Category Archives: Corpus Luteum

Corpus Luteum Development and Function in Cattle: DISCUSSION(8)

It is therefore assumed that LHRH antagonist-induced modulations of FSH concentrations cannot explain why luteal function is suppressed in cattle treated with the LHRH antagonist during the period of luteal development. In summary, inhibition of release of episodic LH pulses from 2 days before the preovulatory surge of LH until Day 7 of the estrous cycle had the greatest inhibitory effect on development of a … Continue reading

Corpus Luteum Development and Function in Cattle: DISCUSSION(7)

The latter possibility is not likely, however, because contrary to the situation in human and rat ovaries, in which the gene for LHRH receptor is expressed, this gene is not expressed in the CL of cattle. Apparently the gene encoding for LHRH, however, is expressed in cumulus-oocyte complexes of cattle. LHRH can be involved in regulation of FSH secretion in some physiological states, and FSH … Continue reading

Corpus Luteum Development and Function in Cattle: DISCUSSION(6)

In the present study, the diameter of the CL that developed in the absence of episodic LH pulses after the preovulatory surge of LH represented about 60% of the diameter of the CL in control females. However, secretion of progesterone from the CL of females in which episodic LH release was inhibited represented about 25% of that produced by the CL of females from the … Continue reading

Corpus Luteum Development and Function in Cattle: DISCUSSION(5)

However, diameter and function of CL in females of the control group might have been greater than they were in the present study if the ovulatory follicle had been stimulated by the final 24 h of episodic LH secretion before the endogenous preovulatory LH surge. Data from the present study indicate a dissociation of structural and functional development of the CL in cattle. Function of … Continue reading

Corpus Luteum Development and Function in Cattle: DISCUSSION(4)

Observations in the present study are also consistent with earlier work in sheep in which induced premature ovulation of dominant ovarian follicles with injections of LH resulted in development of subfunctional CL. Subfunctional CL that developed as a consequence of the early induced ovulation in sheep likely resulted from the truncation of LH support during the final stages of development of the dominant ovarian follicles. … Continue reading

Corpus Luteum Development and Function in Cattle: DISCUSSION(3)

During luteinization, there is hypertrophy and hyperplasia of theca cells, which give rise to small luteal cells. Small luteal cells possess functional LH receptors that are involved in regulation of progesterone secretion, but LH receptors in large luteal cells of granulosa origin are not involved in regulation of secretion of progesterone; these large cells secrete large amounts of progesterone in the absence of LH stimulation. … Continue reading

Corpus Luteum Development and Function in Cattle: DISCUSSION(2)

Results from previous studies indicate that abnormal patterns of release of LH pulses during the follicular phase of the menstrual cycle of women (either more or less frequent than normal) result in luteal phase deficiency and infertility. Development of a normal CL may depend on a healthy preovulatory follicle with adequate numbers of granulosa cells before ovulation, granulosa cells capable of synthesizing adequate quantities of … Continue reading

Corpus Luteum Development and Function in Cattle: DISCUSSION(1)

The present study is the first to provide evidence that episodic release of LH during the 48 h before the preovulatory surge of LH is important for development of the CL in cattle. Inhibition of LH release for the 48 h preceding the preovulatory surge of LH resulted in development of a CL smaller in diameter than those from females of the control group or … Continue reading

Corpus Luteum Development and Function in Cattle: RESULTS(2)

Day of detection of behavioral estrus was earlier (P < 0.05) in females of the control group than in females in any of the treated groups, and earlier (P < 0.05) in the Ant 2-treated females than in the females of the other two treated groups. Maximum diameter of the CL during the luteal phase of the estrous cycle when treatments were administered was greatest … Continue reading

Corpus Luteum Development and Function in Cattle: RESULTS(1)

Treatment with bLH to mimic a preovulatory surge of LH resulted in concentrations of LH in circulation above 50 ng/ml in all females (Fig. 1). Data for mean concentrations of LH in circulation during the 3-h treatment with purified bLH are included in Table 1. Ovulation was successfully induced in 16 females within 48 h after treatment with bLH (untreated control = 5; Ant 2 … Continue reading