Accuracy of three pre- and intra-operative measurement techniques for osteotomy positioning in the tibial plateau levelling procedure.

OBJECTIVES: To prospectively compare the accuracy of three preoperative measurement techniques in tibial plateau levelling osteotomy (TPLO) planning. METHODS: Fifty-nine dogs were randomly assigned to one of three measurement techniques; A, B or C. Surgeons measured the intended osteotomy location on preoperative radiographs according to the assigned technique. Measurements were used intra-operatively during osteotomy placement. Postoperative measurements were made by a single blinded observer and compared to preoperative measurements. RESULTS: Fifty-one dogs were included for final statistical analysis. The mean absolute differences between pre- and postoperative measurements was 1.72 mm ± 0.958, 1.79 mm ± 1.010, and 3.56 mm ± 1.839, for techniques A, B and C, respectively. No significant differences were identified for patient age, gender, limb or surgeon. Techniques A and B were not significantly different (p = 0.8799). Techniques A and B were significantly more accurate than C (p = 0.0001 and p = 0.0003, respectively). Weight was significantly different among the groups (p = 0.047) but the statistical results did not change when an adjustment was made for bodyweight (p = 0.4971, p <0.001 and p = 0.0007, respectively). CLINICAL SIGNIFICANCE: Preoperative measuring for planning a TPLO osteotomy is recommended. Techniques A and B in the current study were clinically practical and significantly more accurate compared to technique C.

Altered placental morphology associated with murine trisomy 16 and murine trisomy 19.

The morphology of placentas from trisomy 16 and trisomy 19 mouse conceptuses aged 12 to 18 gestational days was studied at the light microscopic level. Comparisons were made with placentas from normal littermate animals. Trisomy 16 placentas showed marked changes from normal: 1) the junctional zone showed little indication of normal morphologic differentiation throughout gestation; 2) clusters of germinal trophoblast cells persisted in the labyrinth throughout gestation, whereas these cells disappeared by gestational day 16 in the normal littermate placentas; 3) the labyrinth was reduced in size in the trisomic placentas, and the differentiation of the interhemal membranes was delayed. The size of the labyrinths from trisomy 19 placentas appeared to be decreased, but otherwise the placentas appeared to have normal morphology. These observations and others from the literature show that placental development is affected by the presence of a trisomic genome, and that different trisomies influence the development of the placenta differently. For trisomy 16, we propose that the striking changes of the junctional zone may be associated with the trisomy 16-related gene dosage effect for alpha- and beta-interferon cell surface receptors. Because of the homology for this and other genes on mouse chromosome 16 with genes on human chromosome 21, findings related to the altered development of the trisomy 16 mouse may be relevant to understanding some of the phenotypic variations associated with human trisomy 21, the Down syndrome.

Comparative development of ruminant placentomes.

Histological examination of placentomes from cows, sheep, deer, and several antelope species revealed a common pattern of development of the utero-placental junction. Chorionic membrane in contact with the uterine caruncles developed "milky patches" composed of a thick trophoblastic epithelium and multiple allantoic blood vessels, while caruncles formed simultaneously a network of crypts. The milky patches formed chorioallantoic villi that penetrated into the caruncular crypts usually simultaneously with both the villi and crypt formation but partial delay between the villi/crypt formation and penetration had no apparent detrimental effect on the fetus. The villi penetrated into caruncles in a row until they reached the dense basal layer separating caruncular mass from adjacent glandular endometrium. Further placentome growth continued by increasing the length, diameter, branching, and surface corrugation of the villi. Placentomes in different stages of development coexisted at different locations within the uterus throughout the pregnancy. During placental release after parturition, entire villi or only the villi mainstems can pull out of the maternal crypts, or the entire placentome mass can separate from the uterine wall. The remaining maternal portions of the placentomes are destroyed and sloughed down to the basal layer, leaving only a narrow band of the caruncular tissue for the regeneration of caruncles. The bare, wrinkled caruncular surface is then covered with a new epithelium and ultimately becomes smooth.

Comparative histology of antelope placentomes.

The histological structure of ruminant (family: Bovidae) placentomes in eight antelope species was compared to that of domestic cattle and sheep. The chorioallantoic villi differed in degree of branching, surface corrugation, and complexity of utero-placental junction. All species had the epitheliochorial type of placenta, with the epithelial lining of maternal caruncular crypts varying between cellular and syncytial types. Uganda kob (Kobus kob, Reduncinae) and common duiker (Sylvicapra grimmia, Cephalophinae) had the simplest structures with minimal villous branching, round to polygonal villous cross-sections, and cellular crypt lining. Common eland (Taurotragus oryx, Tragelaphinae) and greater kudu (Tragelaphus strepsiceros, Tragelaphinae) had moderate villous branching, polygonal to mildly corrugated villous cross-sections, and cellular crypt lining with slight signs of syncytium. Wildebeest (gnu, Connochaetes gnou, Alcelaphinae) and sable antelope (Hippotragus niger, Hippotraginae) had moderate villous branching with corrugated surface and almost completely syncytial crypt lining. Steenbok (Raphicerus campestris, Neotraginae) and impala (Aepyceros melampus, Aepycerotinae) had the most complicated branching of villi and corrugation, and their crypt lining was clearly syncytial. Cattle (Bos taurus) and sheep (Ovis aries) had villous branching and corrugation similar to impala, and their crypt lining resembled that of eland and impala, respectively.

Ultrastructure of the placenta and fetal membranes of the dog: II. The yolk sac.

