Category: Hormone Receptor

DISCUSSION(5)

In conclusion, these results, which are summarized in Figure 11, demonstrate that gonadotropin receptor expression in ovarian follicles of the pig during the estrous cycle is heterogeneous and depends both on follicular maturation and on stage of the estrous cycle. The relative abundance of these mRNAs changes in total ovary during the estrous cycle, and in situ hybridization analyses indicate considerable cyclic variation in expression among mature small, medium, and large follicles. In small follicles of both immature prepubertal ovaries and mature adult ovaries at all days of the cycle studied, FSHr expression was strongly positive and was spatially restricted to granulosa cells.

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LHr mRNA localized only to theca cells in small follicles from prepubertal ovaries (Fig. 3) and from estrous cycle Day 4 (Fig. 5), Day 7 (Fig. 6), and Day 16 (Fig. 8) ovaries. LHr mRNA was expressed weakly in granulosa cells of some small follicles on Day 7 (Fig. 6D) and of medium follicles on Day 12. Small follicles on Day 16 expressed little LHr mRNA (Fig. 8B). At estrus, granulosa cells of preovulatory follicles expressed LHr mRNA (Fig. 4B). These data are in agreement with previous studies which indicated that in immature follicles LHr are localized exclusively in theca. buy antibiotics online

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DISCUSSION(3)

There have been conflicting reports of the changes in FSHr in granulosa cells during follicular growth and maturation. In rats and sheep, binding of 125I-FSH shows little change during the estrous cycle. In the pig and the domestic hen, FSHr decline as follicles enlarge. In the cow, some reports indicate that FSHr increase as follicles enlarge, some indicate that FSHr decrease, and some indicate no change. The present observation that preovulatory follicles had little FSHr mRNA (Fig. 4A) agrees with the previous reports that FSHr decrease as follicles enlarge, with the report that FSHr mRNA levels in rat follicles decrease from metestrus to estrus, and with the previous report with pig follicles obtained in proestrus. buy prednisone

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In situ hybridization analysis demonstrated that the distribution of FSHr and LHr mRNAs changed dramatically during the estrous cycle and that follicles were very heterogeneous in their FSHr and LHr mRNA content. In agreement with ligand autoradiographic studies and in situ hybridization studies of rat, cow, and pig ovaries, FSHr mRNA localized only to granulosa cells in the developing follicle (Figs. 3-7). FSHr mRNA was not evident in corpora lutea either on Day 4 (Fig. 9A), Day 7 (not shown), or Day 12 (Fig. 9B). asthma inhalers

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DISCUSSION(1)

Expression of mRNAs for FSHr and LHr in the ovaries of prepubertal and mature pigs was studied by RNA blotting and in situ hybridization in order to determine the variation in mRNA transcripts and the cellular distribution of receptor message expression. This is important because pigs are multiple ovulators with large numbers of follicles at different stages of development throughout the estrous cycle.

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On Day 7, mid-diestrus, FSHr mRNA hybridization was positive in granulosa cells of small antral follicles (Fig. 6A), and LHr mRNA hybridization was positive in theca cells but negative in granulosa cells (Fig. 6B). Comparison of the follicle on the left with the follicle on the right in Figure 6C revealed that FSHr mRNA was expressed in granulosa cells of some degenerating follicles (right) but not in granulosa cells of other degenerating follicles (left). Degeneration was established by examination of HE-stained sections (not shown). LHr mRNA expression was weak (Fig. 6D, left) to strong (Fig. 6D, right) in theca cells of the same follicles.

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RESULTS(2)In Situ Hybridization

The cellular localization of FSHr and LHr mRNAs was studied by in situ hybridization. Adjacent sections of ovary obtained at each day of the estrous cycle were hybridized with antisense and sense cRNA probes. Hybridization with sense probes (negative control) for FSHr mRNA (Fig. 2A) and for LHr mRNA (Fig. 2B) was comparable to hybridization observed in nonfollicular or nonluteal regions of ovarian sections. Hybridization of both antisense and sense FSHr and LHr probes to spleen was comparable and thus served as a negative tissue control (not shown).

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