Studies of development of hypothalamic nuclei and hypothalamo-hypophyseal connection in ontogenesis of female rats.
The development of neurocytes of arcuate (ABC) and suprachiasmatic (SC) and the median eminence (ME) together with portal capillaries during embryogenesis and post-natal periods in female Wistar rats were studied at light and electron microscope level. Neurocytes of ARC nucleus producing secretory granules was observed first at 20 day of embryogenesis. After birth the number of such neurocytes producing secretory granules was greatly increased. In SC nucleus the neurocytes begin producing secretory granules in 5...7 day old animals. The results of the karyometric study also reveal that the development of ARC nucleus neurocyte proceeds the SC nucleus. This asynchronous development of tonic (ARC nucleus) and cyclic centre (SC nucleus) probably determines the critical period of sexual programming in female rats. Development of ME including the differentiation of portal capillaries is structurally completed during 3-4 weeks after birth. The significance of these findings in relation to the role of ARC and SC nuclei in sexual cycle regulation in female rats has been pointed out and discussed.
D000818:Animals; D002196:Capillaries / Q000033:anatomy & histology / Q000196:embryology; D002454:Cell Differentiation; D004727:Endothelium / Q000196:embryology; D005260:Female; D007030:Hypothalamo-Hypophyseal System / Q000196:embryology*; D007031:Hypothalamus / Q000196:embryology*; D008473:Median Eminence / Q000098:blood supply / Q000196:embryology; D009474:Neurons / Q000502:physiology; D011247:Pregnancy; D051381:Rats / Q000196:embryology*