title: Occurrence of the myoid cell in the Harderian gland of the Japanese colubrid snake, Rhabdophis tigrinus.
abstract: An electron microscope study of the Harderian gland of the snake, Rhabdophis tigrinus, revealed the occurrence of a myoid cell in the glandular body. The myoid cell, in oval profile, is located in the perivascular space and enveloped by a basement membrane. The plasma membrane of the cell is studded with a number of vesicular caveoli. The myoid cell cytoplasm is largely occupied by myofilaments which do not form discrete bundles of myofibrils. The striations comprise the A and I bands together with Z lines, but neither an M nor an H zone is detectable. Although the transverse tubule appears to be scarce, the sarcoplasmic reticulum is well developed. No triadic configuration is observed. The cytoplasm includes a few numbers of mitochondria, sarcoplasmic reticulum, fat droplets, dense membrane-bound granules and free ribosomes. The histological characteristics of the present myoid cell are compared to those of identical cells commonly existing in the thymus.
mesh_terms: D000818:Animals; D005260:Female; D006243:Harderian Gland / Q000166:cytology* / Q000648:ultrastructure; D007765:Lacrimal Apparatus / Q000166:cytology*; D008854:Microscopy, Electron; D009132:Muscles / Q000166:cytology* / Q000648:ultrastructure; D009210:Myofibrils / Q000648:ultrastructure; D012519:Sarcoplasmic Reticulum / Q000648:ultrastructure; D012911:Snakes / Q000033:anatomy & histology*; D013950:Thymus Gland / Q000166:cytology