Somatotrophs and Mammotrophs in Adenohypophysis of Japanese Black Steers : an Immunohistochemical and Morphological Study

摘要

The distribution and proportion of somatotrophs (GH cells) and mammotrophs (PRL cells) were immunohistochemically detailed in the adenohypophysis of pure bred of Japanese Black steers. The animals were divided into four groups of six each of 8, 14, 21and 28 months-old. The morphometrical analysis was evaluated in four regions of the midsagittal plane - zona tuberalis (ZT), and hind dorsal (HD), fore ventral (FV) and hind ventral (HV) regions. GH cells mainly existed solitarily and densely populatedin the HD, and PRL cells were numerously distributed in the FV and HV as various sizes of cell clusters, whereas, in the ZT, the proportion of both GH cells and PRL cells was very low. The proportion of GH cells gradually diminished until 21 months-old and that of PRL cells notably decreased until 28 months-old. However, the distribution pattern of GH cells and PRL cells did not change during 8 to 28 months-old. These results initially showed that GH cells and PRL cells were differentially distributed in the whole adenohypophysis of Japanese Black steers and the proportion declined age-dependently.