Embryonic and Fetal Development of the Cardiorespiratory Apparatus in Horses (Equus Caballus) from 20 to 115 Days of GestationRodrigues RF1*, Rodrigues MN1, Franciolli ALR1, Carvalho RC1, Rigoglio N1, Jacob JCF2, Gastal EL3 and Miglino MA1
- *Corresponding Author:
- Rosângela Felipe Rodrigues
Department of Surgery, FMVZ
University of Sao Paulo, Sao Paulo, Brazil
Tel: +55 11 301917690
E-mail: [email protected]
Received date: December 18, 2013; Accepted date: April 24, 2014; Published date: April 26, 2014
Citation: Rodrigues RF, Rodrigues MN, Franciolli ALR, Carvalho RC, Rigoglio N, et al. (2014) Embryonic and Fetal Development of the Cardiorespiratory Apparatus in Horses (Equus Caballus) from 20 to 115 Days of Gestation. J Cytol Histol 5:240. doi:10.4172/2157-7099.1000240
Copyright: © 2014 Rodrigues, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
Horses have always sparked social and economic interest, awakening in the scientific community an interest in embryology and reproductive biology. To date, little is known about horse embryology because this species has several morphological and physiological characteristics that are peculiar to its own reproductive process. This study describes morphological aspects of developing cardiorespiratory apparatus in equine embryos and fetuses during 20-115 days of gestation. At 21 days, the equine embryo had a forming heart with two chambers and a distinct atrium and ventricle. There was a clear cellular protuberance in the lumen of both chambers and in the region of the endocardium. During this phase, the embryo had a nose rostral to the eyes and dorsal to the mouth, but no speciesspecific characteristics. Only at 40 days did it show external characteristics that were specific to the species, such as a nasal diverticulum. The larynx and pharynx were observed at 26 days of gestation. Additionally, at 26 days, the formation of the epiglottal protrusions was noted, and as embryonic development advanced, cartilage formed, while over the larynx, a non-uniform epithelial lining was observed. At day 30 of gestation, the thyroid and cricoid cartilage were seen, and the formation of the epiglottis was clear. At 45 days, the larynx was completely formed, and the thyroid, cricoid, and cricoarytenoid muscle were identified. Lung tissue was observed in embryos from 24 to 49 days, and then a pseudoglandular transitional phase started between days 50 and 60. At this time, light bronchi and terminal bronchioles were observed and became wider as the lung tissue became more vascularized. Between days 90 and 105, the primary and secondary bronchi were tubular structures composed of columnar epithelium layers. Blood capillaries were observed in the lung. Structures similar to alveoli were not seen. This work contributes to advance knowledge regarding the organogenesis of the cardiorespiratory apparatus in horses.