ISSN:
0003-276X
Keywords:
Life and Medical Sciences
;
Cell & Developmental Biology
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Medicine
Notes:
The localization of alkaline phosphatase activity in the ultimobranchial bodies was studied at the fine structural level in Holtzman rat embryos from the 15th to the 19th day of gestation, and also in four-week old rats of the same strain. In the embryos, no alkaline phosphatase activity was found before the 17th day of gestation. From that day on, plasma membranes of glycogen-rich cells show the reaction product regardless of their location in the wall of the ultimobranchial bodies. However, when the same cells are seen on cell cords of the median thyroid, they are negative. In the four-week old rats, plasma membranes of ultimobranchial cells are strongly reactive. C cells are negative both before and after birth. Small thyroid follicular lumina with positive apical cell membranes are also noted in four-week old rats. These positive thyroid follicles are not more differentiated than those previously described in 19-day old rat embryos. It is concluded that new thyroid follicles are formed after birth. These results are discussed in relation to the hypothesis that when ultimobranchial cells are transformed into follicular cells, they undergo the same alkaline phosphatase changes as those observed during the maturation of follicular cells derived from the median thyroid primordium. The cytochemical method used is also criticized.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/ar.1091800411
