[Changes in the innervation of the uterus during pregnancy and following parturition. Histochemical and electron microscopic observations in rat and humans].
A histochemical, electronmicroscopic study was made of time changes in uterine nerves during and after pregnancy in rats. Uterine observations in pregnant humans were also conducted with the following results. 1. Except at the oviductal end, the catecholamine (CA) fluorescence of adrenergic nerves distributed in the uterine horn myometrium begins to decrease around the implantation sites, and this spreads peripherally until most of the fluorescence in the uterine horns, including the mesometrium, disappears directly after parturition. 2. In lactating rats, fluorescence is almost completely restored by 1 month after parturition. But in non-lactating rats, recovery of fluorescence after parturition is delayed about 3 months. 3. The activity of acetylcholinesterase (AChE) in rat uterine cholinergic nerves clearly decreased during pregnancy. 4. In the early, middle and late periods of pregnancy, axonal swelling, agglutination of axonal cytoplasm and mitochondrial breakdown were observed, but no marked degeneration appeared in virgin rat uteri. 5. In humans, there was a sporadic distribution of adrenergic nerves in the uterine body myometrium, but fluorescent fibers were present in the terminal period of pregnancy. These results suggest that rat uterine nerves, especially most adrenergic nerves, degenerate and regenerate throughout pregnancy, parturition and puerperium. Apparently a localized humoral factor from the placenta and systemic endocrine environment affected by lactation or non-lactation is involved in the process.
Yamada
M
M
Department of Obstetrics and Gynecology, School of Medicine, Kanazawa University.
D000320:Adrenergic Fibers / Q000648:ultrastructure*; D000818:Animals; D001369:Axons / Q000648:ultrastructure; D005260:Female; D006801:Humans; D007774:Lactation; D011247:Pregnancy; D011270:Pregnancy, Animal; D051381:Rats; D011919:Rats, Inbred Strains; D014599:Uterus / Q000294:innervation* / Q000648:ultrastructure