Biomedical subjects
Publications and source records attributed to P Hradecký.
This review summarizes current knowledge of oncogenes and tumour-suppressor genes in development and progression of malignant melanoma.
Histological examination of a single placentome recovered from a Holstein heifer (Bos taurus ) after delivery of a dead 9.5-mo-old gaur (Bos gaurus ) calf revealed failure of proper development of the chorioallantoic villi after interspecies embryo transfer. Macroscopically, the placentome appeared normal in size, its surface was rough, and on crosssection, the penetration of the villi was irregular and very different from the homogeneous penetration in developed cow placentomes. Microscopically, the heifer caruncle had an extensive system of maternal crypts but the villi failed to branch completely and entered only about one half of the available crypt spaces. The epithelial lining of the maternal crypts in the heifer placentome was nearly missing, which was rather unusual for a species of the genus Bos . The overall picture suggested a decreased feto-maternal compatibility, resulting in poor development of the utero-placental contact, retarded fetal growth, and ultimate fetal death.
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.
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 histological features of the chorionic villi in placental cotyledons of the common eland (Taurotragus oryx ) and bongo (Boocercus euryceros ) antelopes and okapi (Okapia johnstoni ) and giraffe (Giraffa camelopardalis ) were examined. The chorionic villi in both antelope species showed only moderate branching and/or surface corrugation and their cross-sections were polygonal to oval. The close similarity in the structure of cotyledons has been apparently a contributing factor for success in mutual interspecies embryo transfer. The chorionic villi in okapi and giraffe had very different structures. In okapi the villi on cross-section were round and filled with thin connective tissue. They showed minimal branching and surface corrugation. In giraffe the villi showed extensive surface corrugation, had multiple fine branches, and were filled with a more dense connective tissue. Prospect for materno-fetal compatibility in mutual embryo transfer between these species is guarded.
Ketone body concentrations were determined in six body fluids of cows in late pregnancy and their fetuses (blood plasma and urine of cows, amniotic and allantoic fetal fluids, and fetal blood serum and urine) using the head-space gas chromatographic method. Physiological ratios O/T% of oxidized (acetone and acetoacetic acid) to total (acetone, isopropanol, acetoacetic and 3-hydroxybutyric acid) ketone bodies were below 10% in cow blood plasma and urine, fetal serum and urine, and allantoic fluid, and below 20% in amniotic fluid. A scheme for the evaluation of the degree and duration of ketosis based on the O/T% ratio is proposed. The existence of a renal regulatory mechanism for excretion of ketone bodies is suggested by analogy with the renal acidobasic regulation.
Uteri of 69 African antelopes and a giraffe were morphologically examined and numbers of caruncles and their rows in each horn were recorded. Antelopes of subfamilies Taurotraginae, Aepycerotinae, Antilopinae, and Alcelaphinae had about 50 to 100 caruncles arranged in four rows in each uterine horn. Hippotraginae had about 100 to 200 caruncles in six to eight rows in each horn, and Reduncinae had about 10 to 20 caruncles in two rows in each uterine horn. The giraffe had about 70 caruncles arranged in four rows in each uterine horn. Uterine caruncles in some antelopes had specific features such as pigmentation of apices, caruncles on stems, and caruncles with honeycomb structure.
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