title: Greater rhea (Rhea americana) external morphology at different stages of embryonic and fetal development.
abstract: Knowledge of wild species embryonic development is important for their maintenance in captivity or the wild. The objective of the present study was to characterize the external morphology and define the biometry of greater rhea embryos and fetuses at different stages of development. A total of 41 embryos and fetuses were analyzed to describe their external morphology using a stereoscopic microscope. The crown-rump (CR), total length (TL), cephalocaudal length (CCL), biparietal diameter (BPD), beak, humerus and tibio-tarsal lengths were measured by digital pachymeter, millimetric scale ruler and cotton thread. The weight of the embryos and fetuses was measured on digital scales. The greater rhea embryos at 5, 6 and 7 days incubation presented a "C" shape. At 9, 10 and 11 days the eyes were big and pigmented. At 11, 12 and 13 days the eyelid covered more than half the eye, resulting in an oval slit. In 14 and 15 day-old embryos, the skin was still thin and the ribs evident, but at 18 days this structure was thicker. In embryos at 21 and 27 days of development closed eyelids were observed forming an eyelid slit, and the eye ball was less pronounced at 27 days. Weight gain presented an exponential growth curve, while measurements such as TL, DBP, beak, humerus and tibio-tarsal length had linear growth over time. Thus it was possible to characterize the greater rhea embryos and fetuses at several incubation ages using their external morphology and morphometric analyses.
authors.affiliation: Animal Science Postgraduate Program, Federal University of Piauí, Teresina, PI 64049-650, Brazil; Federal University of Piauí, Department of Morphology, Teresina, PI 64049-650, Brazil.
authors.forename: Hatawa Melo
authors.initials: HM
authors.lastname: de Almeida
authors.affiliation: Animal Science Postgraduate Program, Federal University of Piauí, Teresina, PI 64049-650, Brazil.
authors.forename: Renata Patrícia
authors.initials: RP
authors.lastname: Sousa
authors.affiliation: Animal Science Postgraduate Program, Federal University of Piauí, Teresina, PI 64049-650, Brazil.
authors.forename: Dayseanny Oliveira
authors.initials: DO
authors.lastname: Bezerra
authors.affiliation: Federal University of Piauí, Medicine Veterinary Graduation Course, Teresina, PI 64049-650, Brazil.
authors.forename: Rodrigo Fernando Gomes
authors.initials: RF
authors.lastname: Olivindo
authors.affiliation: Animal Science Postgraduate Program, Federal University of Piauí, Teresina, PI 64049-650, Brazil.
authors.forename: Anaemilia
authors.initials: A
authors.lastname: das Neves Diniz
authors.affiliation: Animal Science Postgraduate Program, Federal University of Piauí, Teresina, PI 64049-650, Brazil.
authors.forename: Sâmia Clara
authors.initials: SC
authors.lastname: de Oliveira
authors.affiliation: Animal Science Postgraduate Program, Federal University of Piauí, Teresina, PI 64049-650, Brazil.
authors.forename: Matheus Levi Tajra
authors.initials: ML
authors.lastname: Feitosa
authors.affiliation: Federal University of Piauí, Department of Morphology, Teresina, PI 64049-650, Brazil.
authors.forename: Eunice Anita
authors.initials: EA
authors.lastname: de Moura Fortes
authors.affiliation: Federal University of Piauí, Department of Morphology, Teresina, PI 64049-650, Brazil.
authors.forename: Maíra Soares
authors.initials: MS
authors.lastname: Ferraz
authors.affiliation: Network Northeast Biotechnology, Federal University of Piauí, Teresina, PI 64049-650, Brazil.
authors.forename: Yulla Klinger Pereira
authors.initials: YK
authors.lastname: de Carvalho
authors.affiliation: Federal University of Campina Grande, Academic Unity of Veterinary Medicine, Jatobá, Patos, PB 58700-970, Brazil.
authors.forename: Danilo José Ayres
authors.initials: DJ
authors.lastname: de Menezes
authors.affiliation: Federal University of Piauí, Department of Veterinary Morphophysiology, Teresina, PI 64049-650, Brazil. Electronic address: mcelina@ufpi.edu.br.
authors.forename: Maria Acelina Martins
authors.initials: MA
authors.lastname: de Carvalho
mesh_terms: D000818:Animals; D001699:Biometry; D004625:Embryo, Nonmammalian / Q000033:anatomy & histology; D047108:Embryonic Development; D020311:Rheiformes / Q000196:embryology*
keywords: Embryo; Fetus; Flightless birds; Morphometry