Healthy Corpora Lutea Research Articles

Expression of CCAAT/Enhancer Binding Proteins Alpha and Beta in the Porcine Ovary and Regulation in Primary Cultures of Granulosa Cells1

CCAAT/enhancer binding proteins alpha and beta (CEBPA/ CEBPB) were evaluated in the porcine ovary during the estrous cycle. CEBPB mRNA was present in antral follicles and was significantly increased in healthy corpora lutea (CL), whereas CEBPA mRNA was constitutively expressed in these structures. Both isoforms of CEBPA (42 and 30 kDa) exhibited greater expression in preovulatory follicles, and the 42-kDa isoform increased in CL, whereas the 30-kDa isoform decreased. All major isoforms of CEBPB (38, 34, and 20 kDa) were expressed, with the 34- and 20-kDa isoforms being more abundant in preovulatory follicles and further increased in CL. The effects of FSH and cAMP analogue on the distribution of CEBP isoforms were evaluated in primary cultures of porcine granulosa cells. FSH and 8-Br-cAMP had little stimulatory effect on isoform distribution, but cAMP treatment for 24 h tended to decrease the 30-kDa form of CEBPA and the 34-kDa form of CEBPB. The 34-kDa form of CEBPB was decreased by the protein kinase A inhibitor H89 at 4 h (with FSH treatment), and by both protein kinase A and phosphatidylinositol 3-kinase inhibitors at 24 h of treatment. In transfected granulosa cells, FSH and cAMP analogue stimulated a CEBP consensus sequence-reporter construct that was blocked by H89. These data implicate protein kinase A as the major regulator of CEBPB isoform distribution and CEBP-mediated transactivation in granulosa cells. The differential expression of specific CEBPA/B isoforms observed in maturing follicles and CL may contribute to changes in follicular cell differentiation and increasing steroidogenic capacity.

Aspects of the histology of reproduction in the female Angolan free‐tailed bat Mops condylurus (Microchiroptera: Molossidae) in Mpumalanga, South Africa

AbstractThe reproductive pattern of the female Angolan free‐tailed bat Mops condylurus (A. Smith, 1933) was investigated at two localities in Mpumalanga. Female Angolan free‐tailed bats displayed a seasonal bimodally polyoestrous reproductive pattern. Parturition in December was followed closely by a post‐partum oestrus. Ovarian follicle and endometrium cycles also closely followed the breeding season. The reproductive tract displayed complete dextral dominance with the right ovary and uterus being functionally dominant. Luteal activity was maintained throughout pregnancy and healthy corpora lutea were observed until late in pregnancy. Shedding of the zona pellucida occurred in the oviduct in the region of the ampulla–isthmus junction. The embryo entered the uterus as a morula, where it was transformed into a unilaminar, free‐lying blastocyst. A unique feature of the pre‐implantation uterus was the formation of a distinct decidua at the implantation site on the mesometrial side. Implantation in the Angolan free‐tailed bat was centric and superficial. First attachment of the trophoblast to the endometrium was mesometrial. The formation of a pre‐placental pad of trophoblast cells was also initiated on the mesometrial side, while orientation of the embryonic disc was anti‐mesometrial. Placental development occurred in the abembryonic hemisphere. Proliferation of the trophoblast over the embryonic hemisphere was slow and a bilaminar arrangement of the trophoblast was not observed in this region until after the primitive streak stage.

Pregnancy-Associated Plasma Protein-A Gene Expression in Human Ovaries Is Restricted to Healthy Follicles and Corpora Lutea

