Hüseyin TÜRKER, Turan GÜVEN, Mustafa YEL

Kör fare (Spalax leucodon) tiroit bezi foliküler hücrelerinin ince yapısı

Kör fare (Spalax leucodon) tiroit bezi foliküler hücrelerinin ince yapısı transmisyon elektron mikroskobu (TEM) ile incelenmiştir. Tiroit bezi çok sayıda folikülden meydana gelmiştir. Peliküller tek sıra halinde dizilmiş küresel veya oval şekilli foliküler hücrelerden ibarettir. Foliküllerin ortasında bulunan lümen kolloit adı verilen salgı ile doludur. Foliküler hücrelerin luminal membranmda az sayıda ve küt mikrovilluslar bulunmaktadır. Hücrelerin apikal kısmında çok sayıda elektron-yoğun granüllere rastlanmıştır. Mitokondriler genellikle enine dizilmiş kristalara sahiptir. Bunlar daha çok" hücrenin bazal ve orta kısımlarında bulunur. İyi gelişmiş Golgi kompleksi çekirdeğin apikal tarafında yer alır. Salgı keseleri Golgi kompleksine yakın bulunur. Granüllü endoplâzmik retikulum yaygın olarak sitoplâzmada bulunur ve bazen vezikülleri genişlemiştir. Hücrelerarası bağlantı yapılarından dezmozomlar belirgindir. Tiroit folikülleri zengin kapiler ağına sahiptir. Kapiler endotellerinde bulunan fenestrasyonlar hormonların foliküler hücrelerden damar lümenine geçişini kolaylaştırır.

Ultrastructure of the follicular cells of thyroid gland in the molerat (Spalax leucodon)

The ultrastracture of the follicular cells of the thyroid gland in the molerat (Spalax leucodon) has been examined by transmission electron microscope (TEM). The thyroid gland consists of many follicles. The follicles are composed of follicular cells which have spherical and oval shapes, and they are arranged on monolayer around the lumen. The lumen in the middle of the follicles is full of a secretion called colloid.A'few,:shbrt and stubby microvilli are seen in the luminal membrane of the follieuiar cells. Numerous small electron dense granules have been found in the apical surface. Generally the mitochondria are seen in the basal and central parts of the cells. Frequently, mitochondrial cristae exhibit as arranged trasversal structure. The well-developed Golgi complex was found in the apical side of nucleus. The secretory vesicles are found near the Golgi complex. The rough endoplasmic reticulum is found commonly in the cytoplasm and sometimes has dilated structure. The desmosomes of intercellular connections are discerned. The follicles of thyroid glands have an extensive capillary network. Endothelial cells of capillaries have fenestrations which facilitate the passage of the hormones into the lumen of capillary from endothelial cell.

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