Geslachtsverschillen in regulatie van ovariumactiviteit bij de rat

De activiteit van gonaden manifesteert zich onder andere in de vorming van geslachtscellen en de afgifte van geslachtshormonen. Deze activiteit wordt geregeld door tal van factoren in het inwendige en in het uitwendige milieu. Het is bekend, dat de dagelijkse wisselingen van licht en danker een belangrijke factor bij regulatie van gonade-activiteit zijn in het uitwendige milieu. Onder de factoren van het inwendige milieu nemen hormonen een vooraanstaande plaats in en wel speciaal (1) hypothalamische 'releasing factor', (2) hypofysair gonadotropine en (3) door de g6naden geproduceerde steroidhorrnonen

Effect of constant light on parturition and postpartum reproduction in the rat

Light-dark (LD) cyclicity contributes to a number of reproductive events in the rat, including estrus cyclicity, and the timing of parturition and postpartum estrus. Constant light (LL) disrupts the female's cyclicity, and fertility is typically diminished. To ascertain whether constant light similarly diminishes the fertility of postpartum females, LL and LD animals were compared over three successive pregnancies on several reproductive measures including parturition, postpartum estrus and spontaneous ovulation, the timing of estrus relative to parturition, and the number, body weights, and viability of offspring. While the 24 h pattern of parturition differed for LL and LD groups, postpartum estrus and ovulation occurred reliably in both groups. The LD group showed greater variation in the birth-estrus interval, the result of a delayed estrus in those females giving birth late in the light phase. The likelihood of spontaneous ovulation and overall successful reproduction was high for both groups. Thus, unlike the cycling female, the fertility of the postpartum female is relatively unaffected by constant light. As such, these findings suggest that LD cyclicity is not critical for postpartum ovulation and estrus

A novel member of the transmembrane serine/threonine kinase receptor family is specifically expressed in the gonads and in mesenchymal cells adjacent to the mullerian duct

The activin and TGF-beta type II receptors are members of a separate subfamily of transmembrane receptors with intrinsic protein kinase activity, wh

Development of the gubernaculum and processus vaginalis in freemartinism: Further evidence in support of a specific fetal testis hormone governing male-specific gubernacular development

Background: Freemartinism occurs in some speices of ruminants and affects most female bovine fetuses in hterrosexual, multiple pregnancies owing of susion of the chorionic blood circulations soon after implantation. Maldevelopment of the ovaries and Müllerian ducts have been described and recognized as resulting from exposure of their respective primoridia to an excess of anti-Müllerian hormone. The Present study aimed to analyse the prenatal growth the development of the gubernaculum in freemartins to find out its pssible affliction through foetal testis hormones derived from their male co-twin. Methods: Histolgical sections of young and frawings and photographs of further developed freemartins and conrol male and female bovine foeuses were analysed. The specimens had been collected ealier for analsis of the time course of male and female gonadal and gential development and its impairment associated with freemartinism. Results: The gubernaculum of 35–40 day-old male and female fetuses was in the intial stage of development and of similar appearance in all specimens. Gubenacula of 60–70-day-old male fetuss differed from those of females of similar age in various respects: the male gubernaculum size was larger and extensio