Cystic Ovarian Follicles Research Articles

The menstrual cycle of the primates VIII—The œstrin-withdrawal theory of menstruation

In spite of ample evidence that œstrin is not the sole endocrine factor directly concerned in the changes which take place in the uterus, the hypothesis that normal menstruation is essentially a katabolic process following a temporary cessation of œstrin activity, still finds acceptance ( e. g ., De Jongh and Laqueur, 1931; Allen, 1932). This hypothesis, formulated originally by Allen (1927), is primarily based upon three sets of well-established observations on monkeys. These are: ( a ) uterine bleeding follows soon after bilateral, sometimes after unilateral, ovariectomy;( b ) uterine bleeding may be precipitated by injury to large or cystic ovarian follicles; and ( c ) uterine bleeding almost always begins a few days after the cessation of injection of œstrin into both normal and castrate monkeys. Corresponding observations have also been reported for man. Thus, the first is a clinical fact which had been recognized long before monkeys were used experimentally in studies of the reproductive processes. The same applies to the second; for example, as long ago as 1890 Cohnstein reported that menstruation is precipitated by manual pressure of the ovaries. The third finding has also been recently shown to be true for man; thus Kaufmann (1934) found that uterine bleeding occurs in women after the administration of 1,000,000 international units of œstrin. In spite of its apparently solid foundation, the œstrin-withdrawal theory of menstruation nevertheless falls short as an adequate statement because of its failure to account for certain essential facts. These deficiencies are discussed in the conclusion to this paper. Regarded purely as a working hypothesis, however, the theory immediately suggests that menstruation would be completely inhibited or delayed by the administration of œstrin previous to the expected onset of uterine bleeding. This deduction has not been systematically tested. The following are the only observations bearing on the question that I have been able to find, ( a ) Kurzrok (1932) has reported that too prolonged injections of œstrin may completely stop menstruation in young patients with oligomenorrhœa; ( b ) Hartman (1934) has described an experiment in which a monkey was given 995 rat units of œstrin over a period of 8 days, beginning on the 18th day of a cycle. Menstruation began during the course of injections, at approximately the time that it would have occurred if œstrin had not been given, and demarcated a cycle of 24 days. Unfortunately, conclusions cannot be drawn from either of these observations, although what both Kurzrok and Hartman did is essentially what should be done if the œstrin-withdrawl hypothesis of menstruation is to be critically tested. The experiments described in this paper, carried out in 1933 and 1934, aimed at providing such a test. Attempts were made, by injecting keto-hydroxy-œstrin (œstrone), to influence the rhythm of successive cycles of two regularly menstruating monkeys.

THE REGULATION OF THE HYPOPHYSIS BY THE TESTICLE, AND SOME PROBLEMS OF SEXUAL DYNAMICS

The parabiotic experiments on a normal adult female rat connected with a castrated partner, described by Matsuyama and Yatsu, brought into evidence very important facts. The ovaries and uterus of the former presented a large hypertrophy, at times pyometra or hydrometra; enormous cystic ovarian follicles, or considerable luteinization were found. In cases of parabiosis of two normal females no noteworthy alteration was observed. Goto reproduced and confirmed the above experiments. Matsuyama did not draw any causal conclusion therefrom, and Goto admitted the existence of a “Kastrohormon, ” a substance which would be present, in a greater quantity, in castrated animals, without any further analysis as to its nature. Our present knowledge, mainly due to the works of Evans, Zondek and Aschheim, Smith and Engle, on the influence of the anterior hypophysis upon the gonads enables us to understand the phenomena above referred to: the prehypophyseal hormones which exist in greater quantity in the circulation of castrated animals are those which by their passage into a normal partner induce such effects to appear. In other words, the parabiosis of a normal animal with a castrated one (“C.M.” or “S.F.”) is* equivalent to a chronic treatment with hormones of the anterior lobe.

FERTILITY AND STERILITY IN DOMESTIC ANIMALS.

For most of the domestic animals the fertility rate is generally very good. If a uniparous female animal is served during the oestrus period by a male with good sperm quality, the pregnancy rate is 60 to 70%. Among the animals that deliver more than one offspring, in many cases the pregnancy rate even reaches more than 90%. Nevertheless, veterinarians are very frequently consulted for fertility problems in individual animals or in cattle or swine herds. The main causes of subfertility are: Insufficient sperm quality An inseminator with insufficient professional knowledge. The majority of the cows, horses and pigs are inseminated artificially (AI). The insemination is not always carried out by experts. Not the right time for insemination. It especially occurs in animals with weak oestrus symptoms. Venereal infections. In earlier days these infections would occur very often. Due to the application of AI, most of these infections have been eradicated. The malfunctioning of the female genital system, which can be caused by various factors, such as cystic ovarian follicles, endometritis and anatomic abnormalities. The research on reproduction which has been going on during the past ten years in the department of Obstetrics, Reproduction and Herd Health, has been mainly concerned with: Embryo transplantation, in vitro fertilisation and ovum pick up The evaluation of sperm quality Improved freezing methods for both sperm and embryo's The development of new insemination techniques The composition of a new diluent for fresh sperm Cystic ovarian follicles in cows Subfertility in different species of animals Next to the above mentioned study fields, the department is also involved in the research into swine fever, respiratory diseases in pigs, antibiotic resistance in pigs and cattle, mastitis and metabolic problems in cattle and salmonella infections in pigs.