Catecholaminergic innervation of the chicken ovary. With special reference to the follicular wall.

Abstract

The innervation of the chicken ovary was investigated with special emphasis on adrenergic nerves in the follicular wall. Quantitative determinations of catecholamines (CA) by high-performance liquid chromatography and electrochemical detection (hplc-ed) revealed 15.4 +/- 3.3 ng/mg protein of norepinephrine (NE) and 3.14 ng/mg protein of epinephrine (E), with even larger amounts in the cranial part of the ovary close to the adrenal gland. Serial sections that had been processed for the visualisation of aminergic nerves (Falck-Hillarp- or glyoxylic acid techniques) showed CA localized in nerve-fibre bundles; cell bodies of chromaffin and sympathetic neurons were only found at the ovarian-adrenal junction suggesting that ovarian nerves stored considerable quantities of E. An antiserum against bovine phenylethanolamine N-methyltransferase (PNMT, the E-synthesizing enzyme) produced no immunostaining in chicken ovary or adrenal gland, due to a lack of cross-reactivity between the antiserum and chicken PNMT. Serial sections processed alternately for the visualisation of aminergic nerves and myosin (from chicken gizzard) immunoreactivity revealed a scarce nerve supply of contractile cells in the theca externa compared to an extraordinarily dense innervation of the endocrine interstitial tissue of the theca interna. This distribution pattern of nerve fibres in the follicular wall was confirmed by electron microscopy in ovarian tissue that had been pretreated with 5- or 6-hydroxydopamine (HDA). More than 90% of the terminal axons were specifically labeled by these false adrenergic transmitters. Many of these terminals were seen in close contact (20 nm) with steroidogenic cells suggesting a neuromodulatory function of CA in hormone synthesis and/or release. It is yet unclear whether E and NE are stored in separate or identical axon moieties and within the same organelles. Choline acetyltransferase activity, which was taken as a measure for a cholinergic nerve component in the ovary, amounted to only 7% of its adrenal activity. It is suggested that the chicken ovary may serve as an excellent model to investigate the modulatory role of nerves in the endocrine function of the ovary.