Luteal Tissue Volume Research Articles

Standing Oestrus, Ovarian Function and Early Pregnancy in Virgin and Repeat Breeder Heifers

Seventeen virgin heifers (VH) and 14 repeat breeder heifers (RBH) were inseminated in spontaneous oestrus during a total of 86 oestrous cycles. Pregnancy was checked either by non-surgical embryo collections 14 or 17 days after ovulation or by real time ultrasonography 20-26 days after ovulation. The two categories of heifers were compared with respect to duration of standing oestrus, ovarian function and plasma progesterone levels after insemination and during early pregnancy. The results indicate that the duration of standing oestrus was longer in RBHs than in VHs. Ovulation disturbances occurred and were more common among the RBHs than among the VHs. Disturbances in the development of the corpus luteum were noted in both categories of heifers, the RBHs having less luteal tissue volume than the VHs. In general, plasma progesterone levels did not differ significantly between the two categories of heifers. Despite the strict control of oestrus and ovulation as well as additional AI when necessary in this study, a poorer pregnancy result for the RBHs than for the VHs was seen.

Circulating progesterone concentrations and ovarian functional anatomy in the African elephant (Loxodonta africana).

Mean plasma progesterone concentrations measured in pregnant and non-pregnant elephants did not differ significantly from each other because of considerable variation, particularly for stage of pregnancy. Maximum progesterone values were recorded during pregnancy (5-8 months) and declined towards term (22 months). The numbers of corpora lutea or total luteal tissue volume were not critical in maintaining progesterone secretion. An increase in plasma progesterone concentrations with the luteal phase of the ovarian cycle was evident. A possible role of the placenta in the second half of gestation is indicated by an increase in fetal progesterone concentrations towards term.

Functional anatomy of the ovaries of pregnant and lactating Cape porcupines, Hystrix africaeaustralis.

The constituent cell types of the ovary of the porcupine were similar to those of New World hystricomorph rodents and accessory corpora lutea and luteal bodies were formed through the luteinization of the membrana granulosa or theca interna of antral follicles. All luteal bodies were histologically similar. The total volume of luteal tissue per female was not affected by fetal age and was unrelated to circulating concentrations of maternal plasma progesterone. Maternal plasma progesterone concentrations were correlated with fetal age. Follicular activity occurred throughout pregnancy but was not affected by fetal age or related to circulating values of oestradiol-17 beta. The formation of accessory corpora lutea during pregnancy is regarded as important in supplementing progesterone during pregnancy.

EFFECTS OF SUPEROVULATION ON OVARIAN DELTA 5-3 BETA-HYDROXYSTEROID DEHYDROGENASE IN RATS OF DIFFERENT AGES.

Administration of gonadotrophic hormones to rats, utilizing a procedure that produces superovulation, resulted, as expected, in increases in ovarian Δ5-3β-hydroxysteroid dehydrogenase activity. However, differences in the magnitude of the response were observed depending upon the ages of the rats used. The maximum degree of response was seen in immature rats (22–43 days of age when treatment was initiated). There is a distinct diminution of responsiveness in animals 3–4 months of age. Mature animals (over 5 months of age) responded, but to higher doses, and less consistently, than immature rats. Moreover, increases in enzymic activity generally paralleled increases in ovarian weight, while the specific activity of the enzyme remained, as a rule, unchanged. The magnitude of the increase appeared to parallel the increased volume of luteal tissue. (Endocrinology 76: 382, 1965)