Morphology of provisional organs of the horse in relation to newborn foals viability

The aim of the study is to identify the morphofunctional features of the fetal part of the equine placenta in relation to prenatal growth and development of newborn foals. The fetal parts of the placentas of the most viable foals of the first subtype have a maximum weight of (8.02 ± 0.24) kg, area of (14287.48 ± 311.72) cm2, length of the umbilical cord of (57.68 ± 0.75) cm, thickness of (3.76 ± 0.07) cm. The diameter of the arteries and veins in the umbilical cord is almost the same - 11-12 mm, their lumen is strongly narrowed, the thickness of the wall of the umbilical arteries and vein is also equal to (5-6 mm). The thickness of the chorion reaches (8.00 ± 0.91) mm, the number of villi per 1 cm2 of the chorion is (41.80 ± 1.56) pcs., the thickness of the allantoamnion is (6.20 ± 0.58) mm, and the diameter of the vessels is from 4 to 6 mm, their number on the allantoamnion section of 100 cm2 is 5-10. The weight of the fetal parts of the placentas of less viable foals of the second subtype is (5.93 ± 0.24) kg, the area is (10854.92 ± 407.67) cm2, the length of the umbilical cord is (60.00 ± 0.84) cm, the diameter is (3.62 ± 0.06) cm. The diameter of the vein in the umbilical cord is slightly larger (12 mm) than the arteries (11 and 8 mm). The thickness of the chorion decreases to 4-6 mm (5.20 ± 0.37) mm, the number of villi per 1 cm2 of the chorion is 38.40 ± 1.17, there are areas in which the height and density of the villi are even smaller. The thickness of the allantoamnion is (4.06 ± 0.45) mm, and the diameter of the vessels is from 4 to 6 mm, from 3 to 7 vessels are found in an area of 100 cm2 of the allantoamnion. The weight of the fetal parts of the placentas of the third subtype of the least viable foals is significantly (by 37.37 %) lower than the first, as is the area, the length of the umbilical cord is (57.20 ± 0.66) cm, the diameter is (3.44 ± 0.05) cm. The diameter of the vein in the umbilical cord is slightly smaller (9 mm) than the arteries (12 and 11 mm). The chorion is unevenly covered with small, slightly branching villi, not shiny, its thickness reaches (2.84 ± 0.07) mm, and the number of villi per 1 cm2 is from 20 to 40. The diameter of the walls of the allantoamnion vessels decreases and is no more than 3.5 mm at most, their number is from 3 to 5 per 100 cm2.