A Quantitative Histological Assessment of Cellular Death, in Relation to Mitosis, in Rat Thymus During Growth and Age Involution

Abstract

The rates of cellular proliferation and cellular death were investigated in the rat thymus during growth and involution. It was found that the percentage of dead cells gradually increased with age, whilst the rate of cell proliferation declined, indicating that a substantial proportion of lymphocytes that divide in the thymus also die there. It was also found that there exists a density-dependent distribution pattern of mitotic and dead cells and that this distribution pattern changed with age. It is suggested that this mechanism of density-dependent control of the thymus may be an important factor in the age involution of the thymus.

Changes in the Human Thymus During Aging

“…Our findings in human thymi did not confirm this assumption, but correspond to observations of HINSULL et al (1977) in aging rats. Until today, no report has come up which evidences that the majority of lymphocytes produced in the thymus die in situ.…”

“…Our observation corresponds to the findings of HINSULL et al (1977). These authors observed a similar quantitative relationship between aging and spontaneous thymocyte proliferation in rats.…”

“…In relation to aging, HINSULL et al (1977) showed in rats an increase in the number of trypan-blue-positive cells up to the 12th week of age. The rate of mitosis was great after birth, at the same level up to the 8th week of age, and small in rats older than 8 weeks.…”

An improved method for combined autoradiography and histochemistry: the simultaneous detection of 6‐3H thymidine and acid phosphatase activity in cryostat sections of mouse thymus and duodenum

“…The choice of azo dye technique ) employing a bromine-rich reaction product also has advantages in that it allows a further extension of the method in the analytical scanning electron microscope (Bowen & Lewis, 1980a;. Hinsull et al (1977) have reported an assessment of cell death and mitosis in rat thymus during growth and age involution, using a trypan blue based method. Bowen & Ryder (1974, working on planarian worms, established the use of acid phosphatase activity as a marker for cell lysis and deletion.…”

Combined autoradiography and histochemistry: the simultaneous detection of 6‐3H thymidine and acid phosphatase activity in cryostat sections

“…Interest in the assessment of cell death and mitosis in relation to tissue dynamics is general. A quantitative histological assessment of cell death in relation to mitosis in rat thymus during growth and age involution has been presented by Hinsull et al (1977), where trypan blue was used to mark dying and pyknotic cells.…”