The duration of pregnancy in guinea‐pigs after removal and also after transplantation of the ovaries

Abstract

The work of various investigators indicates a relationship between the ovary and a successful pregnancy. The details of the relationship, however, appear to vary somewhat in the different species studied.The early work of Fraenkel ('03) in removing the ovaries and also burning out corpora lutea of rabbits, one to six days after coitus, prevented implantation of the ova and prcgnancy. Removal of one ovary or burning out of only some of the corpora lutea usually resulted in birth of young. He concluded there is a close relationship between the corpus luteum and occurrence of pregnancy, but that in later pregnancy both ovaries may be removed without disturbing the pregnancy. He maintained that the corpus luteum produces the only hormone of the ovary and that it exerts an influence on the generative functions throughout the reproductive period of the life of the animal, and that it causes heat, menstruation, implantation, and the formation of the placenta. These several functions attributed to the corpus luteum by Fraenkel have been disputed, in part, by Marshall and Jolley ('05), who, from the work on pregnant dogs and rats, consider that, "The ovary is an organ providing an internal secretion from the follicular, epithelial cells or by the iiiterstitial cells of the stroma. This secretion induces menstruation and heat. The corpus luteum provides a secretiou essential for the attachment and development of the early ' Contribution no. 97 of the

Quantitative Changes in Myometrial Activity in the Guinea-Pig During Pregnancy

“…The fact that the loss of activity in the gravid horn was significantly greater than in the sterile horn during the middle third of pregnancy, suggests that the mechan¬ ism originates in the conceptuses and although it exerts its major action upon the gravid horn, it has systemic effects. This view is consistent with the fact that the ovaries (Herrick, 1928;Heap & Deanesly, 1966) and pituitary (Pencharz & Lyons, 1934;Nelson, 1935) can be removed in the latter half of pregnancy without causing abortion.…”

Gonadotrophic activity of the guinea-pig placenta during pregnancy

“…The length of gestation varies between 58 and 78 days with a modal duration of 68 days (Blandau & Young, 1939). Abortion does not occur when hypophysectomy is performed 3-6 days after mating (Heap, Perry & Rowlands, 1967), or in animals ovariectomized 3-4 weeks post coitum (Herrick, 1928;Courrier, Kehl & Skeletal muscle, placentae and subplacentae were homogenized in ice-cold acetone (5 ml/g) and ice-cold ether (1 ml/g) according to Hobson (1972 (Hobson, 1972;Wide & Hobson, 1978). The dried acetone-ether material, before analysis or assay, was taken up in saline (9 g NaCl/1), left overnight at +4°C, centrifuged, and the supernatant assayed.…”

Effect of Ovariectomy and of Various Hormones on the Synthesis of Progesterone by the Guinea-Pig Placenta in Vitro

“…The guinea-pig placenta may have endocrine functions similar to those of the human placenta, since ovariectomy after the first half of pregnancy does not necessarily lead to abortion (Herrick, 1928;Amoroso, 1955). Further evidence for this comes from the observation that the concentration of progesterone in uterine venous blood from ovariectomized animals is greater than that in systemic arterial blood (Heap & Deanesly, 1966) though histochemical and biochemical techniques have failed to show the presence of 3/?-hydroxysteroid dehydrogenase in the guinea-pig placenta at this time (Heap & Deanesly, 1966;Ferguson & Christie, 1967 The incubation medium consisted of 10 ml Krebs-Ringer solution con¬ taining nicotinamide (10 mg/ml) and nicotinamide adenine dinucleotide (NAD, 0-3 mg/ml) (Pearlman, Cerceo & Thomas, 1954).…”