Yolk sacs from dogs at 40, 50, and 60 days of gestation were examined by electron microscopy. Free ribosomes, mitochondria, and rough endoplasmic reticulum (rER) are more prominent in both endoderm and mesothelium at 40 and 50 days than at 60 days, suggesting a greater synthetic capacity at the earlier stages. Smooth endoplasmic reticulum (sER) and glycogen are also present in greater amounts in the endoderm in the earlier stages. In the mesothelium, however, low amounts of sER and glycogen are consistently present. Certain possibilities relative to the nature of the synthetic activities in these two tissues are discussed. Large amounts of smooth-surfaced vesicles were observed along the basal edges of the 60-day mesothelium; they are indicative of transport processes occurring at this time. As gestation proceeds, in both endoderm and mesothelium, the Golgi complex remains well developed, there are more numerous lysosomelike bodies, and bundles of intermediate filaments either increase or become more diffused. In some endoderm cells at 60 days, large vacuoles and dense glycogen deposits were noted. These observations indicate that degenerative processes are gradually occurring in the endoderm and mesothelium as parturition draws near. Erythropoiesis occurs in the mesenchyme at 40 and 50 days. At 40 days also, segments of endothelium were seen within blood islands, indicating that the endothelial lining of some yolk sac vessels differentiates from cells located in the interior of such islands.

Development and phylogenetic significance of the fetal membranes and placenta of the African hystricognathous rodents Bathyergus and Hystrix.

Morphogenesis of fetal membranes in African and American hystricognathous rodents is essentially the same, even in the possession of such uniquely derived features as a subplacenta and a capillary ring on the inverted yolk sac, features that are unknown in any other rodent group. This is good evidence that the African and American hystricognaths comprise a monophyletic group. Certain interesting features of the decidua, decidual giant cells, periplacental bilaminar omphalopleure, and epamnion are described in Bathyergus and Hystrix. Of special interest in Bathyergus is the widespread decidualization of the uterine connective tissue, even that of the myometrium and perimetrium; and the presence of numerous, usually binucleate, decidual giant cells.

Morphogenesis of the fetal membranes of an American mole, Scalopus aquaticus.

Scalopus membranes are characterized by: Superficial nidation; antimesometrial orientation of the embryonic disc; amniogenesis by folding; an extensive but transitory choriovitelline placenta; a large yolk sac with late and incomplete inversion; large persistent allantoic vesicle; a very broad, thin, villous, epitheliochorial chorioallantoic placenta of annular shape interrupted mesometrially, dotted with numerous areolae, and bordered by a nonvillous sparsely vascular chorioallantoic membrane connected with the persistent bilaminar omphalopleure by a very narrow rim of chorion. There is no decidua. Electron microscopy shows that at 8 mm, CR, (limb bud embryo) the uterine epithelium of the interhemal membrane may be 0.5 micron or less in thickness, but that it shows no signs of degeneration. Trophoblastic microvilli often penetrate the epithelium to within 0.2 micron of its base. At this time there is active secretion by the uterine glands, and cellular hypertrophy and cytolysis of the epithelium at the gland mouths, with active phagocytosis by the areolar cytotrophoblast. The occurrence of absorptive areolae in an insectivore emphasizes the probable primitiveness of this widely distributed placental mechanism. In spite of similarities of the yolk sac to that of rabbits and rodents, the bilaminar omphalopleure produces no invasive trophoblastic giant cells. The definitive membranes of Parascalops breweri and Scapanus latimanus are like those of Scalopus. The placentae of Talpa europaea, Condylura cristata, and Neurotrichus gibbsii are discoid and relatively much smaller, thicker and more complex in internal structure. There is some reason to believe that the fetal membrane systems of moles and shrews (Soricoidea) are more like those of the ancestral mammalian stock than are those of any other recent eutherians.

Decidual cells in the human ovary at term. I. Incidence, gross anatomy and ultrastructural features of merocrine secretion.

Decidual tissue occurring within the human ovarian cortex was examined by light and electron microscopy. Of 21 ovarian specimens obtained at term (36-42 weeks of gestation), decidual cells were confirmed in each. Decidual cells were found within the tunica albuginea as single cells, in nodules, in polyps or in confluent sheets. Decidual cells exhibited several characteristics of cells engaged in secretory activity: abundant rough and smooth endoplasmic reticulum, numerous profiles of the Golgi complex and a large, euchromatic nucleus devoid of heterochromatin and displaying a prominent fibrous lamina. Peduncular protrusions at the periphery of the cell contained numerous dense bodies 0.4-0.9 micron in diameter. These dense bodies were bounded by a single membrane and contained granular subunits 30-60 nm in diameter. These granular subunits were observed in the process of apparent exocytosis, as well as free in the extracellular space. Secretory bodies and their granular content also were observed both in the region of the Golgi complex and partially extruded into peduncular processes. By far the greatest number of secretory bodies occurred within peduncular processes where they may be stored prior to release. Migration of a secretory body into a peduncular process and exocytosis from such a process appears to be an unusual mode of meocrine secretion, perhaps unique to decidual cells.

Evidence of a specific nidation site in ruminants.

The site of umbilical cord attachment in ruminants indicates the limited segment of the uterus where the blastocyst attachment occurs and could have potential significance for locating presumptive nidation sites. Measurements of the site of cord attachment were made on impala (Aepyceros melampus) and common duiker (Sylvicapra grimmia) at several stages of gestation. Both implant only in the right uterine horn although they ovulate from either ovary. Relative to uterine length, cord attachment in impala is somewhat closer to the cervix than it is in common duiker. As pregnancy advances in common duiker, the relative position of cord attachment becomes closer to the tubal end. This relationship was not seen in impala and may perhaps to be attributed inadequate data. Upon extrapolation of the data from common duiker, a presumptive attachment area is suggested for this species. This region is located at about 41% of the distance from the internal cervical os to the uterotubal junction. Similar cord attachment data could be used in any ruminant species to indicate the existence and location of a specific nidation site.