Recently, Pregnancy-Associated Plasma Protein-A (PAPP-A) in human follicular fluid was identified as an insulin-like growth factor binding protein-4 protease (IGFBP-4ase). The ability of IGFBP-4ase to inactivate the FSH antagonist, IGFBP-4, has suggested a possible role for PAPP-A in regulating FSH action. Despite growing interest in this protease, the question of whether the PAPP-A gene is expressed in ovaries of normal cycling women is unknown. To fill this basic gap in our knowledge, we have identified the cellular sites of PAPP-A gene expression in normal human ovaries by in situ hybridization. PAPP-A mRNA was low or undetectable in preantral follicles, small (1–2 mm) healthy and atretic antral follicles, larger atretic antral follicles, surface epithelium, tunica albuginea and connective tissue cells. In contrast, an intense PAPP-A hybridization signal was evident in the healthy antral follicles examined from 5 mm to the preovulatory stage. In these follicles, the signal was restricted to the granulosa cells (GC). An intense signal for PAPP-A mRNA was also present in healthy corpora lutea (CL), being localized to a subset of large luteal cells. Collectively, these results provide the first evidence that the gene encoding PAPP-A is expressed in ovaries of normal cycling women and show that the gene is expressed almost exclusively in healthy GC and CL cells. The restricted pattern of PAPP-A expression in normal human ovaries suggests that PAPP-A may be a functional marker of the dominant follicle and its product, the CL. Although the physiological function of ovarian PAPP-A remains to be identified, we hypothesize it might play a role in controlling survival, growth, and/or differentiation of the dominant follicle and CL by inactivating the gonadotropin antagonist, IGFBP-4.

Pregnancy-associated plasma protein-A gene expression in human ovaries is restricted to healthy follicles and corpora lutea.

Recently, Pregnancy-Associated Plasma Protein-A (PAPP-A) in human follicular fluid was identified as an insulin-like growth factor binding protein-4 protease (IGFBP-4ase). The ability of IGFBP-4ase to inactivate the FSH antagonist, IGFBP-4, has suggested a possible role for PAPP-A in regulating FSH action. Despite growing interest in this protease, the question of whether the PAPP-A gene is expressed in ovaries of normal cycling women is unknown. To fill this basic gap in our knowledge, we have identified the cellular sites of PAPP-A gene expression in normal human ovaries by in situ hybridization. PAPP-A mRNA was low or undetectable in preantral follicles, small (1-2 mm) healthy and atretic antral follicles, larger atretic antral follicles, surface epithelium, tunica albuginea and connective tissue cells. In contrast, an intense PAPP-A hybridization signal was evident in the healthy antral follicles examined from 5 mm to the preovulatory stage. In these follicles, the signal was restricted to the granulosa cells (GC). An intense signal for PAPP-A mRNA was also present in healthy corpora lutea (CL), being localized to a subset of large luteal cells. Collectively, these results provide the first evidence that the gene encoding PAPP-A is expressed in ovaries of normal cycling women and show that the gene is expressed almost exclusively in healthy GC and CL cells. The restricted pattern of PAPP-A expression in normal human ovaries suggests that PAPP-A may be a functional marker of the dominant follicle and its product, the CL. Although the physiological function of ovarian PAPP-A remains to be identified, we hypothesize it might play a role in controlling survival, growth, and/or differentiation of the dominant follicle and CL by inactivating the gonadotropin antagonist, IGFBP-4.

Expression of an Intracisternal A-Particle-like Element in Rat Ovary

We have isolated a rat intracisternal-A particle element (IAP)-like element (IAP-LE) from ovarian granulosa cells that appears to be identical to the rat EST clone AA964260. The compiled cDNA sequences contain several putative in-frame translation initiation codons with the largest capable of encoding a 365 amino acid protein with a reverse transcriptase domain in the N-terminus as well as a bipartite nuclear localization signal sequence in the middle. Northern blotting shows a major ∼7 Kb transcript and a minor ∼5 Kb transcript that are abundantly expressed in the ovary. In situ hybridization histochemistry using ovaries from gonadotropin-treated immature rats and regularly cycling adult rats show that this transcript is predominantly localized to granulosa cells of all healthy follicles, including primary follicles, and to newly-formed and healthy corpora lutea. This cell-specific expression pattern of the IAP-LE gene is distinct from those of the several known retroviral elements, suggesting the potentially novel functional importance of the IAP-LE gene. Taken together, our results demonstrate abundant and cell-specific expression of a novel IAP-LE in rat granulosa cells.