Seasonal histophysiological study of the pineal gland in relation to gonadal and adrenal gland activities in adult domestic pigeon, Columba livia Gmelin

Abstract

Some aspects of physiology related to the pineal gland in the adult male domestic pigeon, Columba livia Gmelin have been investigated. It was also correlated with the activity of the gonadal and adrenal glands by changing environmental conditions (e.g., seasonal photoperiods, temperature, humidity and rainfall). The maximum daily temperature was noticed in April and minimum in January, 2003. Pineal gland weights showed significant (F = 52.04, P < 0.01) annual variations with a maximum relative weight of the pineal gland being recorded in the month of July, when testicular relative weight was minimum. Testis and adrenal gland weights showed significant (F = 144.31, P < 0.01; F = 106.36, P < 0.01 respectively) annual variations with a maximum relative adrenal weight being recorded in the month of April, when testicular relative weight reaches a maximum value. Besides, assessment of pineal in relation to seasonal activity showed a completely inverse relationship with gonadal and adrenal gland. During the months of June–August and November–January, the testis remained in a state of atrophy. The rise in temperature contributed to rise in adrenal-gonadal function and reduced pineal function. Testicular weight peaked in March, April and May when the longest days and the highest temperatures prevailed and humidity was moderately low. A second testicular weight peak was also noticed in September and October when the temperature was also moderately high. These observations have been interpreted to suggest that two breeding and two nonbreeding phases are existed in the animal. Ultra structural study of the pineal gland and adrenocortical tissue indicate some features related to the breeding phase of pigeons. Within the pineal gland, mitochondria, dense cored vesicle with material and lipid droplets were found to be maximal within the pinealocyte cell cytoplasm of the regressive phase-I than the primary breeding phase. Golgi body and lysosomes were well defined. Furthermore, rough endoplasmic reticulum sacs were enlarged in size in the regressive phase-I. On the other hand, the number of mitochondria and cytoplasmic secretory granules within both the SCZ and CZ of the adrenocortical regions were found to be maximum during the primary breeding phase than the regressive phase-I. Extensive rough endoplasmic reticulum was found in the cytoplasm also. Furthermore, Golgi complex was enlarged within the breeding season.