Temporal relationships between hormonal concentrations and the electrical resistance of the vaginal tract of blue foxes (Alopex lagopus) at pro-oestrus and oestrus

Abstract

Summary. During pro-oestrus, baseline LH concentrations for 9 vixens (pooled data) ranged from 0\m=.\8 to 5\m=.\3ng/ml. In each vixen, baseline levels were interrupted by elevations of LH ranging from 3\m=.\1to 10\m=.\4 ng/ml. A major preovulatory LH surge was detected in all the vixens. The LH peak ranged from 13\m=.\5to 73\m=.\0 ng/ml with an average of 27\m=.\8 \m=+-\18\m=.\8(s.d.) ng/ml. Plasma LH concentrations declined to a basal level of 1\m=.\3\ m=+-\ 1\ m=. \ 0 ng/ml within 48 h of the peak value. The duration of the LH surge was 1\p=n-\3 days. The LH peak occurred 1 or 2 days before any sexual receptivity was observed. All the vixens were mated twice 2\p=n-\5 days after the LH peak; 8 conceived. Plasma concentrations of oestradiol-17\g=b\increased gradually during the last 6\p=n-\7 days before oestrus and reached maximum values (124\p=n-\373pg/ml) at the time of the preovulatory LH peak. The first significant increase in plasma progesterone concentration occurred simultaneously with the LH peak. During oestrus (normally 3\p=n-\5 days), progesterone levels rose steeply, attaining a mean concentration of 57\m=.\0 \m=+-\ 17\m=.\5 ng/ml when the vixens went out of heat. Androstenedione and testosterone values changed similarly, both increasing at the beginning of pro-oestrus and reaching maximum values (805\p=n-\1879pg/ml and 328\p=n-\501 pg/ml respectively) 1 day before to 1 day after the oestradiol-17\g=b\peak.The electrical resistance of the vaginal tract increased rapidly during the last 2\p=n-\3 days of pro-oestrus, reaching a maximum value (300\p=n-\640\g=W\)~2 days after the oestradiol-17\g=b\peak that corresponded with the onset of sexual receptivity. Towards the end of oestrus, the values fell to 100\p=n-\200\ g=W\ .

Structural aspects of oocyte maturation in the blue fox (Alopex lagopus)

“…However, other investigations of dogs show a less • 33000 well-defined time relationship between these two events, but indicate that most ovulations occur between 24 and 72 h after the LH peak, and that the majority of LH peaks are detected _+ 3 days from the first day of oestrus (Wildt et al 1978). In the blue fox the first day of clinical oestrus occurs I to 2 days after the LH peak (Moller et al 1984;Farstad et al 1989), which according to the present material is around the time of ovulation. Both in vivo (Holst and Phemister 1971) and in vitro (Mahi and Yanagimachi 1976) studies of dog oocytes indicate that the time required for immature oocytes to reach the metaphase of the second meiotic division is about 72 h. In the present investigation, resumption of meiosis was initiated 1 to 2 days after the LH peak, i.e.…”

“…Plasma concentrations of LH were measured by radioimmunoassay (RIA), as described previously for the fox, using GDN 15 antiovine LH Moller et al 1984). The competing ligand was ovine LH labelled with 125I (LER 1056-C2).…”

Fertilization and early embryonic development in the blue fox (Alopex lagopus)

“…The blood plasma samples were analysed for LH using a modification of the double antibody radioimmunoassay previously described MGller et al, 1984). For plasma samples analysed in 1988, the inter-and intraassay coefficients of varia- Fig.…”

“…Ovulation is spontaneous and occurs in most vixens 2 days after the preovulatory peak of luteinizing hormone (LH; Farstad et al, 1989;Hyttel et al, 1990). Ovulation procedes over a period of 12-24 hr, and the onset of clinical estrus corresponds with ovulation in 0 1993 WILEY-LISS, INC. most vixens, but may vary by 2 1-2 days from ovulation (Mgller et al, 1984;Farstad et al, 1989). Fox oocytes are ovulated as primary oocytes, as in the domestic bitch (Canis familaris), and oocyte maturation is completed within the oviduct during the following 2-3 days (Farstad et al, 1989, Hyttel et al, 1990.…”

Impedance pattern of vaginal and vestibular mucosa in cyclic goats

“…One approach that could be suitable is the impedance technique. Cyclic changes of vaginal impedance were found in cattle (Carter and Du y, 1980;Smith et al, 1989;Řezáč and Pöschl, 1991), pigs (Řezáč and Olič, 1988;Dusza et al, 1996), sheep (Adam et al, 1981;Olič et al, 1990;Bartlewski et al, 1999), and a number of other species (Moller et al, 1984;Lilley et al, 1997;Gupta and Purohit, 2001). The main problem of this technique is the wide fl uctuation of impedance values (Peters, 1989).…”