Morfologia comparada da laringe e traqueia de Chelonia mydas (Linnaeus, 1758) (Testudines: cheloniidae), Caiman yacare (Daudin, 1802) e Caiman latirostris (Daudin, 1802) (Crocodylia: alligatoridae) e morfologia do aparelho urogenital e glândula adrenal de Caiman yacare (Daudin, 1802) (Crocodylia: alligatoridae)

Abstract

Testudines and crocodilians have morphological and behavioral divergences; however, their way of life permeates the land-water interface. In the respiratory system, one observes structures such as: larynx, trachea, two pulmonary bronchi and two lungs. Differences are found in the formation of these structures for each species; however, it is possible to state that both perform similar functions. The kidney tissue of crocodilians is an important factor of analysis for the identification of agents causing environmental degradation at molecular, biochemical, and physiological levels through morphophysiological changes indicated by population assessments. Knowledge of the reproductive system is an important tool in the reproductive management of the various species of crocodilians to delineate reproductive periods. Thus, it is necessary to know the reproductive morphology and physiology of the species to align it with behavioral studies. We aimed to describe and compare the morphology of the larynx of Chelonia mydas, Caiman yacare and Caiman latirostris, as well as to describe the morphology of the kidneys, adrenal gland, and gonads of young individuals of Caiman yacare. The work was carried out at the Federal University of Espírito Santo (UFES), campus Alegre. For the study of the larynx and trachea, 9 specimens of C. mydas, 20 specimens of C. yacare and 4 specimens of C. latirostris were used. For the study of the kidneys, adrenal gland, and gonads, 29 females and 29 males were used, totaling 58 individuals. For the anatomical analysis, the larynx, trachea, kidneys, adrenal glands, and gonads were described from observation. For histology, the specimens were cleaved, processed according to the routine standards of the Pathology Laboratory of UFES, cut on a microtome and analyzed under a photomicroscope. For morphometry of the kidneys of C. yacare macroscopic and microscopic measurements were performed. The values were statistically evaluated. The larynx of the three species showed four similar macroscopic structures: hyoid apparatus, two arytenoid cartilages, and one cricoid cartilage. The trachea showed divergent number of tracheal rings, besides C. mydas exhibiting complete rings and C. yacare and C. latirostris incomplete rings and tracheal muscle. Histologically, the laryngeal skeleton was composed of hyaline cartilage. The kidneys were reddish brown, covered by fibrous membrane and fatty capsule. Histologically, formed by collecting tubules, cortical and medullary region formed by distal and proximal contorted tubules, and renal corpuscles. Morphometrically, the male kidneys were longer than the female kidneys. The adrenals showed a subcapsular zone, and an inner zone formed by light and dark cells. The testicles were ellipse shaped, and the ovaries were oval shaped. Histologically, both were immature. The testicles had early spermatozoa, seminiferous tubules and lined by tunica albuginea. The ovaries with immature, pre-vitellogenic ovarian follicles, encapsulated by the germinative epithelium. It is concluded that the larynx of the three species is similar and formed by hyaline cartilage. The trachea differs for C. mydas compared to C. yacare and C. latirostris. The kidneys of C. yacare were morphologically similar between males and females, but morphometrically larger in males. The adrenal gland did not present cortical and medullary division and are formed by two cell types. The gonads were pairs, attached to the kidneys and the adrenal gland.