Gross and microscopic anatomy of the pineal gland in Nasua nasua--coati (Linnaeus, 1766).

Nasua nasua, coati, is a mammal of the Carnivora order and Procyonidae family. It lives in bands composed of females and young males. The pineal gland or epiphysis of brain is endocrine, producing the melatonin. Its function is the control of the cycle of light environment, characteristic of day and night. For this research, five adult coatis were used, originating from CECRIMPAS-UNIfeob (Proc. IBAMA 02027.003731/04-76), Brazil. The animals were killed and perfusion-fixed in 10% formaldehyde. Pineals were measured and a medium size was found to be 2.3-mm-long and 1.3-mm-wide. Pineal gland was located in the habenular commissure in the most caudal portion of the third ventricular roof, lying in a dorso-caudal position from the base to the apex. Pinealocytes were predominantly found in the glandular parenchyma. Distinct and heterogeneous arrangements of these cells throughout the three pineal portions were observed as follows: linear cords at the apex, circular cords at the base of the gland, whereas at the body a transition arrangement was found. Calcareous concretions could be observed in the apex. The pineal gland was classified as subcallosal type [Rec. Méd. Vét.1, 36 (1956)] and as AB type [Prog. Brain Res. 42, 25 (1979); The Pineal Organ, Berlin/Heidelberg: Springer-Verlag (1981)].