Ovarian development in young toads, Bufo bufo bufo (L.): Effects of unilateral ovariectomy, hypophysectomy, treatment with gonadotropin (hCG), growth hormone, and prolactin, and importance of body growth

Effects of unilateral ovariectomy on recruitment and growth of follicles in the rainbow trout, Oncorhynchus mykiss

“…Recent evidence suggests that sensory innervation may also play a role in ovarian growth and development (Deshmukh et al 1992). In non-mammalian vertebrates there is evidence that growth hormone restores follicle recruitment in ULO toads on a restricted diet (a restricted diet inhibits ovarian hypertrophy; Billeter and Jorgensen 1976), but the absence of homologous FSH (gonadotrophin-I) assays, until very recently, have precluded assessing the role of gonadotrophin in follicle growth and recruitment. The compensatory systems controlling follicle numbers in the rainbow trout, however, appear to be limited to stages of ovary development up to around mid-vitellogenesis; half of the females unilaterally ovarectomised in August did not recruit a second population of follicles into the maturing pool and the other half of the females that did only partially compensated in that they recruited only 70%o more follicles into the maturing population rather than doubling the number.…”

“…Similarly, studies in a few species of lizards (Jones et al 1977Sinervo and Licht 1991) and amphibians (Kjaer and Jorgensen 1971;Jorgensen 1973;Billeter and Jorgensen 1976) have shown that unilateral ovariectomy (ULO) results in a hypertrophy of the remaining ovary.…”

Early onset of a large pool of previtellogenic oocytes and cyclic escape by vitellogenesis : the pattern of ovarian activity of Xenopus laevis females and its physiological consequences

“…A large pool of previtellogenic oocytes (about 40 000) is established in wild Bufo females a few months after metamorphosis, largely before sexual maturity is attained (during the third year) ; this pool is so large that it appears to be constant throughout adult life (Billeter and Jorgensen, 1976). Since 3 000-4 000 eggs are laid annually, it appears that in the toad, as in Xenopus, the total number of ovarian follicles corresponds to several years of egg production, even in immature females.…”

“…The present paper presents a quantitative description of the onset of the activity of the adult Xenopus laevis ovary during the second year of life since we have previously demonstrated (Callen et al, 1980b) (Jorgensen, 1973(Jorgensen, a, b,1974(Jorgensen, , 1975Billeter and Jorgensen, 1976 Callen et al, 1980b) (Gurdon, 1968 (Dumont, 1972) and pooled in homogeneous size classes (size interval : 100 11m). The numbers and dimensions of the oocytes were estimated directly under a binocular lens using a micrometer eye-piece.…”

“…Moreover, the weight increase of the ovaries during their early growth phase is mainly due to an increase in the number of previtellogenic oocytes that, one after the other, reach a diameter of 300 11m and then remain in that state (Billeter and Jorgensen, 1976) ; this also holds true for Xenopus since we observed that (1) « the size of the young ovary increases significantly without increase of the diameter of the largest previtellogenic cells : 150 11m » and (2) the growth of these previtellogenic cells is biphasic, the first rapid growth phase spanning only 1.5 months (Callen et al, 1980a,b). In summary, oocyte growth is very similar in both wild Bufo females and in laboratory bred Xenopus females and occurs in two phases : it is first rapid and then slow, leading to the early onset of a large previtellogenic pool in the ovaries ; later, the oocytes progressively escape from this pool throughout another biphasic period of vitellogenic growth (Callen et al, 1980b ;Callen, 1984 (Mizell, 1964 ;Smith, 1955 ;Jorgensen, 1973a) ; in Xenopus leavis this value reaches 31 % (Gitlin, 1939 (Callen et al, 1980b) and (2) (Mizell, 1964 ;Smith, 1955 ;Jorgensen, 1973a).…”