Effects on hamster vaginal development of a single dose of testosterone or estradiol given neonatally

Postnatal injections of a single dose of testosterone propionate or estradiol benzoate to newborn female hamsters produce a precocious vaginal opening at 5 days of age. Vaginal postnatal development, histologically, has shown that in testosterone-propionate-injected animals sinusal vagina is absent. The Müllerian vagina presented a stimulated epithelium at early ages. After 40 days, the Müllerian epithelium was stratified keratinized, with zones of stratified cuboidal epithelium. In estradiol-benzoate-treated animals, the Müllerian epithelium rapidly changes to stratified keratinized epithelium (10 days), with zones of stratified cuboidal after 20 days of life. The sinusal epithelium was stratified squamous at 10 days, and after 40 days changes to stratified keratinized epithelium were seen. Probably, early changes are due to a direct effect of steroid action. Later effects are due to ovarian secretion. Histologically, no significant changes were observed in the preputial and urethral glands. The clitoris showed malformations.

Postnatal development of vagina, clitoris and urethral glands of the golden hamster

We have made a histological study of the postnatal development of the clitoris, preputial glands, urethral glands and vagina of the golden hamster. The 'phallic groove' of the clitoris is closed at 10 days of life, then the urethra has a cuboidal stratified, a stratified squamous and a stratified keratinized epithelium. The preputial glands are composed of branched saccular glands. These glands develop, with few changes during their maturation period. Formation of the urethral glands begins at 5 days and the alveoli are fully developed at puberty. The hamster vagina has two origins; the upper part is Müllerian, the caudal part is sinusal. The wall of the Müllerian vagina has a cylindrical epithelium at birth, which becomes 'double epithelium' at puberty and thereafter changes cyclically in connection with the estrous cycle. The sinusal vagina is solid at birth, its lumen being formed in the first 10 days of life and its wall having a cuboidal stratified epithelium. At 15 days it becomes a stratified keratinized epithelium, which will later line the vaginal pouch. At the 5th day, an ectodermic invagination (stratified keratinized epithelium) is observed in the zone of the future introitus. At the time of vaginal opening this zone forms the distal segment.

Sex-chromosome ratios in cattle and their relationship to reproductive development in freemartins

Nineteen "female" Holstein-Friesian calves born co-twin with a bull were purchased shortly after birth. One subsequently was judged to be a normal female with 0% XY (100% XX) karyotypes in cultures of blood lymphocytes. However, one typical freemartin also had 0% XY (100% XX) Karyotypes in 300 cells when examined at three ages. Overall, 18 freemartins examined at 1, 24, and 52 weeks of age averaged 60.7%, 57.9%, and 55.5% XY cells, respectively (P greater than 0.05). No systematic relationship was found between the proportion of XY cells and the abnormalities of the reproductive organs, as judged by vaginal depth and clitoral development at 1, 24, and 52 weeks, and examination of the reproductive organs per rectum at 54 weeks of age. The clitoris of untreated freemartins and those treated with estrone or estradiol postnatally did not enlarge. Testosterone treatment caused enlargement. None of the hormones affected vaginal depth. These studies provide convincing evidence that the blood lymphocyte XX:XY karyotype ratio (1) is not related to the degree of masculinization and (2) is stabile in the postnatal freemartin. Thirdly, the freemartin reproductive organs do not respond to common sex-steroid hormones postnatally other than the clitoral response to testosterone.

Stromal induction and specification of morphogenesis and cytodifferentiation of the epithelia of the Mullerian ducts and urogenital sinus during development of the uterus and vagina in mice

Homotypic and heterotypic recombinations were preapred with trypsin-separated epithelium and stroma from uterus of 1- to 9-day-old and vagina of 2- to 150-day-old mice. Growth of homotypic recombinants in adult female hosts resulted in normal uterine and vaginal morphogenesis. Heterotypic recombinants composed of uterine stroma and vaginal epithelium (VE) usually formed uterus, while recombinants composed of vaginal stroma and uterine epithelium (UE) usually underwent vaginal morphogenesis. The developmental responses of these heterotypic recombinants was age-dependent. Epithelia (UE and VE) from mice two to five-days old were responsive to stromal induction. However, from days 5 to 9 postpartum a progressive loss in competence was observed in both epithelia, and vaginal epithelium nine or more days old was unresponsive to heterotypic inductors. Inductive activities of uterine stroma were demonstrated in 2- to 7-day-old neonates and of vaginal stroma in 2- to 150-day-old mice. These results indicate that establishment of the regional specification of Mullerian and sinus epithelium during uterine and vaginal morphogenesis is due to inductive activities of the stroma.

