Histophysiological studies on the hypophysio-mammary axis in sheep (Ovis aries) - Somatotrophs

The pituitary gland and mammary glands of 30 Madras red ewes of different age groups were utilized for the current study. Two types of acidophils were identified in the pars distalis adenohypophysis. The size of type I acidophils (orangeophils) ranged from 9.30 ± 0.22 µm in dry animals to 9.90 ± 0.28 µm in pubertal animals. The number of these cells was more in pregnant (1866 ± 95.85 cells/mm2) and lactating (1687 ± 62.41 cells/mm2) animals when compared to dry (1650 ± 108.92 cells/mm2) age groups in sheep. The size of type II acidophils (carminophils) ranged from 9.15 ± 0.26 µm in prepubertal age to 10.05 ± 0.29 µm in lactating sheep. The average number of type II acidophils in prepubertal sheep was 550 ± 34.88 cells/mm2 which increased gradually upto lactation (2043 ± 107.48 cells/mm2) but showed marked decrease in dry animals (1269 ± 117.71 cells/mm2). The alveolar size was 39.88 ± 1.39 µm in pregnant sheep, 106.05 ± 14.70 µm in lactating sheep but decreased significantly to 32.45 ± 1.64 µm in the mammary glands of dry sheep. The increased number and size of the lobulo-alveolar system in mammary glands of pregnant and lactating sheep may be correlated with the corresponding increase in the number and secretory activity of somatotrophs in adenohypohysis of hypophysis cerebri of Madras red sheep.