R. Frink

Intranuclear rodlets in woodchuck thyroid follicular cells

SummaryIntranuclear rodlets are seen in thyroid follicular cells of woodchucks fixed during summer and fall. They are not observed in winter and spring animals. A functional significance of these structures is suggested.

The effect of anti-hypertensive drug treatment on brown adipocyte diameter and locule distribution in rats

To determine the effects of sympathoplegic anti-hypertensive drug treatment on brown adipose tissue morphology, groups of adult male Wistar-Kyoto (WKY) and spontaneous hypertensive (SHR) rats were orally administered a solution containing 2.3 microM reserpine, 0.5 M hydralazine and 1.68 mM hydrochlorothiazide ad libitum or tap water and brown adipocyte diameter and extent of fat loculization were determined 3 weeks later. Pulse rates of rats were significantly greater in SHR than WKY and were unaffected by treatment, while drug treatment resulted in significant decreases in mean arterial pressure of both groups at the end of the study. Mean adipocyte diameters were smaller in untreated SHR than WKY and drug treatment of both groups was associated with increases in adipocyte diameter and cytological change from physiologically more active to less active cells. These drug-induced alterations in BAT morphology area consistent with decreased sympathetic activity and suggest that thermogenic capacity of brown adipose tissue may be pharmacologically modified, thereby altering an animals capacity for energy expenditure.

The parathyroid gland of the woodchuck (Marmota monax): A study of seasonal variations in the chief cells

The ultrastructure of the parathyroid chief cell in the woodchuck, Marmota monax, was studied during the four seasons of the year. Spring chief cells have stacks of granular endoplasmic reticulum, prominent multiple Golgi zones and many clumped mitochondria. Summer cells resemble those seen in the spring but the mitochondria are associated with stacks of granular endoplasmic reticulum. Multiple areas of stacked granular endoplasmic reticulum characterize the fall chief cells. Their Golgi zones are large and are associated with many dense core secretory granules. Lipoid vacuoles are frequently noted. Winter chief cells have secretory granules and phagolysosomes (dense bodies). Some of these cells contain stacked arrays of granular endoplasmic reticulum associated with mitochondria, others have only short segments. The above morphological findings are discussed in relation to those in other hibernators, the parafollicular (C) cell, and to the cyclic seasonal activities of the woodchuck.

Effects of Blood Pressure Reduction on the Ultrastructure of the Adrenal Cortex of the Spontaneously Hypertensive Rat

Antihypertensive drugs were given to 25-week-old spontaneously hypertensive rats (SHR) and Wistar Kyoto rats, and the animals were sacrificed at 45-47 weeks of age. The effects of the decreased blood pressure on the adrenal zona glomerulosa and zona fasciculata were studied ultrastructurally and morphometrically. It was found that both groups of animals responded to the lower blood pressure in a similar manner, but the ability to respond is structurally compromised in the zona glomerulosa of SHR. This malfunction may be congenital in origin.

Effects of vitamin a deficiency on ultimobranchial cysts in the thyroid gland

SummaryUltimobranchial cysts in the thyroid glands of rats receiving a diet adequate in vitamin A are lined with stratified squamous epithelium and contain non-keratinized cellular debris. The epithelium of these cysts in vitamin A deficient animals is keratinized, and their lumina contain keratinized cellular strands surrounding a core of cellular debris. Upon return to a diet adequate in vitamin A the epithelium returns to a non-keratinized state, and the lumina contain keratinized strands surrounded by cell fragments and desquamated whole cells. Occasionally these cysts have an epithelium that is highly irregular in appearance. The relationship of alterations in this tisssue to possible subsequent development of neoplasias is discussed.

Staining Cells on a Membrane Filter with Giemsa Stock and Tap Water

Cells grown on type AM 6 Alpha Metricel Gelman filter membranes are fixed 1-2 min with OsO4 vapor, washed in distilled water, dehydrated 4 min in 95% and 4 min in absolute ethanol. They are then stained for 2 min in a 1:1 dilution of Giemsa stock solution and an approximately neutral, low mineral content tap water. The stain is removed from the filter by 1 min in 50%, 1 min in 95%, 1 min in absolute ethanol and 1 min in a mixture of absolute ethanol and xylene 1:1. The filter is finally cleared in xylene and mounted with a synthetic resin. This procedure gave polychrome staining on neonatal thymic cells from C57 black pedigreed mice and on human leucocytes, with little or no stain retained by the filter membrane.