PRESENCE OF PIGMENT IN THE OVINE PINEAL-GLAND DURING EMBRYONIC-DEVELOPMENT

Light- and electron-microscopic analyses were used to identify and des cribe the characteristic features of cells containing pigment in the o vine pineal gland during prenatal development. 72 ovine embryos (36 ma le, 36 female) ranging in age from 54 to 150 days were used for this s tudy. Cells containing pigment granules were a constant feature in thi s gland. When samples from the different groups were inspected using t he naked eye, the detection of pigment was of 61% in groups I (54 to 6 7 days of prenatal development) and II (71 to 92 days of prenatal deve lopment), 83% in group III (98 to 113 days of prenatal development) an d 25% in group IV (118 to 150 days of prenatal development). The morph ological features and histochemical properties of the pineal pigment e nabled it to be identified as melanin. Several types of pigment granul es were ultrastructurally distinguished; these varied in size, shape a nd location within pineal cell populations. The pigment granules were detected in pinealocytes, interstitial cells and pigmented cells. The largest amount and the widest variety of pigmented granules were found in pigmented cells. The presence of cells containing pigmented granul es amongst the cell populations of the developing ovine pineal gland w as analysed and compared with that of other mammalian species.