Sterility and delayed vaginal opening following electrolytic lesions placed neonatally in medial preoptic area in female rats

Electrolytic lesions were placed in the preoptic area or in the middle and posterior hypothalamus of female rats within 48 hrs after birth. Vaginal opening was delayed significantly in rats having the medial preoptic area (mPOA) destructed as compared to sham-operated animals and those given lesions in the other parts of the hypothalamus. Only rats with the mPOA completely destructed developed the anovulatory syndrome. In these animals, unilateral ovariectomy was not followed by enlargement of its fellow. The present results are not in agreement with those of previous workers that electrolytic destructions of the diencephalon induced precocious puberty. The difference may be ascribable to difference in size and locus of lesions.

Hydrocolpos

The method of presentation and problems in diagnosis of 3 cases of hydrocolpos are discussed. The anatomy and embryology of the abnormality is described. The methods of treatment and results are outlined.

Effect of electrical stimulation of the hypothalamus on gonadotrophin release and the onset of puberty

Electrical stimulation of the hypothalamus with biphasic pulses was performed in immature female rats. When performed at 27 days of age or later, electrical stimulation in the arcuate nucleus region advanced puberty in all animals, as did stimulation of the anterior hypothalamus at 29 days of age or later. Stimulation in younger rats did not uniformly advance puberty. The responsiveness to electrical stimulation thus seems to develop a few days earlier in the arcuate nucleus region than in the anterior hypothalamus.

In a second experiment the possible involvement of follicle-stimulating hormone (FSH) in the advancement of puberty was investigated: the simplified augmented ovarian weight assay for endogenous FSH was performed in rats stimulated in the arcuate nucleus region as well as in controls. A marked increase in ovarian weight, indicating increased FSH levels, was demonstrated in all animals stimulated on day 27 or later; at earlier ages only a percentage of the stimulated animals responded. This percentage paralleled the percentage of animals that showed advancement of puberty.

It is concluded that electrical stimulation in both the arcuate nucleus region and the anterior hypothalamus advances the onset of puberty. It is suggested that electrical stimulation causes increased plasma FSH levels and, in consequence, precocious puberty.

Seasonal changes in reproductive productivity, growth rate, and food intake in mice exposed to different regimes of day length and environmental temperature

Groups of mice were maintained in three different environments: (1) constant day length and constant temperature; (2) seasonal fluctuations in day length and constant temperature; (3) seasonal fluctuations in day length and seasonal fluctua-tions in temperature.

The effect of protein deficiency and calorie deficiency on the reproduction of rats

1. Groups of twelve female rats were fed from 4 weeks of age on four different experimental dietary regimens, and on a stock diet containing 18% protein givenad lib.as a control (group 1). The rats in two of the experimental groups were malnourished either by being given a low-protein (9%) dietad lib.(group 2), or the stock diet containing 18% protein in limited amounts to maintain weight as in group 2. These animals were designated calorie-deficient (group 3). Two other groups of twelve rats were more severely malnourished from 4 to 13 weeks of age by being given a low-protein (6%) dietad lib.(group 4) or the stock diet in limited amounts to maintain weight as in group 4 (group 5). From 13 weeks all the rats in groups 4 and 5 were rehabilitated on stock dietad lib.

2. Well-nourished males were introduced into the cages 1 week after the vaginas opened, and again immediately after the females had suckled successive litters. This was repeated until the females were 60 weeks old and had reared up to six litters.

3. Chronic deprivation of protein or of calories delayed puberty, reduced fertility and gave rise to smaller numbers in the litters. It also interfered with lactation.

4. More severe malnutrition for 9 weeks further delayed puberty, but when these animals were rehabilitated they produced as many young as those that had been well-nourished throughout. They lactated well and there was no carry-over of the effects of the early deficiencies.