Ultrastructure of the cell types of the anterior hypophysis in a lizard. I. Corticotrophs.
Corticotrophs of the teiid lizard Cnemidophorus lemniscatus are situated in the rostral zone of the pars distalis. In normal animals, they are usually rounded cells with slightly eccentric vesicular nuclei, especially characterized by a lucent hyaloplasm and medium-sized secretory granules of uniform high density. Granules are almost spherical, with small angular deformations, and closely bounded by a fuzzy membrane. Many cells have only a few or a moderate number of granules, with large areas of cytoplasm devoid of them; in others, granules fill the supranuclear region. The cytoplasm exhibits numerous ribosomes, often in rosettes and mostly free, a series of loosely superimposed cisternae of rough endoplasmic reticulum, small dictyosomes, and elongate mitochondria of light matrix. Metyrapone administration during 2-8 days causes dramatic alterations in corticotrophs; they become hypertrophic and extensively degranulated, with a great development of the endoplasmic reticulum and Golgi apparatus, eventually showing a row of large peripheral granules of uneven structure, enclosed in ample vesicles studded with ribosomes. A lesser degree of hypertrophy and degranulation of corticotrophs appears during the first two weeks after thyroidectomy or gonadectomy, and may be partially attributed to surgical stress. Well granulated enlarged corticotrophs, with hypertrophic endoplasmic reticulum and Golgi apparatus, are probably a result of hormonal imbalance in lizards of both sexes gonadectomized for one or two months.
D000324:Adrenocorticotropic Hormone / Q000378:metabolism*; D000818:Animals; D002369:Castration; D005260:Female; D008116:Lizards / Q000033:anatomy & histology*; D008297:Male; D008797:Metyrapone / Q000494:pharmacology; D008854:Microscopy, Electron; D010903:Pituitary Gland, Anterior / Q000166:cytology* / Q000378:metabolism / Q000648:ultrastructure; D013965:Thyroidectomy; D013997:Time Factors
D000324:Adrenocorticotropic Hormone; D008797:Metyrapone