Placental and fetal development during multiple bovine pregnancy. Anatomical and physiological studies

Abstract

Cattle were injected with PMS, bred and slaughtered 3, 30, 45, 60 and 90 days after ovulation and the genital tracts dissected. From 30 to 90 days of pregnancy the percentage increase in the weight of single embryos was 85 times as much as the increase in crown-rump length. The volume of amniotic fluid increased 580 times in the second month of pregnancy and increased twice during the third month of pregnancy. The allantochorion did not lengthen between 60 and 90 days of pregnancy. At 30 days of pregnancy there was no significant difference in the crown-rump length or the weight of embryos of singles, twins, triplets, quadruplets or quintuplets. The volume of placental fluid per embryo was higher in singles than in twins and triplets; the volume of placental fluids per embryo decreased further in quadruplets and quintuplets. The weight of the placental membranes per embryo was heavier in singles than in twins, triplets and quadruplets; the weight of membranes was markedly decreased in quintuplets. The effects of overcrowding in utero on the conceptus was more pronounced at 60 days than at 30 days and in quintuplets than in triplets and quad- and Reece, '53). Interlocking between the chorion and the maternal cotyledons does not begin until the fortieth to fiftieth day (Chang, '52). Before that time, the relationship between the chorion and the endometrium is more or less of a diffused epitheliochorial placenta; during the second month this begins to change to a cotyledonary placenta.The development of the allantochorion in the cow is of particular interest. Essentially, the chorion is formed by elongation of the trophoblast, which becomes invested with a layer of endodenn followed by the lateral development of the mesoderm. The allantois develops as an outgrowth of the hind end of the gut, and rapidly elongates and closely invests the chorion. The vascularized allantois brings its blood vesseIs in close opposition with the chorion, so 303

The Biometry of the Gravid Uterus in Egyptian Buffalo Cows

“…Nevertheless, the difference becomes highly significant later. Comparing the present results in the buffalo with those found for cattle by HATCH (1941) and HAFEZ and RAJAKOSKI (1964) it becomes apparent that the greater curvature of the gravid and the non-gravid horn is longer in the buffalo than in cattle at corresponding stages of gestation. O n the other hand the changes in the lesser curvature are not so great when compared with the greater curvature.…”

“…Similarly there is no significant difference between the number of the caruncles in the right and left horns. The caruncles 849 counted in the non-gravid buffalo uterus are higher than those reported for cattle by RAINARD (1879) and HAFEZ and RAJAKOSKI (1964).…”

“…EL-WISHI (1965) clinically estimated the average diameter of the gravid uterus in buffaloes and stated that during the first 90 days it was comparatively smaller than that reported in cattle at the corresponding stage. HATCH (1941) and HAFEZ and RAJAKOSKI (1964) found that the gravid horn lengthens progressively throughout pregnancy.…”

Prenatal and pre-weaning growth and nutrition of cattle: long-term consequences for beef production

“…Individuals within litters have reduced foetal growth compared with singletons due to a reduced number of placentomes and mass of placenta per foetus (Hafez and Rajakoski, 1964;Greenwood et al, 2000b) and because of greater total nutrient requirements of the litter. On average, twin calves range from 7.4 to 9.8 kg lighter than singletons (Gregory et al, 1990 andDe Rose and Wilton, 1991;Cummins, 1994;Wilkins et al, 1994).…”

A Quantitative Evaluation of Placentome Development in Zebu Cattle (Bos indicus)

“…The complete dependancy of the developing bovine embryo upon the placenta, and more particularly upon the placentomes, for all its metabolic requirements is not established until around the fiftieth day of gestation (SMIDT, 1951). The way in which the developing embryo receives its nutritional requirements prior to this stage has been fully investigated (GREEN, 1946; MELTON, 1951) while extensive morphological studies have also provided much qualitative information on placental/placentome development after this stage (BOYD et al, 1944; HAFEZ/RAJAKOSKI, 1964). However, quantitative studies of placentome development from the fiftieth day onwards appear to be lacking in the literature.…”