Category Archives: Ovary

Luteotropic Hormone Receptors: MATERIALS AND METHODS(6)

The samples were pelleted and washed twice with PBS plus BSA and counted on a gamma spectrometer. Protein concentrations were used to standardize the results.

Hormone Assays

Mink serum progesterone concentrations were determined by liquid-phase RIA after extraction in 10 volumes of hexane (BDH; Darmstadt, Germany). Extraction recoveries ranged between 95% and 98%. Antiserum, provided by Dr. A.K. Goff (University of Montreal, St-Hyacinthe, QC, Canada), had been previously validated for mink serum. Progesterone-11a-glucuronide-[125I]iodotyra mine (Amersham) was used as radioactive trace, and goat anti-rabbit IgG (Prince Laboratories, Toronto, ON, Canada) was used as the precipitating second antibody.

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Luteotropic Hormone Receptors: MATERIALS AND METHODS(5)


Northern blot analysis was performed on samples of 15 ^g total RNA as previously described. The homologous mink prolactin and LH receptor probes were labeled by random primer extension (Boehringer-Mannheim, Indianapolis, IN) with [32P]dCTP (DuPont, Mississauga, ON, Canada) to a specific activity of between 1.5 and 3.0 X 106 dpm/^g. Membranes were hybridized overnight at 65°C followed by two washes at the same temperature. All membranes were rehybridized with a ribosomal 28S probe.

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Luteotropic Hormone Receptors: MATERIALS AND METHODS(4)

Total ovarian and testicular RNA (5 ^g) were reverse transcribed by combination with 1 ^l of 25 mM antisense primer, 2 ^l 10-strength RT buffer (0.5 M Tris, 0.7 M KCl, 0.1 MgCl2, 0.04 dithiothreitol), 0.5 ^l RNAsin (Pharmacia), 1 ^l nucleotide mixture (25 ^M each of dATP, dCTP, dGTP, dTTP), and 0.5 ^l murine Moloney leukemia virus reverse transcriptase (Pharmacia) and incubation for 30 min at 42°C, 30 min at 45°C, and 30 min at 47°C. PCR reactions contained 10 ^l 10-strength PCR buffer (0.5 M Tris, pH 9, 15 mM MgCl2, 0.2 M NH2SO4), 25 pmol of each of the sense and antisense primers, 1 ^l of 20 ^M of each nucleotide (dNTP; Pharmacia), 0.5 ^l of cDNa pool, and 1 ^l (5 units) Taq polymerase (Pharmacia). PCR reactions were performed in a thermocycler for 40 cycles. canadian health care mall

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Luteotropic Hormone Receptors: MATERIALS AND METHODS(3)


In the subsequent year, large follicles (0.8-1.0 mm) and CL were dissected from the stroma of the ovaries of untreated pregnant mink at three phases of gestation: diapause (March 21; 10 animals; follicles and CL), luteal activation (March 25; 10 animals; CL only, no large follicles present), and postimplantation (April 10; 10 animals, CL only).

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Luteotropic Hormone Receptors: MATERIALS AND METHODS(2)

The second group (control) received pumps that contained saline on March 19. A terminal blood sample was taken by cardiac puncture under ketamine-promazine (Rogar STB, Montreal, PQ, Canada) anesthesia, and animals were killed with a single injection of T-61 euthanasia solution (Hoechst Canada, Regina, SK, Healthcare Canada). The ovaries were collected from 3 untreated pregnant animals every 2 days between March 19 and 31 and every 5 days thereafter until April 15, and also from 3 each of the bromocriptine- and saline-treated mink on alternate days from March 19 to 31. No differences were observed between untreated and saline-treated animals, so these groups were combined for statistical analysis and presentation.

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Luteotropic Hormone Receptors: MATERIALS AND METHODS(1)


Experimental Design and Tissue Collection

Adult female mink of the Standard Dark variety were purchased from and maintained on a commercial mink ranch (Morrow Fourrures, St Paul d’Abbotsford, PQ, Canada). All procedures followed the regulations of the Canadian Council of Animal Care, and the protocol was approved by the Comite de deontologie, Faculte de medecine veterinaire, Universite de Montreal. Animals were subject to commercial husbandry, including provision of water ad libitum and of a daily ration compatible with successful reproduction. Female mink were mated twice, at 7- to 9-day intervals, according to standard husbandry practice. Successful matings were confirmed by the presence of motile sperm in vaginal smears. buy asthma inhalers

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Luteotropic Hormone Receptors in the Ovary of the Mink (Mustela vison) during Delayed Implantation and Early-Postimplantation Gestation(2)

Nevertheless, passive immunization against GnRH interferes with postimplantation luteal function, suggesting that LH may play a role in the maintenance of the CL. Further evidence for a role of LH is derived from in vitro studies of mink luteal cells, which indicate that LH and its second messenger, cAMP, increase steroidogenesis and steroidogenic enzyme gene expression both in involuted luteal cells of diapause and in those derived from postimplantation gestation. buy ortho tri-cyclen online

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Luteotropic Hormone Receptors in the Ovary of the Mink (Mustela vison) during Delayed Implantation and Early-Postimplantation Gestation(1)

Early-Postimplantation Gestation(1)

The mink has a brief and well-defined reproductive season in the Northern Hemisphere, during which mating takes place in March. Gestation is characterized by a variable period of obligate embryonic diapause that terminates with implantation, usually between March 31 and April 6. In the early part of this delay phase, the mink corpus luteum (CL) involutes and synthesizes low levels of progesterone. In late March, increasing photoperiod activates the mink CL, and progesterone output is increased severalfold to a peak some 2 wk prior to parturition. Progesterone levels then decline slowly through the end of gestation. buy asthma inhaler

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