff walls and are empty. Veins have well formed clot. The whole uterus and adnexa were slightly turned to the right, but the twist does not seem to have been sufficient to cause rupture of a broad ligament vessel. Microscopic section of the broad ligament shows a parovarian cyst into which there has been hemorrhage. The cyst is separated from the ovary proper by a short band of tissue which apparently consists of thinnedout ovarian cortex.

TUMORS.

Tumors of this tract in the mammals have been confined to the uterus proper, none having been found in the vagina, tubes or ovaries; in birds one oviductal growth and two ovarian tumors are recorded. These tumors are reported briefly according to their histological structures, a brief summary being added at the end.

A Black Lemur (_Lemur macaco_) showed a local leiomyofibromatous nodule on the lateral aspect of the uterine body near the cornu.

A nine banded Armadillo (_Tatu novemcinctus_) gave an interesting specimen which can be described as follows: The uterus is enlarged so that it measures 90 mm. from external os to fundus. Tubes and ovaries apparently normal. There is considerable grumous blood in the vagina and cervix; the former is normal. The cervix is pale and opaque in its lower half; upper half is slightly congested and mucosa decidedly rugous. The uterus itself shows an attenuated muscular wall with a thickened irregular mucosa which is the seat of pseudomembranous tabs of a dull red color, while the mucous membrane itself is irregularly red and yellow; also some grumous blood in the cavity. The size of the uterus is due to a large fibroma attached to the left lateral wall near the cornu. The mucous membrane of this is irregularly disturbed in some places, the tumor being partly bare. Here and there the mucous membrane shows the same degenerating hypertrophic character as seen on uterine wall. The tumor is attached to the wall by a narrow peduncle (Fig. 25).

A nylghaie with multiple fibromata has already been described.

A Jaguar (_Felis onca_) presented in the middle of the right uterine cornu a cystic resilient tumor 3 × 4 cm., which proved to be a fibroadenoma.

A lioness (_Felis leo_) presented a penetrating malignant adenoma of the uterine cervix upon which an active endometritis was implanted. The tumor penetrated the uterine wall, which gave way, an acute fatal peritonitis resulting. Metastases had occurred to the lung.

A Wild Boar (_Sus scrofa_) had a generalized ulcerating carcinoma of the uterine body.

An instance of chorionepithelioma in a Canada porcupine is worthy of separate description.