Ovarian follicular development during early pregnancy in cattle

Abstract

Summary. On the day of oestrus (Day 0), 23 cows were assigned randomly to 4 groups in a 2 \ m=x\2 factorial experiment. Main percentage of non-atretic follicles (<4 pycnotic bodies) was lower (P<0\m=.\002) in pregnant than non-pregnant groups in the smallest class of antral follicles (0\ m=. \ 16\ p=n-\ 0\ m=. \ 28mm) but was higher (P<0\m=.\03) in larger classes (0\ m=. \ 68\ p=n-\ 3\ m=. \ 67mm) for pregnant groups. Percentages of atretic follicles were 3\m=.\7and 4\m=.\9(P>0\m=.\1)for follicles of 0\m=.\16\p=n-\0\m=.\67 mm, 91\m=.\1and 78\m=.\9for follicles of 0\m=.\68\p=n-\3\m=.\67mm (P<0\m=.\04) and 5\m=.\1and 16\m=.\1 (P<0\m=.\05) for follicles of 3\m=.\67\p=n-\78\m=.\56mm in pregnant and non-pregnant groups respectively. The percentage of atretic follicles classified as late atretic was higher in pregnant than in non-pregnant groups for follicles of 0\m=.\68\p=n-\1\m=.\57mm (P < 0\m=.\06) and 3\m=.\68\p=n-\8\m=.\56mm (P < 0\m=.\05). The results suggest that, as early as Day 17, the presence of a conceptus favours a more rapid turnover of follicles from class 1 (0\ m=. \ 16\ p=n-\ 0\ m=. \ 28mm) to classes 3 and 4 (0\ m=. \ 68\ p=n-\ 3\ m=. \ 67mm) but limits further growth by increasing atresia.

FAILURE OF EXOGENOUS PROSTAGLANDIN F2α TO ENHANCE UTERINE INVOLUTION IN BEEF COWS

“…Surface areas of caruncular endometrium were between 7 and 13 cm2 on day 35 compared to approximately 0.5 -1 cm2 in a study reported by Gier and Marion (1968 Uterine involution is faster in suckled cows when compared to non-suckled cows separated from their calves within24 h after parturition (Riesen et al 1968;Lauderdale et al 1968 prostaglandins early postpartum also has no effect on uterine involution (Guilbault et al 1987a), but PGF2. seems to be implicated in resumption of ovarian activity (Madej et al 1984;Guilbault et al 1987a).…”

“…seems to be implicated in resumption of ovarian activity (Madej et al 1984;Guilbault et al 1987a). Collectively this suggests that postpartum PGF2.…”

“…Preliminary observations with three cows (Lindell and Kindahl 1983) (Guilbault et al 1987a Guilbault et al 1984b) and is considered to be physiological (Guilbault et al 1987a Both on days 15 and 35 postpartum , the previously gravid uterine horns were easily discerned by their larger size from the previously nongravid uterine horns. Diameter of each uterine horn was measured at the external bifurcation and length from the external bifurcation to the cranial end of each extended uterine horn was estimated.…”

Ovarian Follicular Dynamics and Hormonal Changes in Goats during Early Pregnancy

“…It has been evidenced that inhibin acts as a modulator of folliculogenesis through inhibition of FSH release from the pituitary gland [30]. However, the mean plasma ir-inhibin levels remained low during early pregnancy, and this might be related to the decrease in follicular maturation or the decrease in the number of the large follicles.…”

Influence of pregnancy on the onset of oestrus and luteal function after prostaglandin-induced luteolysis in cattle

“…During the oestrous cycle in cattle, more large antral follicles are observed in the ovary bearing the corpus luteum (CL) than in the contralateral ovary (Pierson & Ginther, 1987a). In contrast, follicular growth in the CL-bearing ovary is decreased during early and mid-gestation (Rexroad & Casida, 1975;Thatcher et ai, 1986;Pierson & Ginther, 1987b;Guilbault et al, 1988) due to an increased rate of atresia (Guilbault et al, 1986 (Louis et al, 1973) and plasma oestradiol was measured after extraction (1-5-2-Oml plasma) with a mixture (5 ml) of petroleum ether:ethyl acetate (5-5:1 v/v). Recovery of labelled steroids after extraction was 89 + 0-8% for progesterone and 88 ± 1-2% for oestradiol.…”