identifier	taxonID	type	CVterm	format	language	title	description	additionalInformationURL	UsageTerms	rights	Owner	contributor	creator	bibliographicCitation
03DBFB55B869FF9AFB8BFE2C352EF9A6.text	03DBFB55B869FF9AFB8BFE2C352EF9A6.taxon	http://purl.org/dc/dcmitype/Text	http://rs.tdwg.org/ontology/voc/SPMInfoItems#GeneralDescription	text/html	en	Paracheirodon axelrodi (Schlutz 1956)	<div><p>Results</p><p>Preoptic area. The preoptic area in P. axelrodi extends from the medial region of the ventral telencephalon to the beginning of the diencephalon (Fig. 1). It surrounds the anterior diencephalic ventricle (DiV), also known as the third ventricle. Anteriorly, it is limited by the pars dorsalis (Cantd) and pars ventralis (Cantv) of the anterior commissure (Figs. 2 a-b). Dorsally, it is limited by the dorsal telencephalic area (D), the post commissural nucleus of the ventral telencephalon (Vp), the supra commissural nucleus of the ventral telencephalon (Vs), the ventro-lateral thalamic nucleus (VL) and the ventromedial thalamic nucleus (VM) (Figs. 2 a-e). Ventrally, it is adjacent to the optic chiasm (CO) and the postoptic commissure (Cpop) (Figs. 2 c-f, 3g). Posteriorly, it borders the ventral zone of the periventricular hypothalamus (Hv) (Fig. 3g).</p><p>The magnocellular preoptic nucleus (PM) (Figs. 2 a-c) is located in the telencephalon, dorsal to the parvocellular preoptic nucleus (PP). It adopts a more diffused disposition towards the caudal region. The parvocellular nucleus is divided in two regions, the anterior part (PPa), located ventrally in the medial telencephalon (Figs. 2 a-c), and the posterior part (PPp), located ventrally between the caudal telencephalon and the anterior diencephalon (Figs. 2 d-f, 3g). The most ventral margin of the DiV is surrounded by the suprachiasmatic nucleus (SC), situated dorsal to the CO and ventral to the PPp (Figs. 2 d-f, 3g).</p><p>Neurons of the PM are spherical and stain moderately with Cresyl Violet acetate and toluidine blue. They are characterized by being dispersed toward the PP dorsolateral region. They have little visible cytoplasm and a spherical central nucleus with one or more nucleoli (Figs. 4 a-b). Neurons in the PPa and PPp are spherical and stain strongly with Cresyl Violet acetate and toluidine blue. They form compact groups near the ventral PM region. Visible cytoplasm is scarce and the nucleus occupies the center of the cell (Figs. 4 a-b). In the SC, spherical neurons stain strongly with Cresyl Violet acetate and toluidine blue. They possess little visible cytoplasm and a central nucleus (Fig. 4c).</p><p>Regarding neuron size (Fig. 6a), PM neurons (n = 318) are significantly larger in terms of area (mean ± S.D. 27.72 ± 4.73 µm 2) and perimeter (mean ± S.D. 19.66 ± 1.86 µm) than those in the PPa (12.03 ± 0.97 µm 2; 12.89 ± 0.51 µm; n = 452), PPp (12.78 ± 0.68 µm 2; 13.23 ± 0.35 µm; n = 326) and SC (12.41 ± 0.43 µm 2; 13.09 ± 0.25 µm; n = 336) (P &lt;0.0001).</p><p>Additionally, a cellular layer commonly known as the organum vasculosum of the lamina terminalis (OVLT) was identified in the preoptic area surrounding the DiV. The OVLT is a circumventricular organ made up of a layer of ependymal cells, which contains tanycytes, and another more diversified layer of subependymal cells, that contains glial cells, nervous fibers and small capillaries, as well as the PPa neurons (Fig. 4d). Tanycytes (T) in this region are characterized by its spindle cellular shape and central elongated nucleus with one nucleolus (Figs. 4 d-e).</p><p>Hypothalamus. The hypothalamus, part of the diencephalon, is located ventral to the thalamus and caudal to the optic region (Fig. 1). The anteriormost portion is located caudoventrally to the SC and can be easily recognized due to the highly dense cell groups and its position surrounding the paired latero-caudal ventricular recesses (LR). Anteriorly, it is limited by the postoptic commissure (Cpop) and the PPp (Fig. 3g). Dorsally, it neighbours the limitant zone (LZ), the periventricular nucleus of the posterior tuberculum (TPp) and the paraventricular organ (PVO) (Figs. 3 h-i); ventrally it is limited by the hypophysis (Figs. 3 k-l).