An immunohistochemical study of ovarian innervation in the emu (<i>Dromaius novaehollandiae</i>)

Abstract

The present study investigated the distribution of nerves in the ovary of the emu. The neuronal markers, protein gene product 9.5, neurofilament protein and neuron specific enolase demonstrated the constituents of the extrinsic and intrinsic ovarian neural systems. The extrinsic neural system was composed of ganglia in the ovarian stalk, as well as nerve bundles, which were distributed throughout the ovary. Isolated neuronal cell bodies, in the medulla and cortex, formed the intrinsic neural system. An interesting finding of the study was the presence of nerve bundles, circumscribed by lymphocytes, in the ovarian stalk. The findings of the study indicate that the distribution of nerve fibres and neuronal cell bodies in the emu ovary is similar, but not identical to that of the domestic fowl and ostrich.

Neuroendocrine cells are present in the domestic fowl ovary

“…Taken together, the cellular features observed in immature chick ovaries are common traits of the NE phenotype (Pearse, 1986;Flatmark, 2000;Toni, 2004), and suggest these ovarian cells belong to the NE lineage. Hence, our observations differ from previous reports claiming the existence of neuron-like cells in bird ovaries (Kimaro & Madekurozwa, 2006;Madekurozwa, 2008). Our findings also suggest the need to re-examine the idea of the existence of intrinsic neurons in mammalian ovaries (Dees et al 1995;D'Albora & Barcia, 1996;Mayerhofer et al 1996;Anesetti et al 2001;D'Albora et al 2002), given that the phenotypical characterization supporting such claims might also be incomplete.…”

“…Neuroendocrine cells constitute a heterogeneous population distributed in most organs of the vertebrate body; however, it has been unclear whether these cells are found in the ovaries. Although the presence of neuron-like cells in the immature ostrich ovary was reported previously (Kimaro & Madekurozwa, 2006;Madekurozwa, 2008), the identity of these cells could not be conclusive, as neuron specific enolase and protein gene product 9.5 are not exclusively neuronal markers but may also be present in cells of neuroendocrine lineage (Perez et al 1990;Martín et al 2000;Portela-Gomes et al 2004). Here, we describe ovarian interstitial cells that were positively labelled for NF-H, SYP, ChgA, TH, TPH, DDC and DBH, as well as displaying cytoplasmic dense-core secretory granules.…”

“…This cellular phenotype has been identified in epithelia, submucosae and/or interstitial spaces of the urethra, prostate, vas deferens, epididymis and testis (di Sant'Agnese & De Mesy Jensen, 1984;Hanyu et al 1987;Davidoff et al 1993Davidoff et al , 2005Jimé nez-Trejo et al 2007). Sev-eral reports have suggested the existence of neuron-like cells or intrinsic neurons in the ovarian interstitial space of some birds and mammals (Dees et al 1995;D'Albora & Barcia, 1996;Mayerhofer et al 1996;Anesetti et al 2001;D'Albora et al 2002;Kimaro & Madekurozwa, 2006;Madekurozwa, 2008). However, proteins such as neurofilaments, tyrosine hydroxylase and neuron specific enolase also exist in NE cells, giving rise to the possibility that the previously identified ovarian intrinsic neurons or neuron-like cells might instead possess a neuroendocrine phenotype.…”

Morphology and Chemical Phenotype of the Ovarian Intrinsic Neurons in Neonate and Sexually Mature Reproductive Guinea Pig

“…The sympathetic fibers predominantly release noradrenaline (NA) and vasoactive intestinal peptide (VIP), and the sensory fibers release peptides such as CGRP, substance P (SP) and galanin, among others [9]- [12]. Under physiological conditions, nerve fibers are involved in early follicular development and ovarian steroidogenesis [2] [13]- [15], i.e., NA stimulates androgen and progesterone secretion [16] [17], VIP stimulates estrogen production [18] [19] and CGRP and SP are involved in ovarian vascular fluid [9] [12]. Ovarian intrinsic neurons have been studied in several mammals (rats, monkeys and humans) [5] [7] and birds (hen and emu) [18] [19] and modulate steroidogenesis and local vascular fluid [2] [6] [14].…”

“…Under physiological conditions, nerve fibers are involved in early follicular development and ovarian steroidogenesis [2] [13]- [15], i.e., NA stimulates androgen and progesterone secretion [16] [17], VIP stimulates estrogen production [18] [19] and CGRP and SP are involved in ovarian vascular fluid [9] [12]. Ovarian intrinsic neurons have been studied in several mammals (rats, monkeys and humans) [5] [7] and birds (hen and emu) [18] [19] and modulate steroidogenesis and local vascular fluid [2] [6] [14]. In the rat ovary, intrinsic neurons are located in the hilum and medulla of the ovary, first appear in the cortex during the juvenile period [5], and increase significantly during prepubertal development, reaching maximum values before puberty [6].…”