</p><p>Several nuclei can be identified in the hypothalamus. They are mostly located towards the ventral diencephalon region along the DiV. Three regions can be clearly distinguishable: the ventral hypothalamic region, the dorsal hypothalamic region and the caudal hypothalamic region. The ventral hypothalamic region corresponds with the ventral zone of the periventricular hypothalamus (Hv), the anterior tuberal nucleus (ATN) and the hypothalamic lateral nucleus (Hl) (Figs. 3 g-i). The dorsal hypothalamic region forms the paired latero-caudal ventricular recesses (LR) that are surrounded by a cellular mass known as the dorsal zone of the periventricular hypothalamus (Hd) (Figs. 3 hl). The caudal hypothalamic region corresponds with the caudal zone of the periventricular hypothalamus (Hc) and the posterior recess of the diencephalic ventricle (PR). The Hc is located ventral to the posterior tuberal nucleus (PTN) of the posterior tuberculum (Figs. 3 j-k).</p><p>The ventral and caudal regions cover most of the tuberal hypothalamus (HT). The dorsal region in turn extends laterally to form the hypothalamic inferior lobes (IL) (Fig. 1). The ILs are separated from the HT by a deep ventral furrow. Within the IL there are two other nuclei, the central nucleus of the interior lobe (CIL) (Figs. 3 k-l) and the diffuse inferior lobe nucleus (DIL) (Figs. 3 i-l).</p><p>Ventral hypothalamic region. Neurons in the Hv (Fig. 5a) and Hl (Fig. 5b) are characterized by their spherical shape, little visible cytoplasm, strong Cresyl Violet staining and moderate toluidine blue staining. Cell nuclei are spherical, central, containing a single nucleolus. In the Hv, neurons form a lamina with 7 or more cell layers. Neurons of the Hl form a lamina with 10 or more cell layers in the vicinity of the Hv; whereas in the farthest lateral region this lamina is only 6 to 7 cell layers. Towards the DiV, cylindrically shaped tanycytes (T) can be seen forming a multi-layered structure (Fig. 5a). Neurons in the ATN are spherical, dispersed and strongly stained with Cresyl Violet and toluidine blue. They have little or no visible cytoplasm and are surrounded by amielinic fibers.</p><p>Hypothalamic dorsal region. Neurons in the Hd are spherical, with little cytoplasm, a large nucleus, and stain strongly with Cresyl Violet and weakly with toluidine blue. They can be found forming groups surrounding the LR (Fig. 5c). Towards the medial LR neurons form 5 cell layers increasing to 7 or more cell layers through the lateral LR. In the lateral LR a single layer of spindle shaped tanycytes (T) strongly stained with toluidine blue can also be observed (Fig. 5c).</p><p>Caudal hypothalamic region. Neurons in the Hc are spherical, with scarce cytoplasm, and a large nucleus. They stain strongly with Cresyl Violet and weakly with toluidine blue (Fig. 5d). They cluster in tight groups when surrounding the posterior recess of the diencephalic ventricle (PR), forming more than 6-cell layers. Towards the dorsal nuclei region, these tight groups branch off into several 5-cell layers areas. Some dispersed tanycytes (T) and glial (Gl) cells can also be observed in this region, both cell types strongly stained with toluidine blue. The Hc region is completely surrounded by amielinic fibers, which in some locations are also visible within the nuclei (Fig. 5d). Neurons of the PTN are spherical with scarce cytoplasm, a big central nucleus and one or two nucleoli. They are found dispersed within the nuclei. Some PTN neurons stain weakly while others stain strongly with both Cresyl Violet and toluidine blue. This region also includes some amielinic fibers and glial cells.</p><p>Morphometric analysis showed no significant differences for mean area (P = 0.127) and perimeter (P = 0.167) between neurons of the different hypothalamic regions (Fig. 6b). Mean area ± S.D.: Hv, 12.01 ± 2.34 µm 2; Hd, 12.25 ± 1.21 µm 2; Hl, 11.59 ± 0.50 µm 2; Hc, 11.60 ± 0.70 µm 2; ATN, 13.94 ± 1.62 µm 2; and PTN, 11.59 ± 1.17 µm 2. Mean perimeter ± S.D.: Hv, 12.84 ± 1.22 µm; Hd, 12.95 ± 0.65 µm; Hl, 12.64 ± 0.27 µm; Hc, 12.63 ± 0.38 µm; ATN, 13.82 ± 0.78 µm; and PTN, 12.69 ± 0.71 µm. Number of neurons measured (n) for each region was as follows: Hv = 339, Hd = 399, Hl = 416, Hc = 329, ATN = 270 and PTN = 271.</p></div>	https://treatment.plazi.org/id/03DBFB55B869FF9AFB8BFE2C352EF9A6	Public Domain	No known copyright restrictions apply. See Agosti, D., Egloff, W., 2009. Taxonomic information exchange and copyright: the Plazi approach. BMC Research Notes 2009, 2:53 for further explanation.		Plazi	Rincón, Laura;Obando, Martha J.;Tovar, Mario O.;Pandolfi, Matías;Hurtado, Hernan	Rincón, Laura, Obando, Martha J., Tovar, Mario O., Pandolfi, Matías, Hurtado, Hernan (2017): Topological and histological description of preoptic area and hypothalamus in cardinal tetra Paracheirodon axelrodi (Characiformes: Characidae). Neotropical Ichthyology 15 (1): e 160145, DOI: 10.1590/1982-0224-20160145, URL: http://dx.doi.org/10.1590/1982-0224-20160145
